which of the substance is used for stop microbial growth in gellies? *
Answers
Answer:
The lethal temperature varies in microorganisms. The time required to kill depends on the number of organisms, species, nature of the product being heated, pH, and temperature. Autoclaving, which kills all microorganisms with heat, is commonly employed in canning, bottling, and other sterile packaging procedures. This is an ultimate form of preservation against microbes. But, there are some other uses of heat to control growth of microbes although it may not kill all organisms present.
Boiling: 100o for 30 minutes (more time at high altitude). Kills everything except some endospores. It also inactivates viruses. For the purposes of purifying drinking water, 100o for five minutes is a "standard" in the mountains" though there have been some reports that Giardia cysts can survive this process. Longer boiling might be recommended for Mississippi River water the closer to the Gulf.
Pasteurization is the use of mild heat to reduce the number of microorganisms in a product or food. In the case of pasteurization of milk, the time and temperature depend on killing potential pathogens that are transmitted in milk, i.e., staphylococci, streptococci, Brucella abortus and Mycobacterium tuberculosis. But pasteurization kills many spoilage organisms, as well, and therefore increases the shelf life of milk especially at refrigeration temperatures (2°C).
Milk is usually pasteurized by heating, typically at 63°C for 30 minutes (batch method) or at 71°C for 15 seconds (flash method), to kill bacteria and extend the milk's usable life. The process kills pathogens but leaves relatively benign microorganisms that can sour improperly stored milk.
During the process of ultrapasteurization, also known as ultra high-temperature (UHT) pasteurization, milk is heated to temperatures of 140 °C. In the direct method, the milk is brought into contact with steam at 140°C for one or two seconds. A thin film of milk falls through a chamber of high-pressure steam, heating the milk instantaneously. The milk is flash cooled by application of a slight vacuum, which serves the dual purpose of removing excess water in the milk from condensing steam. In the indirect method of ultrapasteurization, milk is heated in a plate heat exchanger. It takes several seconds for the temperature of the milk to reach 140°C, and it is during this time that the milk is scalded, invariably leading to a burned taste. If ultrapasteurization is coupled with aseptic packaging, the result is a long shelf life and a product that does not need refrigeration.
Answer:
Sodium benzoate, calcium propionate, and potassium sorbate are used to prevent microbial growth that causes spoilage and to slow changes in color, texture, and flavor. Potassium sorbate and sodium benzoate both prevent spoilage by inhibiting mold and yeast.