i. Desi Butter
It is a freshly churned butter prepared by rural households in a traditional method and commonly referred as Makkhan. It is made by hand churning of dahi or malai in an earthen pot with a wooden ladle usually known as mathani, Desi butter has unique flavour and rich attributes.Cow, buffalo or mixed milk is boiled, cooled and cultured with lactic starter culture(0.8-0.9% lactic acid) obtained from previous days batch. Milk is then stored overnight at ambient temperature to convert it into dahi by lactic fermentation.Next morning dahi is mixed with equal amount of cold water and transferred in an earthen pot. A wooden ladle (mathani) is then immersed in dahi and rotated manually in circular motion with the help of a rope. Rope is encircled around the mathani in the centre. After continuous agitation for sometime grains of Makkhan are formed, which floats on the surface. These grains are skimmed off from the surface with a ladle and pooled in a suitable container.
It is then patted in a compact mass with the help of a corrugated flat wooden block resulting in a compact mass of butter with soft consistency. Since churning is usually carried out at ambient temperature, a portion of fat, which is in liquid state is lost along with the buttermilk. It contains higher moisture, curd, lactic acid and flavour components than the creamery butter. The yield of Makkhan in the range of 4.5-7.0 per cent of milk and is influenced by the fat content of milk and the loss of fat in buttermilk. Buffalo milk by virtue of its higher fat content and larger fat globules than cow milk yields higher. Buffalo milk butter is white with greenish tinge in colour while that obtained from cow milk is creamy yellowish. Desi butter has a distinct pleasant flavour without the addition of colour or salt. It has a low keeping quality of about 3-5 days at refrigerated temperature.Alternatively, Makkhan can also be prepared from Malai. Malai is obtained by holding the boiled and cooled milk for sufficiently enough time at low temperature to form a layer of fat on the surface. This layer is skimmed off, pooled for few days and used for Makkhan preparation in the same way as it is made from dahi.
The flow diagram for the manufacture of Makkhan is depicted in Fig.
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| Flow diagram for manufacture of desi butter |
ii. Creamery Butter
The steps involved in the manufacture of creamery butter are explained in Fig.
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| Flow diagram for manufacture of creamery butter |
Preparation of cream: For the manufacture of creamery butter, the cream is obtained by separation of milk in the dairy plant or by procuring it directly from the producers or through the contractors. Cream for good quality butter should always be obtained by separation of good quality milk and used fresh. The milk should be fresh and sweet with pleasant flavour without any foreign matter and developed acidity. Milk is preheated to about 50°C and then separated by centrifugal separation process. Cream thus obtained does not require any neutralization of developed acidity if used fresh. Most of the dairy plants in the country prepare good quality cream from fresh milk and use it for butter making or for preparation of any other product.
The other route of obtaining cream is directly from the dairy farm or collection centers or suppliers. The technique used for grading of cream before reception is similar to that used for milk at the reception platform. It is examined for smell, taste,sediment, appearance, temperature and acidity. Then it is weighed and a sample is drawn for chemical and microbiological tests. Generally such cream may have developed acidity and require neutralization before it is subjected to subsequent processing steps.
Neutralization: It refers to the partial reduction of acidity of cream to make it suitable for churning and produce good quality butter. It reduces fat losses in butter-milk during churning, controls development of undesirable flavour and improves the keeping quality of butter. The cream acidity is reduced to 0.06- 0.08% before churning by neutralization with standard alkali solution, if the butter is intended for longer storage. In case butter is made for early consumption the reduction of acidity to 0.25-0. 30% before churning may serve the purpose. The cream acidity is determined on 10 ml of thoroughly mixed cream sample by adding a known quantity(say, A ml) of standard alkali solution for partial neutralization of acidity. The mixture is boiled for one minute and again required quantity (say, B ml) of standard alkali solution is added in the presence of phenolphthalein indicator until complete neutralization. The pink colour, which develops on addition of alkali solution in presence of an indicator disappears on further addition of alkali solution. This indicates the neutral point. The total volume (A+ B ml) consumed to get the neutral point is recorded and the acidity calculated in the same manner as calculated for milk. It is essential to determine correct acidity as the quantity of neutralizer to be added in cream vary with the acidity level and is calculated on the basis of final acidity desired. Commonly two types of neutralizers, either singly or in combination,are used.
Soda neutralizer: This group of neutralizers consists of sodium bicarbonate, sodium carbonate or a mixture of these two compounds. These are relatively mild neutralizers. Soda neutralizers offer the advantages of being highly pure, highly soluble and neutralizing the acidity at a faster speed but they are costly and sometimes produce foam and impart soapy flavour to resulting butter.
Lime neutralizers: This group of neutralizers consists of calcium hydroxide or magnesium hydroxide or a mixture of these two compounds. This group has low purity, low solubility and low neutralizing speed. It also imparts lime flavour, but it does not produce foam and costs less. When calcium hydroxide is used alone, it is used 20% more than the calculated quantity because 20% of it is consumed in reaction with casein and phosphate present in cream and hence it is not available for neutralization of acidity.
The quantity of neutralizer is calculated by the formula given below:
Quantity of neutralizer = ((a – b) x Quantity of cream x 100)/Neutralization factor
Where,
a = Initial acidity of cream (% L. A.)
b = Desired acidity of cream for churning (% L. A.)
Neutralization factor (N. F.) = It is the part of lactic acidity neutralized per part of the neutralizer used. The neutralizer factor for some commonly used neutralizers is mentioned Table
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| Neutralization factor for various neutralizers |
Cream is heated to 29- 32°C before addition of neutralizer. The calculated amount of neutralizer is dissolved or suspended in water (1 part in 10-15 parts of water),added to cream quickly and mixed thoroughly by vigorous stirring. Stirring is continued for 10- 15 min after addition of neutralizer. In case of neutralization of high acid cream it is always preferred to use double neutralization process, i.e., using both lime and soda neutralizers. High acid cream requires large amounts of neutralizer.In order to avoid the effect of large quantity of any one type of neutralizer and production of excessive amount of carbon dioxide, double neutralization is suggested.First lime neutralizer is used to bring down the cream acidity to 0.3- 0.4% and then soda neutralizer to bring down the acidity to desired level as mentioned above.
Standardization: The fat content of cream after neutralization is standardized to 35-40%, which is considered optimum for butter production. More or less fat content than this level causes increased loss of fat in buttermilk. Cream is standardized for fat content with the addition of skim milk or water depending upon the intended use of buttermilk. Reduction of fat by addition of water should be avoided as it interferes with the ripening process of cream and yields a flat flavoured butter.
Pasteurization: It refers to heating every particles of cream to a suitable time-temperature combination to meet the following objectives:
i. Destroy pathogenic microorganisms and make cream and the resulting butter
safe for human consumption.
ii. Destroy other bacteria, yeast and mould, enzymes and other biochemical agents (enzymes) that may lower the keeping quality of butter.
iii. Eliminate some of the gaseous and taint producing substances.
There are several methods to accomplish the pasteurization process. Low temperature- long time method (LTLT) or batch method prescribes heating of cream to 74°C for 30 min; whereas high temperature short time method recommends heating to 85°C for 15 sec. Yet in another method direct steam is injected to heat the cream to a suitable temperature. The equipment is known as Vacreator and the method as vacreation. Severe heat treatment is avoided as higher temperature increases the migration of copper from milk serum to fat globules. This, in turn,produces butter, which is prone to development of oxidative rancidity and has short keeping quality. However, for ripened cream butter, cream is heated to 90- 95°C for 15 min or 105- 110°C with no holding. Heating to such temperatures, coagulates whey proteins and releases sulphahydryl group, which enhances the growth of starter organisms and also acts as anti-oxidant. Thus, it improves the keeping quality of butter.
Ripening: The process in which, the cream is allowed to develop acidity(fermentation) with the use of selected microorganisms is known as ripening process.Ripening of cream aims at producing butter with pleasant characteristic butter flavour and low fat losses in buttermilk. Ripening improves the keeping quality of un-salted butter but reduces the keeping quality of salted butter. Ripening involves addition of starter culture, mixing it thoroughly and storing the cream (incubating) at controlled temperature. The starter culture consists of a mixture of acid forming microorganisms like Streptococcus lactis, Streptococcus cremoris and flavour producing microorganisms like Streptococcus diacetilactis, Leuconostoc citrovorum or dextrnicum. Usually starter is added at the rate of 0.5- 2.0% of the weight of cream at 22°C followed by incubation at the same temperature. The cream is held at this temperature until the acidity develops to 0.2- 0.4%. Subsequently cream is cooled to 5-10°C to arrest the further development of acidity and stored at this temperature. However, many of the dairy plants prefer to make butter from sweet cream because the resulting butter- milk can be used for drying along with skim milk or for the manufacture of some other dairy products and gives an economic return. The dairy factories, which manufacture butter from sweet cream, do not follow the ripening step. Butter flavour can also be improved by the addition of starter distillate or synthetic flavour instead of ripening of cream. But it does not impart a characteristic permanent type of uniform butter flavour.
Cooling and Ageing: Butter- fat exists in both solid and liquid state in fat globules in cream. During pasteurization the solid fat is converted to liquid fat and thus the proportion of liquid fat increases. Cream containing more liquid fat does not churn properly. Therefore it is essential to cool the cream and store it at low temperature(5-10°C) for sometime so that partial re-solidification of the melted fat takes place.Cream is preferably cooled to 7-9°C in summer and 10-13°C in winter after pasteurization and held at this temperature for 15-16 hr or at least for 2-4 hr. High temperatures of cooling and ageing, though reduces the churning time it increases the loss of fat and produces soft- bodied butter. If the fat is not solidified properly,the losses of fat in butter-milk increases and the resulting butter will have a weak body. On the other hand, cooling cream to much lower temperature (less than 5°C)and holding it for longer duration makes the fat globules too hard to adhere together.Hence churning takes longer time and the resulting butter is too hard. Normally a cream, which has been properly cooled and aged takes about 35-45 min for churning (to produce butter grains). However, the conditions for cooling and ageing are selected to suit the requirements of the manufacturers.The optimum temperatures of cooling and ageing depends on the following factors:
i) Composition of fat
ii) Size of fat globules
iii) Fat percentage in cream
iv) Acidity of cream
v) Period of ageing
vi) Temperature of churning
Churning: The objective of churning is to produce butter. The theory of churning has already been discussed in the Unit 4 in Section . During churning continuous agitation of cream destabilizes the oil-in-water type emulsion of cream, the emulsion breaks and butter grains are formed. The cream used for churning should possess good churn-ability. It means that it should produce sufficiently firm grains of butterfat easily and completely in optimum time (35-45 min). In short churn-ability of cream refers to the ease,completeness and duration of churning to produce sufficiently firm grains of butterfat, which can easily be washed. The following factors may cause delayed churning, high fat losses in buttermilk, excessive foam production,defective butter production, etc. and thus cause difficulties in churning of cream:
i) Excessive hardness of fat
ii) Small size fat globules
iii) Excessive thin cream
iv) Overloading of churn
v) Excessively low temperature of churning
vi) Abnormal cream
Loading the churn: Before the start of the operation the butter-churn, it should be properly washed and sanitized. The cooled and aged cream is then filled into it. The lumps, if any, should be mixed either by stirring or straining. The cream temperature should be 7-9°C in summer and 10-13°C in winter season. The quantity of cream in the churn should preferably be slightly below the rated capacity of
churn.
Addition of colour: After the churn is loaded and butter colour is added to cream,the door of the churn is closed. Addition of colour results in a uniform yellow colour of butter throughout the year. Generally the quantity of added colour varies in the range of 0-250 ml per 100 kg of butter fat. The colour should be non-toxic, oil soluble, free from off-flavour, concentrated and permanent. Usually two types of colour are used, which include annatto colour and carotene colour. Annatto colour is a yellowish red extract of a colouring substance from the seeds of annatto plant in oil. It is grown in tropical countries like West Indies, Brazil, India, etc. The colour is extracted by dissolving the seeds in neutral oil such as caster oil, groundnut oil or sesame oil. Carotene colour is an extract from carrots and other carotene rich vegetables. The carotene colour is slightly greenish but is rich in vitamin A. Colour is also available from mineral sources, which are harmless, oil soluble, more concentrated and permanent and includes Yellow AB (Benzene-Azo-beta-napthyl-amine) and Yellow OB (Orthotoluene-Azo-beta napthyl-amine). But addition of these colours in butter is not permitted by PFA. Butter colour is always stored in opaque and airtight containers at about 18-25°C.
Operation of the churn: Initially churn is given few revolutions in about 5-10 min and then churn vent or air vent is opened once or twice. It permits air and the gases to escape. Churn is then stopped. The valve provided at the bottom of the churn is opened and sample of cream is drawn. The churn is again allowed to rotate until butter grains are formed. The temperature, throughout churning process;is maintained in the range of 7-13°C depending on the season. During the churning process the temperature of cream increases by 1-3°C and also foam is produced,emulsion breaks, grains of butter-fat are formed. This stage is known as breaking-stage. At this stage churn is stopped and break- water is added to control the temperature of the contents of the churn. The churning process is continued further,until the smaller grains join together to form pea size grains. Usually the temperature of break-water is kept at or below 10°C depending upon the temperature reduction required.
Draining of buttermilk: On completion of the churning process, which normally takes about 35-45 min the churn is stopped and the butter-milk removed by opening the drain valve provided at bottom. It is essential to stop the churn in proper position so that the butter- milk is completely drained. Also a strainer is used to retain the smaller grains coming out with the buttermilk.
Washing: It helps to remove the loose buttermilk adhering to the butter grains,impart firmness and reduce the intensity of certain off-flavours. Removal of residual buttermilk in turn reduces the curd content in butter and improves the keeping quality. Water at a temperature of 1-2°C lower than the churning temperature of cream and in quantity equal to the amount of butter-milk drained is used for washing. After addition of wash water the churn is again rotated few revolution and then the water is drained out. Normally one washing is sufficient. Only good quality water, which is chemically and bacteriologically safe should be used.
Initial working: After draining the wash water, the churn is revolved few rotation so that the butter is kneaded to form a compact mass. The excess or loose moisture is also released and drained off.
Salting: The purpose of salting is to improve keeping quality, enhance taste and increase over-run in butter. There are three methods of salting butter, namely, dry salting, wet salting and brine salting.Dry salting calculated amount of salt is sprinkled over the surface of butter in the churn during working. This is most common method of salting.Wet salting method consists of wetting the calculated quantity of salt with minimum quantity of water and then sprinkling it over the butter during working.
Brine salting : It is suitable only for butter in which light salt is desired. In this case, salt is added in the form of a saturated brine solution.
Quantity of salt : The quantity of salt to be added varies in the range of 1.25-3.0%. It depends on the market requirements and legal standards. It is calculated as follows:
Kg. of Salt = (Rate of salting x 1.25 x Kg. of fat in churn)/100
The calculation is based on the assumption that 80 kg fat yields 100 kg butter. It means each kg of fat will yield 1.25 kg of butter. Hence is the factor 1.25.The quality of salt should meet the standards prescribed by BIS, i.e., IS: 1845: 1961.It should be 99.5- 99.8% pure sodium chloride and the grains should pass through IS: 85 sieve (aperture 8424).The microbial count should be less than 10g.
Moisture control: According to legal standard, the butter must not contain more than 16% moisture. Therefore, it is necessary to know the moisture content of butter in the churn. After addition of salt, butter churn is rotated until the butter develops dry appearance. A representative sample of butter is then taken with the help of a butter-trier and analyzed for its moisture content. Normally, it is less than the desired moisture content. So it requires addition of water. The required quantity of water is calculated as follows:
Amount of water = (1.5 x F (M- m))/100
Where,
F = Fat in churn (kg)
M = Desired moisture per cent in final butter
m = Initial moisture content in butter
The calculated amount of make-up water is added and the working is continued further until the additional water is thoroughly mixed with butter.
Working: It refers to kneading of butter at appropriate temperature to obtain a desired smooth texture. Modern churns produce a very close textured product because they work under vacuum. The purpose of working is:
i) To dissolve and uniformly distribute salt in butter;
ii) To uniformly incorporate added moisture;
iii) To break up the remaining intact fat globule membrane and form a continuous fat phase.
The working is continued until the butter attains a compact body and even distribution of salt and moisture. The temperature control throughout the working process is essential. Although overworking and under working both have damaging effect on body and texture of butter, it is always safe to slightly overwork the butter than under-work. Under-worked butter may have a leaky body, large visible water droplets and uneven colour. Working affects the colour of butter. It may produce slightly lighter coloured butter. It also increases the air content in butter. Increased air content is however un-desirable as it favours oxidative deterioration and microbial growth in butter. Therefore, working of butter under vacuum of 15-40 cm of mercury is preferred. Air content in butter worked without vacuum ranges between 3-7% by volume while in butter worked under vacuum it is only 1 ml/ 100g.Removal of butter from churn: This is done either manually or by gravity or by mechanical means. Mechanical method requires soft butter and compressed air (3-5 psi) for removal. Butter from the churn is always taken out on a trolley provided with wheels to facilitate its movement to the storage room or packaging room.Continuous butter making machine may be set to discharge butter directly to the storage tanks or silo from where it moves to the packaging machine.
