Our yogurt recipe is really pretty good but sometimes our customers just can’t get it to work for them – could it be the milk? Over the last couple of weeks I’ve bought 28 different types of milk and made yogurt with them. All milk is not created equal and yogurt it turns out, is a great judge of character. Of the 28 milks I tried only 16 made decent yogurt. The others did not. Any milk that didn’t work got tested again to make sure. So what’s the deal?
Pasteurised milk is not the problem, Yogurt culture prefers pasteurised milk because it kills off competing bacteria. It can also cope with “homogenised” milk that has had the fat suspended evenly through the milk. What really made the yogurt culture turn it’s nose up was any milk that had been “standardised”. If you buy milk that is “standardised” it means that the manufacturer may have added in a substance called permeate.
Yogurt is particularly fussy about the level of protein present in the milk. It is what helps it set. Commercial yogurt makers know this. The way permeate is being used in milk changes the protein levels occurring naturally in the milk and the yogurt culture doesn’t like it. Finding out which milks have permeate in them is tricky as they don’t have to put it on the label but the word “standardised” is sometimes an indicator – but not always. If in doubt email the supplier to ask.
The milks below were the ones that didn’t make great yogurt. You’ll see most of them are blue top, there are a fair few cheap brands but also a couple of organic and expensive brands in there too. We found that heating these milks to 90 C and cooling helped to bind all the proteins back together again into something that set better but even then the resulting yogurts from these milks were consistently weak, grainy, scummy and susceptible to splitting.
So what is permeate? It is a waste product from the dairy industry. It is the stuff that passes through an industrial membrane used to filter out the good bits from either milk or whey leftover from cheese making. The good bits (retentate) are kept for use in other products. The permeate that gets through contains mostly water, some minerals and lactose and possibly some proteins depending on the type of membrane used.
And why on earth is it being added to milk? Because under NZ law, to call milk, milk it must contain at least 3% protein. The milk that comes out of the cow has more than this and it varies depending on the time of year. This protein is also valuable stuff and if you can add a waste product (permeate) back to the milk to achieve a consistent 3% protein then you’re lowering the cost of production.
Not all milk producers do this but one leading one who does has been quoted as saying that permeate is just “adding milk to milk” and therefore there is no need to put it on the label and confuse consumers. I’d like to invite them to sit down and knock back a nice glass or two of permeate with me some time. Together with some permeate cheddar and crackers. I think if it is just milk why not have a whole range of permeate dairy goods in the pipeline (literally).
The good news is that there are dairy producers out there who are not using permeate in their milk and I believe that within a short space of time they will start advertising the fact on their bottles as consumers demand to know. This will put pressure on other producers and we will see an industry move to more transparent labeling if not an industry accord to stop the use of permeate. Let it go down the drain where it belongs please, not back into our milk.
Until then, here are the milks we found made consistently good yogurt and there is not a “standardised” label among them. Enough said. We can also add Green Valley brand milk to this list, even their standardised milk does not contain permeate. Way to go Green Valley.
If you are interested in reading more about Permeate I’d recommend this good article by Amelia Wade in the Herald from last year and Wendyl Nissens book “The Supermarket Companion” as a good reference guide to what’s actually in our food. If you are interested in making good yogurt at home check out our nifty little “How to Make Yogurt” book and Probiotic Yogurt Culture.