Grain Ops: Silo bags as a storage option
مرسل: السبت أغسطس 11, 2018 11:30 am
For the global food system to keep up, more food grain must be produced and less must be lost post-harvest and wasted before consumption. Hermetic storage is an ancient technology used to control insect infestation in grain and preserve its nutrient quality and caloric value.
In ancient times, agricultural societies stored their surplus grain in containers or structures that kept it safe from the elements and restricted the entry of rodents, birds and insects. Well-sealed structures also prevent air exchange between the inside and outside of the storage space. By preventing air ingress to the grain, the aerobic respiration of grain, and, if present, insects and fungi, decreases O2 and increases CO2 in the interstitial space within the grain mass, creating a biomodified atmosphere. It has been shown that CO2 generated from aerobic respiration alone does not increase to levels high enough to kill insects; instead, it is the lower O2 level that is the key factor in halting insect development.
In large-scale hermetic storage, it may take weeks or months for O2 levels to decrease by respiration to levels lethal to stored product insects (below 4% to 5%), especially when infestation is low. As a result, practical commodity management may require supplementing biomodified hermetic storage with additional control methods such as adding CO2 or nitrogen injection or fumigation with phosphine or sulfuryl-fluoride.
Historically, cereal grains were stored hermetically in underground pits lined with clay or in small containers such as gourds or clay pots, but today technology exists that allows large quantities of grain to be stored hermetically. Large bulk silos and warehouses for both bulk and bag storage have been sealed to a high degree, most notably in Australia.
Making large structures completely gastight is a challenging and costly undertaking. In permanent structures, allowing for a small amount of air exchange between the interior and exterior of the structure (i.e., pressure venting) is a practical necessity because of potential structural damage due to internal and external pressure fluctuations. Airtightness (i.e., hermeticity) standards have been extensively researched, and the half-life pressure decay test remains the simplest and most effective test to quantify hermeticity.
Hermetic storage has been accomplished successfully on large scales in the form of underground pits covered with flexible roofs in Cyprus and Argentina, sealed commercial silos in Australia, sealed warehouses for bulk grain in China, hermetic bunker storage in Israel, and grain bag stacks enclosed within gastight liners (cocoons) in several African countries.
http://www.world-grain.com/Departments/Grain-Operations/2018/2/Grain-Ops-Silo-bags-as-a-storage-option.aspx?e=abdelrahman050289@gmail.com
In ancient times, agricultural societies stored their surplus grain in containers or structures that kept it safe from the elements and restricted the entry of rodents, birds and insects. Well-sealed structures also prevent air exchange between the inside and outside of the storage space. By preventing air ingress to the grain, the aerobic respiration of grain, and, if present, insects and fungi, decreases O2 and increases CO2 in the interstitial space within the grain mass, creating a biomodified atmosphere. It has been shown that CO2 generated from aerobic respiration alone does not increase to levels high enough to kill insects; instead, it is the lower O2 level that is the key factor in halting insect development.
In large-scale hermetic storage, it may take weeks or months for O2 levels to decrease by respiration to levels lethal to stored product insects (below 4% to 5%), especially when infestation is low. As a result, practical commodity management may require supplementing biomodified hermetic storage with additional control methods such as adding CO2 or nitrogen injection or fumigation with phosphine or sulfuryl-fluoride.
Historically, cereal grains were stored hermetically in underground pits lined with clay or in small containers such as gourds or clay pots, but today technology exists that allows large quantities of grain to be stored hermetically. Large bulk silos and warehouses for both bulk and bag storage have been sealed to a high degree, most notably in Australia.
Making large structures completely gastight is a challenging and costly undertaking. In permanent structures, allowing for a small amount of air exchange between the interior and exterior of the structure (i.e., pressure venting) is a practical necessity because of potential structural damage due to internal and external pressure fluctuations. Airtightness (i.e., hermeticity) standards have been extensively researched, and the half-life pressure decay test remains the simplest and most effective test to quantify hermeticity.
Hermetic storage has been accomplished successfully on large scales in the form of underground pits covered with flexible roofs in Cyprus and Argentina, sealed commercial silos in Australia, sealed warehouses for bulk grain in China, hermetic bunker storage in Israel, and grain bag stacks enclosed within gastight liners (cocoons) in several African countries.
http://www.world-grain.com/Departments/Grain-Operations/2018/2/Grain-Ops-Silo-bags-as-a-storage-option.aspx?e=abdelrahman050289@gmail.com