Factors that Affect the Development of Microorganisms in Foods
Food is considered to be a complicated thing and to anticipate the rate of growth of microorganisms in any food is not easy even with the use of microscopy using the compound-light-microscope. Majority of foods have enough nutrients to support the development of microbes. Certain factors enhance, deter, or regulate the development of microorganisms in foods. These factors include the acidity or alkalinity, temperature and water activity.
Water molecules can be rearranged easily and are freely oriented in pure liquid water. Water molecules adjust themselves on the surface of the solute when solutes are mixed to water, and the attributes of the solution vary gradually. The microbial cell should race with solute molecules for free water molecules. As observed by means of microscopy using the compound-light-microscope, bacteria are somewhat weak contenders with the exception of Staphylococcus aureus, while molds are superb rivals.
Water activity differs incredibly little with temperature on the range of temperatures that sustain the microbial development. The water activity of a solution may gradually influence the capability of heat to destroy a bacterium at a specified temperature. The water activity value given for a bacterium is commonly the minimal water activity that sustains its growth. The growth of microbes at minimum water activity is slow and gradually increases when the water activity also increases. When the water activity is less than the minimum for bacterial growth, the microbes do not instantly die though some of them do die. The bacteria may stay inactive but contagious as observed under the microscope using the compound-light-microscope. Other factors such as acidity or alkalinity and temperature must also be taken into consideration. It is the interaction among the factors that finally establishes if a bacterium will remain alive or not. The water activity of a food may not be of permanent value. It can vary as time goes by or change substantially between analogous foods from various sources.
The acidity or alkalinity range of a microorganism is described via the lowest value situated at the acidic point of the scale, and of the highest value located at the basic point of the scale. There is an acidity or alkalinity maximum for every microorganism where growth is optimal as observed under the microscope using the compound-light-microscope. Stirring away from the acidity or alkalinity maximum in either direction dawdle the growth of the microbes.
As examined by means of a microscope such as compound-light-microscope, variations in the acidity or alkalinity of a food over time may reveal microbial activity, and foods that are weakly protected like vegetables, may alter acidity or alkalinity values substantially. In case of meats, the acidity or alkalinity of muscle from a relaxed animal may vary from that of a stressed animal. As observed with the aid of microscopy using the compound-light-microscope, food can begin with an acidity or alkalinity value that inhibits the growth of bacteria but as a consequence of the metabolism of other microbes such as yeasts or molds, the acidity or alkalinity values changes and allow the growth of bacteria.
Temperature rates for the growth of bacteria also have the lowest and highest range with a maximum temperature for optimal development. The speed of development at boundaries of temperature establishes the categorization of an organism such as psychrotroph or thermotroph. The maximum growth temperature identifies its categorization as thermophile, mesophile, or psychrophile.
The interaction among the factors finally ascertains whether a microorganism will grow in a certain food. Frequently, the outcomes of the interaction are erratic as weakly comprehended synergism or antagonism can take place. Hence, anticipations regarding whether or not a certain microorganism will develop in a canned food commonly be done by means of experimentation with the aid of the microscope such as compound-light-microscope. Furthermore, numerous microorganisms need not proliferate in food in order to trigger an illness.
