What is the difference between aged grain and deteriorated grain? Grain storage moves toward ecological transformation
Now the grain market supply is very abundant, and consumers can buy the finished grain they need on the market at any time. However, some consumers worry: could the grain circulating on the market be aged grain? Can grain quality and safety be fully guaranteed?
Recently, a reporter from the Economic Daily learned during an in-depth investigation that the grain currently circulating on the market includes both new grain and aged grain. In order to ensure consumers' food safety, reserve grain depots at all levels across the country, as well as the grain depots of grain processing enterprises, widely use advanced grain storage technologies, effectively solving the problems of mold prevention, insect prevention, and freshness preservation in grain storage, and ensuring that reserve grain is always stored and always fresh.
Three channels of grain storage
In order to ensure the quality of rotated grain, central reserve grain must undergo testing before rotation, and only grain whose quality meets the standards may be rotated
After new grain comes onto the market each year, China mainly stores it through three channels: policy-based grain storage, enterprise turnover grain storage, and farmer household grain storage.
At present, farmer households in China store more than 500 billion jin of grain at staged intervals each year, accounting for about 50% of the country's total grain output. The grain stored by farmer households is mainly used for self-consumption. Some large grain-growing households, family farms, and other new agricultural operating entities that have grain storage facilities generally store grain at staged intervals, and by selling at staggered times, they maximize returns as much as possible.
Enterprise turnover grain storage is mainly to meet the needs of grain processing. As soon as new grain comes onto the market each year, grain processing enterprises purchase and store new grain at market prices. The storage period is at most one year, and before new grain comes onto the market, the stored grain is continuously processed and put onto the market. In recent years, due to multiple factors, grain processing enterprises have generally faced operating difficulties. In order to reduce storage costs, some grain processing enterprises have reduced the amount of grain they purchase, and they often obtain part of their grain supply through competitive bidding transactions at grain wholesale markets.
At present, part of the grain circulating on the market also comes from policy-based grain storage, composed of national reserve grain and national temporary storage grain, with a storage period generally exceeding one year.
National reserve grain is divided into central reserve grain and local reserve grain. The authority over central reserve grain belongs to the central government, while local reserve grain is divided into provincial, municipal, and county-level reserve grain, with the authority over the grain belonging to the local authorities. In order to ensure the quality safety and storage safety of reserve grain, reserve grain must be rotated out of storage on a regular basis, and the rotation time differs according to the region. According to the Measures for the Administration of the Rotation of Central Reserve Grain and Oil (Trial), the storage period of central reserve grain is calculated based on production time, and the storage time varies according to the region. In areas south of the Yangtze River, the storage period for paddy rice is 2 to 3 years, wheat 3 to 4 years, corn 1 to 2 years, and beans 1 to 2 years; in areas north of the Yangtze River, the storage period for paddy rice is 2 to 3 years, wheat 3 to 5 years, corn 2 to 3 years, and beans 1 to 2 years. In order to ensure the quality of rotated grain, central reserve grain must undergo testing before rotation, and only grain whose quality meets the standards may be rotated.
Aged grain is not deteriorated grain
As the storage time lengthens, especially after exceeding the normal storage period, even if the grain has not heated up, become infested with insects, or become moldy, the natural phenomenon of grain deterioration still exists
How can new grain, aged grain, and deteriorated grain be effectively distinguished? Is aged grain the same as deteriorated grain?
Experts told reporters that aged grain is not a standard term in the grain industry, but a general term used in society for grain not produced in the current year. Deteriorated grain refers to paddy rice, wheat, and corn whose storage quality has clearly declined and which are generally not suitable for direct use as food, and it does not include finished grain. Deterioration, suitability for storage, and unsuitability for storage are grain storage quality indicators, while mycotoxins, pesticide residues, and heavy metal content are food safety indicators. Storage quality indicators and food safety indicators are two independent systems. The former is used to judge whether grain is still suitable for storage, while the latter is used to judge whether grain is toxic or harmful. Being unsuitable for storage or deteriorated does not necessarily mean it cannot be eaten; the key is whether food safety indicators exceed the standards.
It is understood that before 2007, the Rules for Determining the Storage Quality of Cereals divided the storage quality of grain and oil into grain and oil suitable for storage, grain and oil unsuitable for storage, and deteriorated grain and oil. In 2007, relevant national departments jointly issued the Notice on Implementing the National Standard of the Rules for Determining the Storage Quality of Cereals, adjusting the storage quality indicators for paddy rice, corn, and wheat to suitable for storage, mildly unsuitable for storage, and severely unsuitable for storage, and the concept of deteriorated grain was abolished as a result.
Experts said that grain deterioration is a natural phenomenon. Grain is alive. As the storage time lengthens, especially after exceeding the normal storage period, even if it has not heated up, become infested with insects, or become moldy, the natural phenomenon of deterioration still exists. It is mainly manifested as a decline in eating quality and use quality, and when deterioration is severe, the color, smell, and taste clearly worsen. Judging whether grain has deteriorated is mainly based on eating quality indicators such as color, smell, taste, and fatty acid value. Whether grain can be eaten by people should be judged by hygiene indicators, not by storage quality. Grain that is not deteriorated but does not meet hygiene indicator requirements also cannot be eaten.
Storage technology continues to improve
As grain storage technology continues to upgrade, China's concept of grain storage is changing, and it is developing toward ecological grain storage that is “green, ecological, intelligent, and efficient”
With advances in grain storage technology, the quality of grain storage in China has already improved markedly. During interviews, reporters learned that central reserve grain depots, local reserve grain depots at all levels, and grain depots of grain processing enterprises throughout the country widely use the “four-in-one” grain storage technology of mechanical ventilation, circulating fumigation, grain cooling, and grain condition monitoring, effectively solving problems such as mold prevention, freshness preservation, and pest control in grain storage. According to estimates, after adopting this technology, the loss rate of central reserve grain dropped from 4% to within 1%, the suitable-for-storage rate rose from 70% to 99%, and the use of chemical agents for grain storage decreased by 80%.
Seamless supervision of stored grain is an important means of ensuring the quality of grain storage. Ge Liang, deputy director of the Anhui Modern Grain Logistics Center Depot, told reporters that before grain enters the depot, during entry, during exit, and during storage, they must conduct strict inspections of grain quality and storage quality. In order to ensure that the grain entering the depot is new grain, during the grain purchase period, strict closed-door inspections must be carried out on grain entering the depot to strictly prevent “favoritism grain.” If depot keepers have doubts about the quality of grain entering the depot, they may at any time refuse to allow questionable grain to enter the depot. In order to ensure the quality safety of stored grain, they adopt the method of timing rotations to accelerate the pace of grain rotation and ensure that reserve grain is always stored and always fresh.
As grain storage technology continues to upgrade, China's concept of grain storage is changing and developing toward ecological grain storage.
It is understood that central reserve grain depots, local reserve grain depots, and some enterprise grain depots now widely promote the use of non-chemical pest control technologies to reduce the use of chemical agents for grain storage. The China Grain Reserves Corporation has promoted technologies such as heat insulation and cold preservation, under-film circulating ventilation, and slow-release ventilation in directly affiliated depots in the Northeast, Northwest, and North China regions, achieving good results.