Cooking Chemistry: lemon juice/soymilk buttermilk substitute turning bitter and 'rising'
I made a soup recipe the other night (mainly potato, spinach, and veggie broth) that called for buttermilk. I substituted soymilk and lemon juice, reading online that that was a good substitution for buttermilk.
Now, about 48h of refrigeration later, the leftovers are bitter and a little bit bubbly - it's as if they are 'rising' like a baked good would (I imagine my buttermilk substitute was intended for baking).
What can I put in to stop this chemistry and, for bonus points, nullify the bitterness? It's to the point where it's physically difficult to eat - I'm having trouble keeping the few bites I forced myself through down - but I abhor the idea of wasting food.
(I tagged this baking thinking that people who frequent that tag may have a better than average understanding of the chemistry behind this)
Best Answer
Soy milk is bitter. Enzymes in the beans (lipoxygenase) combine with fats in the presence of water to produce what is usually described as a "beany flavor"; bitter and grassy.
The solution to this problem, although not done in many traditional soy milk preparations, is to cook the soy milk long enough to destroy the enzyme. Many, but not all, soy milk manufacturers will cook the milk as well as add a lot of flavorings to mask the bean flavor.
When enough lemon juice is added to soy milk it will coagulate but in my experience it does not produce flavors more bitter than the milk itself. I have, however, found that, regardless of coagulant, soy milk declines in quality very quickly and, even when I thoroughly boil it to deactivate enzymes and "beany" compounds, it will go from sweet to bitter in just a few days. I have also had homemade soy milk start to turn after a relatively short amount of time developing rancid flavors or activity that implied fermentation such as independently souring or clabbering.
I don't have any proof but based on my own experience I suspect that the lemon is not the culprit. If your milk has become so bitter as to be inedible then I think your soy milk may have spoiled.
As for the foaming- in your comment below you mentioned that the soymilk in question was Silk. Silk is one of the most modified soymilks- they definitely err on the side of flavor rather than simplicity and have a lot of additives for flavor and texture.
One of the additives is Calcium Carbonate. Calcium Carbonate gently coagulates soymilk and is sometimes used for making silken tofu. In Silk it is no doubt used to make the product more creamy.
The existence of Calcium Carbonate in your milk could explain your foaming as it can form CO2 in the presence of acids.
Notes
Soy milk does not coagulate well with lemon juice. It requires a lot of acid to coagulate and so is overly sour and it abruptly produces a very fragile curd. I agree that the advice that you read must have been for baking. If you can't use real buttermilk then in such a dish I would recommend silken tofu for the creaminess and don't worry about the acidity.
In general the way to temper bitterness is to add salt.
As a rule of thumb food that is bitter is often poisonous. I don't imply that that is the case here but you should trust your tongue better and not feel forced to eat questionable food.
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Will lemon juice curdle soy milk?
Add 1 tablespoon of lemon juice to a measuring jug. Add soy milk up to the 1 cup (240ml) line. Allow to sit for a minute. It will thicken and curdle.Why does soy milk spoil?
Sour milk of any kind \u2014 dairy and nondairy \u2014 will have a rancid odor due to the growth of mold and bacteria. Though not expired, unopened soy milk left out overnight is likely to yield a sour smell if it is the refrigerated kind.Does vinegar or lemon juice work better to make buttermilk?
Acid: You'll need one tablespoon of an acidic ingredient for each cup of buttermilk you plan to make. You have options here! Lemon juice or lime juice will work, as will white vinegar or apple cider vinegar. Personally, I prefer using either lemon juice or white vinegar.What happens if you use milk instead of buttermilk?
Store bought buttermilk is a slightly sour milk that comes from a combination of milk and lactic acid. It is thicker than plain milk, with a subtle tang. In recipes that call for buttermilk, it is not recommended to replace buttermilk with plain milk, because the absence of acid will not produce the same end result.🔵 Truth About Buttermilk - What Is It? How To Substitute?
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