Quick Answer: Technically speaking, tofu is a processed food because the final product is pressed curd that's extracted from soy beans. But of course, this doesn't necessarily mean that it's bad for you or that it can be placed in the same category as a candy bar or processed meat. Many of the longest living populations enjoy tofu on a regular basis.
Technically speaking, every food is processed to some degree, even whole vegetables which could be cut, rinsed, or have wax applied to the skin before hitting the shelves.
That said, it's probably best to consider processed foods to be a spectrum rather than black and white.
Almost every item you can see on the grocery store shelf starts with a "real" food. The processing can step can be as simple as cooking it and adding seasoning or to using enzymes extracting certain components from the food (think high-fructose corn syrup which turns corn starch into a syrup high in fructose using enzymes).
In the case of tofu, it's somewhere in the middle of this spectrum. Once you have a look at the processing steps, you'll see what I mean...
The way tofu is made for consumption can be broken down to an 8-step process.
- Soaking - Making tofu starts with soybeans and first these soybeans must be soaked. The soaking process allows these legumes to expand and soften which makes them easier to make into a tofu block.
- Mashing - Once the soybeans are properly soaked they need to be mashed and made into a slurry. This is basically just a combination of the pulp and liquid that comes out of the soybean.
- Separating - The pulp is then separated from the liquid and the pulp is shipped off for things like baking or animal feed.
- Coagulating - Have you ever seen things on your tofu ingredients such as: magnesium sulfate, magnesium chloride, or nigari? These are curdling agents that allow the liquid soy milk to form into a block of tofu. The process is similar to making cottage cheese (which is why cottage cheese has curds). Except with tofu, the curds are going to be pressed together and meshed in the text step.
- Pressing - Using a large press which applies even pressure on both sides, the tofu is condensed into the block that you're familiar with. Often times, a large cheese cloth is used as well to prevent the curds from falling or dripping out. You can actually do this process at home yourself if you get one of our best tofu press picks. Learn more here.
- Cutting - Once it's pressed the tofu is ready to cut. In a commercial setting, the block is going to be far too big for home use so it's cut down into manageable blocks for packaging.
- Packaging - The cut block is added to the packaging and it's sealed in the way that you're familiar with.
- Pasteurization - For shelf life and safety, the tofu is then exposed to ~180F while it's still in the package. It's then chilled and ready to get shipped off to the supermarket shelf.
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