Presentation on theme: "Food contamination. Methods of Disease Transfer Direct : - Many disease microorganisms are transferred directly from one person to another through."— Presentation transcript:
Methods of Disease Transfer Direct : - Many disease microorganisms are transferred directly from one person to another through close contact. - Examples are influenza, tuberculosis. Indirect: - The host (infected person or animal) of an infectious disease may transfer organisms to water, food, objects, or soil. - Salmonellosis is example of diseases that can be spread indirectly.
Food Contamination Pathogens are found in food more often because scientists have developed better methods Pathogens are found in food more often than in the past, but it may be because scientists have developed better methods to detect pathogens, rather than because foods are more contaminated. Other reasons why pathogens are found more often include the following: Tourists immigrants * Changes in the population. Tourists and immigrants may spread certain diseases worldwide. *. Changes in food production. Raw materials are often produced in large amounts takes longer to cool to refrigerator Raw materials are often produced in large amounts. Large batches can easily create places for microorganisms to grow (e.g., because the center takes longer to cool to refrigerator temperature after cooking).
Vacuum packages and cold storage allow facultative microorganisms *. Changes in food processing. Vacuum packages and cold storage allow facultative microorganisms and psychrotrophs to survive. longer in the refrigerator growth of psychrotrophic *. Changes in food storage. Food processors and consumers can store foods such as vegetables, salads, soft cheeses, and meats for longer in the refrigerator, but this can allow growth of psychrotrophic pathogens such as Listeria monocytogenes.
genetic makeup *. Changes in microorganisms. Over time, the genetic makeup of microorganisms can change. New strains may develop New strains may develop that have characteristics from different bacteria. For example, a pathogen may become able to grow in cold temperatures, survive cooking, or grow in more acid or alkaline foods.
How FOODS BECOME CONTAMINATED The food itself is the most common source of contamination. Equipment and waste products are other common sources. Dairy Products -The udders of cows -milking equipment -Cross-contamination : when staff working with unpasteurized milk products move to an area containing pasteurized milk products.
Red-Meat Products The muscles of healthy animals are nearly free of microorganisms while alive. hair, skin, intestines, and lungs Meat is contaminated by microorganisms on the animal's surfaces that have external contact (hair, skin, intestines, and lungs). While the animal is alive, its white blood cells and antibodies control infection. While the animal is alive, its white blood cells and antibodies control infection. But these defense mechanisms are lost during slaughter. Microorganisms first reach the meat if contaminated knives Microorganisms first reach the meat if contaminated knives are used to bleed animals. The blood is still circulating and quickly carries these microorganisms throughout the animal's body.
Poultry Products defeathering evisceration These microorganisms are easily spread from one carcass to another during defeathering and removal of the intestines (evisceration). Poultry may be contaminated by Salmonella and Campylobacter during processing. Seafood Products handled a lot from the time Seafoods are handled a lot from the time they are harvested until they are eaten, which provides many opportunities for contamination. sometimes be stored without being refrigerated They may be also sometimes be stored without being refrigerated, which allows microorganisms to grow.
OTHER SOURCES OF CONTAMINATION Humans The hands, hair, nose, and mouth harbor microorganisms that can be easily transferred to food during processing by touching, breathing, coughing, or sneezing. Several factors affect whether and how microbes from people contaminate food: face, neck, hands, and hair are more densely populated 1. Body site. Different areas of the body carry different types of bacteria. The face, neck, hands, and hair are more densely populated by bacteria than are other body parts. Hair oil production Hair encourages growth of microbes because of its density and oil production.
2. Age. The type and amount of bacteria people carry change as they grow older. Adolescents' skin glands produce large quantities of oily Adolescents' skin glands produce large quantities of oily sebum that encourages the microorganisms that cause acne. 3. pH. 5.5. Skin usually has a pH of about 5.5. This encourages the growth of the resident microorganisms (ones that live on the skin all the time) and discourages transient microbes (ones that come and go). Soaps, creams, and other products that change the pH Soaps, creams, and other products that change the pH of the skin also alter the type of bacteria that grow.
Equipment Air and Water Sewage Insects, Rodents, and Birds
Handwashing: Improper handwashing causes about 25% of foodborne illnesses. Handwashing with soap and water removes bacteria. The antimicrobial agent needs to be in contact with the hands for more than 5 seconds to have an effect on the number of microbes.