LOOSE MILK VERSUS PACKAGED MILK

IS THE MILK WE DRINK SAFE?

SAIMA IBRAHIM
(feedback@pgeconomist.com)

Mar
8 - 14, 2010

In this health conscious society, we all get very paranoid as to what to drink and eat. Milk is a vital component of our diet. Milk is a powerhouse of natural nutrients containing all the essential vitamins, proteins and minerals that are necessary to sustain a healthy mind and body. But, milk in its loose form is a natural breeding ground for disease-carrying microorganisms, and is prone to microbial activity if left unprocessed. The only way to prevent this from happening is to continuously and repeatedly boil the milk at home. But every time we boil the milk we affect its nutritional content.

Now, the question that arises- 'Is the milk we drink safe?' The answer is NO. There are two kinds of milk available in the market - Pasteurized and Loose/Un-pasteurized. There are still many people who are not aware of the difference between the two.

Milk from healthy cows contains relatively few bacteria (102103 /ml), and the health risk from drinking raw milk would be minimal. However, milk is a natural food that has no protection from external contamination and can be contaminated easily when it is separated from the cow. Raw milk normally has a varied microbes arising from several sources, such as the exterior surfaces of the animal and the surfaces of milk handling equipment such as milking machines, pipeline, and containers, Therefore, milk is susceptible to contamination by many pathogenic microorganisms, which result in infection and threat to consumer's health. Additionally, there is the potential that disease of cows such as tuberculosis, brucellosis, typhoid, and listeriosis can be transmitted. Though, during boiling few common bacteria get expunged, but quite often, the dangerous pathogens survive normal boiling temperatures also.

UN-PASTEURIZED MILK

Loose/Un-pasteurized milk can be a carrier of disease causing microorganisms, especially while mixed with water. Usually, milk is heat-processed to destroy harmful microorganisms, using different time-temperature combinations. Anyone who drinks un- pasteurized milk is at potential risk of being exposed to many infections.

PASTEURIZED MILK

Pasteurization is a thermal process widely used in the food and dairy industry with the objective of minimizing health hazards from pathogenic microorganisms and to prolong product shelf life. Pasteurization involves heating milk to high temperatures to kill harmful bacteria that can cause illness. It makes milk safe to drink and increases the length of time it can be kept before it spoils. There are several temperature-time combinations to pasteurize milk that range from 63∞C (145∞F)/30 minutes or 72∞C (161∞F)/15 seconds to 100∞C (212∞F)/0.01 seconds.

The bacteria standards for Grade "A" pasteurized milk are 20,000 bacteria/ML. Heat may denature milk proteins. This effect is not considered a disadvantage from the nutritional point of view because it only involves changes in the specific arrangement of the casein protein. There is no breakdown of peptide linkages; therefore, casein can be considered a thermal-resistant compound. Although -lactalbumin is relatively heat stable, other whey proteins can be denatured as a result of heating. These denatured proteins are more digestible than their naturally occurring form because the protein's structure is loosened and enzymes can act easier.

Pasteurization does not impair the nutritional quality of milk fat, calcium, and phosphorus. Pasteurization temperature does not affect fat-soluble vitamins (A, D, and E), as well as the B-complex vitamins riboflavin, pantothenic acid, biotin, and niacin. The losses of vitamins, such as thiamin (less than 3%), pyridoxine (0-8%), cobalamin (less than 10%), and folic acid (less than 10%) are considered lower than those that take place during the normal handling and preparation of foodstuffs at home. Milk which is pasteurized by a special method involving Ultra High Temperatures (UHT) is called UHT milk.

Although, pasteurization kills and delays the growth of new bacteria it is less beneficial than claimed. It also kills beneficial bacteria like lactobacillus acidophilus, which help the gut synthesis B vitamins and hold 'unfriendly' bacteria in check, certain enzymes and heat sensitive vitamins are killed during pasteurization. It destroys up to 60% of fat soluble vitamins such as A and E and up to 80% of water soluble vitamins such as B and C. Most of the vitamin C is lost during handling, pasteurization, packaging, and oxidation of milk; about 70% of the remaining vitamin C and 90% of riboflavin can be destroyed by sunlight exposure during storage. It destroys 20% of available iodine and lesser percentages of other minerals, fats, proteins and hormones are damaged or destroyed, making them less available for tissue repair. The enzyme phosphate is destroyed, without which the body struggles to absorb calcium from the milk. Some researchers believe that less than 50% of the calcium in pasteurized milk is absorbed. Pasteurization destroys the germicidal properties of milk. Whilst the numbers of bacteria are reduced temporarily, new bacteria multiply more rapidly in pasteurized milk than in raw. And because pasteurized milk slows down the curdling process, which is a sign of infection, bacteria like salmonella, can go undetected for longer. Ironically, pasteurization does not heat milk sufficiently to kill organisms such as typhoid, bacilli coli, tuberculosis and undulant fever. The heated milk proteins (not fat) in pasteurized milk help raise cholesterol levels whereas raw milk does not.

Milkmen also put some chemicals mixed in ice to keep milk for longer time period and that is an acidic compound and of cheap quality and very bad for health. While packed milk companies are actually given a standard protocol by the health department and other such institutes like food testing lab they adjust the components of milk. Fat composition is considered the most important according to the standardized protocol and human requirements/ needs. Scientific research has shown that the detrimental effects of pasteurization on the nutritional and physiological values of milk are less significant as compared to raw milk, considering the safety benefits in regards to consumers' health, hence making it safe to drink.

HYGIENIC ASPECTS OF PASTEURIZATION

UHT milk is aseptically packaged. Aseptically packaged milk has been regarded as one of science's most useful techniques as it assures fresh, high-quality milk to the consumer without the hassle of refrigeration. When milk is processed for packaging it goes through a number of steps that ensure purity. Vitamin D is added to fresh milk and it is pasteurized at 280oF (138oC) for at least two seconds which increases the shelf life. The UHT processed milk is cooled rapidly to at least seven degrees Celsius and packaged into pre-sterilized containers and aseptically sealed. Since bacteria cannot enter the UHT milk, it can be stored at room temperature for at least three months.

UHT process extends the shelf life of the milk without changing the nutrient content. UHT milk does not require refrigeration until after it is opened. UHT processing kills all bacteria. That is why this milk can stay intact forever from bacterial spoilage, as long as pack is intact. It has also become easier to transport the milk to people living in remote areas who can also benefit from it now.

The per capita consumption of milk in Pakistan is around 170 litres per year, which is much lower than other Asian countries. World wide statistics report that a total of 145 countries produce milk and its products, measuring up to 550 million tons a year with the US as the top producer and consumer of milk with 83 million tons. Pakistan ranks fifth in the world with a total production of 32 million tons per year.

A survey conducted earlier by the Animal Husbandry and Veterinary Sciences, Agricultural University Peshawar, revealed that loose milk turns into a source of various diseases including high incidence of zoonotic diseases due to filthy housing system at dairy farms, unhygienic practices during milking, dirty utensils, transportation and marketing and water adulteration.

The researchers found that the unpacked milk contained an alarming ratio of brucellosis, which cause early abortions in expectant mothers, generalized body pain and temperature in older women.

SPECIAL PACKAGING OF PASTEURIZED MILK

The misconception that aseptically packaged UHT milk contains preservatives which make it possible to keep milk without refrigeration, is not true. The aseptically packaged UHT milk is preservative free. The special six-layered aseptic package is the reason why packaged milk can be stored without refrigeration for several months.

Milk consumers in Pakistan are today becoming more and more aware of the diseases associated with the use of open milk. Milk consumption patterns have shown a steady shift towards packaged milk as more people realize its health and packaging benefits. The total share of packaged milk has grown from 0.96 per cent to 5 per cent in just four years, indicating that the consumers are now becoming more health conscious. As it flows out of the pasteurizer, most milk is homogenized by being pumped through extremely tiny openings. As a result, the milk fat is broken up into particles too small to stick together and remains mixed throughout the milk rather than rising to the top as cream.

Changing lifestyles have also influenced innovative variations in packaged milk, such as low-fat, skimmed and flavoured milk. Weight conscious people and those suffering from ailments such as diabetes etc. prefer other varieties such as skimmed milk. Many companies produce different clinically tested milk brand in Pakistan, like Nestle, Good Milk and Haleeb. They use modern technique of UHT to provide hygienic & safe milk to its consumers. Packaged milk has clearly surpassed open milk in its advantages and should be encouraged more so that people realize its benefits and switch to a healthier lifestyle.