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Butter acts as a balance wheel of dairy industry. Whenever surplus milk is produced, it is usually converted in to butter. During the periods of scarcity, the milk meant for butter production would be used for production of other essential items. References to the butter found a place in the Old Testament.

Butter may be defined as a fat concentrate, obtained by churning cream, gathering the fat into compact mass and then working it.

According to the PFA rules (1976), table or creamery butter is the product obtained from cow or buffalo milk or a combination there of, or from cream or curd from cow or buffalo milk or a combination thereof with or without the addition of common salt and annatto or carotene as colouring matter. It should be free from other animal fats, wax, and mineral oils, vegetable oils and fats. No preservatives except common salt and no colouring matter except annatto and carotene may be added.

Butter must contain not less than 80 % by weight of milk fat, not more than 1.5 % by weight of curd, and not more than 3% by weight of common salt. Diacetyl may be added as a flavouring agent but if so used the total diacetyl content must not exceed 4 ppm. Calcium hydroxide, sodium carbonate, sodium polyphosphate may be added, but must not exceed the weight of butter as whole by more than 0.2 %. These are the standards prescribed for butter as per the PFA rules. It is very rich in fat and fat soluble vitamins A, D, E and K.

DETAILS OF MANUFACTURE OF BUTTER

In order to prepare butter, the raw material cream is essential. It is unloaded from the cans, graded, sampled, weighed and tested for its quality. If sour cream is used as source of raw material, it has to be necessarily neutralized using a suitable alkali such as lime (calcium hydroxide and magnesium hydroxide) and soda (caustic soda, sodium carbonate, sodium bicarbonate and sodium sesquicarbonate). Pasteurization of cream is done by either holder method (LTLT) in which the cream is usually heated to 71'C for 20 min and then promptly cooled or HTST method of pasteurization may be done at 95 - 100'C for 15 sec.

Cream ripening is done to achieve a butter with a pleasing flavour and aroma uniformly from day to day and to obtain an exhaustive churning, i.e., a low fat loss in buttermilk. Ripening is done at a temperature of 20-22'C for 16 hours using lactic cultures such as Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris together with aroma (diacetyl) producers such as Lacotcoccus lactis subsp. lactis biovar diacetylactis, Leuconostoc mesenteroides subsp. dextranicum and / or L. citrovorum, in correct proportions.

Sometimes, synthetic flavours or starter distillate are mixed with sweet cream butter during the working process to impart the characteristic flavour to the ripened cream butter or to the finished product. One way of improving flavour is to increase the citric acid content of cream or milk before fermentation begins.

Churning of cream consists of agitation at suitable temperatures until the fat globules adhere, forming larger and larger masses and until a relatively complete separation of fat and serum occurs. The fat exists in the form of emulsion i.e. in a continuous phase. This emulsion is fairly stable. As long as it remains intact, there is no formation of butter. After the completion of churning, the fat globules will coalesce in to a compact mass.

After draining the buttermilk, the compact mass is washed with potable cool water. Then salt is added in the form of fine powder or in the form of concentrated salt solution at the rate of 2.0 - 2.5% of butter fat. Then butter granules are worked by kneading. Kneading helps to completely dissolve, uniformly distribute, properly incorporate the salt. It also aids in expulsion of buttermilk and to control the moisture content of the product.

The storage temperature of the product ranges from -23 to -29'C. There is invariably some flavour deterioration of the product during commercial cold storage; thus a fishy off flavour develops in salted acid butter when stored for a prolonged period.

Uses of butter

It can be used for direct consumption, in the preparation of sauces, as a cooking medium, in the baking and confectionery industries and in the manufacture of ice cream. It is also used in the manufacture of butteroil and ghee and in the production of reconstituted milk.