Tuesday, August 14, 2012

Milk & permeate

Milk has for a long time had permeate added to it. Is that good or bad? I mean, you probably don’t like the idea that anything is added to milk, except maybe a nutrient like calcium, folate or vitamin D. I was asked by a milk manufacturer to make a comment to the media about their “permeate-free” milk.

Permeate is “milk water”
So it was time to do some searching and making of telephone calls. Put simply, permeate is a watery liquid left over after making cheese and yogurt. When making cheese, the protein and the fat is extracted from milk, leaving water, lactose (the sugar in milk), minerals and vitamin. What to do with this “leftover”? Throwing it away doesn’t seem right.

The food laws in Australia stipulate that milk has a minimum protein content (3.0% protein). Now, if you have a batch of milk with more that 3.0% protein then you can add permeate to the milk to dilute it down to be just over the minimum level of protein. This is all legal and certainly doesn’t greatly influence the nutrient density of milk.

Closer to the farm
Despite this, some folk believe that adding permeate to milk is not natural and is just a way for milk companies to save money. The companies did their surveys and found that the public prefer their milk to be as close as possible to what it is as it leaves the farm.

So, some milk companies in Australia are declaring on their labels that their milk is permeate-free. That will mean that there will be some seasonal variation in the composition of milk. It will always meet the minimal standards, but the protein content may vary from 3.0 – 3.5%. That won’t make any difference to the taste. Well, it didn’t to me because, without my knowledge my own milk became permeate-free in January without a whisper from the milk company. Didn’t notice a thing.

What does it all mean?
Not a lot from a taste or nutritional point of view. Not adding permeate will make milk processing simpler and you will experience some natural seasonal variation.

See my full story on dietitian Emma Stirling’s blog.

See what another dietitian, Cath Saxelby has to say and Dairy Australia’s point of view. The Sydney Morning Herald has a more hard-nosed article.

Banana - always good

Serendipity. There I was, checking out some banana nutrition publications on the internet when I clicked the ‘last’ button instead of the ‘next’ button. Suddenly I was looking at some of the oldest research on bananas rather than the latest research. (I write a regular article on banana research for the farmers). So it came that I was reading a January 1927 article in the American Journal of Public Health, written by Walter Eddy and Minerva Kellogg from Columbia University.

Scurvy stopper
The Eddy and Kellogg research article wasn’t the first. Even back in 1919 we knew that 10-15g of banana protected the guinea pig from scurvy. Guinea pigs, like humans, do not make their own vitamin C, therefore they need C in their diet. The 1927 paper I found confirmed that bananas were an important source of the ‘anti scorbutic’ factor vitamin C.

Eddy and Kellogg’s work also supported the view that the banana smoothie was good nutrition and that “A combination of bananas and milk, in proper proportion, constitutes a complete food”. We might not say that now because the banana smoothie is not a great source of iron. However, in essence, the banana smoothie is an excellent combination providing many of our essential nutrients.

“Its potency in C, the availability and the relative cheapness of the fruit, make it a competitor with tomato juice and orange juice for use in infant feeding on vitamin basis alone,” say the authors. Nothing has changed. The banana is an excellent first solid food for infants as it is soft, nutritious and unlikely to cause an allergy.

Are bananas digestible?
Their analysis revealed that bananas are about 22% carbohydrate and that the starch in the unripe banana becomes sugars as it ripens. They spend a page trying to answer the question of whether the banana is digestible. Yes, is their conclusion, although they weren’t sure why unripe bananas may cause “disturbances”. We now know this is likely to be due to the higher levels of resistant starch in the unripe banana, which travels into the large intestine to be consumed by gut bacteria, which in turn produce plenty of gas. That can be uncomfortable for both you and those around you.

What does it all mean?
We knew that fruit was a good thing years ago and the early research confirmed it. It’s funny that we know fruit is great for you, yet so difficult to get people to choose fruit over a bucket of fries. The Canadian Medical Association Journal had an editorial on the banana, published in 1937, telling us: “We can hardly resist the conclusion that the banana is the ne plus ultra among fruits and foods.” The phrase ne plus ultra literally means ‘nothing more beyond’ or simply the best of the best. And so say all of us (and just about every athlete in the Tour de France and the Olympics).
Eddy WH, Kellogg M. American Journal of Public Health 1927; 17 (1): 27-35
Canadian Medical Association Journal 1937; 37 (6): 586-588