COMPOSITION
Vitamin D, a fat-soluble vitamin that enhances the intestinal absorption of calcium and phosphorus, is essential for the maintenance of a healthy skeleton throughout life. Vitamin D is not naturally present in South African milk and therefore milk is not considered a source of vitamin D. However, 30–40 minutes’ exposure to sunlight every day should provide adequate vitamin D for most people living in South Africa. The best time to be exposed to safe sunlight is before 11:00 or after 15:00 every day. In some regions (e.g. the US and Europe), milk is fortified with vitamin D, hence the reference to vitamin D in some research articles
Dairy alternatives are generally derived from plant-based ingredients such as soya, rice, almond, oat, coconut, hazelnut or hemp, mixed with water. While they are sometimes used as a replacement for cow’s milk, they are not nutritionally equivalent to milk.
The main difference is that dairy alternatives are low in protein and not a natural source of calcium and vitamin B12. Plant-based drinks are often fortified with calcium and vitamin B12, whereas dairy milk is a natural source of calcium and contains a rich matrix of other micronutrients (including riboflavin (vitamin B 2), vitamin B12, iodine, potassium and phosphorus).
Dairy milk is naturally higher in good-quality protein (about 3.3%) than milk alternatives, which generally contain only around 0.5% protein. (Soy milk is the only plant-based alternative that contains a notable amount of protein, namely 3%.)
Most milk alternatives contain added sugar, whereas plain milk contains only lactose, a type of sugar naturally part of milk.
Rice milk is the lowest in protein and most often fortified with calcium, and vitamins D and B12. Oat milk is higher in carbohydrates and naturally sweet. In general it is a more palatable non-dairy milk options, however, sugar is added and this beverage contains very little protein (less than 1 gram per glass). Almond milk is made out of ground almonds with water. This non-dairy drink is very low in protein with just 1 g per glass) compared to dairy milk’s 8g of protein per glass), but may have more calcium (if fortified) than dairy milk, along with vitamins D and E. Hemp milk is made of hemp seeds, which are high in heart-healthy omega-3 fatty acids. It also has some protein but still far too little and falls short in calcium. Coconut milk has very little protein and is high in fats. It contains about the same amount of saturated fat as whole milk — about 4 grams in a cup. However, the fat in whole dairy milk within its natural matrix differ from the fat in coconut milk and do not have the same health effects.
Flavoured milk is a pasteurised and homogenised low fat dairy milk product that is coloured, sweetened and flavoured. It then undergoes a sterilisation process which removes all micro organisms and helps to extend its shelf life. This product can be kept on shelf for longer than regular dairy beverages.
Raw milk can contain harmful bacteria and therefore, the consumption of raw (unpasteurised) milk increases the risk of developing foodborne illness. Pasteurisation is an important and well-established food safety measure, which is practiced globally. It is a simple heating process which usually involves heating milk at 72°C for 15 seconds to destroy any harmful micro-organisms.
Not all milk is pasteurised but it is illegal to sell raw milk in South Africa for direct use unless the specific municipality where the sale is taking place is authorised to do so in terms of the law (R1510). Even then, raw milk should be dealt with cautiously and rather be properly heated prior to use.10
Appropriate heat treatment limits harmful bacteria that may be present in food and ensures that the food is safe for consumption. Milk can be heat treated through four different methods. Pasteurisation involves heating milk to a high temperature (72°C), followed by a rapid cooling to 4°C. Ultra-pasteurisation involves treatment at a higher temperature and claims a shelf life of more than 14 days if kept at 4°C or lower. Ultra-high temperature treatment involves heating milk to between 135°C and 150°C for up to two to four seconds and then cooling it to 4°C or lower. This treatment is used to produce long-life milk with an extended shelf life. Sterilization involves heating of bottled milk to 110°C to 130°C for 10 to 30 minutes after which the bottles are cooled. Unopened bottles of sterilized milk keep for a long time without the need for refrigeration.
Fortified milk is milk that has been enriched with specific nutrients. The nutrients that are added are often based on population insufficiencies and often tailored for specific consumer categories e.g. folic acid, vitamin D, iron, protein.
Organic farming is a system of farming which avoids the use of soluble fertilisers, pesticides, feed additives and other chemicals. Most of the nutritional differences are small and related to the pasture grazing of organic cows. Organic milk usually contains higher amounts of omega-3 fatty acids, although the absolute amount is still quite low. Therefore, this may have little effect in the context of an individual’s overall diet. Organic milk also contains about a third less iodine compared to regular milk. Iodine is an important nutrient that contributes to cognitive function and is therefore particularly important for pregnant women.
Raw milk defined in terms of national health legislation means milk that has not undergone pasteurization, sterilization or ultra-high temperature treatment. Raw milk for direct consumption is generally considered to be of higher risk due to its potential as a carrier of harmful bacteria not normally associated with pasteurized milk. The general convention is that while the milk is in the production system of a healthy cow it is considered to be virtually sterile.