Milk under the microscope- permeate, lactose- should we worry?

Milk seems to be a pretty contentious issues among some, and is the breeding ground for a lot of confusion! Love it or hate it, or even be ambivalent towards it, I don't mind, but let's have a look at some key facts about milk so we can be well informed consumers! 

Milk is made up of: 

87.6% water
 4.7% Carbohydrates (lactose) 
3.8% fat
3.3% protein
0.6% Vitamins and minerals

The sugar in milk is lactose, is a disaccharide from one molecule of galactose and one molecule of glucose, which can cause tummy troubles for those with intolerance's. This is caused by a lack of, or complete absence, of the stomach enzyme lactase, which breaks down the sugar in the stomach. The two proteins in milk are casein and whey. Milk also contains calcium, as most are familiar with, but also contains  vitamin A, vitamin B12, iodine, riboflavin, potassium, magnesium, zinc and phosphorus.

So that is what milk is made of, when it's fresh from the cow, but what about the processing of it? Milk can be simply squeezed from the cow and drunk as it- I am told this is pretty excellent! However there are some food safety issues when looking at milk production on a grand scale, and to reduce risk as much as possible, there are some steps milk producers take to make sure that we can drink milk with no worries of bacterial contamination- they only happen on occasion, but the outcomes can be pretty nasty so risk vs reward says take the precaution. 

So what can happen to my milk? 

Dairy manufacturers standardise the fat content of milk and some may standardise protein levels of the milk. Lactose and vitamin/mineral content can also be standardised. These levels vary across the season, due to nutrition status of cow/the season. In a bid to keep products consistent all year round, standardising practices are how farmers can ensure product consistency. Milk processors can pretty much separate all the parts of milk and put it together again, and in doing so are able to engineer a product that will be the same all year.

So what’s the G-O with permeate…?

Oh the dreaded permeate! You will see the 'permeate free' tag on a lot of milk products of late and I have to say, it does sound ominous but let’s all cool our jets for a moment. Permeate, while it does sound like a chemical or something, is a by-product of the milk processing…process. ‘Ultra-filtration’ is a process used my some manufacturers to separate the lactose and other minerals from the rest of the fluid- water and protein components.  Permeate is the term given to the lactose/vitamin/mineral fluid separated during ultrafiltration. Adding permeate back into milk in essence is not adding anything that wasn’t already there. It does not increase the lactose content, as the whole point of its use it to keep lactose levels consistent year round. In a nut shell, It is done to keep products consistent. Not all companies do it, and it would depend on the time of year as to whether it’s a technique they adopt.

Under Australian food standards law, milk needs to meet specific levels to be sold. Full cream milk requires at least 3.2% of fat and 3.0% of protein, which is why such processes, as outlined above are used.

The minimum process that milk MUST go through to be sold in Australia is pasteurisation. This is a heat treatment, developed by Luis Pasteur in France a while back, that ensure any harmful bacteria is removed before consumption. In this process, milk is heated to 72°C for no less than 15 seconds and cooled immediately.

Homogenisation is commonly used to evenly distribute fat globules in milk. Most will have experience milk where the fat has floated to the top in a glorious fashion to be gulped by the first with their hands to it! Homogenisation passes the milk under pressure through very fine nozzles, evenly dispersing the fat globules giving a consistent mouth feel and taste.

When making the different types of milk- full fat, reduced fat, skim/no fat milk, the skim milk and cream are first separated in a centrifuge- think giant washing machine that spins all the fat to the sides, leaving the skimmed milk in the centre. The skim milk and cream are then mixed in different proportions to provide flexibility in adjusting the fat and protein levels required for each product.

So that’s what you need to know to make an informed choice about the milk you choose. As long as you are not drinking gallons of the stuff, full cream is fine. And if you don’t like the idea of your food being fiddled with, hit up the smaller local producers and go have a chat- they can tell you what they do to their products. Personally I am a BIG fan of Tilba milk from the South coast sold at the Farmers Markets in Canberra. Bonus is there are lots of other independent dairy’s breaking out and milking it for all it’s worth. But for Pete’s sake, let’s not demonise milk. It’s pretty much just water, if it upsets your stomach, go seek professional advice as to whether you need to reduce or remove it from your diet, and how to do so in a healthy manner. All you need to ask, and you can find out lots of useful and constructive information about food without assigning devil status and then make your own informed decision. Moo. 

Harriet WalkerComment