Soya beans were cultivated as long as 5000 years ago in China, although they arrived by accident in the USA in 1804, as ballast in a boat from the Far East. Out of curiosity, someone planted them - and the enormous potential of the crop was realised. During the First World War, sources of vegetable oil were needed and soya beans found a new role. With the advent of the Second World War, the high protein content of the beans provided a fresh focus for research. These days, USA, China and Brazil are the largest growers of a plant which remains the world's main source of cooking oil.
The Nutritional Profile of a Soya Bean
Compared to most plants, soya is stuffed full of useful nutrients;
- Its high PUFA (polyunsaturated fat) content of almost 7%, gives it an energy value of 640kcals per 100g of cooked beans, more than milk chocolate at 540kcals/100g (1).
- The protein content at 13% is unusually high for a plant, but there is a drawback. Soya, in common with other beans, lacks an essential amino acid, methionine, but is rich in lysine. Bread contains the missing methionine, but lacks lysine, so traditional “beans on toast” provide the perfect nutritional balance (2).
- Soya beans also contain 6% fibre, useful amounts of calcium, iron, thiamine and riboflavin.
Versatile Soya
In the West, the acceptance of soya has been a slow process, but not so further east, where it has been part of the culinary culture for a very long time. The cooked beans are used both as a vegetable and salad item, and the flour from the dried beans finds its way into soya milk, cheese, curd and breads. Dried beans can be made into a form of coffee (caffeine free) and fermented bean paste makes an excellent range of soy sauces. Possibly some lingering fungi on the surface of a chinese soya bush produced the first hint of this delicious ferment now worth millions to the food industry (3).
Steaks from Plant Protein?
The ultimate accolade to soya’s versatility is the manufacture of TVP, or textured vegetable protein which can be shaped into meat sized chunks. The flour is made into dough and heated under pressure. It is then extruded through a nozzle at normal atmospheric pressure, causing the dough to expand and achieve the desired texture, suitable for use as a meat extender in stews and pies. Along similar lines, spun vegetable protein can be shaped into fibres and sold as a convincing meat substitute. Throw in some added colouring and flavouring, and there you have it – soya steak on a plate. Better inspect that sizzling steak carefully..
References
- Fox B, Cameron A, (1995). Food Science, Nuton and Health. Arnold.
- Davidson A.(2002) The Penguin Companion to Food. Penguin Books
- Wiseman G. (2002) Nutrition and Health. Taylor and Francis.
 |
