Definition of pasteurization in microbiology

Power of heat penetration is low because hot air is a bad conductor of heat.Heated air circulates throughout the chamber at a high velocity, causing rapid transfer of energy from the air to the instrument, thatвЂ™s why it reduces the time required for sterilization.The heating coils in the sides or bottom of the chamber causes rise of hot air inside the chamber through natural convection (transmission).Coagulation and oxidation of cellular proteins.After 1 hour, oven is switched off and allowed to cool to about 60вЊ.Once desired temperature is achieved, door is closed to reach the temperature of 150вЊ.Adjust the temperature to 150вЊ and ventilator is kept open until the temperature reaches to 115вЊ.Materials to be sterilized are placed properly.Fan, thermometer and ventilator are also provided.Heating elements are fitted at the bottom of the chamber.Inner surface of door- Gasket made up of asbestos.Outer case- Thick layer of glass fibre for insulation.Metallic chamber made up of stainless steel or aluminium.So, long period of exposure to high temperature is necessary. Heat does not penetrate materials inside easily. This instrument is actually a heated chamber that allows air to circulate in gentle flow. Hot air oven is widely used for sterilization by dry heat. UHT treated products are used in Europe, less developed countries or areas where refrigerators are not available. Then milk or juice are packaged in an airtight container.ДЄll the microorganisms gets killed so, products can be stored for several months without refrigeration. Ultra-high Temperature (UHT)- After reaching 140вЊ for 4 seconds, fluid is cooled rapidly in a vacuum chamber.Milk can be stored in refrigerator for prolonged time. High Temperature Short Time (HTST)/ Flash PasteurizationвЂ“ Providing 72вЊ for at least 15 seconds before cooling to 10вЊ.Low Temperature Hold method (LTH)вЂ“ Providing of 63вЊ for 30 minutes before cooling to 7вЊ.Pasteurization is the treatment for eliminating harmful pathogens from milk, yogurt, ice-cream, fruit juice, beer and other packaged food (specially liquids). The same principle was applied to milk and its products which is known as pasteurization. He provided mild heating, which was adequate enough to kill the microbes that were causing the spoilage problem.ДЄt the same time, taste of product didnвЂ™t change. Louis Pasteur invented the method of pasteurization in order to prevent decaying of beer and wine.

Definition of pasteurization in microbiology