CONTROL OF MICROORGANISMS BY PHYSICAL METHODS
MOIST HEAT BELOW 100C: It is used in Pasteurization process in which moist heat is used below 100c to kill only organisms that may cause spoilage & human diseases.ie Pasteurization kills only certain microorganisms but not all mos. Spores are not affected by Pasteurization. Pasteurization is carried out on milk, cream, & certain alcoholic beverages, the methods of Pasteurization are as shown in the following table;
- Vaccine Bath: The contaminating bacteria in vaccine preparation can be inactivated by heating in a water bath at 60c for an hour. Only the vegetative bacteria are killed spores survive.
- Serum Bath: The contaminating bacteria in a serum preparation can be inactivated by heating in water at 56c for an hour on successive days. Proteins in the serum will coagulate at higher temperature. Only vegetative bacteria are killed spores survive.
- Inspissation: This is a technique used to solidify as well as disinfect egg & serum containing bacteria. The medium containing serum & egg are placed in a slopes of inspissator & heated at 80-85 c for 30 minutes on three successive days. On the first day, the vegetative bacteria would die & those spores germinate by next day are killed the following day. The process depend upon the germination of spores in between inspissation.