Storage and Spoilage Control
Storage and spoilage control explains why foods deteriorate and how temperature, moisture, atmosphere and handling are managed. The exam tests spoilage types, intrinsic and extrinsic factors, grain and cold storage, controlled atmosphere, modified atmosphere packaging and stock rotation.
Core rules
- Spoilage can be microbial, enzymatic, chemical or physical. Each has different control measures.
- Intrinsic factors include aw, pH, nutrient content and antimicrobial compounds; extrinsic factors include temperature, relative humidity, gases and light.
- Grain must be dried to a safe moisture level, commonly about 12–14% for cereals, to limit mould growth and mycotoxin formation.
- Cold storage slows microbial growth and enzyme activity but does not kill microorganisms.
- Controlled atmosphere modifies O2 and CO2 continuously; MAP modifies the package headspace. Ethylene-producing produce should be separated from ethylene-sensitive produce.
- FEFO (first expired, first out) is preferred for perishable and date-marked stock; FIFO is a general stock rotation rule.
Worked example
Wheat at 18% moisture is stored in a warm godown. The safe storage moisture is about 12%. Drying to 12% lowers aw and restricts mould growth, reducing aflatoxin risk. The reasoning is that available water, not total water alone, controls microbial growth.
Traps
- Believing cold storage sterilizes food.
- Mixing ethylene producers with sensitive produce.
- Ignoring condensation and drip in cold rooms.
- Using FIFO when FEFO is required for dated stock.
- Storing grain without checking moisture and temperature.