This heat treatment is intended to destroy all microbial forms, including spores and is therefore a much more drastic treatment of pasteurization. The product, however, is not a completely clean and can not remain indefinitely. To achieve this goal ...... or it would take temperatures and exposure times detrimental to the Product Characteristics: this is called a commercial sterilization, defined as the treatment to destroy all organisms that reproduce in the food during storage and distribution.
The temperatures used in sterilization are related to the acidity of the food: with a pH below 4.5 (acidic foods) are enough 100 degrees, with a pH greater than 4.5 it takes 115-120 degrees for at least 20 minutes.
The treatment can be done on the food already in the container, or loose on the food which is then packaged in sterile container.
The classic sterilization system is not very different from what has always performed by housewives for the sterilization of canned tomatoes, jams and preserves in general: the product is packaged and submitted to the appropriate temperature for the allotted time, if the sterilization temperatures above 100 degrees, should be used an autoclave (which increases pressure and thus the temperature of boiling water over 100 degrees). The new systems provide for the sterilization of the food exposure to a very high temperature (140 degrees) for a few seconds, followed by cooling and aseptic packaging sterile containers, usually in cartons flexible multilayer (in the case of UHT milk). We will then
the following types of sterilization:
- classical sterilization or apertizzazione: 100-120 degrees for longer than 20 minutes, made up boxed food;
- UHT (Ultra High Temperature) indirect: 140-150 degrees for a few seconds, made on the food in bulk immersed in water or in an autoclave;
- direct or UHT UHT: 140-150 degrees for a few seconds, performed with injection of superheated steam in the bulk. Show All
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