【Smart Farmers】The World of Beans: Exploring the Secrets of a Nutritional Treasure House

Beans are a popular food that is not only delicious but also nutritious. Each type of bean has its own characteristics and nutritional value. The nutritional differences between different beans are huge, including protein, fat, carbohydrates, vitamins and minerals. Let's take a look at the nutritional differences of different beans from these five aspects.

Bean nutrition comparison: significant differences in protein content

Soy protein is the main source of plant protein. It also contains eight essential amino acids for the human body, so it is regarded as "one of the most ideal sources of protein". In my country, the average content of soybean protein is about 40%, while in soybean varieties in the southern region, the protein content can reach more than 45%, and some resources even exceed 50%.

In addition to soybeans, other edible beans are also good sources of protein. For example, every 100 grams of mung bean seeds contain 20 to 30 grams of protein, and its content of essential amino acids for the human body is high, such as methionine, tryptophan, lysine, leucine and threonine, which are 2.3 times that of wheat, 2.7 times that of millet, 3 times that of corn, and 3.2 times that of rice.

The protein content of dry pea seeds is about 15%-30%. Pea protein includes albumin, globulin and gluten. In the amino acid composition of pea protein, tryptophan, lysine, threonine and methionine are more abundant, but the content of arginine, leucine and phenylalanine is less than that of globulin. The content of lysine in pea protein is relatively high, which is a good raw material for extracting lysine.

The biological value of pea protein is 48%~64%, and the efficacy ratio is 0.6~1.2, which is higher than soybeans but lower than corn, rice, wheat and peanuts.

Broad bean protein is rich in lysine, leucine, theanine and tyrosine. Compared with several other major field crops, the content of essential amino acids in broad beans is second only to soybeans and significantly higher than wheat, corn and peas.

Eating beans is rich in fatty acids and has a miraculous effect in lowering cholesterol

Soybeans are rich in fatty acids, accounting for about 20%, mainly including palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. Among them, palmitic acid and stearic acid are saturated fatty acids, while oleic acid, linoleic acid and linolenic acid are unsaturated fatty acids.

The fat content of edible beans is usually low, generally between 0.5 and 5%. In addition, edible beans do not contain trans fats and cholesterol. Its fatty acids mainly include palmitic acid, stearic acid, oleic acid, linoleic acid and α-linolenic acid, among which the content of linoleic acid is relatively high. In general, there are large differences in the content of major fatty acids in different edible beans, but their unsaturated fatty acid content is high. For example, the relative content of palmitic acid in mung beans and red beans is 24.46% and 20.01%, respectively, α-linolenic acid is 20.13% and 27.86%, respectively, and total unsaturated fatty acids are 61.82% and 69.28%, respectively.

The lipid content in broad bean seeds is low, only 0.5 to 2%. Among them, neutral triglycerides are the main components, accounting for 35.6%; phospholipids account for 29.49%. Among broad bean lipids, linoleic acid has a high content. Linoleic acid helps lower the cholesterol content in the blood and lungs, and also has a good effect on brain health.

The fat content in pea seeds is 0.5% to 4%, most of which exists in the form of oil. The fat content in the seed coat is very small, while the fat contained in the cotyledons accounts for about 90% of the fat content of the entire seed; the fat content in the embryo is very high, and a higher fat content is often associated with wrinkled grains. Studies have shown that 60% of the fatty acids in pea seeds are unsaturated fatty acids.

Carbohydrates: Beans' main energy source

Mature soybean seeds are rich in starch, which accounts for 1% to 5% of the dry weight of the seeds. The carbohydrate content of edible beans is about 50% to 80%, and the total dietary fiber content is about 10% to 20%, making them an important source of dietary fiber. Since edible beans are low-glycemic index foods, they are beneficial in reducing the risk of diabetes.

Broad bean seeds contain about 60% total carbohydrates. Of these, starch accounts for 95.6% of the total carbohydrates. This makes starch the main source of calories in broad bean foods. In addition, crude fiber accounts for 8% of the weight of broad bean seeds. Of this 8%, hemicellulose accounts for more than 60% of the crude fiber weight, while cellulose accounts for about 35%. Most of these fibers are found in the seed coat. In the past, cellulose was considered an ineffective ingredient in terms of nutrition. However, recent reports have shown that cellulose can promote digestion and lower blood cholesterol levels.

About 60% of pea seeds are carbohydrates, including starch, sugars and crude fiber. Generally, wrinkled peas have a relatively low starch content, while round peas have a relatively high starch content. Wrinkled dry pea seeds contain 20% to 40% starch, while round dry pea seeds contain 35% to 50% starch. In addition, the starch in wrinkled peas is mainly amylose, while the starch in round peas is mainly amylopectin.

The total starch content of adzuki beans is 40% to 70%. Compared with cereals, its starch content is lower, but higher than soybeans. Therefore, adzuki beans are crops with medium starch content. In adzuki beans, resistant starch is an important carbohydrate that has the physiological effects of lowering blood sugar and blood lipids, and has gradually attracted widespread attention from nutritionists. Resistant starch has a wide range of applications in food and can be added to extruded foods, baked foods, and breakfast foods to increase the content of dietary fiber and improve the quality of dietary fiber-fortified foods. Studies have shown that the average content of resistant starch in adzuki beans is about 15%, among which the content of resistant starch in adzuki beans in Jilin Province is the highest, about 15.71%.

Pulses are a treasure trove of vitamins and minerals

Beans are rich in mineral elements such as iron, magnesium, potassium, phosphorus, zinc, and B vitamins such as thiamine, riboflavin, niacin, vitamin B6, and folic acid, which are essential for maintaining human health. Eating beans, especially the high iron and zinc content, is particularly beneficial for women and children who are prone to anemia. Beans can be an important source of mineral elements for the human body. There is evidence that beans also contain bioactive compounds that can fight cancer, diabetes, and heart disease. Some studies have also shown that regular consumption of beans can help prevent and control obesity.

Adzuki beans are a special type of legumes with richer nutritional value. Studies have shown that every 100 grams of dried adzuki beans contains an average of 67-91 mg of calcium, 340-450 mg of phosphorus, 4.5-5.6 mg of iron, 0.5-3.3 mg of vitamin A, 0.2-0.5 mg of vitamin B, and 1.8-2.1 mg of niacin. In addition, it also contains three types of crystalline saponins, which makes the nutritional value of adzuki beans much higher than that of cereals and tubers. Therefore, adzuki beans are an important source of mineral elements such as calcium, phosphorus, iron, and B vitamins.

Bioactive substances: what makes beans unique

Pea peptides have significant antioxidant capacity, can effectively remove free radicals, and show strong anti-attachment ability to Helicobacter pylori. In addition, it also has diverse physiological activities such as lowering blood lipids, anti-fatigue, and anti-cancer.

Polyphenols are an important substance in edible beans that have health benefits such as antioxidant and anti-tumor effects. The total polyphenol content in beans such as cowpeas, adzuki beans, mung beans, and broad beans is about 10 to 12 mg/g. The total flavonoid content in these beans is about 5 to 7 mg/g, which plays an important role in human health.

GABA is a hot topic in the bean food processing industry. It is a non-protein amino acid. In the central nervous system of mammals, GABA is an important inhibitory neurotransmitter. It has a variety of effects, such as lowering blood pressure, anticonvulsant, analgesic, improving brain function, promoting growth hormone secretion, activating kidney function, activating liver function, etc.

Produced by: Popular Science in China to Benefit Farmers

Scientific Advisor: Xue Chenchen, Associate Researcher, Legume Crop Innovation Team, Jiangsu Academy of Agricultural Sciences

Zhang Xiaoyan Associate Researcher, Legume Crop Innovation Team, Jiangsu Academy of Agricultural Sciences

Huang Lu Assistant Researcher, Legume Crop Innovation Team, Jiangsu Academy of Agricultural Sciences

Co-ordinators: Liao Danfeng, Zheng Fengmao, Wang Changhai, Zhang Ruijie

Planning: Wu Yuetong

Editor: Yan Shuo (internship)