What Grain Crops Are There?

Food is the people's top priority; everyone eats three meals a day. Amid today's changing circumstances, food security has again become a topic of discussion. So which grain crops can we eat? Below is an introduction to common grain crops.

Grain crops fall into three categories: cereals, tubers and legumes.

Cereal crops belong to the grass family (Poaceae), except buckwheat (Polygonaceae), and include wheat, rice, corn, oats, rye, barley, millet, sorghum and highland barley. Their seeds feed people and livestock, and their straw and bran mostly serve as feed. Wheat, rice and corn alone provide over half of the world's food. Cereals mainly supply starch, plant protein, fat, vitamins and other nutrients.

Legume crops include soybeans, broad beans, peas, mung beans, adzuki beans, common beans, cowpeas, sword beans and hyacinth beans. They are also concentrated feed for livestock, in great demand and with considerable planting area and share. Legume seeds are rich in starch, protein and fat—a highly nutritious food.

Tuber crops mainly include sweet potatoes, potatoes, yams and taros. They serve as food, vegetables, feed and industrial raw materials.

Grain Storage

Post-harvest moisture content is crucial for both commercial and seed use. Ideally, grain is dried to near the critical point for storage-microorganism growth. At this moisture level, storage safety is assured while freshness, eating quality, germination rate and seed quality are preserved to the greatest extent.

Grain also respires. Respiration is the physiological process by which animals take in oxygen and release carbon dioxide. Plants lack a dedicated respiratory system but likewise consume oxygen and release CO2, so the same term is used. In viable seeds, the embryo is the main site of respiration. Processed products such as flour and rice also consume oxygen and release CO2 under sealed conditions, mainly due to microbial and pest infestation. These organisms respire more intensely than the seed itself, so "grain respiration" is a general term—actually the aggregate behavior of the grain-mass ecosystem.

Moisture and temperature are the main factors affecting grain respiration, and they are interdependent rather than independent. At low grain moisture, temperature has little effect on respiration; as moisture rises, temperature-driven changes in respiration intensity become dramatic. Experiments show that grain at18%–23% moisture shows a sharp rise then sudden drop in respiration at 50–55°C, while grain at 14%–16% moisture shows almost no change over several days at the same temperature. In storage, keep grain respiration to a minimum wherever possible.