Soybean: classification, quality and applications

Soybean (Glycine max) is an annual herbaceous plant of the legume family, whose seeds are one of the most important global oilseed and high-protein crops. Soybean occupies a unique position in world agriculture and the food industry, as it combines two key products — vegetable oil and high-quality protein. Due to its ability to fix atmospheric nitrogen, soybean improves soil fertility and serves as a valuable preceding crop in rotation. Amid global population growth and demand for protein, soybean remains a strategic resource ensuring food security and the feed base for livestock.

Chemical Nature and Seed Composition

Soybean seeds are distinguished by a high content of protein and fat. The chemical composition (in % on a dry basis) varies depending on the variety and growing conditions: protein — 35–45%, oil — 17–22%, carbohydrates — 20–30%, fibre — 4–6%, ash — 4–5%. Soybean proteins are represented mainly by globulins (glycinin and conglycinin) and albumins; they are well balanced in amino acid composition and close to animal proteins. Soybean oil is rich in unsaturated fatty acids (linoleic and oleic) and also contains phospholipids (lecithin), vitamin E and phytosterols. In addition, soybean contains bioactive compounds — isoflavones and saponins, which have antioxidant properties. It is important to note that raw soybean seeds contain anti-nutritional factors (trypsin inhibitors), which are inactivated by heat treatment.

Classification, Quality and Standards

In Russia and CIS countries, requirements for soybean harvested and supplied for processing are regulated by GOST 17109-88 "Soybean. Requirements for state purchases and deliveries". According to the standard, soybean seeds must be in a healthy, non-heating state, have the shape, colour and odour characteristic of normal seeds, without musty, mouldy or foreign odours.

The standard distinguishes two types of seeds by hull colour: type I (yellow soybean) — yellow or greenish-yellow seeds of various shades, and other types. For harvested and supplied soybean, base and restrictive norms are established for moisture, foreign and oilseed impurities, and pest infestation. For example, base moisture is not more than 12%, foreign matter — not more than 3%, oilseed impurities — not more than 15%. The content of toxic elements, mycotoxins and pesticides is controlled in accordance with safety requirements. For seed purposes, a separate standard applies — GOST 9669-75 "Soybean seeds. Varietal and sowing qualities", which standardises germination, purity and other indicators.

Production and Processing Technology

Soybean cultivation includes soil preparation, sowing, care and harvesting. Soybean is demanding of warmth and moisture, especially during flowering and pod formation. After harvesting, seeds are cleaned, dried and sorted. The main directions of soybean processing include:

• Oil extraction production: soybean oil (by pressing or extraction) and soybean meal are obtained from seeds. Soybean oil is used for food purposes, for the production of margarine, mayonnaise, as well as for technical purposes (biodiesel, paints, varnishes). Meal is the main protein component of compound feeds.

• Soy protein production: concentrates (protein content 65–70%) and isolates (protein content at least 90%) are obtained from soybean meal. These products are widely used in the meat processing, dairy, baking and confectionery industries to enrich products with protein and improve their functional and technological properties.

• Production of food soy products: soy milk, tofu, soy flour, textured soy protein, soy okara. These products are the basis for plant-based analogues of dairy and meat products.

• Feed production: soybean meal and full-fat soybean are used in compound feeds for all types of farm animals and poultry as a highly valuable source of protein and energy.

Applications

Feed production. Soybean meal is the largest product of soybean processing, used as the main protein component of compound feeds for pigs, poultry and cattle. Its balanced amino acid composition and high digestibility make it the reference source of plant protein.

Food industry. Soy protein isolates and concentrates are used for the production of sausages, meat semi-finished products, dairy products (soy milk, yoghurts, cheeses), bakery and confectionery products, sports and dietary nutrition. Soybean oil is used as edible oil and as an ingredient for the production of margarines and spreads.

Technical and industrial purposes. Soybean oil serves as a raw material for the production of biodiesel, lubricants, paints, varnishes and solvents. Lecithin obtained from soybean oil is used as an emulsifier in the food and pharmaceutical industries.

Agriculture. Soybean as a legume crop enriches the soil with nitrogen, improves its structure and serves as a good preceding crop for cereals.

Safety and Storage

Soybean is a combustible material, but the main risk during storage is associated with biological processes. Seeds are hygroscopic: at moisture above 12–14%, respiration, mould growth and mycotoxin accumulation are activated. Storage is carried out in dry, well-ventilated grain stores (elevators, flat stores) at controlled temperature and humidity. Regular monitoring of pest infestation and active ventilation must be ensured. When working with soybean dust, respirators are recommended.

Market and Trends

The global soybean market is one of the largest and most dynamic agricultural markets. According to the International Grains Council (IGC), in recent seasons global soybean production has reached about 428 million tonnes, and consumption — about 430 million tonnes, an all-time high. Global soybean trade amounts to about 187 million tonnes. The largest producers are Brazil, the USA, Argentina, China and India; Russia is also increasing production (about 8 million tonnes). China remains the main importer, purchasing over 110 million tonnes of soybean.

Key industry trends include growing demand for plant proteins and soy isolates for the production of alternative meat and dairy products, the development of deep soybean processing, and the expansion of soybean oil use for biodiesel production. Producers with access to quality raw materials and modern processing capacities occupy stable competitive positions.

Conclusion

Soybean remains a strategically important oilseed and protein crop of global agriculture and the food industry. Understanding the classification according to GOST 17109-88, chemical composition, processing directions (oil, meal, isolate, food products) and applications is the basis for competent selection of raw materials for specific purposes — from feed production to plant-based food analogues. Organising supplies of soybean and its processed products, including quality selection and safety control, requires an individual approach.