Shelf Life and Preservation

i.Paneer

The relatively short shelf life of paneer is a major handicap in the commercial adoption of paneer manufacture. The shelf life of paneer is reported to be only 6 days under refrigeration though its freshness is lost within 3 days. At room temperature paneer does not keep good for more than one day. The heat treatment given to milk is more than enough to destroy all the pathogenic and spoilage microorganisms. Thus it is the contamination either during or post manufacturing which is responsible for this spoilage. Paneer blocks obtained after pressing are immersed in water for cooling.It is during this period that microorganisms establish themselves in the product and proliferate on storage later on. The dipping water is a potent source of contamination and its quality is very important.

The spoilage in paneer occurs due to the surface growth of microorganisms. A greenish yellow slime forms on the surface and the discolouration is accompanied by an off-odour. It is only the surface that gets spoiled early while the interior remains good for a longer time. To curb the surface growth of microorganisms and thereby increase the shelf-life of paneer, the following practices can be successfully adopted.

Chilling: Rapid chilling of paneer is necessary to arrest the growth of microorganisms.Normally the producers do not see to it that the temperature of paneer has been brought down sufficiently (5-10oC) and it usually remains in the range of 20-30oC at the time of packaging. If such paneer is transferred to a refrigerator or cold store, it takes quite some time to cool down to the desired temperature. Microorganisms get fully established by that time and cause spoilage of the product. The bacteriological quality of chilled water should also be very high. It is essential that pasteurized chilled water should be used for cooling of paneer blocks.

Brining: Paneer dipped in 5 percent brine solution lasts for nearly 20 days as against control that is spoiled after 6 days of storage at 8-10oC. The sensory attributes are rated higher for salted samples. Since paneer is mostly salted and spiced before consumption, the salting at the time of dipping can be advantageously used in extending the shelf life of paneer. For preparation of brine salt should be dissolved in pasteurized water.

Use of chemical preservatives: A shelf life of 32 days under refrigeration can be achieved when paneer is treated with a combination of delvocid and hydrogen peroxide. Shelf life of 40 days using benzoic acid (1200 ppm) under refrigeration conditions and 20 days at 37oC has been reported. Further, enhanced shelf life of 36 days at room temperature by adding sorbic acid to milk (0.15%) and subsequent wrapping of paneer in sorbic acid coated paper can be achieved.

Freezing: On storage of paneer at sub zero temperature i.e. –13oC and –32oC for 120 days, the flavour and appearance is not affected but its body and texture deteriorates and the product becomes crumbly and fluffy on thawing. Blast freezing has recently been used to enhance the shelf life of paneer. The paneer block is cut into pieces of approx. 1.5 x 1.5 x 1.5 cm size and blast frozen at a temperature below –20oC. The product can be stored under frozen conditions (below –18oC) for more than one year without any deterioration in its quality.

Vacuum packaging: Vacuum packaging of paneer in laminated pouches can help to increase its shelf life to about 30 days at 6±1oC. The body and texture of paneer also improves on vacuum packaging as it becomes more compact and shows better sliceability. Paneer packaged in high film (EVA/ EVA/ PVDC/ EVA) under vacuum and heat treated at 90oC for one minute is reported to have a shelf life of 90 days under refrigeration.

Heat sterilization: Although the refrigerated shelf life improves markedly by the various treatments given to raw paneer, the shelf life at room temperature does not improve noticeably. Heat sterilization of paneer is an effective treatment for improving its shelf life at room temperature. Paneer packed in tins along with water/ brine and sterilized in an autoclave at 15 psi for 15 min lasts for 4 months. The perception of an oxidized flavour renders the product unacceptable afterwards. A slight amount of cooked flavour accompanied by maillard browning, the intensity of which increases slightly during storage, is noticed.

Grass additives: In order to enhance the keeping quality of paneer, the efficacy of four grass additives viz. cardamom, clove, cinnamon and ginger were investigated.The additives were individually added to milk at the time of coagulation. Ginger was added at the of 5, 9 and 11 g per kg milk and cardamom, clove and cinnamon were added at the rates of 1.0, 1.5 and 2.0 g per kg of milk. Paneer samples containing ginger, cardamom, clove and cinnamon each for low, medium and high dose showed shelf life of 32, 36 and 40 days; 23, 32 and 36 days; 24, 28 and 32 days; 23, 28,and 32 days, respectively at refrigerated temperature (5±1oC) while paneer was treated with brine (4.5%) and packed in polyethylene pouch (550 gauge), pre- sterilized with hydrogen peroxide (20% v/v). Clove and Cinnamon treated samples exhibited same shelf life as per their respective dosage. On the basis of sensory evaluation and physico-chemical changes during storage, medium dosage of four spices were found to be most effective and in totality, the treatment of paneer with
medium dose of ginger followed by medium dose of cardamom and clove/ cinnamon,respectively was most effective.

 

ii.Chhana

Chhana is perishable milk product. At ambient temperatures, its quality deteriorates within a day or two. The shelf life of chhana is greatly influenced by the composition of chhana particularly moisture content, storage temperature and nature of packaging material. The average shelf life of chhana from both cow and buffalo milk at 4oC,22oC and 37oC is about 10-12 days, 3-4 days and 2-3 days, respectively. The cow milk and buffalo milk chhana stored in tin cans and cellulose film/ LDPE was found acceptable upto 3 days at 37oC, and 20 days at 4-5oC. The shelf life enhancement of chhana using sodium benzoate, sodium propionate and sugar has also been demonstrated. Under refrigeration, the shelf life is extended to six days.

 

iii. Chhana Based Sweets

The shelf life of chhana based sweets is largely depend on the processing and packaging conditions, method of handling, season and moisture content in the product.Normally sandesh has a very limited shelf life of two to three days. Hard grade has better shelf life than soft grade ones. In summer, the shelf life of hard grade Sandesh is between three to four days while in winter it kept well four to six days. The relatively longer shelf life of this product may be due to low moisture and high sugar contents. Serpak Sandesh is having maximum shelf life of two to three months under refrigeration storage. Serpak is prepared by heating chhana and sugar for a longer duration. Babupak Sandesh deteriorates rapidly and in summer its shelf life is one day. Whereas, Batupak sandesh is having shelf life of two of three days. In winter,the shelf life of Babupak and Batupak sandesh may be extended upto two and five days, respectively.

The shelf life of rasogulla is quite longer as compared to sandesh. Rasogulla is packaged in lacquered tin cans with hot syrup. Sodium metabisulphite is added to maintain white colour to tinned rasogulla. The shelf life of rasogulla with permissible preservatives in tin containers is above three months.

Deffects in Paneer and Chhana

The defects in paneer and chhana and their prevention is presented in below Tables , respectively.

Defects in paneer and their prevention

Defects in Chhana and their prevention

Microbiological Quality of Chhana Based Sweets

Few studies have been conducted to examine the chhana based sweets for microbiological quality with a view to assess the standard of cleanliness during production, transportation, storage and marketing. The present information cannot be used in formulating the microbiological standards for these products.Contaminated chhana and its rasogulla, prepared by heating raw milk, containing staphylococci grown to a level of 108 and 109 cfu/ ml, thermo stable deoxy-ribonuclease and enterotoxins showed the absence of staphylococci but the presence of the latter two. However, the non-selective enrichment of such chhana and rasogulla samples in BHI broth showed the growth of staphylococci to a level of 104 to 109 cfu/ g with an increase in thermo stable deoxy ribonuclease activity. It indicated that the public health hazard posed by chhana and rasogulla made from raw milk heavily contaminated with enterotoxigenic strains of staphylococcus aureus.

Sandesh samples examined for total plate count, coliform count, staphylococcal count, yeast and mould count and their counts per gram of product ranged from 0-1 x 105, 0-55 x 101, 0-49 x 102 and 0-35 x 102, respectively. The most prevalent organisms identified were E. coli, staphylococcal strains, and moulds such as A.niger, A fumigates and A. nidulans.

Microbiological Quality of Chhana

The microbiological quality of chhana depend upon the standard of cleanliness during production, packaging, transportation and storage, and these factors affect the keeping quality of chhana. The microbiological spoilage of chhana is characterized by a heavy growth of moulds on its surface and a stale flavour at refrigeration temperature of 4-5oC. The product develops a sour smell and a bitter taste at 22-25oC and 37-39oC while its surface is sparsely covered with fungi. The most common moulds contaminating chhana samples are Penicillium, Aspergillus, Mucor,Rhizophus, Fusarium and Parcillomyces.

Market samples of chhana have shown wide variations in microbial counts (Table). The total viable counts are in the range of 0.0-9.0 x 106 and 0.0 – 2.2 x 105,while coliforms, yeasts and moulds are in the range of 0.0-13.9 x 106, respectively.The wide range of fluctuations observed in microbial counts is attributed to the market conditions.

It has been further examined that three kinds of fresh chhana samples viz. cow milk,buffalo milk and market samples for total plate, acid producing, proteolytic,chromogenic, aerobic spore forming bacilli and yeast and mould counts. The market samples carried higher counts in all cases as compared with cow and buffalo chhana except for yeast and mould counts. Cow milk chhana showed high counts in all tests except for lipolytic, yeast and mould counts.

Microbial quality of fresh chhana

Microbiological Quality of Paneer

The microbiological quality of paneer depends chiefly upon the conditions of
manufacturing, handling, storage and marketing of the product. It has been observed that fresh paneer manufactured under strict sanitary conditions does not contain organisms capable of producing toxins or diseases in human beings. The published reports indicate that bacteria, yeasts and moulds enter the milk products through sources like air, water, utensils, cutting knife, cloth and persons handling the product.Coliforms, yeasts and moulds which are present in sufficient numbers in raw milk get destroyed totally after subjecting it to a heat treatment of 82oC for 5 min. But these organisms again reappear as contaminants in paneer wrapped in cloth and also in packaged paneer suggesting thereby that the contaminating organisms have entered during post processing and handling of product. Fresh paneer made from standardized milk generally exhibits a total plate count of several thousands colony-forming-unitscfu)/g. Storage at the ambient temperature for two or three weeks causes the total count to increase rapidly to tens of millions cfu/g. The pH of paneer drops from 5.5 to 4.5 with concomitant separation of visible free moisture in pouches. Without the use of sorbic acid or other preservatives, paneer retains optimal quality for about a week. Domestically/ cottage-scale produced paneer remains fresh for two-three days. Shelf-life extension for a longer period would make its marketing possible to distant places.

Packaging of Chhana Based Sweets

These sweets need to be saved from light, oxygen ingress or egress of moisture,yeast and moulds. The shape and body and texture of these products have also to be protected and some of these sweets are sold dipped in sugar syrup. Rasogulla are usually packed in lacquered tin cans of one kg capacity. The cleaned empty cans are first sterilized in hot air inside a closed chamber. Rasogulla balls with hot sugar syrup and permissible preservatives are filled in containers, and seaming tightly seals the lid. Sodium metabisulphate is used to maintain white colour of tinned rasogulla.The shelf-life of rasogulla in tin containers is around three months. Lacquered tin can is most suitable package, but its cost is very high. Hence, there is a case to develop plastic cans similar to “Letpak” used in European countries. Letpak is extruded and laminated with a PP-Al. foil material. The foil provides the necessary water vapour barrier property, smooth curved corners and good printing surface for multi colour designs. The ends are injection moulded and lined with the same type of laminate as used for the body. They are welded into palce by high frequency sealing. No tool is required to open the lid. The materials are heat resistant and suitable for food contact.The size and dimensions can be standardized to suit the distribution system and consumers need. In the similar fashion rasmalai can be packaged.

Presently sandesh, chhana-murki, etc. are packaged in paper carton or duplex board boxes. These traditional packages do not provide sufficient protection to the product from atmospheric contamination and manual handling. Consequently, the sweets soon lose their typical organoleptic characteristics such as flavour, body and texture,pick up foreign odors, become rancid, get oxidized and result in undesirable appearance due to the mould growth. Also sweets packed in these packages are not suitable for long distance transportation, as they do not provide adequate mechanical, physical and protective properties. The improved packages such as saran coated films, laminates having Al. foil; multi-layered co-extruded films,metallized polyester, etc. could be used for packaging of such sweets.

Packaging of Chhana

At present chhana is manufactured in rural households and packed in bamboo baskets lined with leaves or parchment paper and is locally sold to retailers engaged in the manufacture of confection. In eastern part of the country, chhana is also transported to far off places by immersing in chhana-whey containing earthen pots. These methods of packaging are not effective and adequate. During transport and handling the product gets heavily contaminated and deteriorates at faster rate.
 

There is a lack of appropriate packaging systems for chhana meant for marketing.The packaging material should protect chhana from heat, light, oxygen, microbial contamination, moisture loss, foreign odour, etc. The package should also be non-toxic. At best, vegetable parchment paper has been used for chhana packaging, but with limited success. Chhana packaged in tin cans and cellulose films/ LDPE and stored at 37oC has a shelf life of only three days. When poster-paper/ Al. foil/LDPE is used, refrigerated storage for chhana at 4-5oC is required. Chhana stored in tin cans showed the least chemical changes during storage at 37oC. Tin cans and poster-paper/ Al. foil/ LDPE also provided maximum protection against chemical deterioration as compared to other packaging material. The storage of chhana in different types of flexible packaging material tends to increase the water vapour transmission rates and oxygen transmission rates both at 5oC and 37oC. Polycel(300 and 150 gauge, coloured) is low cost and good packaging material for chhana.

Packaging of Paneer

The prominent traditional dairy products include paneer, chhana, milk sweets such as rasogulla, Burfi, peda, kalakand, gulab jamun, etc., dahi, mishti dahi, shrikhand,chakka, etc. These products are generally manufactured in small lots by private traders and halwais. Most of the preparations are labour intensive and rely on local inputs. Very little attention is paid to sanitary handling practices and packaging. Paneer is highly susceptible to microbiological and chemical changes. Therefore, its packaging, should protect it against microbiological and chemical spoilage, maintain quality and provide consumer convenience. In general, various packaging materials used for preserving paneer at refrigeration temperature include wax coated parchment paper, polyethylene pouches, flexible films, heat induced shrink films, and saran films. Flexible packaging films like polypropylene, retort pouches and co-extruded laminates hold a great promise for packaging paneer for longer period.

Packaging,Stroage,Common Deffects,Shelf Life and Preservation of Paneer and Chhana

The production of various indigenous milk products is largely confined to small entrepreneurs (halwais) in rural areas, the hygienic considerations are not being paid their due attention, and as a result most samples reveal gross contamination on analysis. Due to high heat treatment during preparation of these products, the microbial load is very low in fresh products. It is the post-processing/ manufacturing contamination during handling and storage which leads to sharp increase in the population of spoilage and pathogenic microorganisms. Packaging plays an important role in this context to protect and preserves the quality of the products for longer time. Packaging also appeals to, or attracts the customers, thus helps in selling of the product. In recent years rapid developments are taking place in the mode of packaging of dairy products. Today most of the dairy products in western countries are being sold in flexible packages, like paper carton, plastic pouches, laminates, moulded containers, etc. because of the advantages, flexible packages offer over the conventional type of packages. The flexible packages are light in weight, thus reducing the cost of transportation, can be used for single-service, are easy to carry home,suitable for super market display most economic and can be made attractive.

Defination and Methods of Manufacture of Chhana Murki

i.Definition

Chhana-murki is a sugar-coated chhana based sweet. This product is very popular in the northern parts of the country. It is mainly served during weddings and feasts.Chhana-murki has the shape of small cubes coated with sugar and has a firm body and close-knit texture. Buffalo milk is preferred for the preparation of this sweet.

 

ii.Method of Manufacture

Chhana or paneer is cut into small cubes of about 10 mm. The cubes are cooked in boiling sugar syrup (of 3 strings consistency) in an open vessel (karahi) for about five minutes with gentle stirring. The vessel is removed from the fire and stirring is continued till the sugar is coated uniformly around the cubes. The cooked cubes are then removed from syrup. After cooling, a few drops of Kewara flavour are sprinkled.The product may be coloured using food grade colours in sugar syrup. The final product contains moisture 13.3, fat 17.4, protein 11.6, sugar 56.1 and ash 1.6 per cent. The flow chart for manufacture of chhana murki is presented in Fig.

Flow chart for manufacture of chhana murki

Defination and Methods of Manufacture of Rasmalai

i.Definition

Rasmalai is a chhana based sweet prepared essentially by suspending flat circular shaped rasogulla in sweetened condensed milk. Rasmalai is popular all over India,particularly in eastern and northern parts. It is a very delicate, spongy and chewy sweet that has a delectable taste. It is also flavoured with saffron and pista. Theproduct is refrigerated and served chilled.

 

ii.Method of Manufacture

Milk is heated with continuous stirring in open pan to evaporate to about one-half of its original volume. At this stage sugar is added at the rate of 4.0 per of original milk.The heating and stirring is continued at slow fire till the content is reduced to about one-third of its original volume. The addition of sugar during heating imparts pleasant flavour and palatable taste to the end product. Subsequently, flat circular shape rasogulla is added to this concentrated milk and content is further heated for few minutes (2-5 min). Thereafter, the container is removed from the fire and content is allowed to cool to room temperature, chilled and stored under refrigeration. The product is served chilled. Rasmalai has limited shelf life of 3-5 days. The flow chart for manufacture of Rasmalai is presented in Fig.

Flow chart for manufacture of chhana murki

Defination and Methods of Manufacture of Sandesh

Sandesh is the most popular chhana based sweet delicacy of the eastern parts of India, especially West Bengal where there is a traditional custom to send some “Sandesh” along with a good message to relatives and friends. Utilization of chhana for sandesh production is greater than for all other Bengali sweets, including rasogulla.It is reported that about 80 per cent of chhana produced in Kolkata is converted into sandesh.

Sandesh is known for its taste, palatability, and aroma and as a rich source of milk proteins, fat, sucrose, and fat-soluble vitamins. It has firm body and smooth texture.Several varieties of sandesh are sold in the market and each variety differs in appearance, flavour, body & texture, palatability and composition. Three distinct varieties of sandesh are popular: soft grade (naram-pak), hard grade (kara-pak)and raw grade (Kachagola). The most common variety is the soft grade sandesh,which has a soft body and smooth texture with fine grains. It contains a relatively smaller amount of sugar and has higher moisture content than the hard grade sandesh.Kara-pak has a firm body and dry appearance. Kachagola possesses raw-chhana like flavour, moist appearance, soft body and coarse, grainy texture. One more variety, known as Nolan gur sandesh is prepared from Khajur gur (date jaggery).It is considered a novel delicacy and fetches premium price.

 i.Sandesh from cow milk

Cow milk is standardized to 4.0 per cent fat and thereafter chhana is prepared by coagulation at 80oC using 2.0 per cent citric acid solution or pasteurized sour whey.Chhana is kneaded or ground into smooth paste and divided into two equal lots.Ground sugar, at the rate of 30 per cent of total weight of chhana is mixed with one lot of chhana. The mixture is then slowly cooked with continuous stirring and scrapping in a shallow vessel and the temperature is raised upto 75oC.When patting stage has reached the second lot of chhana is also mixed to it. Heating and scrapping of this mixture is continued till a final temperature of 60oC is attained. Thereafter, the mix is cooled to room temperature and moulded in desired shape and size. The production process of soft grade sandesh is presented in Fig .

 ii.Chhana Based Sweets

Sandesh from buffalo milk For making good quality sandesh from buffalo milk, the process for making chhana is slightly modified. The buffalo milk is standardized to 4.0 per cent fat and heated to boil. When boiling has attained, heating is discontinued and milk is diluted with water(30 per cent the volume of milk). The diluted milk is then coagulated at 70oC using 0.5 per cent citric acid solution or with sour whey. Whey is drained completely and chhana thus obtained is kneaded to smooth paste. The remaining steps are same as to that of cow milk sandesh production.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Flow chart for manufacture of sandesh

 

iii. Yield

The average yield of sandesh from cow and buffalo milk is about 16.50 and 20.50 per cent, respectively.

 

iv. Composition

The chemical composition of sandesh from cow and buffalo milk is given in table

Chemical composition of sandesh from cow and buffalo milk

The chemical profile of market samples of three types of sandesh is presented in
table 

Chemical profile of market sample of sandesh

Rasogulla

Rasogulla is undoubtedly the most popular traditional Indian milk sweet prepared from chhana. It is undisputed king not only of Bengali sweets, but also of all Indian sweets. This soft, sweetest ball of chhana soaked in sugar syrup has delighted the taste buds of millions of sweet loving clientele for more than hundred years. It is difficult to trace the origin and history of this sweet, however, according to a report; it was made for the first time in 1868 in Kolkata at a place known as “Bag-Bazaar” by a sweet confectioner – Mr. Nobin Chandra Das.

There are various types of rasogulla sold in the market. These include ordinary type,spongy variety, covered with syrup and diabetic rasogulla. Spongy rasogulla differs in terms of taste, texture, body and succulence as compared to ordinary rasogulla.Diabetic rasogulla is prepared by replacing sucrose with low caloric sweetness or with alcoholic sugar such as sorbitol to cater the need of people suffering from diabetes or health conscious consumers. The Bureau of Indian Standards (BIS) has laid down the standards for rasogulla, which are presented in Table.

BIS standard for rasogulla

 i.Method of preparation

Rasogulla is prepared from soft and freshly made chhana. Cow milk is preferred for the production of rasogulla because it gives soft, spongy and juicy product. Use of chhana made from buffalo or mixed milk is avoided because of its somewhat hard body and coarse and grainy texture. As such buffalo milk chhana is not suitable for rasogulla making. Now attempt have been made to develop new method for production of rasogulla from buffalo milk.For rasogulla production, chhana is kneaded to a smooth paste and then small balls of about 15-20 mm diameter and 10-12 grams in weight are made. The surface of balls should be smooth and free from of any cracks. In case of buffalo milk chhana,arrowroot, semolina, and baking powder are mixed and kneaded manually to a smooth paste. One kg of chhana yields about 90-100 rasogullas. Rasogulla balls are cooked in sugar syrup having 50-60 per cent sugar concentration for about 15-20 minutes. During cooking, a small amount of water is continuously added to maintain sugar concentration. This makes up for the loss of water due to evaporation. About 10 per cent of cooking solution is replaced by fresh one, every time it is reused to cook another batch of rasogullas. After cooking rasogulla, balls are soaked in 40-45 per cent sugar syrup for about 1-2 hours. The rasogulla balls are cooled to room temperature and finally stored at refrigeration temperature. The flow diagram for manufacture of rasogulla from cow milk and buffalo milk is presented in below  Figs.  respectively.

  ii.Rasogulla Mix Powder

In order to meet the demand of rasogulla round the year and also to make the product available at place of scarcity, R&D studies have been undertaken to develop a process for production of dried rasogulla mix. Skim milk is concentrated to desired total solids level by using ultrafiltration process. The retentate is standardized for desired level of fat using cream. This mixture is spray dried. Certain additives and binders are dry blended in the standardized retentate powder to yield dried rasogulla mix. Rasogulla prepared from mix powder is reported to yield good flavour and soft and spongy body & texture.

  iii. Yield

The yield of rasogulla is about 260 grams per 100 grams of cow milk chhana. In case of buffalo milk, the yield of rasogulla is about 240 grams/100 grams of chhana.

Flow chart for manufacture of rasogulla from cow milk

Flow chart for manufacture of rasogulla from buffalo milk

Chhana Based Sweets

Chhana is used as a base and filler for the preparation of a large number of Bengali sweets such as rasogulla, sandesh, rasmalai, rajbhog, chhana murki, cham-cham, etc. In chhana-based sweets, milk protein constitutes the basis of structure and texture of the product. Depending on the texturization process adopted during the production, the milk protein imparts different characteristics to the final product.The end product may be fibrous and chewy with good water holding characteristics such as rasogulla and rasmalai and on the other hand end product may be soft, hard and grainy with low water binding properties such as chhana murki. The textural characteristics of the end product can be manipulated by including small amounts of additives such as starch, flour, amylase, CMC, etc. The milk fat also influences the textural profile as well as the flavour of the end product

Yield of Paneer and Chhana

The yield of paneer and chhana is largely depend upon the total solids content of
milk, type of milk, manufacturing conditions and moisture retained in the paneer and chhana. Normally, the average yield of chhana is about 20 per cent from cow milk and about 25 per cent from buffalo milk. The yield of paneer depends on the fat and solids-not-fat content of milk, manufacturing conditions and moisture, fat retained in the paneer. An average yield of about 19-20 percent for buffalo milk and about 16- 17 per cent for cow milk is generally obtained.

Type of Chhana

i.Cow Milk Chhana

For chhana production, cow milk is preferred since it yields a soft-bodied and smooth textured product, which is highly suitable for preparation of high-grade chhana sweets such as rasogulla, sandesh, etc. Cow milk is standardized to 4.0 per cent fat. The milk is heated to near boiling without holding. Thereafter, the temperature of milk is brought down to 82oC and coagulated at this temperature using coagulating acid solution of 1-2 per cent concentration. Acid solution is added to milk with constant stirring till clear whey separated out. The coagulated mass collected in a muslin cloth and hung up for complete drainage of whey. Finally chhana is packaged in suitable packaging material and stored under refrigeration/ cold store. The flow chart for manufacture of cow milk chhana is presented in Fig.

Flow chart for manufacture of cow milk chhana

ii.Chhana from Buffalo Milk

As mentioned above cow milk is an ideal raw material fro chhana making because it yields soft body and smooth textured product which is suitable for chhana based sweets. Buffalo milk, because of many inherent differences in physico-chemical make-up than that of cow milk, poses many technological problems in preparation of good quality chhana and chhana-based sweets. As such buffalo milk yields hard body and coarse textured product, which is not desirable for chhana and chhana based sweets.In order to utilize buffalo milk for chhana making, various technological modifications have been made viz. admixing of cow and buffalo milk (75 parts cow and 25 part buffalo milk), incorporation of additives (sodium dihydrogen phosphate, disodium hydrogen phosphate, CMC, guar gum, sodium citrate, sodium alginate, etc.), dilution of buffalo milk with 25 per cent water (v/v), and homogenization of milk. A method has been developed at National Dairy Research Institute, Karnal for production of chhana for rasogulla making. The standardized method involve: standardization of buffalo milk to 5.0 per cent fat and heating to boiling temperature, addition of 0.05 per cent sodium alginate followed by filtration and cooling to 40oC. Thereafter, the milk is coagulated with 1.0 per cent citric acid solution. The coagulated mass is collected and pressed employing a pressure of 0.05 kg/cm2 to achieve desired quality.

The flow chart for manufacture of buffalo milk chhana is presented in Fig. 6.4.

Flow chart for manufacture of buffalo milk chhana

Methods of Manufacture of Chhana

Chhana making is essentially a process involving destabilization of casein particle by acidification of milk with dilute acid at relatively higher temperature. Acidification affects the stability of casein directly by disturbing the charges carried by the particles and indirectly by releasing the calcium ion from colloidal calcium phospho caseinate.

The destabilization results in formation of large aggregates from the normal colloidal dispersion of casein micelles in which milk fat, serum proteins and other constituents get entrained together. Thus, the large structural aggregates formed is known as coagulum.

 

i.Traditional Method

Milk for chhana making is brought to boil by heating it directly in a large iron karahi over an open fire with continuous stirring to prevent burning. This hot milk is ladled out in batches of about 1-1.5 litre in a separate coagulation vessel and adequate amount of coagulant solution normally cleansed sour chhana-whey is added to it while gentle stirring the contents. After complete coagulation, the contents is poured over a piece of clean muslin cloth stretched over another vessel. The process is repeated till all the milk is used up. The cloth containing the coagulated mass is then removed, tied into a bundle and hung up to drain out the whey completely without applying any external pressure.

 

ii.Bulk Method

In this method, the same steps are followed as mentioned above except instead of small lots of 1-1.5 litres, all the milk (normally 5-20 litres) is coagulated in one bulk.Coagulant solution is added slowly with uniform constant stirring till clear whey separate out. The coagulated solid mass is collected by straining it through a muslin cloth.

 

iii.Improved Method

The method of production of chhana remains the same as mentioned above with some improvements. These involve consideration of equipment, quality of milk,conditions of coagulation and method of straining etc. In this process boiling, cooling,coagulation of milk are accomplished in the same steam jacketed stainless steel kettle by employing steam or tap water as and when required, coagulation of milk is carried out at 80oC by adding 1-2 per cent citric acid solution (pH of coagulation 5.4). The coagulant solution is added with in 30-60 seconds and while addition of coagulant a slow stirring is preferred so as to avoid foam formation and also breakage of curd into fines. After attaining complete coagulation of milk the coagulated mass is strained as mentioned above.

 

iv. Continuous Method

In order to overcome problems of small scale, attempts have been made to mechanize chhana production. A prototype machine with a capacity of 40 kg chhana per hour has been developed at NDRI, Karnal. The major components of the equipment are a balance tank, injection chamber, tubular heat exchanger, cooling chamber,mechanized strainer, whey tank etc. In this mechanized process,standardized cow milk is pumped from a balance tank at the rate of 250-litres/ hour to an injection chamber where culinary live steam is directly injected into the milk. Steam gets completely condensed in milk and raises its temperature to 90-95oC. Thereafter,milk is brought in contact with coagulant solution, the quantity of which is regulated manually in proportion to the rate of flow of milk. The mixture of milk and coagulant is circulated through a holding coil to facilitate complete coagulation of milk. The coagulated product, along with the whey is then pumped to a double-jacketed cooling tank, where it is cooled down to room temperature. Finally, the coagulated mass is directed to a mechanical strainer, a double jacketed inclined sieve, where it is drained thoroughly. Chhana with 55-65 per cent moisture is discharged through the outlet and collected in the basket. Drained whey is transferred to a separate tank for subsequent use. Finally the chhana is packaged in suitable packaging material and stored in cold room.

Methods of Manufacture of Paneer

The manufacture of paneer involves standardization of milk, heat treatment,coagulation, draining of whey, pressing, dipping in chilled water and packaging.

  i.Buffalo Milk Paneer

Buffalo milk is an ideal raw material for manufacture of good quality paneer. Buffalo milk is standardized to a fat level of 5.8 to 6.0 per cent using fresh buffalo skim milk.The standardized milk is heated to 90oC without holding. Thereafter, the temperature of milk is brought down to 70oC and coagulated at this temperature using 1 per cent citric acid solution. The temperature of citric acid solution is also maintained at 70oC.Citric acid solution is added with continuous stirring till clear whey separate out.After complete coagulation, the stirring is stopped and the coagulated mass (curd) is allowed to settle down for about 5 minutes. The whey is then drained through stainless steel strainer. The temperature of the content is not allowed to drop below 63oC until this stage. The curd is collected and filled in hoops (with holes on all its sides to facilitates the expulsion of whey) lined with clean fine cloth. The hoops containing curd is pressed for about 10-20 minutes. Thereafter, the pressed block of curd is removed, cut into pieces and immersed in chilled water of 5-6oC for about 2 hours.

Dipping of paneer pieces facilitates cooling of product and also it absorbs moisture and improves the body and texture of paneer. The chilled pieces of paneer are then removed from water and placed on wooden planks for 10-15 minutes to allow loose water to drain. The paneer is cut into desirable size and packaged in suitable packaging material. Finally it is stored under refrigeration till marketing and consumption. The flow chart for manufacture of buffalo milk paneer is given in Fig

Flow chart for manufacture of paneer from buffalo milk

ii.Cow Milk Paneer

Cow milk is standardized to a fat level of 4.5 to 5.0 per cent using fresh cow cream.To this milk calcium chloride is added at the rate of 0.05 to 0.10 per cent. The milk is heated to 90oC without holding. Thereafter, the temperature of milk is brought down to 85oC and coagulated at this temperature using 2 per cent citric acid solution.The citric acid solution is heated to 85oC prior to its addition to milk. Rest of the manufacturing process is same as in case of buffalo milk Paneer. The flow chart for manufacture of cow milk paneer is presented in Fig.

Flow chart for manufacture of paneer from buffalo milk

 

iii. Recombined Milk Paneer

The manufacture of paneer from recombined milk is not too difficult provided appropriate modifications are made to the standard paneer making techniques. The recombined milk is prepared by blending skim milk powder, with butter oil/ cooking butter/ cream and potable water. The milk is standardized to a fat and SNF content of 5.8 and 9.5 per cent, respectively using skim milk powder and fat from above mentioned sources. The standardized milk is suitably homogenized. The milk is kept aside fro 3-4 hours for complete interaction and hydration of milk constituents. The milk is heated to 90oC without holding. Prior to coagulation, 0.10 to 0.15 per cent calcium chloride is added to milk. The milk is coagulated using 10 per cent citric acid solution heated to 90oC. The citric acid solution is added with continuous stirringtill clear whey separated out. The remaining steps are same as employed incase of conventional paneer.

 

iv. Reconstituted Milk Paneer

The whole milk powder of good quality is required for manufacture of acceptable paneer. The low-heat milk powder is preferred for desirable quality paneer. The whole milk powder is dissolved in potable water at 50oC and kept aside for 3-4 hours for proper hydration of milk constituents. To this 0.1 to 0.15 per cent calcium chloride is added and then content is heated to 90oC without holding. The milk is coagulated with 10 per cent citric acid solution at 90oC. The remaining steps are the same as followed in case of conventional paneer making. Normally, the total solids content in reconstituted milk is kept higher (18-20% TS). The purpose of increasing the total solids level in milk is to reduce the bulk handling and also to reduce the requirements of coagulant, water, energy and labour for manufacture of paneer.

 

v. Filled Paneer

Filled paneer technology involves blending of skim milk with vegetable oils or vanaspati and coagulation of milk with suitable coagulant at desired temperature. Filled milk is prepared by homogenization/ blending/ mixing of skim milk with vegetable oil or vanaspati fat at 40oC. This milk is converted into paneer employing the remaining steps same as in conventional paneer making.

Methods of Manufacture of Paneer and Chhana

Paneer, the indigenous variety of soft cooking type cheese, is obtained by the heat and acid coagulation of milk at relatively higher temperature. The chemical and physical changes in casein and whey proteins brought about by the combined action of heat and acid treatments, form the basis of paneer making. When milk is acidified, the colloidal calcium phosphate in the casein micelles progressively solubilises and aggregation of the casein occurs as the isoelectric point is approached. In milk of normal pH, the casein micelles are stabilized by hydration and steric repulsion due to their negative charge. On acidification the micelles become unstable and aggregate as a result of charge neutralization, leading to the formation of chains and clusters that are linked together to give a three-dimensional network. In milks preheated at high temperatures (90oC), gelation occurs more rapidly at a higher pH than in unheated milk. Interaction of whey proteins with casein micelles on heating milk at its natural pH may increase the hydrophobicity of the micellar surface and reduce the hydration barrier against aggregation, thus allowing aggregation and gelation to occur at a higher pH than in unheated milk. Heating milk also results in dissociation of k-casein from micelles, and this could further sensitize the α-s-casein framework to calcium-induced aggregation. The development of typical rheological characteristics of paneer could be due to the intensive heat induced protein-protein interactions. Paneer manufacture essentially involves the formation co-precipitates due to complexing of whey proteins denatured by the heat and the casein. Serum proteins,particularly β-Lactoglobulin, are bonded to κ-casein via disulphide bridges and calcium linkages. The higher the degree of co-precipitation, the greater will be the total solids recovery and yield of paneer.

Factors Affecting Quality of Chhana

Cow milk is preferred for chhana making because it yields soft and spongy body and smooth textured product, which is suitable for making chhana based sweets.Buffalo milk, because of many inherent differences in physico-chemical make-up than that of cow milk, poses, many technological problems in preparation of chhana and chhana based sweets. The quality of chhana depends mainly on the initial composition of milk, type and quality of milk, the conditions of coagulation, the technique of straining/pressing and the losses of milk solids in the whey.

 

i.Type of Milk

Cow milk produces chhana with moist surface, light yellow colour, soft body, smooth texture and mildly acidic flavour. Cow milk chhana is more suitable for Bengali sweets preparation than buffalo milk chhana; the latter being hard in body and coarse in texture, besides whitish in colour and a greasy surface. Sweets particularly rasogulla prepared from buffalo milk chhana are comparatively hard, coarse and less spongy. Goat milk can also be converted into acceptable quality chhana, which is suitable for sweet preparation.

 

ii.Quality of Milk

Minimum fat level of 4 per cent in cow milk and 5 percent in buffalo milk is necessary for producing good quality chhana. The low fat milk results in a hard body and coarse texture in chhana, whereas higher fat level is also not desirable as it produces greasiness and stickiness in the chhana sweets. For manufacture of good quality chhana sweet milk (fresh milk is the best suitable raw material, as developed acidity or sour milk tends to produce too acidic flavour and bitter taste, which makes it unsuitable for preparation of sweets). The addition of neutralizer to acidic milk,however, helps in obtaining chhana which can be satisfactorily used for making sandesh of an acceptable quality. The adulteration of milk with starch results in a gelatinous mass on coagulation, which is undesirable for sweet making. The mixing of colostrum in milk tends to produce a weak and pasty body and texture in the coagulated mass, which exhibits its unsuitability for sweet making.

 

iii. Type and Strength of Coagulant

The body and texture of chhana is influenced by the conditions of coagulation such as pH of coagulation, strength of coagulating solution, type of acid, speed with which the milk is stirred during coagulation and temperature and time of coagulation.In order to obtain desirable body and texture milk should be sufficiently heated to near the boiling temperature for better protein-to-protein interaction. The optimum pH of coagulation of milk is around 5.4 and the temperature of coagulation is about 82oC. The coagulation of milk should be effected within one minute with gentle stirring. A satisfactory strength of the coagulating acid solution is 1-2 percent. Lactic acid tends to produce a granular texture, which is desirable for rasogulla making,whereas, citric acid tends to produce a pasty product, which is suitable for Sandesh manufacture.

Generally organic acids like citric, lactic or their salts (calcium lactate), lemon juice and sour whey are used as coagulants. Sour whey with about 0.9 percent acidity is most widely used for chhana making. Calcium lactate is another commonly used coagulant.The concentration of coagulant solution is also an important factor which affects the quality of chhana. Low acid strength (0.5 percent) results in very soft body and smooth texture suitable for rasogulla but unsuitable for sandesh making, while high acid strength (8 per cent) results in hard body and less smooth texture, suitable for sandesh making but not for rasogulla. The optimum strength of coagulant solution should be between 1 to 2 per cent citric acid or lactic acid to produce good quality chhana suitable for making both kinds of sweets. To get a satisfactory quality chhana from buffalo milk, 1 per cent citric acid solution or 0.5 per cent lactic acid solution is recommended. Sour whey of 0.9 per cent acidity is suitable for chhana making. Six per cent calcium lactate solution produces most satisfactory quality chhana.The amount of coagulant required to achieve optimum coagulation depends upon the type of milk as also on its acidity and buffering capacity. Usually, 2.5 to 3.5 g of citric acid or 3.0 to 3.9 g of lactic acid per litre of milk is necessary for complete coagulation. The requirement of acid is lower in case of buffalo milk. Nearly 600 ml of sour whey is needed to produce suitable quality chhana from 1 litre of milk. The quantity will largely depend upon the extent of acidity developed in the sour whey.About 6 to 12 g of calcium lactate is required per kg of milk for coagulation, depending on the coagulation temperature.

 

iv. Coagulation Temperature

Chhana of satisfactory quality from cow milk can be obtained at a coagulation temperature of about 82oC. The optimum coagulation temperature for making chhana from buffalo milk is around 50oC. The amount of coagulant required for completing the coagulation of milk is increased with the lowering of coagulation temperature. As the coagulation temperature decreases, the moisture retention in chhana increases leading to its softer body and smoother texture.

 

v. pH of Coagulation

The optimum pH for chhana making from cow and buffalo milk is 5.4 and 5.7 respectively. The pH of coagulation principally regulates the moisture content and the body and texture which are best obtained at the above pH. An optimum pH of 5.35 has been reported when making chhana from cow milk using calcium lactate as coagulant. Higher speed of stirring during coagulation reduces the moisture content in chhana and increases its hardness, whereas with lower speed the reverse holds true. Slow stirring (40-50 rpm) is preferred to avoid foam formation.

 

vi. Method of Straining

The method of straining of coagulated mass effect the body and texture of paneer,moisture retention and solids recovery in chhana. The coagulated mass should be collected in fine cloth and hung to remove moisture.In case of chhana external pressure is not applied for removal of moisture from the coagulated mass. Method of straining is an important factor which affects the body and texture of chhana by influencing the moisture retained in it. In general two types of straining is employed viz. immediate or delayed. Immediate straining is carried out by promptly gathering the coagulated mass and tying it up in a piece of fine cloth and then hung up for draining out the whey and cooling the chhana. In case of delayed straining process, the coagulated mass is left in the whey either as such or loosely enclosed in a piece of cloth, so as to cool it to ambient temperature and thereafter it is hung for removal of whey. The delayed straining results in more retention of moisture in chhana as compared to immediate straining method. Delayed straining produces a comparatively soft and smooth texture chhana than immediate straining.Higher moisture, increased yield, improved recovery of milk solids and lower hardness in chhana is obtained when delayed straining is employed. Chhana made by delayed straining process is useful for rasogulla making and is particularly recommended for buffalo milk chhana production.