Keeping Food Safe for Consumption
Microorganisms greatly contribute to food spoilage, and food preservation methods have been developed to inhibit microbial proliferation on food. These methods alter growth conditions to hinder microbial growth, and they include extreme temperature, oxygen, and water deprivation. Food preservation mechanisms include: drying, freezing, canning, sugaring, salting, vacuum treatment, pickling, chemical preservatives, ionizing radiation, and high heat processing. Drying works by reducing the moisture content in food that is necessary for microbial growth. Freezing inactivates enzymes in microbes and prevents microbial growth. High heat processing methods, such as pasteurization, denature enzymes in bacteria thereby preventing microbial growth. In canning, food is processed and sealed in airtight containers that prevent the entry of microorganisms. Vacuum treatment is similar to canning, but, in this case, food is not processed before it is stored in airtight containers. Sugaring and salting works by dehydrating food and the lack of moisture inhibits microbial growth. Ionizing radiation is used to sterilize food. Pickling is done using preservation liquids such as vinegar, alcohol, and brine to hinder microbial growth (Food preservation methods, 2001).
Defrosting Frozen Foods
Microwave thawing is the best way to defrost frozen foods. This method is the fastest way of defrosting. The microwave should be set to 50 percent power or to the defrost setting. It ensures that the food’s outer edges are not cooked as the inside part remains frozen. In order to speed up the thawing process, fish, poultry, or meat pieces should be separated. The food needs to be cooked immediately after using this microwave thawing method. The cooked food can be refrozen after thawing in case of a last-minute menu change (Shelf talk, n.d.).
Shelf Life of Food
Shelf life refers to the period during which food items remain healthy and fresh to consume. Food maintains the freshest taste before expiration of its shelf life. Shelf life is dependent on several factors such as heat and light exposure, gas transmission/humidity, microbial contamination, and mechanical stresses. According to the Food and Drug Administration (FDA), expiration of shelf life indicates a decline of food quality but not safety, as cited by manufacturers. To maintain maximum freshness, a product should be on a shelf for a period that does not exceed 12 months after the date packaged code. Once a product is opened, it should remain on a shelf for a maximum of 3 months after the packaged date. After expiration of shelf life, food is likely to be stale. Food that is unused for too long is susceptible to microbial contamination. After bacteria colonization, food is not suitable for consumption as it can cause food poisoning. All foods that exhibits color, taste, or odor change should be disposed of (Food shelf life recommendations, 2004).
Food-borne Infections vs. Food-borne Intoxications
Food-borne infections are caused by consumption of food that is contaminated with pathogenic microorganisms such as bacteria, fungi, or viruses. These microorganisms proliferate in the gastrointestinal tract and trigger widespread inflammation. The most common microorganisms include E. coli 0157:H7, Shigella, and Salmonella. Food-borne infections are marked by longer incubation periods of microorganisms than in food intoxications. The onset of infection varies from 6 to 24 hours after consumption of contaminated food. Symptoms include vomiting, nausea, headache, fever, prostration, diarrhea, and abdominal pain (Murray, Rosenthal, & Pfaller, 2009).
Food-borne intoxications are caused by pathogenic bacteria which produce toxins. Enterotoxins produced by microorganisms such as E. coli 0157:H7 and Shigella take little time (not more than 8 hours) to elicit symptoms (Murray, Rosenthal, & Pfaller, 2009). E. coli 0157:H7 produces shiga toxin which is the leading causative agent of hemorrhagic colitis (HC) which progresses to the more potent hemolytic uremic syndrome (HUS).
Food-borne Illnesses in the USA
Salmonella infections cause the majority of food-borne illnesses in the United States. Salmonella serotype Enteritidis, Salmonella serotype Typhimurium, and Salmonella serotype Newport account for almost half of human isolates in the United States. According to the Centre of Disease Control and Prevention, Salmonella infections have risen by 10 percent in recent years. The estimated number of one million people succumbs to Salmonella infections in the United States annually. Medical costs resulting from Salmonella infections are estimated at $365 million (CDC, 2011).
It is challenging to address these infections as Salmonella colonizes different foods such as processed foods, eggs, and meats. Contamination might also occur due to unhygienic food handling. Salmonella Enteritidis causes Salmonellosis, the most prevalent bacterial infection in the United States. 95 percent of all incidences of Salmonellosis are food-borne, but infections due to direct contact with animal carriers are escalating. Upon infection, Salmonellosis is significantly linked to mortality and morbidity. Increasing prevalence, antimicrobial resistance, adaptability, and virulence of Salmonella present a major food-borne challenge all over the world (Owens, 2012).