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.