What is Tofu?
Tofu, also known as soy curd or bean curd, is made of coagulated soy milk. Due to its bland flavor, it is a versatile ingredient and it can be used in a wide variety of recipes, from the main course to dessert. Tofu is an excellent source of protein, and it is often a key part of vegetarian and vegan diets.
Health Risks from Unsafe Handling of Tofu
Most commonly, raw tofu is sold either packed in water in a sealed container, or in a sealed aseptic carton. It is also sometimes available in bulk, unpackaged, and submerged in water. Raw tofu may be contaminated with food-borne pathogens that can cause illness. Microoganisms can grow in the water that the tofu is packed in, especially if it has not been consistently kept refrigerated.
Raw tofu packed in water poses the highest risk, and if not handled properly, it can cause symptoms of abdominal pain, bloating, gas, cramps, diarrhea, nausea, vomiting, headache or fever. These symptoms may lead some people to mistakenly believe that they are allergic to tofu or soy products, when in fact they are actually suffering from food poisoning.
Safe Food Handling Guidelines for Tofu
Here are some safe food handling guidelines for tofu:
- Do not eat raw, water-packed tofu straight out of the package
- Do not feed raw tofu to children
- Boil the tofu in water or steam it for 5 to 10 minutes before using, if it is not going to be used in a dish that requires cooking
- Cut tofu into small pieces before cooking to ensure that it is heated to at least 165 degrees F (74 degrees C) all the way through
- Frozen tofu should be thawed in the refrigerator
- Leftover cooked foods containing tofu should be promptly refrigerated
- Pre-cooked or baked tofu, and tofu that is sold in aseptic, vacuum-sealed packages poses a very low risk of food-borne pathogens, and should be safe to eat directly from the package.
Glucono-Delta Lactone in Silken Tofu
Glucono-Delta lactone (GDL) is a food additive that is found in a variety of foods including wine, fruit juice, honey, sausage, and canned fish. It is used as a coagulant in the production of silken tofu to give it a fine, jelly-like texture. GDL can be produced either biologically by the bacterial fermentation of carbohydrates (starch), or synthetically by enzymatic oxidation of glucose. The body metabolizes GDL back to glucose.
When GDL is produced by the fermentation method, the starch used in its production is commonly derived from corn. Certain individuals who are allergic or very sensitive to corn may experience gastrointestinal upset or other problems when they eat silken tofu. This should not occur with other varieties of tofu, because GDL is not used in their manufacture.