Frequently Asked Questions (FAQs)
1. Is raw milk safe for consumption?
The raw milk is not safe for consumption. Unless and until the health condition of the milch cow and the environment in which the milk is produced and handled till it reaches the consumer is definitely known, it is always advisable to drink pasteurized milk or boiled milk from the safety point of the consumer.
2. What is pasteurization?
Pasteurization refers to the process of heating each and every particle of milk to at least 63°C for 30 min (LTLT method) or 72°C for 15 sec (HTST) or to any approved temperature-time combination which is equally efficient in an approved and properly operated equipment. Immediately after pasteurization, the milk is invariably cooled to 5°C or below.
3. Why does raw milk curdle when heated after standing at room temperature for considerable period of time?
Milk contains a variety of microorganisms, which are capable of converting lactose present in the milk to lactic acid, increasing the acidity. When the milk is stored at room temperature (30-37°C) for considerable period of time, it provides ideal temperature for the growth of most of the spoilage causing organisms and in turn increases the acidity. When the acidity increases beyond 0.20% lactic acid, the milk clots on boiling or heating.
4. Why do strict vegetarians refuse to consume ice cream made with gelatin as a stabilizer?
For ice cream production, stabilizers such as gelatin, sodium alginate, carageenan, agar agar etc. are used. Stabilizers are added in ice cream to produce smoothness in body and texture, retard or reduce ice crystal growth during storage and provide uniformity in the product and resistance to melting. Although the gelatin was the one of the first commercial stabilizers and it is still used, it is obtained from the bone of animals. Hence strict vegetarians often oppose its use as stabilizer in ice cream. Instead, it can be replaced by sodium alginate.
5. Why does milk appear white?
The normal milk ranges in colour from yellowish creamy white (cow milk) to creamy white (buffalo milk). The colour of milk is due to the combined effect of colloidal casein particles and the dispersed fat globules, both of which scatter light and carotene and to some extent xanthophylls, which impart a yellowish tint to milk. The intensity of yellow colour of cow milk is dependent upon factors such as breed, feed, size of fat globule present in milk, fat percentage. In buffalo milk, the carotene is present in the form of vitamin A. Skim milk has a bluish and whey a greenish yellow colour.
6. How to detect adulterated milk (with water)?
Milk adulterated with water can be easily found out with an instrument called ‘lactometer’. The lactometer measures the specific gravity of milk. The average specific gravity of milk ranges (at 60°F) from 1.028 – 1.030 for cow milk and 1.030-1.032 for buffalo milk. Lower values than the standard given indicates that the milk is adulterated with water.
7. Can I make ice ream in my home with conventional refrigerator?
No. It is not possible to prepare ice cream in home with the conventional refrigerator. After the preparation of ice cream mix, it is frozen in the ice cream freezer (batch type or continuous) along with incorporation of air during the freezing process. This step is very essential to get proper body and texture in the finished product.
8. What is the reason for fishy flavour in butter?
Under commercial storage conditions (-23°C to -29°C), high acid salted butter develops fishy flavour in the presence of appreciable amounts of copper and / or iron content. To avoid this defect, unsalted sweet cream butter may be used.
9. What is responsible for the characteristic flavour in curd?
Curd is a fermented dairy product produced by souring milk with mainly lactic starter cultures, which include Lactococcus lactis subspecies lactis, Lactococcus lactis subspecies cremoris and Lactococcus lactis subspecies lactis biovar diacetylactis. Sometimes, the starter may contain Leuconostocs. The Lactococcus lactis subspecies lactis, Lactococcus lactis subspecies cremoris are capable of fermenting lactose present in the milk into lactic acid resulting in coagulation of milk whereas the Lactococcus lactis subspecies lactis biovar diacetylactis is both lactose and citric acid fermenter. Citric acid fermentation results in the production of end products such as diacetyl, acetoin and 2,3 butylene glycol which are responsible for the characteristic desirable flavour production. Leuconostocs are purely citric acid fermenting bacteria and hence responsible for flavour production but not acid production.
10. What is rennet? Where is it used?
Rennet is a crude preparation or extract obtained commercially from the fourth stomach (abomasum) of young calf, known as vell. The preparation methodology include washing, drying and cutting of the lining of the stomach in to small pieces and macerating it in to water containing about 4 percent boric acid at 30 °C for 5 days. Rennet is used in clotting of milk, especially in cheese production. It may be used along with starter cultures.
11. How much energy shall I get from 100ml of milk?
The energy value of milk varies with its composition. On an average cow milk furnishes 75 C per 100 g and buffalo milk 100 C per 100 g. Componentwise, milk fat furnishes 9.3 C / g, milk protein 4.1 C / g and milk sugar (lactose) 4.1 C / g.
12. What is the difference between Maillard browning and caramelization?
The darkening of colour commonly referred to as browning discolouration is a defect, which develops during the manufacture and storage of condensed milk varieties. The browning results from the interaction of amino compounds with sugar i.e. mainly casein with lactose. This defect is called as Maillard browning. Caramelization or non amino browning occurs in milk products due to heat decomposition of sugar in the absence of amino compounds.
13. What is dry ice?
Dry ice is solid carbon dioxide with a freezing point of -78°C (-109°F). It is extensively used for package deliveries of frozen dairy products such as ice cream. It is cut into pieces of appropriate size, which are wrapped in paper to avoid rapid evaporation and then placed around the package of the ice cream inside an insulated packer or in a single service type packer.
14. What is lactose intolerance?
Lactose is the milk sugar present in milk. It acts as a source of energy not only for the individuals who consume milk but also for the microorganisms in milk. Normally, lactose is converted in to glucose and galactose, which are subsequently converted in to lactic acid and absorbed from the intestine. Beta galactosidase is the enzyme that plays a major role in the conversion of lactose in to lactic acid. Lactose intolerance develops when the secretion of enzyme beta galactosidase decreases. Undigested lactose absorbs excess water, while passing through the large intestine. Bacteria present in large intestine act on the lactose and convert it in to acid and gas. This acid, gas and excess water are responsible for flatulence, stomach pain and sometimes enteritis.
The ability to digest lactose differs among different human races. This defect is commonly noticed among Asian races. As an individual grows old, the beta galactosidase secretion decreases. It is related to the genetics of the individual. Temporary lactose intolerance is sometimes noticed among children who have been suffering from intestinal disorders and nutritional deficiency diseases.
15. Does milk act as a source of disease?
Definitely. Milk and milk products act as a source of contamination of various disease causing bacteria such as Salmonella, Shigella, Staphylococci, Clostridium, Bacillus, Pseudomonas, Listeria, Campylobacter, Yersinia, Vibrio, Mycobacterium, Brucella, Corynebacterium, Coxiella and viruses such as Entero viruses, Infectious hepatitis virus, Tick-borne Encephalitis Virus, Foot and Mouth Disease virus. The important mould transmitted through milk products is Aspergillus resulting in aflatoxicosis in the affected individual. The mode of transmission may be through food infection, food intoxication or toxi-infection. Hence it is desirable to pasteurize the milk before consumption.
16. What is probiotic?
'Pro' means for and 'bio' means life. Hence, probiotics are generally considered as agents which favour the well being of a human being or an animal by various mechanisms. Probiotics are generally lactic acid producing live bacteria which, when ingested orally, brings out the desirable effect in the individual by getting implanted in the intestinal tract. The mechanism of action include competitive replacement of the pathogens from the intestinal tract, production of metabolic compounds inimical to the growth of pathogens etc. Generally lactobacilli, especially, Lactobacillus acidophilus is considered as a good probiotic.
17. What is meant by SNF and total solids?
SNF or solids not fat is that nutrient portion present in milk devoid of milk fat. It consists of protein and lactose. When SNF is combined with milk fat, then it is called total solids. The legal standards for standardized milk is 4.5% fat and 8.5% SNF and yes, as you rightly guessed, the total solids is 13%.
18. What is the difference between skim milk and whole milk?
It all depends upon the fat content of milk. Generally cow milk (whole milk) contains 4.0% milk fat whereas buffalo milk contains upto 9.0% milk fat. Milk fat is the valuable portion of milk, based on which, milk is priced in most countries. When skimming is done to separate the fat by means of a cream separator, cream is obtained as a main product, which is rich in milk fat (approximately 25%) and skim milk as a byproduct (containing less than 0.5% milk fat). It is impossible to remove all the fat portion from milk.
19. What is "Clean Milk"?
The term 'clean milk' does not mean milk in which all visible dirt is absent or milk from which it has been removed; rather it does denote raw milk from healthy animals, that has been produced and handled under hygienic conditions; that contains only small number of harmless bacteria and that possesses a good keeping quality without being treated by heat.
In other words, the unhygienic production of milk may lead to inferior keeping quality as a result of rapid microbial multiplication under favourable storage conditions apart from serving as a potential health hazard. These microorganisms cause the milk to sour quickly, putrefy and develop undesirable flavours, colour defects, ropiness and bitterness. On the other hand, the pathogenic microorganisms, which may gain entry through various sources, may cause many diseases to the consumers.
20. What is "homogenization"?
Homogenization is one of the basically important processes of the dairy industry. The principle behind the homogenization is that it breaks up the already small fat globules of milk into even smaller globules and stabilizes the emulsion to an extent that prevents any noticeable rising (cream layer formation) of the fat. Milk to be homogenized is pumped under pressure of several thousand pounds through a narrow or constricted orifice, during which the native fat globules are broken down to uniform smaller size of 2μ.
21. Will eating of cheese and fatty dairy products cause acne?
There is no scientific evidence to show the relationship between acne and dairy products. In fact, dairy products are rich in vitamins A and D that promote skin health care. On the contrary, eating cheese and other dairy products will nourish your skin; but exercise caution. Too much of anything is dangerous.
22. Can dairy products consumption lead to body weight gain?
Generally a positive body weight gain occurs when one consumes more calories than body can burn as energy. Consumption of low fat dairy foods may help greater weight loss. Research shows that there is a strong correlation between increased calcium intake (through consumption of milk and dairy products) and reduced body weight, body fat percentage and a reduction in waist size.
23. If you take calcium supplements, then there is no need to drink milk. Is it correct?
There is a common myth that milk supplies calcium alone and nothing else. But apart from supplying bone forming calcium, milk also supplies other high quality nutrients such as high quality proteins (containing essential amino acids), Vitamins A, B2, B12, D and minerals like zinc, potassium and magnesium. Apart from supplying nutrients, fermented milk products are rich source of probiotic organisms, essential for maintaining health of gastro intestinal tract. Mental pleasure and satisfaction obtained while eating delicious dairy products can never be substituted with milk supplements or substitutes.
24. Human digestive system is not designed to digest cow milk. Is it right?
Humans are omnivorous. The alimentary canal of human beings is designed to digest plant as well as animal products such as meat and dairy products. Through evolution, humans acquired the capacity to synthesize an enzyme “lactase” or “beta galactosidase” that aids in digestion of lactose, the milk sugar. If the humankind is restricted to consuming milk from our own species, we would have missed many of the mouth watering, delicious dairy products that we enjoy today.
25. Does drinking milk cause kidney stone?
Calcium in milk will bind with the oxalates present in food so that they are made unavailable to be absorbed by the body. Hence, milk will in fact, help in reducing the chances of getting kidney stones and foster health of the consumers.