No preservatives except common salt and no colouring matter except annatto and carotene may be added. It should be free from other animal fats, wax, and mineral oils,vegetable oils and fats. Storage of cream at 5 ° C or below to check the yeast growth.Īccording to the PFA rules (1976), table 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. Storage of cream at 5 ° C or below to check microbial growth. Storage of cream at 5 ° C or below to check the acid development.Ĭooked, feed and weed, rancid, oxidized etc.,ĭevelopment of by-products of growth of certain undesirable microorganisms Storage of cream at 5 ° C or below to check the bacterial growth. Growth of proteolytic bacteria leading to casein breakdown. Storage of cream at 5 ° C or below to check bacterial growth. Keeping milk properly covered during production.Ĭhecking lipase activity by avoiding the danger zone during 39-49 ° C during raw cream separation. Not keeping milk properly covered during production. Inactivating lipase by proper pasteurization of milk and cream. Proper tinning of milk or cream or cream holding vessels or using aluminum alloy or stainless steel as contact surface.įat hydrolysis due to lipase action in milk or cream. Using fresh, sweet milk for perpetration.įat oxidation due to direct contact of milk with copper or iron, exposure of milk or cream to sunlight etc. I) Feeding of milk-tainting feeds and weeds soon after milking Proper heating of cream during pasteurization.įeeding of milk-tainting feeds and weeds within 3 hours before milking Similarly the skim milk screw OUT results in richer cream and vice versa.Įxcessive heating of cream during preparation. Screwing OUT the cream screw produces thinner cream. Smaller proportions o cream is therefore discharged, which, containing the same quantity of fat, shows a higher fat percentage. This is because the force tending to discharge cream through the orifice is decreased while that tending to discharge skimmilk remains unaltered. Thus when the cream screw is IN towards the axis of rotation, a higher fat percentage in cream is obtained and vice versa. By altering the position of the cream screw or skim milk screw the ratio of skim milk to cream changes. Similarly the skim milk screw /outlet for the removal of skim milk, once the cream screw or skim milk screw has been adjusted, the cream separator delivers, under normal conditions, a definite ratio of skim milk and cream, which is usually90:10 (or 85:15) by volume. This screw can be driven IN and OUT thus bringing it nearer to and away from, the center of rotation. The cream screw /outlet consists of a small threaded, hollow screw pierced by a circular orifice thorough which the cream emerges. The important factors that influence the fat percentage of cream by centrifugal cream separation methods are R= distance of fat globule from the axis of rotation.įactors influencing the fat percentage of cream Stokes’s law applied to centrifugal separation is as follows R= radius of the circle in which body revolves., The separator is a precision instrument andhence has to be in good condition and operated properly to get maximum skimming efficiency. Separator bowl operate at speeds as great as 20,000 rpm. Such material is deposited on this face of the bowl shell, which is removed latter. These pass along with the skim milk into the space between the outer edge of the discs and the inner face of the bowl shell.
The rate of rise of fat globules in gravity methods is affected byĪny insoluble particles in the milk, such as bits of curd or dirt etc., collects as ‘separator slime’ and is thrown outward as the bowl operates.
V = velocity or rate at which a single fat globule risesĪpplying the stokes law it can be observed that theoretically,velocity is increased byIncrease in radius of fat globules:Increase indifference in densities of skim milk and fat, Decrease in viscosity of skim milk. When the milk is allowed to stand undisturbed for some time,there is a tendency for the fat to rise is given by he following equation,which is known as Stokes Law: Hence when milk is subjected to centrifugal force, the two components, viz., cream and skim milk,gets separated. The average density of milk fat is 0.93 and skim milk is 1.036. The basic principle of cream separation is based on the fact that milk fat is lighter than the skim milk portion (difference in densities). % SNF in cream = (100 - % fat in cream / 100 - % fatin milk) X % SNF in milkĬream can be separated from milk by either ‘gravity’ or‘centrifugal separation’ methods. T he solids not fat (SNF) content of cream can be determined by