Food can be classified into three main categories based on perishability: perishable, semi-perishable, and non-perishable foods. Perishable foods such as milk, curds, fish, and meat spoil quickly, usually within one or two days. Semi-perishable foods, including fruits, vegetables, and root crops like onions and potatoes, typically last for one to four weeks. Non-perishable foods, which can last for over a year, include grains like rice, wheat, and pulses.
The section emphasizes the importance of food processing techniques designed to extend shelf life by mitigating microbial activity and other spoilage factors, such as bacteria, fungi, and yeasts. The key factors influencing microbial growth include moisture, pH, temperature, and oxygen availability. To prevent spoilage, common techniques include applying heat, removing moisture, reducing temperature in storage, lowering pH, and controlling oxygen levels.
Processed foods are further classified based on the extent and type of processing, including minimally processed, preserved, manufactured, formulated, food derivatives, functional foods, and medical foods. This understanding of food classes and spoilage mechanisms is crucial for ensuring food safety, enhancing convenience for consumers, and driving innovation in food technology.