Milk: Essential in your diet

Benefits of dairy consumption

Milk is the product secreted by the mammary glands of female mammals, which is used to feed their offspring during lactation. In different parts of the world, milk from various animal species is used (goat, sheep, camel, donkey, buffalo, llama, etc.); however, in Spain, cow's milk predominates in the market, so the name "milk" is reserved for it.

When we talk about dairy products, we are referring to products obtained from milk, such as skimmed fermented milks, cheeses, curds, cottage cheese, cream, shakes, ice creams, etc.

Fermented milks are products prepared from milk through the action of specific microorganisms, resulting in a reduction of pH and protein coagulation. The specific microorganisms must be viable, active, and abundant in the final product at the time of sale for consumption.

CLASSIFICATION

Milk can be classified according to various criteria:

a. By its pasteurization system

i. Pasteurized milk: milk is subjected to temperatures below 100ºC for varying times. Typically, it is subjected to 72-75º for 15-30 seconds. It eliminates up to 99% of microorganism resistance forms, so it must be kept refrigerated.

ii. Sterilized milk: obtained by treating milk at temperatures between 105 and 120ºC for 15-20 minutes. Pre-sterilization treatment is done at a temperature of 130-140ºC for 2-15 seconds.

iii. UHT (Ultra High Temperature) milk: temperatures of 140 to 150ºC are applied for 2-4 seconds by steam injection. Like sterilized milk, UHT milk can be kept for several months without refrigeration, but once opened, it must be stored in the refrigerator and preferably consumed within 1-2 days.

b. By its physical state

i. Liquid milk: includes milks of different nutrient compositions, but marketed in liquid form.

ii. Evaporated milk: obtained by removing part of the water by evaporation under vacuum. Nutrient losses are similar to those in sterilized milk.

iii. Condensed milk: milk is thickened under vacuum conditions at a temperature of 55-65ºC, then sterilized in cans for about 20 minutes between 110-120ºC.

iv. Powdered milk: first, the milk is allowed to evaporate until a concentrate is obtained; then, this is dehydrated, either by spreading it over hot rollers, salvaging it, and then grinding it, or by spraying it in hot air at 130-140ºC. This method allows increasing the shelf life up to 3 years for skimmed milk and six months for whole milk.

c. By its nutritional content

i. Whole: contains all nutrients and usually provides 3.5% fat.

ii. Semi-skimmed: with less fat and fat-soluble vitamins A and D.

iii. Skimmed: contains no fat or fat-soluble vitamins.

iv. Lipid-modified: when the fat is removed from the milk and replaced by another with a fatty acid profile richer in polyunsaturated and monounsaturated fats. This manipulation aims to improve the lipid quality of the diet, especially for the prevention and treatment of cardiovascular diseases. In these cases, we talk about dairy preparations.

v. With added nutrients: this can be a restitution (replacing lost vitamins) or an enrichment (increasing existing nutrients). The most common commercial form is skimmed milk to which vitamins A and D have been added, which are lost when the milk is defatted.

vi. Low-lactose or low-sodium dairy products: indicated for people intolerant to lactose or who must follow a low-sodium diet.

Regarding fermented milks, these can be classified into:

a. Acid fermented milks: in these, the most important chemical modification is the fermentation of lactose with the formation of lactic acid.

b. Acid-alcoholic fermented milks: the microorganisms added in the production of these products lead to the formation of lactic acid, ethyl alcohol, and carbon dioxide. The most well-known representative of this type of fermented milk is kefir, although there are others such as kumis, fuli, etc.

OBTAINING

Milk is secreted by the mammary gland of the cow from the birth of the calf until a period of about 300 days. Milk is obtained by milking machines, reducing the risk of pathogenic germs.

Refrigerated milk is collected in tank trucks to be taken to the central facility. There, it is analyzed to determine its fat content (a quality criterion for payment) and its hygienic quality (pH, number of pathogenic germs, antibiotic residues). The milk is then cleaned and separated into cream and skimmed milk. By adding cream, its desired fat content is adjusted, it is homogenized, and depending on the method used, it is heated to a temperature between 67 and 140ºC. By adding bacteria and/or other foods, multiple products or dairy shakes are obtained.

Both heat and light affect the shelf life and flavor of milk, so they should be avoided, requiring light-proof packaging.

BENEFITS OF DAIRY CONSUMPTION

Some benefits associated with dairy consumption stem from its nutrient content. The benefits can be summarized as:

a. Osteoporosis prevention: adequate calcium intake to achieve and maintain maximum bone mass throughout life.

b. Cardiovascular diseases: various studies link adequate calcium and/or dairy intake with better blood pressure and blood cholesterol control.

Other health benefits, described in scientific literature, that have led to considering fermented milks as functional foods and specifically as probiotics are the following:

a. Regular consumption of this type of food allows for a balanced colonic microbiological composition.

b. In various digestive disorders, yogurt and fermented milks in general are recommended.

c. Their maximum utility is observed in cases of diarrhea.

d. In cases of dysbiosis, as a consequence of antibiotic therapy, fermented milks help restore the colonic bacterial microbiota.

e. It is also described in scientific literature that it helps overcome cases of constipation.

f. Fermented milks improve immune response.

g. There is a benefit in the prevention of carcinogenesis.

SUMMARY

a. Milk is the only food humans need in the early stages of life.

b. Dairy products provide high-quality proteins and variable amounts of lactose and fat. Regarding vitamins, the most abundant are riboflavin and vitamin B₁₂, with smaller proportions of A, B₁, B₆, and folic acid.

c. Due to nutrients and, in the case of dairy products, live microorganisms that help modulate the composition of the intestinal flora, they provide various health benefits for the consumer, thus protecting against osteoporosis, cardiovascular diseases, digestive disorders, diarrhea, etc.

d. The recommended consumption is 2-3 servings/day, 3-4 for adolescents, athletes, pregnant women, nursing mothers, and the elderly.