Quiz 13: Protecting Our Food Supply
Processes and additives used in foodstuffs have specific role to play. While all of them have the common goal to inhibit the growth of microbes in the food, the mechanisms by which they do so are specific to the type of bacteria whose growth they can inhibit. Escherichia coli in foodstuffs like meat and poultry can be killed by cooking the food thoroughly. FDA has also approved the use of irradiation to reduce the risk of E. coli. Pasteurization is kills Staphylococcus in liquid foodstuffs. Polyphenols are used as additives to inhibit the growth of Staphylococcus and its enterotoxin a.Additives such as antimicrobial agents like salt, sodium benzoate, sorbic acid, and calcium propionate inhibit the growth of mold and fungi. Hence, the options b, c, and d would be incorrect. Salts, nitrates, and nitrites are additives which are used as curing and pickling agents to prevent the growth of Clostridium botulinum. Nitrites inhibit the active transport, oxygen uptake, and oxidative phosphorylation in aerobic bacteria. It also inhibits aldolase from E. coli. Aldolase is an enzyme utilized in the energy production process by the bacteria.Hence, the correct option is the option .
Foodborne illnesses are those which are transmitted to people through food that is infected by microorganisms. Microorganisms can thrive best in foods that are moist, rich in protein, and have a neutral or slightly acidic pH. Such foods are more likely to get spoilt. Some trends in food purchasing and production noticed of recent are responsible for the increase in incidence of foodborne diseases. Centralized food production is a trend noticed of late. It has been propagated as a successful means to reduce overheads in production by the food-processing and restaurant industry. However, this has increased the risk of foodborne illnesses. A food-product contaminated in the central plan can spread the infection down the supply chain. An example of this is the contamination of ice-cream by the Salmonella species during a malfunction at the centralized Minnesota plant of a company. It spread to other parts where the ice-cream was sold and resulted in the death of 4 and infection in 700 people in the Washington area.Increase in the purchase and production of packaged foods is another trend which has influenced the incidence of food-borne diseases. To reduce the logistic costs involved in replenishing the stock at the retailers' end, companies have resorted to increasing the shelf life of products. Longer shelf life allows more time for the bacteria to thrive in the foodstuff. For example, partially cooked food, if moist and stored in the refrigerator, has more chances of getting contaminated. Refrigerated storage helps in slowing the bacterial growth but does not prevent it. Greater consumption of ready-to-eat foods is yet another trend witnessed. Earlier only raw materials for foods were imported into North America and the finished products were manufactured in the country under strict sanitation standards. However, recently finished products were being imported which have led to an increase in the incidence of food borne diseases. For example, food imports of berries and shellfish from Guatemala and Asia, respectively, were found to be contaminated when recently re-examined by the FDa.
PH of substances indicates whether the solution is acidic or alkaline in nature. The pH scale ranges from 0 to 14. Lesser the pH of a solution, the more acidic it is. Vinegar which is acetic acid and citric acid both have low pH of 2.4 and 2.2, respectively and thus, are very acidic in nature. Smoke causes an acidic layer on foods such as meat and fish. It also causes dehydration of the food. Reducing the water content is harmful for the growth of bacteria in the foodstuffs. Irradiation destroys microbes by breaking the chemical bonds, cell walls, cell membranes, and DNA within the microbes. Baking powder and baking soda are additives which act as leavening agents. They introduce carbon dioxide in the food. Adding sugar or salt binds water. This reduces the water availability to the microbes, which in turn, hampers the growth of the microbes. Hence, options a, b, and c would be incorrect. Vinegar and citric acid are both acids. Their addition to the foodstuffs makes the food more acidic by reducing their pH. Microbes can thrive is lightly acidic environment but cannot survive highly acidic conditions. Vinegar and citric acid inhibit the growth of the microbes, by lowering the pH of the food.Hence, the correct option would be the option .