Soya is a legume cultivated all over the world - it is extremely adaptable and resistant - and it is a very important food because its seeds contain proteins, lipids and minerals in greater quantity than other legumes, moreover it has the capacity of lowering the level of cholesterol in blood.

 According to a botanical point of view soya belongs to the leguminosae family and originated in Central Asia, flowers can have colors from red to white as well as violet, it grows, just like most of legumes, in small pods of 3-5 centimeters long (1-2 inches) containing some small seeds similar to beans. Pods grow in the plant concentrated in clusters. Every pod normally contains 2 or 3 seeds although this may vary from plant to plant, both for the shape and for the color, even though, at the time of harvesting, they usually get a brown color because the external part of the pod dries before full ripeness. Just like other plants belonging to the family, soya can absorb azote directly from the air and to store it, thanks to the actions of some bacteria, in its roots. For this reason in China it was cultivated in order to increase the quantity of azote in the soil and the plant was used as a food for animals whereas only sprouts were used for human nutrition. In the western world this function was ensured by lucern, clover and pea.

 Among the main varieties of soya are mentioned:

• Yellow soya - it is the most common soya and from which are produced all the derivatives
• Black soya - mainly consumed in the production places
• Red Soya - also known as “azuki beans”, it has a red color
• Green soya - also known as “mung beans” or “green gram”. It is mainly used for the production of sprouts and the renowned soybean noodles

 The soya varieties are divided in two main groups: determinative and non determinative. Determinative varieties blossom in a specific period of the year, that is when daytime gets shorter. On the other hand, non determinative varieties continue to blossom and to bear fruits.

 The first information about soya are from China where it was cultivated for the first time about 5,000 years ago. The emperor of that time included soya in the five sacred plants (the others were rice, millet, barley and wheat) and he called it “Ta Teou” (big bean). In ancient times soya was used to enrich the soil of azote. The first usage of soya as a food was done with the discovery of fermentation, in fact, the first foods based on soybean were fermented, such as tempeh, natto, miso and soy sauce. It seems that Chinese learnt from Japanese the technique for the production of tofu, the renowned bean curd.

	Yellow soya and soya sprouts

 It was during the Heian dynasty (794-1185) Dutch knew the Japanese soy sauce. The first information of soya outside China is dated back to around 1804 when it was used as a ballast for an American sailing-ship. The first commercial plantations of soya were started around 1929 and the main destination was the production of soy sauce. The spreading and notoriety of soya began soon after this period therefore getting more and more importance as well as becoming a source of proteins for humans and animals, besides, of course, its usage in many industrial products. Today it is being mainly cultivated in the United States, Brazil, China, India, Argentina and Italy. Soya represents the main transgenic cultivation and its commercialization is currently forbidden in Europe, whereas in the United States represents about 50% of total production and in Brazil it is even as high as 64%.

 From soya are being produced many foods and of which are mentioned:

• Soy sauce - produced by boiling soybeans, wheat and barley in water and salt and subsequently fermented
• Sprouts - can be produced with sprouts of yellow, green and red soya and are used as vegetables
• Soybean milk - it is obtained by the maceration of soybeans in water and it is now pretty common. It is used as a substitute of cow milk even though it lacks of vitamin D and calcium, for this reason are being commercialized products based on soybean milk and enriched with vitamins and minerals. Soybean milk does not contain any lactose and therefore can also be consumed by subjects intolerant to this element. Because of the nickel contained in this food, soybean milk can be cause, in sensitive subjects, of allergic reactions. Just like every derivative of soya, it does not contain cholesterol
• Tofu - also known as “bean curd”, it is produced by the coagulation of soybean milk. Just like the other derivatives of soya, it does not contain cholesterol and it is rich in vitamins, however it contains small quantities of calcium and mineral salts. From many it is being used as a substitute of eggs and meat
• Tempeh - it is boiled and fermented soybeans and mashed into a creamy compound with a characteristic taste. It is being used as a condiment for pasta, rice, sandwiches and salads. It is very common in Indonesia
• Tao you - it is a sauce produced with black soya
• Natto - it is fermented soybeans, just like tempeh, however the fermentation is done by using a different type of yeast
• Miso - it is a derivative of soybean milk. It is very common in Japan where it is being used as a condiment for soups
• Soybean ice cream - it is produced with soybean milk. As opposed to regular ice cream, it does not contain any cholesterol or lactose, it is a completely vegetal product and generally provides 50% of the calories provided by regular ice cream
• Tamari - it is a condiment produced with salted yellow soybeans and fermented in wood barrels for three years
• Shoyu - it is just like tamari with wheat added
• Soya lecithin - it is a phospholipid extracted from soybean, used in the industry as an aromatic substance, as antioxidant as well as a natural emulsifying agent. It is usually found in integrative foods and in products for lowering the quantity of cholesterol in blood. Soya lecithin keeps in suspension the cholesterol found in blood while avoiding its deposit in the arteries. Soya lecithin also provide vitamin A and phosphor, two important antioxidant elements
• Soybean flour - soybean flour is obtained by milling the seeds, and in case lipids are being removed, it is obtained a highly proteinic food. Soybean flour can be used for cooking and as a substitute for wheat flour
• Soybean oil - it is obtained by pressing heated soybean seeds and therefore chemically processed, it is rich in fat and polyunsaturated acids
• Soybean meat - it is soybean flour processed with a particular method in order to give it meat consistency
• Soybean nuts - soybeans cooked in oil or toasted, they are used as a condiment in some recipes
• Soybean yogurt - it is produced with soybean milk

 Among these products soya lecithin deserves a thoroughly consideration. Despite the fact the consumption of soya in the form of beans is not very high, its cultivation is practiced extensively and intensively. The reason of this is soya lecithin and its characteristics. In order to understand this phenomenon it is necessary to know that soya lecithin is widely available and at a low cost, moreover it is capable, thanks to its properties, to mix substances that would not be however mixed, such as water and fats. Lecithin lets water to get mixed with cocoa powder therefore obtaining a thick and fluid chocolate, it avoids butter to separate from water and sugar to recrystallize. It also allows to lighten any fat substance by adding water. Thanks to this characteristic it can be produced margarine, made of 80% of fats and 20% of water. In pastry cooking soybean flour is added to wheat flour in order to increases the retention of liquids, therefore delaying products dryness. This anti retroactive property of lecithin gives meat a higher quantity of water and it is also used for the production of cold cuts, hamburger and minced meat. The food industry is not the only one which makes use of soya lecithin: the cosmetic industry makes a wide use of its emulsifying properties, it is also used for the production of paints and in the composition of gas oil. Another characteristic of soya lecithin - which also increase its versatility - is represented by the fact of being odorless, therefore it is widely used as an aroma emphasizer and used as a substitute of fats.

 Soybean is one of the richest legumes in proteins - it contains an average of 33-44% - as well as fats (18%) and carbohydrates (23%). Proteins contained in soybean do not ensure a complete contribution of aminoacids, for this reason it is defined as a product of “average biological value”. Thanks to the presence of phytosterols capable of lowering the quantity of cholesterol in blood, as well as isoflavones, substances which naturally regulate the production of hormones, it is considered as a particularly healthy plant.

 A particular consideration is to be done for soybean's fats, because they contain substances difficult to obtain from the foods of our diet, that is the famous omega 3 and omega 6. In fact, our organism can synthesize all fat acids except alphalinoleic acid (belonging to the family of omega 6) and linoleic acid (belonging to the family of omega 3). From these two fat acids the human organism can synthesize all the other polyunsaturated fat acids. These two substances are very important because play a role in the growing process, the production of energy, the synthesis of hemoglobin, the reduction of total cholesterol and LDL cholesterol. Soybean oil is a good product for the ones who need to integrate these substances in their diet. Among Japanese women, as well as Asiatic women, it is found a low incidence of diseases connected to the production of estrogens, such as endometriosis, fibrocystic mastoiditis, carcinoma and menopause related pathologies. This seems to be because in those people they are widely used soybean products, in particular tofu. Isoflavones contained in soybean can balance both the excess of estrogens - such as in case of premenstrual syndrome - and the lacks of them - such as in menopause - therefore restoring correct values. For men the consumption of soybean can prevent prostate cancer.

 Isoflavones contained in soybean are capable of inhibiting the growth of cancerous cells in breast and in lungs. A regular consumption of soybean, or of its derivatives, it is therefore a natural way of preventing cancerous diseases. According to a report published by the journal of the “National Cancer Institute” it is said that a laboratory study has individuated in “genistein” the possible anticancer agent of soybean. Genistein seems to affect the metabolism of cancerous cells by weakening their defenses, while allowing medical treatment, such as chemotherapy or radiotherapy, to have a better efficacy. This can be seen as a good reason to add soybean in our diet, however it should be remembered genistein is found in the proteinic parts of the seed and therefore it can be found, for example, in tofu but not in soybean oil. All these characteristics could suggest a huge consumption of soybean, however this is not the case: it should be remembered that Chinese, since the most ancient times, have consumed only fermented soybean because the legume contains some toxins. One hundred grams of soybean contains: 36.9 grams of proteins, 18.1 grams of lipids, 23.3 grams of carbohydrates, 0 grams of cholesterol and 398 Kcal. When properly processed soybean can perfectly substitute in taste, appearance and consistency, animal proteins.

 In cooking soybean can be consumed in many ways: soy sauce, soybean milk, tofu, soybean steaks and more. It should be remembered soya is one of the main plants which are subjected to genetic manipulation. Many food producers do not ensure the use of non genetically manipulated soya, therefore it is advisable to carefully read the labels in which it should be clearly written the origin of the food.