Soy it is the fruit of a plant belonging to the Leguminosa. It has the shape of a small pod from which seeds similar to the bean are extracted and varying in color from yellow to brown (so-called “yellow soy”) or black (so-called “soy mera”). Other seeds similar to soy and, sometimes marketed as such, actually belong, to all intents and purposes, to the category of beans, such as “red soy, called azuki, or even“ green soy ”, called mung bean. It is one of the most digestible and rich in proteins legumes, presenting to a lesser extent the effect of flatulence, compared to other legumes. It has also been rediscovered in Western civilization in recent decades for its high content of lecithin, used as a natural cholesterol-lowering agent.
Both the seeds (or soy beans) and the sprouts are eaten from the soy, moreover, numerous derivatives are obtained, some of which are easily available in specialized shops in Italy. The origins of soy are to be found in Asia, although it has been present in Europe since the 18th century. Today, one of the largest soybean producers is America (USA and Brazil), where the seed was brought in the early 19th century.
Soybeans are used like the most common beans, although they require longer cooking times (about 1 hour abundant), in soups, stews or smoothies in velvety or soups. 35% of the overall nutritional value of soybeans is made up of proteins; compared to other legumes it has a rather high lipid content (20%), even though it is unsaturated and polyunsaturated fats. It is also rich in carbohydrates (for this reason it is not recommended to use it during ketogenic slimming diets) and also mineral salts such as calcium, phosphorus, iron and magnesium. The seeds are rich in Vit A, B1, B2, D, E. The shoots, on the other hand, they are obtained from the newly born plant and have a very delicate flavor and are suitable for use in raw or pan-seared salads (preferably with high sides for quick cooking, leaving the sprout crisp). They are even more digestible than soybeans, have a lower protein content but few calories (49 Kcal / 100g), which makes them suitable for use even during slimming, hypoglucidic diet schemes. Bean sprouts are available fresh or, already cooked, in cans.
The most common soy derivatives
The first soy-based foods widely marketed in Italy (of which a famous television advertisement is recalled) were soy milk and ice cream, followed by yogurt extracted from soy milk, a drink extracted from legumes. Soy milk can be produced from whole dried soybean or fatty soybean meal, which is rehydrated and wet ground with the addition of water gradually until a slurry is obtained which is then brought to a boil in order to sterilize the product but also improve the aroma, moreover the high temperatures inactivate the trypsin inhibitors present in the original compound. Finally, filtration is carried out to remove the insoluble residues that are generated at high temperatures (Japanese method). Sometimes, cold filtration precedes boiling, according to the Chinese method. The Japanese method has a higher yield but requires the use of anti-foaming additives which can remain in the final product.
In recent years, “soy cheese” or Tofu is also spreading on our tables ; it is obtained from the rennet of soy milk at 75 ° C (the so-called Japanese Nigari ). It contains few fats, most of which are unsaturated and has considerable versatility in the kitchen.
The tempeh , however , is a stick up about 2 cm obtained from the boiled and inoculated yellow soybeans with a fungus for a day to about 30 ° C. its use in the kitchen is less well known but just as varied.
With the yellow soybean oil is also produced, also used for the production of margarine. Usually the oil is obtained by chemical process using solvents, cold extraction by pressing is much more expensive and practically unused for large productions. It is not suitable for frying because at high temperatures it generates highly toxic HNE (4-hydroxy-trans-2.nonenal) from the reaction of the polyunsaturated fatty acids contained.
On the market, there is a high variety of soy-based foods, which are often supplanting other more traditional products of Mediterranean cuisine, especially in vegan or vegetarian culture, but also as an alternative to traditional cuisine. The virtues of soy are praised by food manufacturers, which enhance the nutritional characteristics of the product almost to the point of presenting it as a preventive or curative medicine. It is clear that the beneficial effect on health must always be understood as a set of healthy elements and behaviors as a function of a correct lifestyle. Furthermore, the consumer is often not fully aware of the methods of cultivation, processing and conservation of this legume and its derivatives, that can alter or destroy the molecules useful for health and generate other harmful ones; likewise, the western population does not know precisely the most suitable cooking methods to preserve the nutrients.
Soy and its derivatives have been processed foods for millennia in the history of humanity; inserting them in the tables of the Mediterranean allows us to expand and stimulate our sense of taste, integrating them with foods rich in precious nutrients. The information and awareness of Western man, however, with respect to these “new foods” must be particularly careful to avoid falling into myths and food errors.