Heat Treatment of Milk
Heat treatment is an energy transfer 0f heat into milk. Heat treatment is often referred to as “heating,” leading to terms of heat treatment processes.
Energy requirement is necessary for heating the milk.
The objective of the heat treatment is to completely inactive all microorganisms which are contained in milk.
Primarily, heat treatment is a hygiene oriented activity within the entire framework of processing.
On the other hand, it is a dominant factor for improving the shelf life of all fresh milk products and is a legal obligation.
The most common thermal process, not only in diary technology, is pasteurization.
Pasteurization is the thermal inactivation of microorganisms at the temperature below 100 degree C, which improves the hygienic quality of food and achieves a certain level of preservation.
Heat Treatment of Milk
Wednesday, November 4, 2009
Saturday, October 17, 2009
Physical and Properties of Milk
Physical and Properties of Milk
Milk is a white or yellow, opaque liquid. The color is influenced by scattering and absorption of light by milk fat globules and protein micelles.
Therefore, skim milk also retains its white color.
A yellowish, i.e., yellow-green, color is derived from carotene (ingested primarily during pasture grazing) present in the fat phase and from riboflavin present in the aqueous phase.
Milk tastes mildly sweet, while its odor and flavor are normally quite faint.
Milk fat occurs in the form of droplets or globules, surrounded by a membrane and emulsified in milk serum (also called whey).
The fat globules (called cream) separate after prolonged storage or after centrifugation. The fat globules float on the skim milk.
Homogenization of milk so finely divides and emulsifies the fat globules that cream separation does not occur even after prolonged standing.
Proteins of various sizes are dispersed in milk serum. They are called micelles and consist mostly of calcium slats of casein molecules.
Furthermore, milk contains lipoprotein particles, also called milk microsomes, which consist of the residues of cell membranes, microvilli, etc., as well as somatic cells, which are mainly leucocytes.
Various proteins, carbohydrate, minerals and other ingredients are solubilized in milk serum.
The specific density of milk decreases with increasing fat content, and increases with increasing amounts of protein, milk sugar and salts.
The specific density of cow’s milk ranges from 1.029 to 1.039 (15 degree C).
Defatted (skim) milk has a higher specific density than whole milk.
The freezing point of milk is -0.53 to -0.55 degree C. This rather constant value is a suitable test for detection of watering of milk.
Physical and Properties of Milk
Milk is a white or yellow, opaque liquid. The color is influenced by scattering and absorption of light by milk fat globules and protein micelles.
Therefore, skim milk also retains its white color.
A yellowish, i.e., yellow-green, color is derived from carotene (ingested primarily during pasture grazing) present in the fat phase and from riboflavin present in the aqueous phase.
Milk tastes mildly sweet, while its odor and flavor are normally quite faint.
Milk fat occurs in the form of droplets or globules, surrounded by a membrane and emulsified in milk serum (also called whey).
The fat globules (called cream) separate after prolonged storage or after centrifugation. The fat globules float on the skim milk.
Homogenization of milk so finely divides and emulsifies the fat globules that cream separation does not occur even after prolonged standing.
Proteins of various sizes are dispersed in milk serum. They are called micelles and consist mostly of calcium slats of casein molecules.
Furthermore, milk contains lipoprotein particles, also called milk microsomes, which consist of the residues of cell membranes, microvilli, etc., as well as somatic cells, which are mainly leucocytes.
Various proteins, carbohydrate, minerals and other ingredients are solubilized in milk serum.
The specific density of milk decreases with increasing fat content, and increases with increasing amounts of protein, milk sugar and salts.
The specific density of cow’s milk ranges from 1.029 to 1.039 (15 degree C).
Defatted (skim) milk has a higher specific density than whole milk.
The freezing point of milk is -0.53 to -0.55 degree C. This rather constant value is a suitable test for detection of watering of milk.
Physical and Properties of Milk
Friday, September 18, 2009
The Origin of Milking
The Origin of Milking
For million of years, breast milk has been the first beverage. Replacement with animal milk carried tremendous implications and potential nutritional advantages.
The first irrefutable evidence for milking domesticated livestock and, by implication, human use of milk and the manufacture of dairy products, dates to approx 4000 BCE and is based on Stone Age rock art produced in the central Sahara region of Africa.
By 1500 BCE, milk use was widely distributed, and in India, many of milk’s qualities and already been described in the Charaka-Samhita.
“Cow milk has ten properties: sweet, cold, soft, fatty, viscous, smooth, slimy, heavy, dull and clear. Buffalo milk is heavier and colder than that from cow; useful to cure sleeplessness and excessive digestive power. Camel milk is rough, hot, slightly saline, light and prescribed for hardness in the bowels, works against worms... Milk from one-hooved animals (donkey; horse) is hot slightly, sour, saline, rough, light, promotes strength, stability, alleviates vata in extremities, Goat milk is astringent...”
Anthropologists, geographers and physicians have written on the physiologic and dietary implications of human using animal milk and use or nonuse o flavored particular societies.
With our ability to feed grass to livestock and the use of milk in its raw form or as fermented cheese, humans expanded into new areas of habitation and increased population density.
The majority of other human populations, following the standard mammalian pattern – lose the ability to maintain lactase production and therefore, cannot digest animal milks easily, a pattern evidenced by most Asians, West Africans, Southern European Mediterraneans and most Central and Southern American.
However, some human populations now maintain lactase production throughout their lives, a physiologic characteristic that links peoples and cultures as diverse as east African cattle pastoralist (the Masai, Suk, and Turkana) with northern European Scandinavians (e.g., Danes, Norwegian and Swedes).
Different cultures have widely diverging regarding the suitability of animal milks as human foods or beverages.
For some, it is question of identification: because animal milks are for the young of specific animal, it is wrong to mix these foods because the consumer may take on characteristics or the animal.
The Origin of Milking
For million of years, breast milk has been the first beverage. Replacement with animal milk carried tremendous implications and potential nutritional advantages.
The first irrefutable evidence for milking domesticated livestock and, by implication, human use of milk and the manufacture of dairy products, dates to approx 4000 BCE and is based on Stone Age rock art produced in the central Sahara region of Africa.
By 1500 BCE, milk use was widely distributed, and in India, many of milk’s qualities and already been described in the Charaka-Samhita.
“Cow milk has ten properties: sweet, cold, soft, fatty, viscous, smooth, slimy, heavy, dull and clear. Buffalo milk is heavier and colder than that from cow; useful to cure sleeplessness and excessive digestive power. Camel milk is rough, hot, slightly saline, light and prescribed for hardness in the bowels, works against worms... Milk from one-hooved animals (donkey; horse) is hot slightly, sour, saline, rough, light, promotes strength, stability, alleviates vata in extremities, Goat milk is astringent...”
Anthropologists, geographers and physicians have written on the physiologic and dietary implications of human using animal milk and use or nonuse o flavored particular societies.
With our ability to feed grass to livestock and the use of milk in its raw form or as fermented cheese, humans expanded into new areas of habitation and increased population density.
The majority of other human populations, following the standard mammalian pattern – lose the ability to maintain lactase production and therefore, cannot digest animal milks easily, a pattern evidenced by most Asians, West Africans, Southern European Mediterraneans and most Central and Southern American.
However, some human populations now maintain lactase production throughout their lives, a physiologic characteristic that links peoples and cultures as diverse as east African cattle pastoralist (the Masai, Suk, and Turkana) with northern European Scandinavians (e.g., Danes, Norwegian and Swedes).
Different cultures have widely diverging regarding the suitability of animal milks as human foods or beverages.
For some, it is question of identification: because animal milks are for the young of specific animal, it is wrong to mix these foods because the consumer may take on characteristics or the animal.
The Origin of Milking
Saturday, August 29, 2009
Lactose Intolerance
Lactose Intolerance
Many individual demonstrate a permanent loss of the enzyme used to digest the principal milk sugar lactose; they are lactose intolerant.
Lactose intolerance may be due to the absence of or insufficient amount of lactase, a birth deficit, or physical impairment.
Caucasian are among the few population groups who can digest lactose.
If lactase remains undigested by lactase in the intestine, it is fermented by microflora to short-chain fatty acids and gasses such as carbon dioxide, hydrogen, and in some individuals to methane.
Symptoms of lactose intolerance include flatulence, abdominal pain and diarrhea due to the high solute concentration of undigested lactose.
A correct understanding of tolerable dose is needed by the lactose intolerant individual and the food industry that develops lactose free food.
Lactose assists in the absorption of calcium, phosphorus, magnesium, zinc and other mineral from small intestine brush border.
Non-dairy “milk” such as soy or imitation milk contains no lactose; therefore, it may be consumed by individuals who milk allergies and by those who would otherwise not drink milk.
The loss of lactase activity in the intestine affects, to some extent, approximately 75% of the world’s population.
Individuals with lactase intolerance may compensate by consuming lactase treated milk (which reduces lactose by 70%) or purchase the lactase enzyme and administer it directly to milk prior to consumption.
It has been shown that small serving (120 ml = 6 g of lactose) of milk and hard cheeses (less than 2 g of lactose) may be consumed without an increase in intolerance symptoms.
Up to 12 g of lactose are tolerated, especially if the individual consumes other foods with the source of lactose.
Some fermented products, such as cheese, are tolerated if lactose has sufficiently been converted to lactic acid. Aged cheese is an example of such food.
Lactose Intolerance
Many individual demonstrate a permanent loss of the enzyme used to digest the principal milk sugar lactose; they are lactose intolerant.
Lactose intolerance may be due to the absence of or insufficient amount of lactase, a birth deficit, or physical impairment.
Caucasian are among the few population groups who can digest lactose.
If lactase remains undigested by lactase in the intestine, it is fermented by microflora to short-chain fatty acids and gasses such as carbon dioxide, hydrogen, and in some individuals to methane.
Symptoms of lactose intolerance include flatulence, abdominal pain and diarrhea due to the high solute concentration of undigested lactose.
A correct understanding of tolerable dose is needed by the lactose intolerant individual and the food industry that develops lactose free food.
Lactose assists in the absorption of calcium, phosphorus, magnesium, zinc and other mineral from small intestine brush border.
Non-dairy “milk” such as soy or imitation milk contains no lactose; therefore, it may be consumed by individuals who milk allergies and by those who would otherwise not drink milk.
The loss of lactase activity in the intestine affects, to some extent, approximately 75% of the world’s population.
Individuals with lactase intolerance may compensate by consuming lactase treated milk (which reduces lactose by 70%) or purchase the lactase enzyme and administer it directly to milk prior to consumption.
It has been shown that small serving (120 ml = 6 g of lactose) of milk and hard cheeses (less than 2 g of lactose) may be consumed without an increase in intolerance symptoms.
Up to 12 g of lactose are tolerated, especially if the individual consumes other foods with the source of lactose.
Some fermented products, such as cheese, are tolerated if lactose has sufficiently been converted to lactic acid. Aged cheese is an example of such food.
Lactose Intolerance
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