By Navodita Maurice
Tofu also known as bean curd is actually a product obtained by coagulating soymilk and then pressing the resulting curd into white blocks. It is native to China and is also a part of East Asian and Southeast Asian cuisines. A number of varieties of tofu are available like the fresh tofu and the tofu processed in other way. It has got very little flavor of its own so can be served with other dishes or even marinated with other agents depending on the dish with which it is being served. It is a very important part of Buddhism as it is rich in protein and forms a part of vegetarian diet of East Asian Buddhist people. It is low in calories but rich in iron and also bears low fat content. Depending upon the coagulant used by the manufacturers it may be having high calcium or magnesium content.
Tofu is prepared by coagulating soymilk and then pressing the resulting curd. Premade soymilk may be used but majority of the tofu producers use soymilk made by them. Soymilk is made by soaking, grinding, boiling and straining dried soybeans. Coagulation of protein and oil suspended in the boiled milk is very important step. This step is carried out with the help of coagulants. Salts and acids are the two important coagulants used for commercial production. Third type includes use of enzymes which is not preferred for commercial production as it slows down the process. Calcium sulphate is the most commonly used traditional salt coagulant for the production of Chinese style tofu. It produces somewhat tender and brittle tofu. This coagulant lacks any taste of its own. Tofu produced by using this coagulant is rich in calcium so mostly preferred by the manufacturers as calcium is important for health. Magnesium chloride and calcium chloride are also used in coagulation process. They produce tender and soft tofu and are mostly preferred by Japanese manufacturers. Glucono delta-lactone (GDL) is most commonly used acid coagulant. It is an edible organic acid used in the production of cheese and produces fine tofu. It is used in making soft and silken tofus. Acetic acid is also used for the same process. Among the enzyme coagulants papain, alkaline and neutral proteases are most commonly preferred.
The coagulants are first dissolved in water and added to the soymilk and allowed to boil unless the mixture produces a soft gel or curd. The curd formed is processed depending upon the type of tofu to be produced. For soft silken tofu the curdled milk is directly transferred to the selling packages. For standard firm Asian one the curd is cut and the strained to remove all the water content and then pressed in the form of white cake. They are easily spoiled by the bacterial activity which adds a sour taste and cloudiness to tofu. A number of varieties are known like fried, silken, soft, pickled, frozen tofu etc. depending upon the mode of processing. It contains relatively high levels of protein. A study carried out at the University of Kentucky indicated that it reduces the serum cholesterol and Low Density Lipoprotein levels. Soy isoflavones have not shown any significant effect on health and research is required in this area. High consumption of this product may result in dementia in older age groups.
Navodita Maurice
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