Tuesday 10th November 9:28 am
Can cows make strawberry-flavoured milk?
Wednesday 29th April 2015 12:50 pm
It’s the innocent question from the small child that most surprises you. So how about this …
“Mummy/Daddy, if you feed cows lots of strawberries, will that make their milk strawberry flavoured?”
The answer is “Ummm, maybe”.
First, a bit of biochemistry. There are two main ways that flavours or tastes get into milk. In one case, the flavour chemical gets into the cows’ feed, and passes, unchanged, into their milk. In the other case, chemicals in the feed get changed by the cow’s metabolism into other chemicals — and it’s these byproducts that then make their way into the milk.
Back in 1990, Australia’s CSIRO did research with cows on how different feeds changed the taste of the milk. For example, cows fed a diet that was low in fats produced what’s called a ‘hard milk’, with flavours of blue cheese, coconut and peaches. In contrast, a synthetic diet free of protein gave a milk that was very low in stinky chemicals such as indole and skatole.
In France, the flavour of Gruyere cheese varied between summer and winter, and also whether the cows fed in the mountains, the plateaus or the plains. In other words, the feed for the cows varied, and so did the milk flavour.
Beet byproducts contain a chemical called ‘betaine’. In the gut of the cow, betaine is converted into another chemical called ‘trimethylamine’, which gives a fishy flavour to the milk. In fact, if you feed rye or wheat to cows, various other chemicals get converted to trimethylamine, and again the milk has a fishy flavour.
As another example, any of the cruciferous vegetables, such as cauliflower, cabbage, broccoli and brussels sprouts, can give the milk a sharp flavour — like radish. And in Australia in the Darling Downs, turnip weed can give the milk a rather off flavour.
But if you supplement the feed of cows with oat and sunflower seeds, you get an interesting surprise. The oats stimulate the growth of certain bacteria in one of the cows’ stomachs. These bacteria then bypass the oats, and attack the oil in the sunflower seeds. This creates a chemical called gamma-dodec-cis-6-enolactone — which tastes just like raspberries. This chemical is so pervasive that it gives a raspberry flavour to both the milk and meat!
What about humans?
Well, the same overall pattern holds for human breastmilk. Previous studies had found that if women drink carrot juice while they are pregnant or breastfeeding, the growing infants get very fond of carrot-flavoured cereal.
So in 2008, Danish investigators at the University of Copenhagen fed some 18 nursing mothers flavour capsules. Very quickly, the babies were drinking banana milkshakes from their mother’s breasts. It took varying times for the flavours to appear in the breast milk — one hour for banana flavour, two hours for caraway and liquorice flavour, while menthol took between two and eight hours. After eight hours, most of the four flavours had disappeared from the mothers’ breast milk.
Flavours in breast milk can affect what baby does. For example, we know that if the mother ingests garlic, alcohol or vanilla flavour, the baby attaches to the breast for longer.
Our adult food choices and dietary habits are behaviours that we have learned from various cultural, psychological and physiological factors.
We know that breastfeeding is associated with a lot of good things such as increased intelligence, greater social mobility and protection against diseases such as heart disease. But now we know that breastfeeding could also help baby develop a more sophisticated palate. It seems that the breastfed babies get quickly used to small changes in flavour, and this means they can become more accepting of a wide variety of flavours when they start to eat solid food. So changes in taste of breastmilk could prime the child to try different foods as they grow.
As for women feeding their babies formula, it might be good to vary the brand of formula so that the baby becomes used to changes in flavour.
So will feeding strawberries to cows produce strawberry-flavoured milk? Dunno. I couldn’t find a single case in the literature where a farmer had enough spare strawberries that were not suitable for human consumption, and had fed them to cows.
But if it does work, perhaps strawberry milk could be the next totally organic, fully natural and permeate-free superfood …
This blog first appeared on Dr Karl's Great Moments in Science
© 2016 Karl S. Kruszelnicki Pty Ltd