Stored plant products

Stored plant products

1. Identification and origin

Stored plant products include cereals, legumes, seeds, nuts, tubers, flours and other plant materials kept in silos, warehouses, cold rooms or conservation structures. The origin is diverse, covering annual and perennial crops. Storage aims to preserve quality, reduce losses and ensure availability throughout the year. Stability depends on factors such as moisture, temperature, ventilation and the structural integrity of the product.

2. Economic importance

Adequate storage is essential for food safety, for the agri-food industry and for domestic and external marketing. Post-harvest losses due to pests, fungi or poor management can reach significant values, affecting the profitability of farms and supply chains. The quality of stored products directly influences the commercial value, the suitability for processing and consumer safety.

3. General characterisation of stored products

Stored plant products have variable characteristics, but share critical factors:

• Adequate moisture content to prevent fungal development
• Density and particle size that influence ventilation and compaction
• Sensitivity to temperature and oxidation
• Vulnerability to specific storage pests
• Need for protection against physical, chemical and biological contamination

Products can be stored in bulk, in bags, containers, pallets or controlled chambers.

4. Storage requirements

The ideal conditions vary according to the product, but include general principles:

• Low relative humidity and water content in the product below the critical threshold
• Reduced temperatures to limit insect and fungal activity
• Adequate ventilation to prevent condensation
• Clean, dry structures protected against infiltration
• Continuous monitoring of temperature, humidity and presence of pests
• Stock rotation (FIFO) to avoid long periods of storage
• Strict hygiene before the entry of new batches

5. Main pests

Stored-product pests are highly specialised and include:

• Weevils (Sitophilus granarius, Sitophilus oryzae): perforations and internal consumption of grains
• Moths (Plodia interpunctella, Ephestia kuehniella): webbing, clumping and contamination
• Flour beetles (Tribolium castaneum, Tribolium confusum): degradation and characteristic odours
• Borer beetles (Rhyzopertha dominica, Stegobium paniceum): perforations and dust
• Storage mites (Acarus siro, Tyrophagus putrescentiae): contamination and allergens
• Rodents: direct losses, contamination and structural damage

6. Main diseases and deterioration

Diseases and deterioration in stored products result mainly from fungi and inadequate conditions:

• Toxigenic fungi (Aspergillus spp., Penicillium spp.): production of mycotoxins and deterioration
• Rots in tubers (Fusarium spp., Phytophthora spp.): browning and loss of consistency
• Spontaneous heating due to high respiration: degradation and fire risk
• Oxidative rancidity in nuts and oilseeds
• Condensation and localised moisture: foci of mould and clumping

7. Cultural and sanitary management of storage

Effective management of stored products is based on preventive measures and continuous monitoring:

• Cleaning and disinfection of structures before the entry of new products
• Adequate drying before storage
• Control of humidity and temperature with regular records
• Ventilation and aeration to prevent condensation
• Periodic inspection for early detection of pests and fungi
• Use of monitoring traps for insects
• Immediate removal of foci of infestation or deterioration
• Stock rotation and separation of batches by date and origin
• Protection against rodents and birds
• Training of operators in good storage practices

Bibliographic references

• EPPO Global Database – Stored products pests
• CABI – Crop Protection Compendium – Stored products
• Hagstrum, D. W., et al. (2012). Stored-product insect resource. AACC International.
• FAO (2019). Post-harvest management and storage of grains.
• Magan, N., et al. (2004). Mycotoxins in stored products. Acta Horticulturae.
• Navarro, S., et al. (2012). Modified atmospheres for stored products. In: Postharvest Technology. Springer.