Food sterilization is the process of eliminating or destroying all forms of microbial life (i.e., plant forms and spores), which is accomplished by various physical and chemical methods. Food goes through many processing steps. Even fresh foods such as fruits and vegetables must be properly packaged after harvesting. The important thing is to prevent the product from losing its quality and to increase its shelf life. Sterilization methods are divided into several methods, which we will learn about through this article.
Although food packaging has been designed in different types and shapes to maintain the quality of food, but this is not enough. It is better to sterilize both the packaging and the product to extend its shelf life. Sterilization is the process of destroying microorganisms, pathogens, and germs in food. Sterilization can be done in two ways as heat treatment and non-heat treatment.
Wet heat sterilization is a method in which hot water or water vapor is used as a sterilizing agent. The temperature of the water vapor ranges from 110 to 130 degrees Celsius. At this temperature, food is sterilized for 20-40 minutes.
There are some foods that do not tolerate high temperatures. It is sufficient to heat at lower temperatures for shorter periods, such as citrus fruit juices, jams or sweets. These foods are usually heated at 80-100 degrees Celsius for 10 minutes.
In dry heat sterilization methods hot air without water vapor is used as a sterilizing agent, hot air oven application is a dry sterilization method. This method takes longer than wet heat sterilization. The temperature range for dry sterilization is 160℃-190℃. Normally, food is sterilized for 2 hours under 160℃ or 1 hour under 170℃. It is enough for 6 to 12 minutes to sterilize food under 190℃.
Heating and cooling of liquid foods can be performed using metal plate heat exchangers These heat exchangers have large surface areas that improve heating and cooling rates Liquid foods containing large solid particles (such as cut fruit) are heated in scraper surface heat exchangers that use these Heat exchangers blades to continuously scrape the inner surface of the heating chamber, the scraping action protects highly viscous foods from burning on the heating surface.
Aseptic packaging is defined as the packaging methods that guarantee non-contamination of the thermally sterilized product to the extent required commercially and economically for product handling. The different methods of aseptic packaging are a means of preserving food products, and they also reduce the changes that occur in the nutritional value and quality of the product, which usually accompany traditional sterilization methods. Such methods differ fundamentally from sterilization preservation methods in that the heat treatment and packaging are carried out independently of each other, while in the traditional methods it is not possible to separate between heat treatment and packaging. The package is less than 10 milliliters, as in the case of sterilized coffee cream, to tanks for preserving sterilized milk in factories, in addition to the possibility of using sterilized tanks to transport and preserve heat-treated products from manufacturing places to packing places.. In addition to that, the possibility of using multiple and renewable types of different packaging materials.
Sterilization is done by exposing packaged foods to radiation to kill or neutralize harmful organisms such as bacteria and other organisms. Gamma rays or X-rays and electron beams are used forms of radiation used in food preservation as a source of radiation. After packing foods in packages, radiation is applied by passing foods packaged through a special radiation chamber using conveyor belts, The small dose of radiation kills the bacteria. It also causes enzymatic activity to stop while producing no or only a few chemical changes in the food. The rays also kill bacteria in food. In addition, radiation kills toxic microorganisms such as salmonella that may cause disease.
Includes: fermentation, fumigation, storage under controlled environmental conditions. As for the fermentation process, it changes the chemical composition of the food and thus helps to preserve it. The fermentation process produces compounds such as alcohol, carbon dioxide, and some organic acids. These compounds act as preservatives for pickles, sauerkraut, salami and some other foods.
As for the process of fumigation, it is spraying food with some poisonous gases to kill mice and insects. For example, methyl bromide gas is widely used to fumigate grains, dried fruits, and spices.
As for storage in controlled environmental conditions that prolong the preservation period of food, especially fruits. The most suitable weather conditions for conservation are 92-95% nitrogen, 3% oxygen and 2-5% carbon dioxide.