1. _____ involves quite a number of stages. The continuous butter maker has become the most common type of equipment used.
The cream can be either supplied by a fluid milk dairy or separated tram whole milk by the butter manufacturer. The cream should be sweet (pH > 6.6; TA = 0.10…0.12 %), not rancid and not oxidized.
2. _____ by the butter manufacturer, the whole milk is preheated to the required temperature in a milk pasteurizer before being passed through a separator. The cream is cooled and led to a storage tank where the fat content is analyzed and adjusted to the desired value, if necessary. The skim milk from the separator is pasteurized and cooled before being pumped to storage. It is usually destined for concentration and drying.
3. _____ tanks, the cream goes to pasteurization at a temperature of 95 °C or more. The high temperature is needed to destroy enzymes and micro-organisms that would impair the keeping quality of the butter.
If ripening is desired for the production of cultured butter. The colder the temperature during ripening the more the flavor development relative to acid production. Ripened butter is usually not washed or salted.
4. _____, the cream is subjected to a program of controlled cooling designed to give the fat the required crystalline structure.
The program is chosen to accord with factors such as the composition of the butterfat expressed, for example, in terms of the iodine value which is a measure of the unsaturated fat content. The treatment can even be modified to obtain butter with good consistency
despite a low iodine value i.e. when the unsaturated proportion of the fat is low.
5. _____ takes 12 – 15 hours. From the aging tank, the cream is pumped to the chum or continuous butter maker via a plate heat exchanger which brings it to the requisite temperature. In the churning process the cream is violently agitated to break down the fat
globules, causing the fat to coagulate into butter grains, while the fat content of the remaining liquid, the buttermilk, decreases.
6. _____ is split into two fractions: butter grains and buttermilk. In traditional churning, the machine stop when the grains have reached a certain size, whereupon the buttermilk is drained off. With the continuous butter maker the draining of the buttermilk is also
continuous.
7. _____, the butter is worked to a continuous fat phase containing a finely dispersed water phase. It used to be common practice to wash the butter after churning to remove any residual buttermilk and milk solids but this is rarely done today.
8. _____ to improve the flavor and the shelf-life, as it acts as a preservative. If the hotter is to be salted, salt (1…3 %) is spread over its surface, in the case of batch production. In the continuous butter faker, a salt slurry is added to the butter. The salt is all
dissolved in the aqueous phase, so the effective salt concentration is approximated 10 % in the water.
9. _____, the butter must be worked vigorously to ensure even distribution of the salt. The working of the butter also influences the characteristics by which the product is judged – aroma, taste, keeping quality, appearance and color. Working is required to obtain
|
|
a homogenous blend of butter granules, water and salt. During working, fat moves from globular to free fat. Water droplets decrease in size during working and should not be visible in properly worked butter. Overworked butter will be too brittle or greasy depending
on whether the fat is hard or soft. Some water may be added to standardize the moisture content. Precise control of composition is essential for maximum yield. The finished butter is discharged into the packaging unit, and from there to cold storage.
E x e r c i s e T w o. Mark whether the statements below are true or false:
1. Milk fat is comprised only of triglycerides.
2. The triglycerides (98 % of milk fat) are of diverse composition with respect to their component fatty acids.
3. The globule membrane is comprised of surface active materials: phospholipids, glycolipids, and lipo-proteins.
4. Many milk products hardly ever foam.
5. Fats tend to spread over the air-water interface and destabilize the foam.
6. Disruption of the fat globule by interaction between the fat globule and air bubbles is frequent.
7. Milk fat is essential for the formation of stable whipped products.
8. When cream is beaten air cells form more slowly partly because of lower viscosity.
9. Churning does not occur at hot temperature.
10. If beating continues the fat clumps increase in size.
The background science of butter churning
The fat globule
Milk fat is comprised mostly of triglycerides, with small amounts of mono- and diglycerides, phospholipids, glycolipids, and lipo-proteins. The triglycerides (98 % of milk fat) are of diverse composition with respect to their component fatty acids;
approximately 40 % of which are unsaturated fat firmness varies with chain length, degree of instauration, and position of the fatty acids on the glycerol. Fat globules vary from 0.1 – 10 micron in diameter. The globule membrane is comprised of surface active
materials: phospholipids and lipoproteins, Fat globules typically aggregate in three ways: flocculation, coalescence, partial coalescence.
Whipping and Churning
Many milk products foam easily. Skim milk foams copiously with the amount of foam being very dependent on the amount of residual fat – fat depresses foaming. The foaming agents are proteins, the amount of proteins in the foam are proportional to their contents in milk. Foaming is decreased in heat treated milk, possibly because denaturated proteins produce a more brittle protein layer at the interface. Fats tend to spread over the air-water interface and destabilize the foam; very small amounts of fats (including phospholipids) can destabilize a foam.
|
|
During the interaction of fat globules with air bubbles the globule may also be disrupted (this is the only way that fat globules can be disrupted without considerable energy input). Disruption of the fat globule by interaction between the fat globule and air
bubbles is rare except in the case of newly formed air bubbles where the air-water interfacial layer is still thin. If part of the fat globule is solid, churning will result, hence the term "flotation churning" – from repeated rupturing of air bubbles and resulting
coalescence of the adsorbed fat.
In spite of the above comments on the destabihzation of foams by fat, milk fat is essential for the formation of stable whipped products which depend on the interaction between fat globules, air bubbles and plasma components (esp. proteins).
When cream is beaten air cells form more slowly partly because of higher viscosity and partly because the presence of fat causes immediate collapse of most of the larger bubbles. If most of the fat is liquid (high temperature) the fat globule membrane is not
readily punctured and churning does not occur at cold temperature where solid fat is present, churning (clumping) of the fat globule takes place. Clumps of globules begin to associate with air bubbles so that a network of air bubbles and fat clumps and globules form
entrapping all the liquid and producing a stable foam.
If beating continues the fat clumps increase in size until they become too large and too few to enclose the air cells, hence air bubbles coalesce, the foam begins to "leak" and ultimately butter and butter milk remain.
E x e r c i s e T h r e e. Choose the best phrase from the given below to fill each of the gaps:
So by modifying the cooling program; The more violent the cooling process; heat treatment; Before churning; low-melting fatty acids; the other hand; In the former case; to their surface by adsorption; If cooling is rapid; A soft milk fat; is always subjected; The consistency of butter.