Substitutions – Best Buttermilk Substitute for Making Creme Fraiche

Actually I would disagree to some extent with the other two answers - I think you can use creme fraiche instead.

I agree with MStodd that it will certainly give a different flavour and texture to the sauce, but if you're just looking for a healthier base to a pasta sauce, I'd say it's fine to substitute. Also as daniel mentions, you have to be careful not to overheat it (although the same is true of cream), as it will curdle.

In my experience, creme fraiche is great to make a very quick and easy pasta sauce. Put it in right at the end of cooking, once everything else is properly cooked and just heat enough so it is warmed through.

It comes down to whether you are wanting to achieve the same flavours though - if you are, maybe you could try what I would call single cream (not sure what it would be called in the US), and thicken the sauce with a bit of cornflour mixed with cold water.

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.