I hadn’t realized this key fact about the production of Greek yoghurt. It produces far more waste than conventional yoghurt production. It takes 3 cups of milk to produce one cup of the product! (That’s about thrice as much as conventional yoghurt, which contains far more fluid than does the Greek version of the yoghurt.)
As an example, consider this. The state where Chobani started- New York, produces some 315 kilotons of Greek yoghurt. That means it also produces 630 kilotons of waste whey.
The waste whey is primarily lactose (a milk sugar), fructose (a simple sugar), and lactic acid (the fermentation by-product). These acidic wastes have a very high BOD (biological oxygen demand) and COD (chemical oxygen demand), which are measures of pollution loading. That’s why, up to now, the method of choice has been to convert these wastes into methane gas (via anaerobic digestion). But, the value of methane is pretty low right now, so folks are looking into better alternative processes to treat the waste.
Dr. Largus Angenent (dual appointment at the University of Tubingen [Germany] and the Chem E department of Cornell), along with his Cornell colleagues, J Xu, J Hao, JJL Guzman, CM Spirito, and LA Harroff, just published some recent results of a different sort of conversion. The article (Temperature-Phased Conversion of Acid Whey Waste Into Medium-Chain Carboxylic Acids via Lactic Acid: No External e-Donor) describes the production of “green anti-microbials”. These antimicrobials can then be fed to livestock, replacing the antibiotics. That practice (feeding conventional antibiotics to livestock) has been amplifying the problem for humans- the developing resistance of disease-causing microbes to antibiotics. (The “green” compounds produced by this research are caproic acid [aka n-hexanoic acid] and caprylic acid [aka n-octanoic acid].) Another potential product from the whey waste could involve the coalescing of these multi-carbon acids into jet biofuels, another high-value product.
When the research started, it relied on a single bioreactor. Those conditions meant the formation of caproic acid was diminished, with a propensity to produce acetic, propionic, and butyric acids (these are 2,3, and 4 carbon organic acids). The next generation process, therefore, employed two cascading fermentors.
The first reactor involves thermophilic operations (50 C) running at a pH of 5; the second employed conditions closer to ambient (mesophilic operation at 30 C, also pH of 5), since chain elongation (such as the production of the 8 carbon organic acids mentioned above) is diminished at higher temperatures. Lactic acid is produced in the first bioreactor (almost 100% conversion of the feed lactose and fructose), which is then converted to MCCA’s (medium chain carboxylic acids; the 8 carbon organic acids) in the second bioreactor. The two reactor system ensures that the desired production involves fewer potential byproducts (and hence less downstream clean-up [called separation] processes).
Moreover, the overall COD conversion was 50%. Yes, that means there still needs to be further waste processing. I’m guessing this new process with still use anaerobic conversion to methane as an additional clean-up step.
I don’t like Greek yogurt, but it’s cool reading about how it is made. It’s far too wasteful pull it off the market! Only kidding, I know it’s a big money maker so they will not pull it.
I think lavne (Israeli, Middle Eastern version of yoghurt) may be similar to Greek. If so, I like it. If not- I’ll stick with whatever is on sale. But, yes, I, too, was amazed as to how much MORE waste whey was involved with the production of Greek yoghurt.
Interesting – I tried to switch to Greek yoghurt from normal yoghurt a couple of weeks ago because I read that it was healthier for you, but couldn’t do it – not a fan of the taste or the thickness. Didn’t know that production produces so much waste comparatively though!
I just keep on choosing chocolate yoghurt, Meghan. Because I like the taste. (I haven’t seen same in the Greek version, but that’s fine by me!)
I love greek yogurt (and Chobani is somewhat “local”, so I am a fan of theirs. But, you never think of the waste product. Fermentation. Reducing methane. This is good research.
Alana recently posted..Alligators and Crab Shacks – FlavoursomeTuesdays
I hadn’t realized how much more environmental impact “greek” yoghurt provided compared to the conventional variety, Alana, either.