Packaging and Stroage

Water- and grease-resistant as well as air-tight containers are required for packaging of a spread. Various kinds of packaging materials namely, plastic cups or tubs,plastic-coated cartons, plastic-coated paper packs, polyethylene-lined paper-board containers, parchment paper, coloured glass containers, etc. are used. The packaged product is allowed to ‘set’ before distribution. Setting is the phenomenon where the spread is usually kept at a low temperature for several hours to get the desired consistency. Crystallization of fat during setting helps in attainment of final body characteristics. Setting temperatures govern the rheological properties of the product.Setting conditions vary from 0°C to 15°C for 4 hours to 48 hours.Low-fat spreads, as mentioned earlier, have a relatively short shelf life (7-90 days at 40 C to 300 C). However, most fat spreads keep well for several weeks under refrigeration. The shelf life of the product is affected by various factors, namely,type of emulsion and serum dispersion, moisture content, processing treatment, type of ingredients, salt content, packaging material, storage temperature, pH of the product and use of preservative.

Principle and Methods of Manufacture

As compared to conventional butter (80% fat), low-fat dairy spreads have much reduced concentration of fat and correspondingly increased level of non-fat constituents viz. water and non-fat milk solids. This altered composition, together with additives, imparts the desired spreadability to the product. In case of non-dairy and mixed spreads blending of liquid and solid fats and the use of other ingredients results in the required plasticity properties. Further, the emulsification and fat-crystallization processes in spread-making ensure the desired body and texture characteristics. Thus, the formulation and processing of spreads generally determine the final product characteristics such as appearance, spreadability and keeping quality.

Processing basically comprises preparation of aqueous and fat phases and their mixing, emulsification, cooling/crystallization, working, filling, packaging and setting.Heat treatment is given to the separate phases prior to blending and/or to the blended mix. As there is a wide range of spread formulations and these could be either an O/W or W/O type emulsion, the processing protocol will largely depend on the type and level of ingredients to be used as well as the kind of emulsion desired. Accordingly, for most O/W type spreads homogenization of a hot spread mix using a pressure homogenizer or a colloid mill or a similar device followed by cooling and fat crystallization, whereas in order to obtain a W/O type spread the finishing steps are usually cooling, crystallization, working and pre-packaging or post-packaging setting. Thus, spread processing is specific to the finished-product formulation. An example of the spread-manufacturing method is shown in Fig.

Schematic Diagram of Manufacture of Low Fat Butter Spread

 

i. Preparation of the Aqueous Phase

Aqueous phase preparation involves dissolving/dispersing of water soluble ingredients namely, protein product, stabilizer, salt, etc. in water or the aqueous medium to be used. Blending temperature between 40-80°C is generally used for faster dispersion and solubilization of ingredients. Cultured buttermilk or synthetic flavour or starter distillate should be incorporated at the end of heating to minimize loss of volatile flavour. Treatments like pasteurization (75-95oC for up to 30 min) and cooling are commonly followed for the aqueous phase before addition/blending it into the fat phase.

 

ii. Preparation of the Fat Phase

Preparation of the fat phase involves melting of fat and mixing it with fat soluble vitamins and colour. Pretreatments of the fat phase depend upon the source or form of fat. Low-fat or medium-fat cream is often pasteurized as is the aqueous phase before being concentrated into a high-fat cream, if so desired, and cooled/precrystallized for blending with the aqueous phase. Phase inversion (O/W to W/O) may also be followed depending on the formulation. This can be achieved by using a continuous butter-maker or a ‘transmutator’ (worm cooler).

Butter- or Butteroil-based processes involve tempering (preferably to the emulsification temperature e.g. 21oC) before converting it into a spread. In a continuous method for low-fat spread-making, butter (80% fat) requires vacuum working, deaeration and warming before blending with the aqueous phase.In case of non-dairy or mixed-fat spreads, partial hydrogenation or interesterification of vegetable oils or their blends followed by refining, bleaching, deodorization, etc. is commonly practiced in preparation of the fat phase.

 

iii. Blending and Emulsification

Separately prepared aqueous and fatty phases are often blended to form a ‘pre-emulsion’. Such a premix may be subjected to heat treatment if the individual phases were not so treated. The heat treatment is then followed by cooling,crystallization, etc. Sometimes one phase, usually the pasteurized and cooled aqueous phase, may be continuously introduced into the pre-treated fatty phase during cooling or crystallization, thus combining the blending and emulsification steps.

Emulsification is carried out by means of a suitable agitating device such as a mixer or a churn, which may involve shearing action with or without simultaneous cooling.It ensures adequate distribution of the dispersed or discontinuous phase into the continuous phase.Homogenization, an emulsification method, particularly suitable for O/W-type spreads,is carried out after pasteurization / heating of the spread base mix. Two most important parameters of homogenization are temperature and pressure. Generally,a single-stage pressure of 5-36 MPa (50-360 bar) is used. In two-stagehomogenization, the pressure used is 7-18 MPa (70-180 bar) in the first stage and 3-5 MPa (30-50 bar) in the second. In general, homogenization of the spread mix is carried out at a temperature employed for pasteurization/heating. However, the temperature may range from 25o to 85oC. Homogenization can also be used for achieving phase inversion in spread-making. Emulsification can also be brought about by churning of cream either in a batch or continuous churn. Churning is often done at 14-16oC.

 

iv. Cooling, Crystallization and Working

Scraped surface coolers are used to achieve the water-in-oil emulsion. Such equipment also known by various generic names such as ‘Votator’, ‘Kombinator’ or ‘Perfector’ are cylindrical devices with a rotor/scraper housed in a double–walled tube provided with an evaporating refrigerant. These multifunctional units are used for carrying out cooling, crystallization and working. Solidification of fat into the desired crystal size and type is important for a smooth, plastic spread. The process of working ideally disperses the fat crystals throughout the emulsion and if the process is carried out satisfactorily, the product will be plastic and spreadable;if not, it will be greasy.

Ingriedients of Low Fat Spreads

The technology of low-fat spread manufacture has two salient aspects: Selection of ingredients, and processing. The important constituents of spreads are fat, (milk) proteins, stabilizers, emulsifiers, emulsifying salts, acidulants, common salt, colouring and flavouring materials, vitamins, preservatives/ antioxidants, etc. Each ingredient has specific importance in production of a good-quality spread.

 

i. Fats and Oils

Fat is a major ingredient of a low-fat spread. The main functions of fat are:

•  To provide structure, texture and taste including creaminess.
•  To act as a carrier of flavour and vitamins
•  To serve as a source of energy and essential fatty acids.

The physical properties of spreads, namely, spredability, firmness, plasticity and thixotropy are mainly determined by the ratio of liquid to solid fat content. For low-fat dairy spreads, sources of milk fat include cream, butter and butteroil of ghee.A somewhat better product in terms of body and texture characteristics can be obtained with the use of cream in place of butter for spread manufacture. To obtain 40 % fat in the finished product, cream having 65-67 % fat content is necessary.Since cream contributes substantial amount of milk solids-not-fat (MSNF), quantity of additional protein/MSMF required is generally less with cream based spreads.Cultured cream imparts butter flavour and desirable spredability to the spread. It also imparts a softer texture to the spread. Use of butter gives less oiling off and a pleasing, characteristic butter flavour as compared to butteroil. It gives firmer body than cream. Equal quantity of butter and 40% fat pasteurized cream can be used as a source of milk fat in a 60% dairy spread. Use of butteroil simplifies compositional control because the gross composition of butteroil is reasonably constant,being almost 100 % fat. The use of butteroil is recommended in case of unavailability of butter, as it offers ease in tempering and re-pasteurization just prior to use in spread-making, which help in improving the bacteriological quality of the product.

However, butteroil has a tendency to yield product with more oiling off and less tight structure than that with butter. Spreads with a stable emulsion can be prepared using 35 to 40% fat. Low-fat dairy spread with milk fat content below 35% may have a weak body and inferior spredability in addition to poor flavour.

Fats sources other than milk fat include vegetable oils such as corn, safflower,sunflower, soybean, and groundnut oils. These oils used in combination or singly, are usually subjected to partial hydrogenation prior to use. Health considerations favour use of monounsaturated (oleic-acid) fats/ oils such as groundnut (or, peanut), sesame and canola (rapeseed) oils. Olive oil would be the most desirable but it is rather expensive. At present most spreads available in the North American and European markets contain 17-33% saturated fat, 22-50% mono-unsaturated fat and 26-45% polyunsaturated fat.

The fat phase of non-dairy spreads comprises unhydrogenated and partially hydrogenated oils. However, hydrogenated fat is regarded as an unhealthy fat because of its ‘trans’ fatty acids (e.g., elaidic acid) content. In view of this‘interesterified’ fat with the desired plasticity but without trans fatty acids has been found more desirable.Another health-related feature of newer spreads is fat containing omega-3 fatty acids which is found in appreciable concentrations (6-10%) in fish oils, walnut oil,mustard (or, rapeseed) oil and soybean oil. Phytosterol (plant sterols) added as an additive and/ or in the form of oils containing the same (e.g. rice-bran oil) is also considered to make low-fat spreads more heart healthy.

 

ii. Protein Products

Milk proteins are generally added to dairy and non-dairy spreads for their organoleptic,functional and nutritional properties. They impart a creamy taste contribute viscosity and water holding capacity to the aqueous phase, thereby improving emulsion stability during processing and storage. The main sources of proteins are skim milk,buttermilk, caseinate and whey solids. Use of ripened cheese in fat spreads would not only provide easily digestible protein but also help in imparting cheese flavour to the product. Skim milk and butter milk are used as such or in a concentrated or dried form.

Condensed skim milk produces spread with a firm body and least wheying off.Skim milk powder (SMP) also yields a product with good body and water retention properties. Spread prepared using calcium-reduced SMP has a very strong water binding characteristic. Use of sodium caseinate imparts a soft body to the spread without causing wheying off. The caseinate can be used for both moisture retention and emulsion stability. However, use of excess (e.g. 1.5%) sodium caseinate imparts a ‘gluey’ taste to the product.

Milk protein concentrate derived from skim milk or buttermilk by ultrafiltration (UF) can be used to ensure formation of desired structure and binding of water. Buttermilk protein together with the butteroil gives a butter-like flavour to the product. In comparison to SMP, butter milk powder is superior in terms of both taste and emulsifying ability.Use of whey solids in spreads may cause a problem of lactose crystal formation.Cheddar cheese whey powder promotes softness in the product and excludes free whey during thawing. Use of whey protein concentrate (WPC) prepared by UF also improves the body of the product with the least wheying off.Among vegetable protein products, soy protein isolates have been frequently used in manufacture of spreads because of high water holding capacity and high protein quality. It can be also used in the form of protein-lipid concentrate so as to utilize the polyunsaturated soy oils as well.The proportion of fat and MSNF influences the quality of a spread. An increase in fat/SNF ratio results in increased wheying off and decreased body strength. Milk protein in the form of MSNF can be used at the level of 5-15 %.

 

iii. Emulsifiers and Emulsifying Salts

In order to get a stable emulsion, various emulsifiers are also employed in spread-making. Emulsifiers yield a softer and more easily spreadable product with a stable emulsion. It improves the mouth-feel of the product. Various emulsifiers are used in spreads, e.g., monoglycerides (MG) of saturated and unsaturated fatty acids, egg yolk solids, lecithin, combination of lecithin and MG, hydrophobic compounds such as methylated silicon oxide, etc. The level of emulsifiers in spreads may vary from 0.1 to 0.6 %.

Chelating or sequestering agents (i.e. chemicals that bind calcium and magnesium),also known as ‘emulsifying salts’ include tri-sodium citrate, di-sodium phosphate,etc. These are used either singly or in combination usually at the rate of 1 to 4 % to improve the emulsification by proteins, and enhance the texture of spread,especially of the O/W type.

 

iv. Stabilizers

A low-fat spread with a moisture content of 30-50% has a tendency to wheying off (or, syneresis), and exhibits poor body and consistency in absence of suitable stabilizers. The high water-holding ability of stabilizers plays an important role in improving body and texture of products. They yield an emulsion that gives good melt-down in the mouth and consequently, rapid flavour release with a satisfying cooling effect. Various stabilizers such as gelatin, carboxymethylcellulose(CMC), starch, modified starch, sodium alginate, xanthan gum, carrageenan,pectin, gum acacia, etc. can be used individually or in combination at the rate of 0.1 to 0.5 %.

 

v. Plasticizers

Plasticizers like glycerol, sorbitol, glycol, etc may be used in spreadable products to improve their pliability or plasticity. They also depress the water activity of the aqueous phase. This may help in extending the shelf life of the product. Addition of glycerol and sorbitol at the rate of 0.5-1.0 % in low fat spreads improves the mouth-feel and spreadability.

 

vi. Acidulants

Spreads, in general, have low a storage stability owing to their high moisture content. Acidification of the product helps in extending the shelf life as well as enhancing the flavour. The pH may be reduced to 4.8 to 6.0 with the use of different acidulants such as citric acid, lactic acid, ascorbic acid, and phosphoric acid. Addition of lactic acid improves the body and imparts a slightly tart flavour to the spread. Very low pH would, however, cause more wheying off. Best body and least syneresis can be obtained with pH from 5.7 to 5.9 in most spreads.

 

vii. Colouring matter

In order to make the spread visually attractive, two types of colour, namely anatto and b-carotene are added. O/W -type spreads require water-soluble annatto colour(anatto cheese colour), whereas W/O spreads require oil soluble anatto colour(anatto butter colour). Use of b-carotene enhances not only the nutritive value but also the oxidative stability of the product. Anatto colour can be used in low-fat spreads at the rate of up to 0.3%. Butter annatto is usually added to the fatty phase.

 

viii. Flavouring Agents

A spread without added flavouring often tastes rather bland. Hence, it is necessary that external flavourings are added. Use of butter starter distillate, synthetic butter flavour, diacetyl, phenols, ä-lactones, etc. have generally been found to effectively simulate the desired butter flavour. Diacetyl (0.5 – 2 ppm) is the most frequently used flavouring. A suitable dairy culture (starter) can be used @ 1% in spreads to give a mild, ripened flavour, acceptable to most people. Cultured buttermilk solids have an advantage of imparting a diacetyl aroma to the spread.

 

ix. Common salt

Sodium chloride or table salt is usually added to spreads. It provides taste and palatability to the spread and also retards the growth of bacteria, thereby acting as a preservative. Generally, the salt content in low-fat spreads varies from 0.25 to 2 %. Cheese-flavoured spreads involve the use of cheese flavour concentrate,aged Cheddar cheese, or blue cheese. Addition of melted cheese as a protein ingredient as well as flavouring material can yield a low fat spread with high overall quality. Other flavourings like herbs, garlic, chocolate, vanilla, honey, nuts, etc. can be used to enhance the acceptability of low-fat spreads.

 

x. Preservatives

In general, high-moisture foods such as spreads have low stability against microbial spoilage. In order to inhibit the growth of spoilage organisms including yeasts and molds, various preservatives may be added besides following an appropriate heat treatment. Sorbic acid and its salts, nisin, propionates, benzoic acid, sodium benzoate, etc. can be added upto 0.1 % to extend the shelf-life of spreads.

 

xi. Other additives

Other additives like anti-oxidants, vitamins, sweeteners, etc. are sometimes incorporated into low-fat spreads. Use of certain antioxidants like nordihydroguaratic acid (NDGA), hydrophobic metal oxide or methylated silicon dioxide, and alcohol etc. have been suggested to prevent oxidation of fat during storage. Spreads are often fortified with vitamins to enhance their nutritional value. These vitamins include ascorbic acid, vitamin A (3000 IU / 100 g) and Vitamin D (300 IU / 100g).

Salient Features of Low Fat Spreads

In addition to its low fat content, spreadability and organoleptic quality are two important properties of a low-fat spread.

 

i. Spreadability

One of the most important properties of spreads from the consumer’s viewpoint is spreadability. It is desirable that product should be spreadable at refrigeration temperature i.e. 50C. To attain such a state of plasticity in a product, there are three essential requirements:

•  There must be two phases, solid and liquid.
•  The solid phase must be so finely dispersed that the crystal mass is held together by lateral cohesive forces.
•  There must be a proper proportion between the solid and liquid phases. If the spread is deficient in solids, not enough crystal will be present to hold the liquid oil. This is noted when product oozes out oil. If the solids content is too high,
•  the interlocking crystals, coupled with insufficient liquid, will cause a brittle texture (breaking into pieces).

 

ii. Organoleptic properties

The organoleptic attributes of the spread are influenced by (besides the flavour of the raw materials used):

•   Lightness of the emul-sion.
•  Melting profile of the fat.
• Storage condition of the finished product.

The other important oral quality aspect called “coolness” is the coldness felt on the tongue, when fat crystals melt at nearly the same temperature, absorbing heat during dispersion in the mouth. The droplet size (in an O/W spread) also affects oral properties of the aqueous phase and it should be uniformly small. A mar-garine in which about 95% of the droplets has a diameter of 1-5 micrometers and 4% of 5-10 micrometers and 1% of 10 - 20 micrometers is described as ‘light on the palate’.

Classification of Fat Spread

In general, spreads are classified on the basis of the origin or type of fat and level of fat. The European Community Commission (ECC) classified fat spreads into different categories on the basis of fat level as shown in (Table 10.1). ECC permits the use of animal body fats as wells as marine oils, and designates 3 types of spreads with 6 different fat levels. Codex specifications for fat spreads are under revision along these lines. AGMARK identifies two grades of fat spreads (milk-fat spreads, mixed-fat spreads and vegetable-fat spreads): ‘Medium-fat’ (60.1 – 80.0% fat and 16.0 – 36.0% moisture) and ‘Low-fat’ (40.0 – 60.0% fat and 36.1 – 56.0% moisture).

ECC classification of fat spreads (Tentative)

Defination of a Fat Spread

According to PFA, a ‘fat spread’ means a product in the form of a water-in-oil emulsion of an aqueous phase and a fat phase of edible oils and fats excluding animal body fats. It may be a ‘milk-fat’ spread (fat content, exclusively milk fat),‘mixed-fat’ spread (based on a mixture of milk fat and one or more of hydrogenated or un-hydrogenated refined edible vegetable oils or interesterfied fat), or a ‘vegetable fat’ spread. A fat spread may contain edible common salt not exceeding 2% by weight in the aqueous phase; milk solids-not-fat, lactic acid, butyric acid, valeric acid, cinnamon oil and ethyl butyrate as flavouring agent up to 0.08% by weight;diacetyl may be added as flavouring agent not exceeding 4.0 ppm; permitted emulsifiers and stabilizers; permitted antioxidants (BHA or TBHQ) not exceeding 0.02% of the fat content of the spread; permitted class II preservatives, namely sorbic acid and its sodium, potassium and calcium salts (calculated as sorbic acid),or benzoic acid and its sodium and potassium salts (calculated as benzoic acid),singly or in combination, not ex-ceeding 1000 ppm by weight; and sequestering agents. It may contain annatto and/or caro-tene as colouring agents. It shall contain starch not less than 100 ppm and not more than 150 ppm. It shall be free from mineral oil and wax. Vegetable fat spread shall contain raw or refined sesame oil(Til oil) in sufficient quantity so that when separated fat is mixed with refined groundnut oil in the proportion of 20:80, the red colour produced by Baudouin test shall not be lighter than 2.5 red units in 1 cm cell on the Lovibond scale.Low-Fat Spreads

It shall also conform to the following standards:

i) Fat - Not more than 80% and not less than 40% by weight.

ii) Moisture - Not more than 56% and not less than 16% by weight.

iii) Melting point of ex-tracted fat (capillary slip method) in case of vegetable fat spread - Not more than 370C.

iv) Unsaponifiable matter of extracted fat

a) In case of milk-fat and mixed-fat spreads - Not more than 1.0 % by weight.
b) In case of vegetable fat spread - Not more than 1.5%

v) Acid value of extracted fat - Not more than 0.5.

The vegetable fat spread shall contain not less than 25 IU synthetic vitamin A per gram at the time of packaging and shall show a positive test for vitamin A, when tested by antimony trichloride (Carr-Price reagents as per IS 5886-1970).

Low Fat Spreads

The current generation of dairy products contains those that have been functionally improved by enhanced formulation of the conventional products. The functionality may be based on physiological or health considerations, or may have physical implications relating to convenience of use. This new type of products is deriving impetus from the consumer focus on health and well-being as well as convenience.

New products formulation/development may also be governed by the consumer’s needs and desires such as extended shelf life, low cost, added flavour/texture appeal and other sensory quality improvements. Demand for special foods on account of dietary reasons is also increasing, more so because of the implication of high-fat dairy products like cream, butter, ghee, etc. in health problems. Butter is one of the important dietary dairy products in India as well as countries advanced in dairying. However, in recent years consumption of butter in most advanced countries has declined because of the following reasons:

•  Very poor spredability at temperatures below 150 C
•  High cost
•  High saturated fatty acids content
•  High cholesterol content
•  High caloric value
•  Suspected role in heart diseases and medical recommendations aimed at promoting the consumption of more unsaturated fat.

Consumer awareness and the resulting demand for new products which have solutions to the problems associated with butter consumption has opened space for dairy manufacturers to introduce ‘modern’ products. This has led to emergence of new categories of dairy products including “low fat spreads”.A ‘spread’ (or ‘table spread’) may be defined as a product, semi-solid in nature,characterized by adequate ‘stand-up’ ability (i.e. capacity to support its own weight) and yet be ‘spreadable’ on a bread slice or toast with moderate effort. Such a ‘plastic’ product usually has a wide ‘plasticity range’ i.e. it will retain its form or shape at normal ambient temperature (or, room temperature) and also be pliable enough ‘directly out of refrigerator’, refrigeration being the commonly required storage condition for such products.A ‘low-fat spread’, as the term indicates is a spread with a fat content appreciably lower than the normal one (which is 80% in conventional table butter). Although the fat content may vary over a wide range low-fat spreads often contain about half the fat content of butter or margarine (a butter-like product obtained essentially from vegetable oils/fats) i.e. approx. 40%. Such spreads may be obtained solely from milk fat (‘dairy’ spreads) or from vegetable fats and oils (‘non-dairy’ spreads) or a blend of the two (‘mixed’ or ‘blended” spreads). A ‘cheese spread’ is also a dairy spread, but is not a ‘fat spread’ as it is rich more in non-fat solids than in fat, and is characterized by a ‘cheese’ flavour and an ‘oil-in-water’ (O/W) emulsion(where fat is dispersed as droplets in a continuous aqueous or water phase carrying the non-fat solids). Most low-fat spreads (fat content, more than 15%), whether ‘dairy’ or ‘non-dairy’ type, are ‘water-in-oil’ (W/O) emulsion, though ‘very-low-fat’ spreads may be of O/w type. The first low-fat spread was developed and marketed in UK during 1968.Low-fat dairy spreads are variously designated as ‘half butter’, ‘half-fat butter’,‘low-calorie spread’, ‘reduced-fat butter’, ‘low-fat butter’ etc. Low-fat spread in which caloric reduction is less than 33% are sometimes termed as ‘reduced-calorie’ spread.

Keeping Quality of Ghee and Butter Oil

Ghee is expected to have the keeping quality of about 9 months on storage at about 21oC when packaged in rust free lacquered tin containers. The spoilage of ghee and butter oil results into:

•  Production of objection off-flavour, thereby loosing the consumers’ acceptability
•  Adversely affect its nutritive value on account of
• - Lestruction of fat-soluble vitamins and carotene
•  Formation of toxic products due to auto oxidation
•  Loss of attractive colour

i. Factors affecting keeping quality

It is highly essential to identify the factors that influence the keeping quality of ghee and butter oil so that they can be effectively controlled during production and storage. Some of these factors are listed as below.

•  Initial moisture content in ghee and butter oil
•  Initial acidity in the products
•  Amount of residue/sediment
•  Oxygen content in packaged products
•  Copper, iron and other catalytic salts
•  Method and type of packaging
•  Storage temperature
•  Exposure to light

Under practical situation the moisture content in ghee and butter oil is about 0.2%(the extreme limit can be 0.5%) when properly processed. The higher moisture content is responsible for faster hydrolysis of fat and other deteriorations. Similarly higher initial acidity, oxygen content and presence of catalytic salts, which accelerate the fat oxidation, always increase the rate of spoilage of anhydrous milk fat. The spoilage of these butterfat products is also directly proportional to the storage temperature and prolonged exposure to direct sunlight.

 

ii. Extension of keeping quality of ghee and butter oil

The following approaches can be used:

Use of good quality raw material: Raw material used for the manufacture of ghee and butter oil should be of good quality. Any off flavour, such as acidic,oxidized, and rancid present in raw material shall be carried over to the final product. The raw material should also be checked for the presence of copper and iron, which should not be more than permissible limits.Method of manufacture of ghee: Ghee prepared by desi method has higher moisture and higher acidity and thus lower keeping quality. If ghee is to be stored for longer time than this method should be avoided. The sulphydryl and phospholipid contents have antioxidant properties in ghee and butter oil. Those methods, which releases higher amounts of these natural antioxidant components should be adopted.Heating butterfat with higher amounts of solids-not-fat, as in case of direct cream method, at higher temperature of clarification will produce more sulphydryl and thus better shelf life. Probably due to this reason the keeping quality of ghee is more than butter oil.The pre-stratification method produces ghee with higher amounts of phospholipids because its loss in ghee residue is minimum. Also the extraction of phospholipids from ghee residue and addition @ 1 percent to the ghee enhance its keeping quality.

Addition of antioxidants: The antioxidants are added universally to anhydrous butterfat and high fat food products. There are two sources of antioxidants, namely synthetic and natural.

Synthetic antioxidants: These include

- Gallates (ethyl, propyl and octyl),
- Butylated hydroxy anisol (BHA)
- Butylated hydroxy toluene (BHT)
- Tertiary butyl hydro quinone (TBHQ), and many more.

PFA rules do not allow any synthetic antioxidant in ghee whereas permits the addition of gallates upto a level 0.01% and BHA & BHT upto 0.02% in butter oil
.
Naturally occurring antioxidants: There are many plants and herbs, which have antioxidant properties and may be added particularly to ghee for extending the keeping quality. Some of the examples of such natural sources are as below:

– The seeds of soybean and safflower are rich source of phospholipids. Their addition to ghee and butter oil at 0.5% level during boiling may delay the oxidative rancidity.

– Juices of Amla (Phyllanthus amblica) at level of 1.25% in ghee can retard the fat oxidation possibly due to high content of ascorbic acid and gallate in amla.

– It has been found that addition of betel and curry leaves (at rate of 1% of ghee) during heat clarification of butterfat improves not only the oxidative stability but also colour and flavour of ghee. The antioxidant properties of these plants are attributed to their phenolic compounds, predominately hydroxy charicol. The betel and curry leaves also contain carotene and ascorbic acid, which have tendency to undergo oxidation by consuming all free oxygen that may be present in the head space of the ghee container.

Packaging and storage conditions: Tin cans are best to protect ghee against oxidative spoilage. The reason being that hot filling of ghee is possible in tin cans, which will exclude most of the oxygen from the product and also enable to replace oxygen with nitrogen gas. The headspace in such containers can also be minimized. Ghee should not be exposed to direct sunlight or irradiation. It should preferably be stored at about 22oC.

Market Quality of Ghee and Regional Preferences

The organoleptic quality and physico-chemical properties of ghee offered for sale in the market are referred to as its market quality. The organoleptic quality includes colour, flavour and body and texture of ghee and is the index of consumers’ acceptability and the market sale including price. The physico-chemical constants are the legal requirements (PFA rules) and are mandatory as far as marketing of ghee is concerned. The physico-chemical constants are affected by many factors and have been discussed in the unit 7. The desirable marketable attributes of good quality ghee are discussed here.

 

i. Colour

The colour of cow ghee varies from deep yellow to straw yellow while that of buffalo is white with a characteristic greenish tinge. Yellow colour of cow ghee is attributed to carotene, which is affected by many factors. The greenish tinge in buffalo ghee is attributable to bilirubin and biliverdin.

 

ii. Flavour

Ghee is greatly valued in our country for its characteristic flavour, which varies from region to region. It is mainly dependent on method of preparation. The flavour of butterfat, as observed in case of fresh butter oil is termed as bland. The typical ghee flavour may be due to a combination of diacetyl, carbonyls, free fatty acids,lactones, alcohols and other compounds generated due to fermentation and/or heating.

The more pleasant flavour of ghee preferred by majority of Indian buyers is that produced by desi method. The flavour of ghee produced by all other methods is comparatively bland or cooked and less preferred in comparison to desi ghee.

 

iii. Granulation

The texture of ghee is an important quality attribute as far as consumer acceptability is concerned. Good quality ghee should have medium sized grains uniformly distributed throughout the lot. Granularity in ghee is considered by the average Indian buyer to be an index of purity in addition to the quality. Since butterfat is a mixture of triglycerides containing several types of fatty acids, the crystallization behaviour of ghee is very complex. There are several factors that contribute to the crystallization of butterfat and consequently to the grain formation of ghee. Proper control of these result in producing desirable texture in ghee.

 

Factors affecting granularity in ghee

Inherent factors: These include the type of milk, feeds and fodders, season, region,etc. The presence of larger proportion of higher melting saturated fatty acids,especially palmitic and stearic results into large size grains, whereas low melting fatty acids and unsaturated fats either produce very small grains or no grains in ghee. All those factors that change the fatty acids profile in milk affect the granulation in ghee. Size of grains in buffalo ghee is larger (0.31 mm) than that of cow (0.24 mm) mainly because of higher proportion of long chain saturated fatty acids in the former. Feeding more of green fodder or on pasture produce higher amount of soft fats, whereas, feeding higher amount of dry feeds and cottonseeds impart bigger sized hard grains/crystals in ghee.

Temperature of clarification: Higher temperature of clarification gives better grain size as well as more number of grains.

Method of preparation: The desi method produces ghee with larger size uniform grains in comparison with industrial methods wherein creamery butter is used as a raw material.

Rate of cooling: It has been observed that heating ghee to 60-100oC, followed by rapid cooling yields small grains in ghee. However, if ghee is gradually cooled to a temperature at about 1oC above the crystallization point of ghee (cow ghee 29oC and buffalo ghee 31oC), bigger size grains are produced.Storage temperature: Fluctuation in storage temperature deteriorates the grain distribution in ghee. Size and quality of grains in better at 28oC than at storage temperature of higher than 35oC.

Seeding: Seeding of ghee with grains of previous batch (1-2%) act as nuclei and develop desirable grains in ghee. The grains shape in this process is needle like as compared to that of spherical found in normal grains formation (without seeding) process.

 

iv. Regional Preferences for Ghee

Though ghee is consumed in all parts of India, the preference of consumers in different regions, in terms of flavour and texture, are not similar. These preferences are shown below in Table

Regional preference for ghee flavour and texture

Stroage and Deffects of Ghee and Butter Oil

The storage temperature of ghee in India ranges from 5 to 38oC depending upon the season of the year and region. Higher temperature of storage (> 30oC)accelerates chemical, particularly oxidative deterioration, whereas, the low storage temperature (< 10oC) though delays the chemical spoilage, it impairs the texture of ghee. At low temperature, ghee becomes greasy and pasty. Best temperature for storage of ghee and butter oil is between 20-30oC. The various defects normally encountered in ghee and their causes are discussed as below:

Acidic: Slight to moderate acidity in ghee, as produced by desi or indigenous method is highly desirable but too much acidity is considered as a defect. Use of raw materials, viz. milk, cream or cooking butter with high acidity along with high initial moisture in ghee is responsible for development of high acidity. This is not a very serious flavour defect.

Curdy: This flavour (referred as defect when pronounced intensity) can be found when cream or butter is undercooked during ghee preparation and all the SNF content (curd) not completely removed. Kachcha ghee prepared under rural conditions by heating makkhan or butter at low fire normally contains curdy and acidic flavour. Sometimes curdy defect resembles to acidic ghee. Ghee packers
normally collect the kachcha ghee having either acidic or curdy flavour and convert it into good ghee by further heat processing.

Smoky: Use of smoky fire, such as of wood/animal dung, for making ghee is responsible for smoky flavour defect in ghee. Storage of ghee under smoky environment may also be responsible for absorption of this flavour. The intensity of this defect, however, decreases on storage.

Burnt: Heating of butterfat, particularly at the last stage of preparation, at a very high temperature (normally at about 125oC and above) is responsible for development of burnt flavour defect in ghee.

Flat or lacking: When there is no flavour in ghee it is criticized as bland or flat or lacking. Butter oil has typically this type of flavour. The use of butter having very low curd content, or maintaining low temperature of heating under vacuum are responsible of producing ghee with flat flavour. This type of ghee, though not completely rejected, but receives lower preferences by consumers.

Rancidity: This is the most serious defect of ghee. It is of two types, viz. hydrolytic and oxidative rancidity. Normally this defect develops in ghee during storage, but in case the raw material used for ghee making is rancid, the freshly prepared ghee will also have this defect. Rancidity in ghee is caused by the formulation of volatile compounds, which exhibit unpleasant odours even when present in small quantities.The nutritive value of ghee is also adversely affected due to rancidity in ghee. Milk fat hydrolysis is faster in liquid state than in solid state. Because of more solid fat in buffalo milk its rate of fat hydrolysis is slower than cow milk fat. Therefore, the cow ghee is more prone to developing rancid flavour during storage.

Hydrolytic rancidity: The fat splitting enzyme, lipoprotein lipase found in milk fat globule membrane, is responsible for hydrolysis of milk fat and production of lower molecular weight fatty acids (butyric, caproic and caprylic). These fatty acids, particularly butyric, impart rancid off flavour in ghee. During manufacture of ghee a very high heat treatment is employed which inactivates the lipase enzyme.Therefore, the hydrolytic rancidity, in ghee is not of much problem, provided raw material of good quality (having no rancidity) is used. Rancid flavour defect is found more commonly in butter oil.

Oxidative rancidity: Oxidation of butterfat (ghee) is a more common problem and caused by oxidation of poly-unsaturated fatty acids in presence of oxygen. The reaction of oxygen with poly-unsaturated fatty acids involves free radical initiation,propagation and termination. In ghee and butter oil the chain reaction is catalyzed by heat, light, ionization reaction and trace metals (copper and iron), etc. The end products of lipid auto-oxidation are ketones, aldehydes, alcohols, hydrocarbons,acids, epoxides, etc.

Greasy texture: Good quality ghee should have well developed and uniformly dispersed ghee grains. Improper storage of ghee, particularly frequent thermal shocks, destroys the granularity of ghee and causes greasiness. Prolonged storage of ghee under refrigeration also leads to developing greasy texture in ghee.

Note: Amongst the above-discussed defects, acidic, curdy, smoky and burnt are normally not encountered in butter oil, whereas flat or lacking is not a common defect of ghee.

Packaging of Ghee and Butter Oil

i. Packaging Requirements

While selecting the packaging material for ghee, it should be carefully observed that

• the material does not react with ghee
•  it is non-toxic and non-tainting
•  easily available at low cost
•  should have good resistance to rough handling
•  does not allow tempering of ghee, and
•  it prevents or delay spoilage of ghee.

With a view to select suitable packages for ghee, it is essential to know the method of handling, nature of spoilage, storage conditions and consumers’ requirements/choices. Ghee is prepared at a temperature of around 110oC at which most of the microorganisms and enzymes (lipase in particular) are eliminated and moisture content is left less than 0.5%; hence there is no microbial spoilage of ghee during storage. However, upon prolonged storage, ghee and butter oil undergo lipid deterioration resulting into either hydrolytic rancidity or oxidative rancidity defects.

The selection of right type of packaging material can play a vital role in delaying the onset of these defects in ghee. The packaging materials being used for ghee and butter oil and that having great potential are discussed here.

 

ii. Packaging Materials

Tin plate containers: Majority of dairies in public as well as private sector are using lacquered or even un-lacquered tin cans of different sizes (250g to 15 kgs) for bulk and retail packaging of ghee. Some dairies sell loose ghee to local consumers through their sale depots or stores, where the possibilities of adulteration are fairly high. The advantages of using tin cans are manifold:
They protect the product against tampering.Being sturdy, they can be transported to distant places without much damage and wastage during transport.

The oxygen content in ghee can be reduced in case of tin cans by either hot filling or minimizing the headspace thereby preventing/delaying the oxidized flavour defects.Ghee packaged in tin cans normally has better developed grains.The only draw back of tin cans is their high cost and involvement of foreign exchange.It is very essential that tin cans be properly lacquered because rusted cans are liable to accelerate the lipid deterioration. BIS specifications for different sizes of tin plate containers are available for packaging of ghee.

Glass bottles: Though glass bottles provide excellent protection, they do not react with the food material and can be used for high-speed operations, but are not in much use for bulk or large size packaging of ghee because of their fragility and high weight. Since ghee is a expensive commodity and all consumers can not afford to buy large size packs, some of the ghee producers have started packaging ghee in glass bottles for retailers in sizes of 100g to 500g.

Semi-rigid containers: Of late, semi-rigid plastic containers are replacing tin plate containers. These are mainly made from high density polyethylene (HDPE). The advantages of using these containers are a) they provide a moderately long shelf life (not as long as tin cans), 2) are lightweight, economical and transport-worthy.These are of several types viz., blow moulded HDPE (high density polyethylene),PET (polyethylene terephthalate) bottles, PVC (poly vinyl chloride) bottles, and recently introduced bag-in-box systems, lines cartons and tetra packs. Blow moulded HDPE are, available in form of bottles (200, 400g), jars (1 kg and 2 kg), and jerry cans (2kg, 5 kg, and 15 kg). PET bottles have excellent clarity, are odour free and have gas barrier properties. All these semi-rigid containers have good scope for packaging of ghee and butter oil.

Flexible films/pouches: Flexible pouch may be made from laminates or multi layer films of different composition. The pouch may be in the form of pillow pouch or as stand-up pouches. Limited quantities of ghee are today packed in flexible pouches upto 1 kg. The most attractive feature of packaging ghee in flexible pouches is that they are cheapest than any other packaging system. The selection of laminate or a multi layer film is governed primarily by the compatibility of the contact layer,heat-sealing ability and heat-seal strength and shelf life required. The indigenously available flexible materials, which have very good values for the above, mentioned properties are HDPE, polypropelene, Al foil, Nylon 6, PVC, Saran, Polyester and numerous laminates of flexible films. Sachets made from a laminate of PVDC/ PVC Al foil/PP (polyvinyliedene chloride/aluminium foil/polypropylene) are suitable for long-term storage of butter oil and ghee.

 

iii. Filling and Sealing

While filling ghee and butter oil utmost care is taken to reduce the oxygen content in it. This can be achieved by

a) Filling containers up to brim, i.e. with minimum headspace.
b) Hot filling of ghee (preferably at 60oC) reduces the level of dissolved oxygen
by its continuous expulsion.
c) Application of vacuum packaging wherever possible or packaging in an inert atmosphere.

Packaging,Stroage,Keeping Quality Extention and Adulteration of Ghee

In the preceding units, we discussed that ghee is the most expensive dairy product,almost three times costlier than vegetable fats. It has several health benefits andmany food applications. Above all, ghee is known for its typical aroma and creamy taste which can not be duplicated by any other fat or oil. The palatability of any food to which ghee is added increases to a very high preference level. These benefits can only be availed if ghee of good quality is prepared, packaged and protected from adulteration and spoilage. We shall discuss these aspects in this unit.The information on butter oil is also provided wherever relevant and necessary.

Setting Up of a Ghee Refinery

Refinery is the place where refining of ghee is done. Refining as applicable to ghee is to improve its flavour, colour and appearance by adopting physical processes of heating and clarification of raw material and not by any chemical process. Normally raw (Kachcha) ghee or butter or cream collected from small producers is the raw material for refining.

 

i. Refining Facilities and Equipment

Building: Ghee refinery building should be spacious, having proper lighting and ventilation, and facilities for employees comfort and hygiene.Ghee collection vessels: These are normally cylindrical vessels with handles and lids, used exclusively for weighing ghee. The capacity of the vessels is 100 and 200 litres.

Water bath: Water bath is used at several ghee refineries for melting the remnants of ghee adhering to the sides of the tins after emptying the Kachcha ghee in the heating pan. It shall be a shallow vessel with a flat bottom or a tray made up of mild steel.

Heating pans (Karahis/kettles): Karahis are used for heating butter, Kachcha ghee or cream. They shall be constructed with hemi-spherical, dished or conical bottom. The joints in the kettle shall be welded and finished smooth. Double jacketed tie table kettles with provision of heating by steam are preferred over Karahis.Stirrers and scoops: Rods, preferably of stainless steel or aluminum alloy with flattened end on one side and wooden handle on other side shall be used for stirring butter/kachcha ghee/cream to prevent charring of casein and facilitate escape of moisture. For large size heating pans mechanical agitator may be used. The scum that rises on the top may be scooped out with metallic scoops.

Strainer: Before ghee is transferred from the heating pan to the settling tank, it shall be strained through a detachable strainer having an aperture width of not more than 14 mm. The strainer shall preferably be made of stainless steel.Transfer device: Ghee shall preferably be transferred from the heating kettle through a stainless steel pipe and a stainless steel pumping arrangement.

Settling tank: A settling tank should be of the capacity in range of 500 to 6000 litres depending on the requirement. It shall be preferably of the cylindrical type with a conical or dished bottom with suitable arrangement for mounting. The interior corners shall be rounded off facilitating cleaning and complete drainage.The lid shall be in two or more parts and of overlapping type. A central outlet at the bottom of settling tank or a side outlet at a suitable height should be provided for completely draining the tank.A centrifugal clarifier may also be used for clarification of ghee and the clarified ghee may be led to a tank similar to settling tank from where it can be drawn for filling into containers/packaging unit.

Heating source: The method of heating butter or kachcha ghee or cream depends on the scale of refining process. Small to medium sized refineries should built a furnace on which heating pans may be mounted. The furnace may be of the single pan or multiple pan type and made of firebrick and fire clay plaster. The fuel for such furnace may be smoke free wood or charcoal. Modern refineries with large capacity make use of steam heating for which necessary facilities, such as boiler,generator, etc. have to be installed.Filling, sealing and seaming arrangements: Proper arrangement for filling of ghee, depending on the type of packaging system, sealing and seaming of the containers should be made.

Packing room: In the packing room, ghee is filled into tins, cooled for granulation,sealed and labelled. The room should be well ventilated and lighted and shall be insect proof and rodent free. The floor should be maintained dry and clean, and drippings while filling ghee shall not be allowed to spread on the floor.

 

ii. Method of Refining

Refining practices differ in different parts of the country but the basic principle and practices involved are the same. In some parts of the southern states, butter is generally the starting material for processing whereas in the northern and western parts of the country, it is kachcha ghee, which contains considerable amount of buttermilk and suspended solids, such as casein. The heating of butter of kachcha ghee is done in karahis/kettles to a certain temperature depending on the regions.The heating temperature in range of 110-115oC (sometimes even upto 130oC) is maintained for the consumers in the southern states so that mild to strong cooked flavour may be induced in ghee. On the other hand kachcha ghee is heated only to about 70o to 80oC to developed slight acidic to strong curdy flavour for the consumers of northern and western states depending on their preferences. The ghee so produced is transferred to settling tank, where kept undisturbed for 4-12 hours depending on the season. The clarified ghee is fil led into tins adopting asuitable system.

 

iii. Reception of Raw Materials for Refining and Grading

All the butter, kachcha ghee or cream received at the refinery should be subjected to preliminary screening before it is accepted or rejected. Preliminary screening generally consists of only following three tests.

•  Organoleptic examination.
•  Butyro-refrectometer reading at 40oC and
•  Baudouin test.

In doubtful cases, the samples may be subjected to further tests, such as determination of Reichart value and polenske values, and free fatty acid content.

Methods of Manufacture of Butter oil

The following methods are used for manufacture of butter oil.

•  Evaporation under vacuum.
•  Decantation of molten butter.
•  Centrifugal separation of butterfat followed by vacuum drying.
•  Direct from cream by de-emulsification and centrifugation.

First three methods make use of butter as raw material.

 

i. Evaporation of Butter under Vacuum

This is a batch process and carried out normally under vacuum. Molten butter is taken in a vacuum pan and boiled under vacuum until moisture is completely removed.SNF (residue) is subsequently removed by physical or mechanical methods. Neither the efficiency of the process nor product quality are satisfactory in this method.

 

ii. Decantation

It is like pre-stratification method of ghee making, i.e. butter is heated to about 80oC, left undisturbed for some time. This results in the formation of three layers,viz. top scum, middle fat and bottom serum. The top layer and bottom layers are discarded and middle fat layer is separated and used as Butter oil. Fat recovery is less, hence method is uneconomical, especially when employed on a large scale.

 

iii. Centrifugal Separation followed by Vacuum Drying

This is a continuous method and produces a product of high quality. Invariably butter oil is prepared by this method. Butter (unsalted) is dumped in the butter melter, which is a vertical jacketed stainless steel tank fitted with an agitator. Hard butter is cut into small pieces before heating.Then steam valve is opened and agitator is started. The temperature of water in tipping tank is adjusted to 77 – 79oC with the help of steam and hot water is allowed to pass through the oil separator. Subsequently molten butter is allowed to go to tipping tank and oil separator. The rate of flow is so adjusted that there is no overflowing. The melt is separated into oil and serum.

The oil flows into the float controlled balance tank and from there into the vacuum pan due to suction. Here it is heated at 56-63oC under a vacuum of 56-62 cm Hg.All the moisture is removed from all the oil at this stage. At the end of operation,the vacuum is released and butter oil allowed to flow by gravity into the receiving kettle for subsequent cooling, packaging and storage.

 

iv. Directly from Cream by De-emulsification and Centrifugal Separation

The process utilizes the principle of de-emulsification of cream used in various continuous butter making processes. De-emulsified fat may then be melted and clarified by centrifuging and vacuum heating.

Comparision of Different Methods

The important merits and limitations of each method of ghee making have already been discussed. The comparison of these methods on the basis of fat recovery and energy consumption, the most vital parameters for gauging efficiency of method is made here (Table).

Comparison of different methods of making ghee

Creamery Butter Method

This is the standard method adopted by organized dairies. In this method unsalted creamery butter or white butter or cooking butter is used a raw material for ghee making. A typical plant assembly for the creamery butter method comprises the following units. (1) a cream separator (2) butter churn (3) butter melting outfits (4) steam-jacketed, stainless steel ghee kettle with agitator and process controls (5) ghee filtration devices, such as disc filters or oil clarifier (6) storage tanks for cream, butter and ghee (7) pumps and pipelines interconnecting these facilities (8) crystallization tanks and (9) product filling and packaging lines.

First, the butter mass is melted at 60oC. The molten butter is pumped into the ghee boiler. Alternatively, solid butter may also be transferred manually to ghee kettle.The steam pressure is increased slowly to raise the temperature of butter to 90oC.This temperature remains constant as long as the moisture is being driven off. The scum, which collects on the top surface of the product may be removed from time to time with the help of a perforated ladle. The temperature gradually rises and the heating at the last stage is carefully controlled. The end-point shows the disappearance of effervescence, appearance of finer air bubbles on the surface of fat, and browning of the curd particles. At this stage, the typical ghee aroma is also produced. The final temperature of clarification is adjusted less than 110oC. Heating beyond this temperature will generate a marked ‘cooked’ flavour. The ghee is then pumped, via an oil filter or clarifier, into crystallization tank, which are cooled by re-circulating water at 60oC. The ghee is then packed in suitable containers.

 

Advantages

•  This method produces ghee of highly consistent quality.
•  Quantity of ghee residue is very less, hence less fat losses.
•  Less space is required for storage of cooking butter, the raw material for this method.
•  Energy requirement are lower than direct cream and indigenous methods.
•  Longer keeping quality than indigenous method

Disadvantages

 The flavour of ghee prepared by creamery butter method is criticized to be either flat/bland or cooked, particularly to the consumers who are habitual of using village ghee made by traditional method. The granulation in ghee is also poor as compared with the earlier discussed method.

 

iv. Pre-stratification Method

The ghee boiler in pre-stratification method is slightly modified. A faucet is provided at lower end (almost at side of bottom) of the boiler to remove most of the buttermilk (moisture and SNF). In this method, white butter is heated at a temperature of about 80oC and left undisturbed for about 30 minutes at this temperature. The melted butter stratifies into three layers, viz., a top layer of floating denatured curd particles, a centre layer of fat, and a bottom layer of buttermilk. This separation of butter into layers is called as pre-stratification. The bottom layer of buttermilk contains 60-70 per cent of milk solids-no-fat and also over 80 per cent of moisture originally present in the butter. The buttermilk is mechanically removed without disturbing the top and middle layers. Afterwards, the temperature of remaining two upper layers is raised to the usual clarifying temperature of about 110oC and ghee prepared as discussed above for creamery butter method.

 

Advantages

•  Economy in fuel consumption to an extent of 60 per cent as compared with direct clarification.
•  The acidity of ghee is less, which results into longer keeping quality.
•  Exposure to high temperature for lesser time.
•  The amount of residue formation is reduced.

 

Disadvantages

 It is essentially a batch method unsuitable for continuous production of ghee.
 The flavour of ghee is very mild or rather flat.

 

v. Continuous Method

The batch methods for making ghee discussed earlier are highly suitable for small and medium scale production of ghee. With the increase in demand and scope for export of ghee, some very large organized dairies prefer to adopt a continuous ghee making methods. Some of the problems associated with the current batch methods of ghee making are:

•  Unsuitable for large-scale production.
•  High-energy consumption.
•  Excessive strain and fatigue on the operators.
•  Product exposed to the environment.
•  Cleaning of equipment is done manually.

All the limitations of the conventional batch methods given above are obviated by continuous ghee making plants. These systems work on the basis of two principles,viz. (a) moisture evaporation from cream/butter using thin film scraped surface heat exchanger (TSSHE) and (b) de-emulsification of cream using high speed clarifixator and oil concentrator followed by moisture evaporation. The design, function and special feature of continuous ghee making units are discussed below:

TSSHE for continuous ghee making: The white or cooking butter from continuous butter melter is pumped in balance tank where it is kept agitated by means of agitator to maintain the homogeneity of molten butter. Then the butter is pumped to the TSSHE. The flow rate of molten butter is indicated by a rotameter and controlled with a value provided on the inlet line. The centrifugal action of the rotor blade make the molten butter spread uniformly in form of a film on the heating surface of the SSHE. Steam is admitted at regulated rate into the jacket of SSHE. The rate of evaporation of water from the butter film is very fast due to turbulence caused by the action of rotating blade. The speed of rotor blade is controlled by a motor drive. The vapour is removed through the outlet provided at the top of the SSHE and can be used for heating the butter in balance tank, thus economizing the steam consumption. The temperatures of molten butter and ghee are indicated by thermometers and adjusted by controlled steam supply with valves. Ghee is collected continuously in the ghee tank. The residue is separated from ghee by the oil clarifier. Residue free ghee is finally transferred to packaging line/tank.
 

Cream de-emulsification method: This method of continuous ghee making is based on the principle of de-emulsification of fat in cream from oil-in-water phase to water-in-oil phase. In this process milk is separated into cream of 40% fat using a centrifugal cream separator. This cream is converted into plastic cream of 80% fat in a clarifixator and then further concentrated in a concentrator, which work under centrifugal force. The de-emulsification of fat is done mechanically in the clarifixator and concentrator. Scraped surface heat exchanger is used to generate flavour and remove most of the moisture from fat concentrate. The traces of moisture left in ghee are removed in a vapour separator and the ghee residue removed by a oil clarifier. The flow diagram of the process is shown in  below.

Flow diagram of Ghee manufacture by Cream de-emulsification method

Methods of Manufacture of Ghee

Different methods are used for the preparation of ghee. The adoption of a particular method is mainly dependent on the scale of production. The classification and description of these methods is given as below:

1 Indigenous (Desi) method
2 Direct cream method
3 Creamery butter method
4 Pre-stratification method
5 Continuous method

The flow diagram of the above methods has been schematically shown in Fig.

Flow diagram of manufacturing ghee by different methods

i. Indigenous (Desi) method

It is an age-old process and largely adopted in rural areas/villages and also at urban household levels because of simplicity in equipment and technique. This traditional method of making ghee contributes about 80% of the total ghee produced in the country. This method usually involves two routes, (1) lactic acid fermentation of raw or heated milk is followed by churning of curd into makkhan (butter) and (2) separation of malai (clotted cream) from the boiled milk and its churning into butter.Dahi or buttermilk of previous day is used as starter culture for fermentation of milk. Churning of curd or malai is done with hand wooden churn. Now-a-days electrically operated butter churns are available and used by many housewives or makkhan producers. Makkhan is stored at room temperature for days together and when sufficient quantity accumulated, it is converted into ghee. For this purpose,makkhan is heated in a earthen pot (now-a-days metal, particularly steel or aluminum containers are also used) on slow fire. The scum gathered on the top of melted butter is continuously removed with perforated ladle. The heating is discontinued on complete removal of scum and froth and getting clear fat (ghee). There are several limitations in this process which are mentioned here:

•  The quality of ghee is highly inconsistent in terms of chemical and sensory quality.
•  Method is incompatible to large-scale production.
•  Recovery of fat is low.
•  Acidity is high and hence keeping quality is low.
•  Manufacture and storage of ghee is done in undesirable containers.
•  Ghee residue being acidic in nature cannot be used.

The indigenous method is not adopted by organized dairies. Most of the ghee produced by this method is either consumed for household purpose or serves as a base material for the blending operations at ghee grading and packing centers functioning under Agricultural Marketing and Grading (AGMARK) scheme in India.To overcome the problems associated with desi method an improved indigenous method has been suggested which is as follows:

•  Always pre-filter/strain milk before use.
•  Give suitable heat treatment, preferably boiling the milk before making dahi.
•  Cool milk to room temperature (22-30oC) and then add starter culture for dahi preparation. The setting of dahi should be done under controlled conditions.Incubate milk till dahi is set and desired acidity (0.80 per cent) is developed.It normally requires about 16-18 hrs in winter and 8-10 hrs in summer.
•  Churn dahi by electrically driven beater or butter churn.
•  Use cold water during churning in summer months to minimize the fat losses in buttermilk (lassi), thereby improving the fat recovery in ghee.
•  Make ghee preferably from fresh makkhan or store makkhan in a refrigerator if it is to be converted into ghee after a long period. Don’t store makkhan or ghee in earthenware or copper or iron containers.
•  Heat makkhan (butter) at sufficiently high (more than 100oC) temperature for ghee making.
•  Strain ghee properly so as to make it completely free from residue.

  ii. Direct Cream Method

The small dairies use a technologically improved method for ghee making which involves the separation of cream from milk by centrifugation. This process omits the need for production of butter because cream is directly converted into ghee.The fresh cream or refined cream or even washed cream is heated in a heating kettle to evaporate moisture. The kettle may be an ordinary kettle heated by gas or a steam heated double jacketed kettle made up of stainless steel. The choice of kettle is made on the scale of operation. A steam heated jacketed ghee kettle is fitted with an agitator, steam control valve, pressure and temperature gauges and a movable, hollow, stainless steel tube centrally bored for emptying out the contents.Alternatively provision can be made for a tilting device on the ghee kettle to decant off the product. High fat cream is heated continuously in the kettle with intermittent agitation to avoid burning at initial stage. At last stage temperature should be controlled between 105-110oC. Heating is discontinued as soon as brownish froth appears on the surface and colour of the ghee residue turns to golden yellow or light brown. At this stage ghee is left undisturbed in the kettle so that residue uettles at the bottom. Ghee is allowed to cool to about 60oC and then filtered properly. In case a oil separator is used for removing residue, then ghee is directly passed through the centrifugal separator. The use of plastic cream or washed cream with about 75-80% fat is recommended for minimizing both fat loss and steam consumption. The final product will have a less intense cooked flavour when low SNF (solids not fat) cream is used.

  Advantages

•  Butter churn and butter storage facilities are not required, therefore, less initial costs are needed.
•  No refrigeration facility required for preparation and storage of butter.
•  Recovery of fat on basis of total butterfat is higher than indigenous methods because of elimination of butter making step.
•  The keeping quality of ghee is better.

 Disadvantages

•  Direct cream method requires a long heating time to remove the moisture.
•  A high content of serum solids in the cream may also produce a highly caramelized flavour in the ghee.
•  This method leads to about 4-6% loss of total butterfat in the ghee residue or during handling operations, depending upon the fat percentage in the cream. However, excessive fat from ghee residue may be recovered.
•  Energy consumption in comparison with creamery butter method is higher.

Principle of Manufacture of Ghee

The principle of manufacturing ghee basically involves following three steps:

a) Concentration of lipid phase : Butterfat in milk is present in form of fat globules, which are properly emulsified by fat globule membrane and dispersed in serum phase. For efficient separation of butterfat from the continuous phase(serum), it has to be concentrated inform of cream or malai. Further concentration of butter fat is possible by converting it into a continuous phase as in case of butter. The purpose of concentrating butterfat in a discontinuous (cream) or continuous phase (butter) is to reduce the amount of water and SNF contents in the raw material and facilitate ghee preparation.Sometimes, some intermediate operations such as fermentation of milk prior to concentration of lipid phase or of cream to emanate desired acidic flavour is also adopted.

b) Heat clarification of cream or butter : Removes practically all the moisture and to generate typical flavour and granulation, and

c) Removal of residue from the heat clarified butter fat : To meet the legal requirements and also to improve the storageability.

Principles and Methods of Manufacture of Ghee and Butter Oil

We know the importance of ghee in our diet and its nutritive value. Now, we should also be able to differentiate between ghee and butter oil. Butterfat is the most expensive constituent of milk and you know ghee is essentially constituted of butterfat. All efforts are made to minimize losses of butterfat while making ghee and butter oil. Another important aspect is to maintain the organoleptic and analytical properties of butterfat to an acceptable level in the final product. Also the technological and economic viability of the method used cannot be underestimated. To achieve these objectives, it is highly essential to adopt a most appropriate method for preparation of ghee and for butter oil. There are different methods of manufacturing ghee. In this unit we shall discuss all these methods along with their merits and demerits.

Grading of Ghee

Agmark grading scheme was initiated by the Agricultural Marketing Department in 1938 under the Agricultural Produce (Grading and marketing) Act of 1937 and revised from time to time. The parties (ghee packers) desirous of packing ghee under Agmark is considered by the Joint Agricultural Marketing Advisor, Nagpur for issue of certificate of authorization on receipt of a written request from the ghee packer. It is followed by a recommendation by the State Agricultural Marketing Department on inspection report about the equipment refining facilities, laboratory and qualified chemists.

 

i. Procedure for using Agmark Label

The ghee packer or the party who intends to use Agmark grade first of all undertakes preliminary screening of raw material for the general characteristics (organoleptic tests) and butyro-refractometer reading, Baudouin test and acid value before purchase of raw material. On passing the preliminary examinations, refining of Kachha ghee or butter or cream is done adopting the recommended temperature and conditions.Refined ghee is transferred to settling tank for separation of residue at the bottom.

A sample of each lot of freshly made ghee from settling tank (also from the dairy plants, which want to sale ghee under Agmark label) is drawn by the respective chemist and divided into 3 parts. One part is analyzed by the chemist himself at the laboratory of refinery or dairy plant. The second part is sent for check analysis to one of the control laboratory maintained by the agricultural marketing department.These laboratories are: The Central Laboratory, Kanpur, and the Subsidiary Control Laboratory, Rajkot (Gujarat). The third part is sealed and maintained with the ghee packer/producer for future reference.

After drawing the samples, ghee is filled in new tin cans, which have been previously marked with the following particulars:

- Name of the authorized packer
- Place of packing
- Date of packing
- Melt/ batch number

Ghee filled in tins should remain in the custody of chemist till the labels are fixed on them. Agmark labels are printed under security condition on watermark paper bearing the words “Government of India” in microtint to avoid counterfeiting.These are affixed on the tins with a special adhesive supplied by the Agricultural Marketing Advisor to the Govt. of India.

 

ii. Quality control check

If the control laboratory finds that a melt sample does not conform to the specifications, immediate intimation is sent to the authorized packer and the chemist to remove the Agmark Label from all the tins filled with the melt/batch in question,and ghee rejected from Agmark grading.A check on the quality and purity of ghee is also exercised by frequent inspection of the grading stations/refineries by the state and central marketing staff. Samples of graded ghee are collected from the grading centers and consuming markets(both retail and wholesale) through specially authorized officers. If on analysis,sample is found to be below specifications, the entire melt/batch is declared mis-graded and the packer has to arrange for the removal of Agmark label from the tins pertaining to that batch.