Soymilk for drinking vs. soymilk for tofu making

Question

Many recipes for tofu start from soymilk, many others start from scratch, but most of either kind share a whole variety of approaches, i.e. the order of the soaking, boiling and blending operations, the duration of the soak, the length of the milk cooking/simmering, whether the milk should be strained before simmering or the other way around. Recipes for drinking soymilk vary on a similar fashion, apart from the fact that they aim to remove the so-called "beany flavor" that seems to be haunting homemakers.

Assuming the invariance of the final product in terms of flavor, firmness, coagulation etc. there are some choices that result in consistent operational advantages, such as the boil-and-blend method which leaves out the discomforts of the soak, or the option of straining the milk before the simmer so that all you have to do to get to the coagulant insertion is wait for it to come down to temperature.

My question now is: can we make such an assumption? Some other sources suggest for example that a soaking time longer than eight hours inhibits the soymilk's ability to coagulate properly, but others point out that it would yield a better drink. Same goes for simmering time, let alone all other variables and orderings I briefly listed above.

I tried making tofu twice using a combo lemon juice and salt as a coagulant, but the results were ricotta-like and silken tofu, while I strive for firm to extra-firm. I mostly blame it on my previous lack of a cooking thermometer which I just purchased specifically (together with some nigari crystals) for this purpose, so I thought I should ask if there are other parameters I might be leaving out of the investigation.

TL; DR: Just read the stuff in bold.

Answer 1

Your title, your problem and your question (btw question is general but complicated) while on the same subject matter are not the same.

In regards to your quest for firm and extra-firm tofu, the OP doesn't state much about the process after the coagulation. Which similarly to cheese making is the (arguably) the most crucial factor in the final texture. firm and extra-firm tofu is pressed with heavier weights, and for longer periods of time.

The choice of coagulent (nikari, gypsum, acid, etc), temperature of the milk and the mixing method can also affect the texture of the final product.

Answer 2

I recently started making tofu, and I have got it to successfully coagulate into firm-ish tofu using nigari.

My recipe (approximately)

Ingredients: Soy beans, cold water, nigari Equipment needed: pot, blender, tofu mold, filter bag

1. Soak the beans at least overnight. Discard the soaking water afterwards.
2. Grind the beans in a blender with a suitable amount of fresh water (dry beans constitute 10-20% of total weight)
3. Put the blended mixture the mixture in a large pot, skim the foam, bring to boil and then simmer for 15-30 minutes.
4. While still hot, pour the mixture into a filter bag, and drain/squeeze out the soy milk into a bowl.
5. Put the soy milk back into the pot and, heat to 70-75 degrees
6. Stir rapidly, quickly mix in the nigari and stop stirring.
7. Cover and leave for 20 minutes for the curds to form.
8. Scoop out the largest curds into a tofu mold lined with filter cloth, pour the rest of the curdled soy milk on top at the end.
9. Use the edges of the filter cloth to cover the top of the tofu, place the 'lid' of the mold on top, and use a ~400g weight (tin of tomatoes) to weigh it down and press out the whey.
10. Wait ~20 minutes for the tofu to harden, then remove it from the mold and soak it in cold water for at least another 20-30 minutes. You can remove the cloth either before or after soaking, but I think after is safer to avoid the tofu sticking to it.

Adjusting firmness

Assuming you are able to get it to coagulate properly, the firmness of firm tofu can be controlled most easily by adjusting the pressing time or weight. I have soaked the beans in water for a range of times - from between 12 and 24 hours or so, and this did not seem to affect the result.

Recipe Variations

Among the many recipes I looked at for making tofu, some said to strain the blended mixture first before cooking (i.e. interchange steps 3 and 4 above), while others had it the way I described. I believe this is a difference between Japanese and Chinese traditional methods of making tofu. The 'hot filtering' method is Japanese. My tofu-making kit is Japanese so that's what I did.

Soy milk for drinking vs for tofu

I noticed that on one unsuccessful attempt at making tofu, I decided to boil the whole beans after soaking (step 1), but before blending. So I simmered them in the pot on low heat for at least an hour, before continuing with steps 2 and later, including the usual cooking step. Crucially, I discarded the water after the first boiling, and used fresh water for blending. In the end, the soy milk hardly curdled at all, even after adding twice as much coagulant, and I was left with no option but to drink it. But interestingly, the taste was distinctly less beany than the soy milk from the previous batch of tofu.

So my theory is that cooking the whole beans and discarding the cooking water can get rid of some compounds (proteins?) in the soybeans that cause the beany flavour in soy milk, but also are necessary for it to coagulate.

However, I have also read that just simmering the blended mixture for longer can reduce the beany taste, so I plan to try this out too.