Policing “Organic Milk” with Fluorescence Spectroscopy

Like organics? I bet you do. But what would you say if I told you your organic milk isn’t always what it’s billed to be?

What’s more, what if I told you there was a relatively simple, inexpensive way for industry watchdogs to determine the difference?

First things first.

Organic milk is the product of cows that are grass-fed. Smaller herds spend the warmer months outdoors, grazing the grass that makes up most of their diets. But the vast majority of American milk comes from cows restricted to large, concrete-floored dairy barns. Farmer feed these cows grass in the form of cut hay, grain fodder and crude protein. That’s where most of your plain old milk comes from.

Organic milk is a different animal. Actually, the same animal, but different diet. According to law, cows that produce organic milk must have outdoor access of at least 120 days a year. Foraged grass must be a minimum of 30 percent of their diets.

The Washington Post did an expose on this a recently, alleging a large Colorado dairy farm misrepresented its product. By testing the fats in the dairy’s product, the paper found a nutritional profile that was much closer to conventional milk than an organic product.

Here’s the significance - in general, grass-fed milk tends to be higher in beneficial fats like conjugated linoleic acids and omega-3 fatty acids. Conventional milk is higher in omega-6 fats, which are more abundant in feed grains.

Gas chromatography, the method the newspaper used to check on the dairy’s product, is too unwieldly and time-consuming to be practicable at industrial volumes. It can cost as much as $100 per sample, which is financially prohibitive for most organic dairy farmers.

Rather than analyze milk’s fat content, the Iowa State scientists used fluorescence spectroscopy to produce a molecular fingerprint of the contents of the milk. Fluorescence spectroscopy measures molecules by luminescent signals in response to a beam of light.

And unlike traditional methods of testing, fluorescence spectroscopy results can be acquired instantly.

Milk contains lingering traces of chlorophyll that have been metabolized by the cow. This substance fluoresces and gives the researchers one marker for grass diets. Scientists found they could instantly spot the differences between various types of milk using this technique.

The results of the study seem to establish that fluorescence spectroscopy can reliably detect how much fresh grass a dairy herd is getting. This could usher in a new level of transparency in the dairy industry. In fact, observers believe spectroscopy could help create a new premium market, a better-than-organic standard that science can easily verify.

Organic Valley dairy, a Midwest cooperative, has already begun marketing “Grassmilk,” a premium product it says comes from 100 percent grass-fed cows that never eat grain. The company boasts, “Our 100% grassfed cows are never fed grains, which gives Grassmilk milk the subtle seasonal flavors of our pastures. This is milk as it was meant to be.”

Spectroscopy could help convince customers of the validity of these claims in the future, as the industry unfolds and innovative market niches develop.