Submitted By
Shubham Dwivedi
Amit Kumar
Megha Mazumdar
Sangita

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Introduction
Milk is a white liquid produced by the mammary glands of mammals. It provides the primary source of nutrition for young mammals before they are able to digest other types of food. The early lactation milk is known as colostrums, and carries the mother's antibodies to the baby. It can reduce the risk of many diseases in the baby. The exact components of raw milk vary by species, but it contains significant amounts of saturated fat, protein and calcium as well as vitamin C. Cow's milk has a pH ranging from 6.4 to 6.8, making it slightly acidic.
Contains not less than 3.25 percent milk fat and 8.25 percent solids-not-fat. Addition of vitamins A and D is optional, but if added, vitamin A must be present at a level of not less than 2,000 International Units (I.U.) Per quart; vitamin D is optional, but must be present at a level of 400 I.U., if added. Characterizing flavoring ingredients may also be added.
Fluid Milk
Milk is approximately 87 percent water and 13 percent solids. As it comes from the cow, the solids portion of milk contains approximately 3.7 percent fat and 9 percent solids-not-fat. Milk fat carries the fat soluble vitamins A, D, E, and K. The solids-not fat portion consists of protein (primarily casein and lactalbumin), carbohydrates (primarily lactose), and minerals (including calcium and phosphorus). Milk also contains significant amounts of riboflavin and other water soluble vitamins.
Fluid Milk Products
1. Sour Cream - is the product resulting from the addition of lactic acid-producing bacteria to pasteurized cream containing not less than 18 percent milk fat. Sour cream may also be called "cultured sour cream.
2. Yogurt - is the product resulting from the culturing of a mixture of milk and cream products with the lactic acid-producing bacteria, Lactobacillus bulgaricus and Streptococcus therm ophilus. Yogurt contains not less than 3.25 percent milk fat and 8.25 percent solids-not-fat.
Types of consumption
There are two distinct types of milk consumption: a natural source of nutrition for all infant mammals and a food product for humans of all ages that is derived from other animals.
1. Nutrition for infant mammals
In almost all mammals, milk is fed to infants through breastfeeding, either directly or by expressing the milk to be stored and consumed later. Some cultures, historically or currently, continue to use breast milk to feed their children until they are seven years old. Human infants sometimes are fed fresh goat milk. There are known risks in this practice, including those of developing electrolyte imbalances, metabolic acidosis, megaloblastic anemia, and a host of allergic reactions.
2. Food product for humans
In many cultures of the world, especially the Western world, humans continue to consume milk beyond infancy, using the milk of other animals (especially cattle, goats and sheep) as a food product. For millennia, cow's milk has been processed into dairy products such as cream, butter, yogurt, kefir, ice cream, and especially the more durable and easily transportable product, cheese. Modern industrial processes produce casein, whey protein, lactose, condensed milk, powdered milk, and many other food-additive and industrial products.
Humans are an exception in the natural world for consuming milk past infancy, despite the fact that many humans show some degree (some as little as 5%) of lactose intolerance, a characteristic that is more prevalent among individuals of African or Asian descent. The sugar lactose is found only in milk, forsythia flowers, and a few tropical shrubs. The enzyme needed to digest lactose, lactase, reaches its highest levels in the small intestines after birth and then begins a slow decline unless milk is consumed regularly.[5] On the other hand, those groups who do continue to tolerate milk often have exercised great creativity in using the milk of domesticated ungulates, not only of cattle, but also sheep, goats, yaks, water buffalo, horses, reindeers and camels. The largest producer and consumer of cattle and buffalo milk in the world
Milk microbiology
Milk and dairy products constitute an important item of our food. These products are very suitable for microbial growth. It thus becomes necessary to know the chemistry of milk, its spoilage, method of preservation and different dairy products where microbes play a positive rather than negative role .Milk is considered as a complete food and it contains proteins, fat, carbohydrates, minerals, vitamins and water. It is also a good medium for the growth of microorganisms. It is therefore, important to know the types of microorganisms present in milk, their control and use for beneficial purposes. Milk contains relatively few bacteria when it is secreted from the udder of a healthy animal. However, during milking operations it gets contaminated from the exterior of the upper and the adjacent areas, dairy untensils, milking machines, the himds of the milkers from the soil and dust. In these way bacteria, yeasts and molds got into the milk and constitute the normal flora of milk. The number of contaminants added from various sources depends on the care taken to avoid contamination. The presence of these nonpathogenic organisms in milk is not serious but if these organisms multiply quickly, they can cause spoilage of milk, such as souring or putrefaction and develop undesirable odours. Control of their multiplication in milk is therefore, very essential. Milk may also contain pathogenic organisms, derived directly from the animal or from the surroundings. Microorganisms that are harmful and found in milk are Streptococcus cremoris, Pseudomonas sp., and Mycobacterium spp.
Serratia marcescens, enteric bacteria etc. Normally, milk is pasteurized before use. However, pasteurization does not kill all the bacteria; the survivors (thermodurics), depending on their initial number. Then multiply and if the initial number is high they cause rapid spoilage. It is imporant, therefore, that the milk be refrigerated at. Around O°C soon after pasteurization to prevent the growth of these under sirable microorganisms
Pasteurization, either at 145°F for 30 minutes or 161°P for 15"'30 seconds eliminates most of the pathogenic bacteria particularly Mycobacterium tuberculosis. Boiling of milk destroys all microorganisms except spore formers. Sometimes, on cooling or under improper refrigeration, spores germinate and cause spoilage of boiled milk.
Composition of Milk
Milk is a complete food, with about pH 7.0,that is an aqueous solution of proteins, fats and carbohydrates with many minerals and vitamins. The following Table 4 shows an average composition of cow milk.
 Casein Casein is the name for a family of related Phosphoprotein proteins (αS1, αS2, β, κ). These proteins are commonly found in mammalian milk, making up 80% of the proteins in cow milk and between 20% to 45% of the proteins in human milk. Casein has a wide variety of uses, from being a major component of cheese, to use as a food additive, to a binder for safety matches. As a food source, casein supplies essential amino acids as well as some carbohydrates and the inorganic elements calcium and phosphorus.
 Lactalbumin Lactalbumin is the albumin contained in milk and obtained from whey. Lactalbumin is found in the milk of many mammals. There are alpha and beta lactalbumins; both contained in milk.
 Lactose It is a disaccharide sugar that is found most notably in milk and is formed from galactose and glucose. Lactose makes up around 2~8% of milk (by weight), although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from lac, the Latin word for milk, plus the -ose ending used to name sugars. It has a formula of C12H22O1