There are three channels for grain storage, and scientific grain storage keeps grain fresh for a long time
The grain market supply is now very abundant, and consumers can buy the finished grain products they need on the market at any time. However, some consumers worry: could the grain circulating on the market be old grain? Can grain quality and safety be fully guaranteed?
A reporter from Economic Daily learned during an in-depth investigation that the grain circulating on the market currently includes both new grain and old grain. In order to ensure consumer 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 remains fresh through regular storage.
Three channels for 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 can 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 in stages 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 types of agricultural business entities that have grain storage facilities generally store grain in stages, 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. Every year when new grain comes onto the market, grain processing enterprises purchase new grain at market prices and store it. The storage period is at most one year, and before new grain comes onto the market they continuously process the stored grain and put it on 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.
Part of the grain circulating on the market currently also comes from policy-based grain storage, which consists of state reserve grain and state temporary storage grain, with a storage period generally exceeding one year.
State reserve grain is divided into central reserve grain and local reserve grain. The grain rights of central reserve grain belong to the central government, while local reserve grain is divided into provincial, municipal and county-level reserve grain, with grain rights belonging to local governments. 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 Rotation of Central Reserve Grain and Oil (Trial), the storage period of central reserve grain is calculated from the production time, and the storage time differs 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 can be rotated.
Old grain is not aged grain
As the storage time lengthens, especially after exceeding the normal storage period, even if the grain does not heat up, become infested with insects or grow mold, the natural phenomenon of aging still occurs
How can new grain, old grain and aged grain be effectively distinguished? Is old grain the same as aged grain?
Experts told the reporter that old grain is not a standard term in the grain industry, but a general social term for grain not produced in the current year. Aged grain refers to paddy rice, wheat and corn whose storage quality has clearly declined and which are generally not suitable to be used directly as food, and it does not include finished grain products. Aging, suitability for storage and unsuitability for storage are grain storage quality indicators, while fungal toxins, 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. Unsuitability for storage or aging does not mean it cannot be eaten; the key is whether food safety indicators exceed the standard.
It is understood that before 2007, the Rules for Judging the Storage Quality of Cereals divided the storage quality of grain and oil into grain and oil suitable for storage, grain and oil not suitable for storage, and aged grain and oil. In 2007, relevant state departments jointly issued the Notice on Implementing the National Standard Rules for Judging 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 aged grain was abolished.
Experts said that grain aging is a natural phenomenon. Grain is alive, and as storage time lengthens, especially after exceeding the normal storage period, even if it does not heat up, become infested with insects or grow mold, the natural phenomenon of aging still occurs. This is mainly manifested as a decline in eating quality and use quality, and in severe aging the color, smell and taste clearly deteriorate. Judging whether grain is aged mainly depends 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. Non-aged grain that does not meet hygiene indicator requirements also cannot be eaten.
Storage technology continues to improve
As grain storage technology continues to upgrade, China's grain storage philosophy is changing, and is developing toward “green, ecological, intelligent and efficient” ecological grain storage
With advances in grain storage technology, the quality of grain storage in China has now clearly improved. The reporter learned during interviews that central reserve grain depots, local reserve grain depots at all levels and grain depots of grain processing enterprises across the country widely use the “four-in-one” grain storage technology of mechanical ventilation, circulation 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 storage rate increased 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 the reporter that before grain enters the depot, during entry, during exit and during storage, they 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 they implement strict closed-door inspections of incoming grain, strictly preventing “favoritism grain”, and warehouse keepers can refuse at any time to admit grain they doubt when there are questions about the quality of incoming grain. In order to ensure the quality safety of stored grain, they adopt the method of timed rotation, accelerating the pace of grain rotation to ensure that reserve grain remains fresh through regular storage.
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 technology 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 circulation ventilation and slow-release ventilation in its directly affiliated depots in the Northeast, Northwest and North China regions, achieving good results.