Key Difference – Long Life Milk vs Fresh Milk
The key difference between Long Life Milk and Fresh Milk is that the long life milk has higher shelf life compared to raw/fresh milk. In addition, the nutritional and organoleptic properties between long life milk and fresh milk may also differ.
Milk is the primary food source for infants, and it can be defined as a white liquid formed by the mammary glands of mammals. Milk consists of all major nutrients such as carbohydrate, protein, fat, minerals and vitamin. As a result of rich nutrient content, it is highly susceptible to microbial spoilage. Thus, raw milk is often sterilized or pasteurized in order to destroy their initial microbial load. This processed milk is also known as long life milk. Long life milk can be stored for a longer period of time either refrigerated or normal conditions whereas raw milk cannot be kept for an extended period of time. In this article, we are going to discuss the difference between long life milk and fresh milk in terms of their nutrients and sensory parameters.
What is Fresh Milk?
Fresh milk is the milk obtained from cow, sheep, camel, buffalo or goat, that has not been processed (pasteurized/sterilized). This fresh and unpasteurized milk can have hazardous microorganisms such as Salmonella, E. coli, and Listeria, which are accountable for causing several foodborne diseases. Fresh milk is highly susceptible to microbial spoilage because milk is rich in many nutrients which are essential for microbial growth and reproduction. In addition, the bacteria in fresh milk can be mainly unsafe to individuals with declining immune activities, older adults, pregnant women, and infants.
Laws and regulation of the marketable packaged raw milk differ across the world. In some countries, selling raw milk is completely/partially banned. However, raw milk is manufactured under good hygienic practices and risk management programmes but has not been exposed to any temperature related processing (Eg. heat treatment) in order to change the sensory or nutritional quality or any characteristics of the milk. Furthermore, fresh milk product is a dairy produce that has not received any kind of pathogenic microorganism elimination step. Therefore, fresh milk has very limited shelf-life (not more than 24 hours) compared to heat treated milk or long-life milk.
What is Long-life Milk?
Long-life milk is a form of milk that has been heated to a high temperature in order to destroy any injurious pathogenic micro-organisms (Eg. E. coli, Listeria and Salmonella) which may be present in the fresh milk. The processed milk is then packaged into sterile containers under aseptic conditions such as Tetra packaged milk. The target of heat-treated milk is to produce milk, safe for human consumption and to improve its shelf life. Thus, heat-treated milk/long-life milk has a longer shelf life (Eg. UHT milk can be stored for about 6 months).
Pasteurization, sterilization,and Ultrahigh temperature treatment (UHT) are more popular methods of heat treatments used to produce long-life milk. This processed milk is available in whole, semi-skimmed or skimmed product ranges. However, the heat treatment results in a change of organoleptic properties such as taste and color and also slightly decreases the nutritional quality of the milk.
What is the difference between Long life Milk and Fresh Milk?
Characteristics of Long Life Milk and Fresh Milk
Fresh milk: Fresh milk has a very limited shelf-life.
Long life milk: Long life milk has a longer shelf life. (For example, sterilized milk keep for approximately 6 months shelf-life without any refrigeration condition)
Fresh milk: Fresh milk is not fortified with nutrients.
Long life milk: Long life milk is often fortified with minerals and vitamins.
Fresh milk: This is usually consumed after homogenization.
Long life milk: Milk is pasteurized to different levels or sterilized before consumption.
Fresh milk: This contains phosphatase which is essential for the absorption of calcium.
Long life milk: Phosphatase content is destroyed.
Fresh milk: This contains lipase which is essential for the digestion of fat.
Long life milk: Lipase content is destroyed.
Fresh milk: Fresh milk contains immunoglobulin which protects the body from infectious diseases.
Long life milk: Immunoglobulin content is destroyed.
Lactase Producing Bacteria
Long life milk: Lactase producing bacteria is destroyed.
Fresh milk: Fresh milk contains probiotic bacteria which help to strengthen the immune system.
Long life milk: Probiotic bacteria is destroyed.
Fresh milk: Protein content is not denatured.
Long life milk: Protein content is denatured.
Vitamin and Mineral Content
Fresh milk: Vitamin and mineral content is 100% available.
Long life milk: Vitamin A, D, and B-12 are diminished. Calcium can be altered, and iodine can be destroyed by heat.
Fresh milk: Organoleptic properties does not change.
Long life milk: Organoleptic properties can change (change in color and/or flavor) during milk processing (Eg. Cooked flavor can observe in pasteurized milk products).
Fresh milk: This is available only in liquid form.
Long life milk: Different long-life milk tends to vary according to the way they are produced and their fat content. UHT milk is available in whole, semi-skimmed and skimmed varieties.
Availability of Microorganisms
Fresh milk: Fresh milk can have pathogenic bacteria such as Salmonella, E. coli, and Listeria, which are responsible for causing numerous foodborne illnesses.
Long life milk: Long life milk do not contain pathogenic bacteria, but if the product is exposed to the environment pasteurized/sterilized milk can be contaminated with pathogenic bacteria.
Fresh milk: It is responsible for causing numerous foodborne illnesses.
Long life milk: It is not (or rarely) responsible for causing numerous foodborne illnesses.
Fresh milk: In most countries, raw milk represents only a very small fraction of total milk consumption.
Long life milk: In most countries, Long life milk represents a very large fraction of total milk consumption.
Fresh milk: Many health agencies of the world strongly recommend that the community do not consume raw milk or raw milk products.
Long life milk: Many health agencies of the world recommend that the community can consume heat treated long life milk products.
In conclusion, people believe that raw milk is a safe healthier alternative because long life milk usually undergoes various heat treatments which result in the destruction of some organoleptic and nutritional quality parameters of milk.
References Wilson, G. S. (1943). The Pasteurization of Milk. British Medical Journal, 1(4286): 261–2. Feskanich, D., Willett, W. C., Stampfer, M. J. and Colditz, G. A. (1997). Milk, dietary calcium, and bone fractures in women: a 12-year prospective study. American Journal of Public Health, 87(6): 992–997. Image Courtesy: “Pccmilkjf” by Ramon FVelasquez – Own work. (CC BY-SA 3.0) via Wikimedia Commons