This video compares the traditional growth rates of mould and bacteria over a period of 5 days.
Both yeasts and moulds cause various degrees of deterioration and decomposition of foods. They can invade and grow on virtually any type of food at any time; they invade crops such as grains, nuts, beans, and fruits in fields before harvesting and during storage. They also grow on processed foods and food mixtures. Their detectability in or on foods depends on food type, organisms involved, and degree of invasion; the contaminated food may be slightly blemished, severely blemished, or completely decomposed, with the actual growth manifested by rot spots of various sizes and colors, unsightly scabs, slime, white cottony mycelium, or highly colored sporulating mould. Abnormal flavors and odors may also be produced. Occasionally, a food appears mould-free but is found upon mycological examination to be contaminated. Contamination of foods by yeasts and moulds can result in substantial economic losses to producer, processor, and consumer.
Several foodborne moulds, and possibly yeasts, may also be hazardous to human or animal health because of their ability to produce toxic metabolites known as mycotoxins. Most mycotoxins are stable compounds that are not destroyed during food processing or home cooking. Even though the generating organisms may not survive food preparation, the preformed toxin may still be present. Certain foodborne moulds and yeasts may also elicit allergic reactions or may cause infections. Although most foodborne fungi are not infectious, some species can cause infection, especially in immunocompromised populations, such as the aged and debilitated, HIV-infected individuals, and persons receiving chemotherapy or antibiotic treatment.
The dilution plating and the direct plating methods may be used to detect fungi in foods. The direct plating method is more efficient than the dilution plating method for detecting individual mould species, including most of the toxin producers, but it is less effective in detecting yeasts. It is also used to determine whether the presence of mould is due to external contamination or internal invasion.
Source: www.fda.gov/Food/FoodScienceR...
18 апр 2017
