Canning and Fish Packaging Technology

Unit 4 - Thermal process for canned foods

4.3.Severity of thermal process
Microorganisms are more heat sensitive in the presence of acids. Even the spores of bacteria cannot germinate in the presence of acids. For instance, any bacteria, yeast or mould found in orange or pineapple juice will be killed by mild heating at 100^oC or less. This type of heat treatment is known as Pasteurization. On the other hand, the bacteria in low acid foods relatively more heat resistant. Even the spores may germinate in low acid foods. Hence, more severe heat treatment required to destroy spores i. e. at a temperature above 110^oC. Such a process in canning is known as Sterilization. The terms pasteurization and sterilization are used to distinguish the thermal processes in terms of their severity and their effects on contaminating microflora.