What Types of Grain are Suitable for Storage Using Grain Coolers?

Bulk grains are the primary application for grain coolers. These crops feature high yields and extended storage periods (1-3 years), requiring focused control of respiratory heat generation, mold proliferation, and insect infestations. Common varieties include:

1. Wheat (Adaptability ★★★★★)

Storage Challenges: Wheat exhibits moderate respiration intensity. However, elevated grain temperatures (>25°C) during summer can trigger Fusarium head blight and root rot, while infestations by corn borers and wheat moths are common. Prolonged storage at humidity levels exceeding 75% leads to moisture absorption and clumping, compromising processing quality (increased flour breakage during milling).

Chiller Function: Maintains grain temperature at 15-20°C and humidity ≤75% to suppress mold and pest activity while preserving wheat gluten protein content (preventing high-temperature protein denaturation). Processing quality remains compliant after 1 year of storage (no significant decline in flour whiteness or dough stability time).

Typical Scenarios: Constant-temperature wheat storage in national reserve warehouses, raw grain storage silos in flour mills.

2. Rice (including brown rice and white rice, adaptability ★★★★★)

Storage challenges: Rice (especially brown rice) has high moisture content (safe moisture 13%-14%) and vigorous respiration. In high-temperature, high-humidity environments (>25°C, humidity >75%), it is prone to mold growth (e.g., aflatoxin contamination) and developing “rancid flavor” (fat oxidation). Polished rice (white rice) lacks seed coat protection, making it more susceptible to moisture absorption and staling.

Air Cooler Function: Maintains grain temperature at 20-24°C and humidity at 65%-70%, delaying rice fat oxidation (postpones rancid odor development by 6-8 months), prevents polished rice from clumping due to moisture absorption, and preserves texture (retains “fresh rice aroma” when cooked after 3 months of storage).

Typical Scenarios: Reserve warehouses in southern rice-producing regions and finished rice holding bins in rice processing plants.

3. Corn (Adaptability: ★★★★☆)

Storage Challenges: Corn is a “high-respiration grain.” Freshly harvested corn often contains 25%-30% moisture, prone to heating (grain temperature can rise 5-10°C within 24 hours) and sprouting. Its high germ fat content (approx. 3.6%) makes it susceptible to oxidation and rancidity, with extremely high risk of aflatoxin contamination during summer heat.

Air Cooler Function: Adapted in two stages: ① Temporary storage period (1-2 weeks): Use “high-dehumidification” air coolers to rapidly reduce moisture (from 25% to below 14%) while maintaining temperature ≤25°C to prevent heating and sprouting. ② Long-term storage period (1+ years): Maintain temperature at 18-22°C and humidity ≤75% to inhibit aflatoxin and fat oxidation while preserving corn bulk density (a core quality indicator).

Typical applications: Post-drying storage silos in major corn-producing regions of Northeast China and corn raw material silos in feed mills.

4. Soybeans (Adaptability ★★★★☆)

Storage Challenges: Soybeans possess high protein content (approx. 40%) and fat content (approx. 20%). They are prone to “denaturation” (protein structure alteration affecting soy product processing) at high temperatures (>25°C) and moisture absorption/mold growth at high humidity (>75%). Additionally, their thin seed coat makes them susceptible to insect infestation (e.g., bean weevils).

Chiller Function: Maintains temperature at 15-18°C and humidity at 65%-70%, delaying protein denaturation and fat oxidation (≤2% protein loss after 1 year storage). Simultaneously suppresses bean weevil reproduction, preventing pest-induced bean breakage rates from exceeding 3%.

Typical Scenarios: Raw material silos in soybean processing plants; reserve silos for oil extraction soybeans in edible oil enterprises.

Specialty Grains / Minor Crops (Suitable for high-value, precision-storage categories)

These grains have relatively low yields but high economic value, demanding stricter temperature, humidity, and stability in storage environments. Grain coolers can meet these needs through “customized parameters”:

1. Oats, Buckwheat, Barley (Suitability ★★★★☆)

Storage Challenges: Oats and buckwheat are rich in dietary fiber and unsaturated fatty acids. They readily absorb moisture and clump under high temperature and humidity, leading to oxidation and rancidity (“off-flavor”). Additionally, highland barley (a high-altitude crop) thrives in cool, dry conditions and is prone to mold growth in low-altitude, high-temperature regions.

Chiller Function: Maintains temperature at 12-16°C (54-57°F) and humidity at 60%-65%, preserving dietary fiber structure (preventing clumping that affects texture), slowing oxidation of unsaturated fatty acids. After 6 months of storage, porridge retains a “soft and chewy” texture without rancid taste.

Typical Scenarios: Raw grain storage for oatmeal manufacturers, ingredient reserve warehouses for Tibetan barley food processors.

2. Sorghum (Adaptability: ★★★☆☆)

Storage challenges: Sorghum is commonly used for distilling spirits (e.g., baijiu). Its starch content (approx. 70%) and tannin levels (affecting liquor quality) are sensitive to storage conditions. High temperatures (>28°C) cause starch gelatinization, while high humidity (>80%) promotes mold growth, both reducing distillation yield.

Air Cooler Function: Maintains temperature at 20-25°C and humidity at 70%-75% to stabilize starch and tannins, ensuring consistent yield (typically above 45%) and quality (avoiding off-flavors) during distillation.

Typical Application: Storage silos for distilling sorghum in liquor factories.

3. Millet, Mung Beans, Red Beans (Adaptability ★★★☆☆)

Storage Challenges: Millet ( sorghum) has thin seed coats prone to moisture absorption (humidity >75%), causing “re-germination” (hardening during cooking); mung beans and red beans are susceptible to weevil infestation and sprouting at high temperatures (moisture >15%).

Air Cooler Function: Maintain millet storage at 18-22°C (64-72°F) and 65%-70% humidity to prevent hardening; control mung beans and red beans at 20-24°C (68-75°F) and ≤75% humidity to suppress weevil infestation and sprouting. After 6 months of storage, germination rates remain above 80% (for seed-grade mung beans/red beans).

Typical applications: Finished product storage in grain processing plants; seed storage facilities for legume seeds at seed companies.

Unsuitable / Requires Caution Categories (Special Characteristic Restrictions)

Although grain coolers have a wide range of applications, the following two types of grains require caution or use with additional equipment due to their inherent characteristics:

High-moisture, sprout-prone fresh grains: Examples include fresh corn (moisture >30%) and fresh glutinous rice (moisture >25%). These require short-term refrigeration (0-5°C), while grain air coolers typically have a minimum temperature setting of 12°C, failing to meet the low-temperature requirement. Dedicated refrigeration equipment must be used instead.

Grains with extremely small particles or prone to dust generation: Examples include sesame seeds (particle diameter < 2mm) and millet (small and lightweight grains). If the airflow speed of the cooler is improperly controlled (>3m/s), it may cause the grains to generate dust or be scattered by the wind. An “ultra-low airflow model” must be selected and paired with dust-proof ducting.