- Thermal Processing of Vegetables
Thermal processing is one of the major techniques, which aims to produce commercially sterile packaged food of optimal quality. Commercial sterility of food has been considered as the condition achieved by application of heat, which renders the food free from viable microorganisms, including those of known public health signiƒcance, capable of growing in the food at temperatures at which the food is likely to be held during distribution and storage. The production and distribution of heat-treated food with respect to intrinsic and extrinsic factors can be divided into (i) mild heat treatment (pasteurization) and (ii) severe heat treatment (sterilization) processes. The success of the either process lies in destroying all viable microorganisms together with nature of food, environmental factors, hermetic packaging, and storage temperature. The choice of processing depends on the severity of the heat treatment and on the objectives to be accomplished . Due to low acidity (pH > 6.0), vegetable products are subjected to severe heat treatment during processing in order to inactivate pathogenic microorganisms. The process is commonly termed as canning. Sometimes, the canning process has been altered to treat the vegetables at lower temperature in combination with other extrinsic factors (pH, preservatives, cooling, and packaging) to reduce microbial growth and for safe handling during transportation and storage.