FoodSafetyConcerns食品安全问题

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1、1,Food: It Shouldnt Be a Mystery,REFERANS: Alan M. Tart, 2012. Regional Retail Food Specialist, U.S. Food and Drug Administration Atlanta, GA.,2,DEFINITIONS,Cleanfree of visible soil, food and dirt particles Sanitizereduce the number of bacteria to a safe level Sterilizeto make free of bacteria Cont

2、aminationthe presence of harmful substances in food,3,Cleaning removing physical contaminants such as soil, food and dirt particles Sanitizing reducing the number of disease causing organisms to safe levels,4,5,Foodborne Illness in the U.S.,6,The Problem Foodborne Illness,Estimated 76 million illnes

3、ses 325,000 hospitalizations annually; hospital stays estimated at more than $3 billion and 5,000 deaths!,Mead et al., Emerg. Infect. Dis. 5:607-625,7,Factors Affecting Foodborne Illness in the U.S.,Globalization of the food supply Food consumption patterns Methods/Surveillance/ Awareness Changing p

4、roduction and processing practices Evolution of new strains Increased longevity,8,Food Safety Hazards,9,Hazard,A physical, chemical, or biological property that may cause an unacceptable consumer health risk.,10,Physical Hazards,Poor handling procedures in the food flow Examples: plastic, bones, woo

5、d, glass, metal fragments,11,Naturally Occurring Chemical Hazards,Scombrotoxin Ciguatera Toxin Shellfish Toxins Tetrodotoxin Toxic Mushrooms Allergens,12,Biological Hazards,Includes bacterial, viral, and parasitic organisms,Dennis Kunkel,13,Percentage of Foodborne Illness Attributable to Known Patho

6、gens,Mead et al., 1999,14,Bacteria, Viruses, and Parasites Whats the Difference?,Bacteria grow in food and in the body Types of illnesses Bacterial Infection Intoxication Toxicoinfection (toxin-mediated infection) Viruses and parasites cannot grow in food, only in the body.,15,Factors Affecting Bact

7、erial Growth,16,Factors Needed for Bacterial Growth,Food Acidity Time Temperature Oxygen Moisture Available Water,17,Food (Nutrients),Protein Carbohydrates (sugars) Fats Vitamins Minerals,18,Acidity (pH),pH is the measure of the hydronium ion (H+) concentration of a product. pH scale is 0-14 Below 7

8、 is acidic, 7 is neutral, above 7 is basic Most bacteria prefer to grow in a relatively neutral environment. Foods may be made shelf stable by adding acid. At a pH of 4.1 or below, foodborne bacterial pathogens do not grow but may survive.,pH, Most bacteria grow between pH 6.5-7.5 Very few grow belo

9、w pH 4 Some foods (pickles & sauerkraut) preserved from spoilage by acids made by bacterial fermentation,19,20,Approximate pH Values of Some Foods,21,Time and Temperature,Basis for most food safety rules and regulations. Easily monitored and implemented. Used to control almost all potential biologic

10、al hazards except viruses.,22,Time and Temperature,Temperature Danger Zone 40F (4.44C) 140F(60C)* *Consumer guidance,Physical Requirements,Temperature Psychrophile: cold loving Range 0C-20C Mesophile: moderate temperature loving Range 20C-40C Thermophile: heat loving Range 40C-100C,23,24,Time and Te

11、mperature,Lag Phase,Bacteria first introduced into environment or media Bacteria get used to their surroundings Bacteria very active metabolically Little to no change in cell # Lasts 1 hr to several days,25,Lag Phase,Bacteria first introduced into environment or media Bacteria get used to their surr

12、oundings Bacteria very active metabolically Little to no change in cell # Lasts 1 hr to several days,26,Log Phase,Rapid (exponential) cell growth Bacterial population doubles every generation Bacteria sensitive to adverse conditions,27,Stationary Phase,Death Rate=rate of reproduction Cells begin to

13、encounter environmental stress Lack of water Lack of nutrients pH change High amounts of metabolic waste Lack of space,28,Death Phase,Number of deaths exceeds the number of new cells formed Due to the limiting factors in the environment,29,30,Oxygen Requirements of Bacteria,Aerobic,Anaerobic,Faculta

14、tive,Oxygen Dependent,Oxygen Intolerant,C. botulinum,Lactic acid bacteria,L. monocytogenes,Pseudomonas,E. coli,Oxygen,31, Bacteria classified based on their oxygen requirements 4 main classifications Obligate Aerobes: Require oxygen to live, Obligate Anaerobes:No growth in the presence of oxygen, Fa

15、cultative: Bacterial growth with or without oxygen, Microaerophilic: Grow best in low concentrations of oxygen (as compared with the normal 21%),32,Moisture Water Activity,Amount of water available for bacteria to “live” or “grow” Generally, the lower the water activity, the lower the growth rate of

16、 organisms The minimum water activity threshold for bacterial pathogen growth in food is 0.87 or less.,33,Water Activity of Some Foods,34,Other Factors,Interaction of pH and water activity Also called “hurdle technology” Competitive microflora,35,Comparing Vegetative, Spore-forming, & Toxin-producin

17、g Bacteria,36,Vegetative Bacteria,Found on many raw animal foods (meat, fish, eggs, milk), as well as processed foods Examples Salmonella E. coli O157:H7 Listeria monocytogenes Vibrio spp. Control Measures Cooking No bare hand contact with RTE food Handwashing Not working when ill Temperature contro

18、l,37,Staphylococcus aureus,High numbers of cells produce heat stable toxin in ready-to-eat food Caused by bare hand contact with ready-to-eat food and temperature abuse Poor competitor on raw foods Normal reheating will not destroy toxin,38,Bacterial Spore Formation,Spore survival mechanism for cert

19、ain bacteria Heat resistance exceeds normal cooking temperatures Spore-forming organisms C. perfringens C. botulinum B. cereus Control Measures Proper cooling Hot and cold holding,39,Clostridium botulinum,Proteolytic strains of Type A and B will not grow below 10C (50F) Non-proteolytic strains of ty

20、pe B and E will not grow below 3.3C (38F) C. botulinum will not grow at a water activity of 0.94 or less,40,Recent Botulism Outbreaks,Most cases of botulism are due to home-prepared foods Nearly all of the recent botulism outbreaks due to commercial foods are the result of extreme temperature abuse

21、of refrigerated foods (2 or more days at room temperature) Outbreaks due to commercially processed low acid canned foods are rare,41,Recent Botulism Outbreaks,Refrigerated pasta sauce in a plastic pouch in a cardboard carton Refrigerated bean dip in a 16 oz plastic tub with a snap fit lid Garlic in

22、oil Sauted onions left in a warm skillet overnight Frozen shredded potato patty Refrigerated carrot juice in a plastic bottle Baked potato wrapped in foil,42,Which would more likely have toxins in it if temperature-abused?,43,Which of following presents a higher risk of causing botulism?,A.,B.,C.,44

23、,Viruses,45,Foodborne Viruses,Hepatitis A 83,000 cases (5% foodborne) Noroviruses (NoV) Formally known as Norwalk-like viruses Responsible for 50% of all foodborne gastroenteritis outbreaks in U.S. Est. to be as frequent as Salmonella in causing illness and death worldwide Other viruses,Mead et al.,

24、 1999,F.P. Williams, U.S. EPA,46,Control of Viruses,NoV survives heating at 140F for 30 minutes Inactivated by boiling at 212F Hand sanitizers/antiseptics ineffective Important controls No bare hand contact with ready-to-eat food Proper handwashing Not preparing food when ill,47,Behavioral Causes of

25、 Foodborne Illness,48,Foodborne Illness Risk Factors,Food from Unsafe Sources Inadequate Cooking Improper Holding Temperatures Contaminated Equipment/Cross Contamination Poor Personal Hygiene,49,Food from Unapproved Source,50,Food from Unapproved Source,51,Unapproved Cheese Product,52,CDCs EHS NET O

26、UTBREAK/ NONOUTBREAK STUDY - Contributing Factors Identified in Outbreaks,EHS-NET, 2002-2003,C- Contamination Factors P- Proliferation Factors S- Survival Factors,Infected Person Handling Food,Bare Hand Contact,Holding Food at Room Temperature,Insufficient Time/Temp. During Initial Cooking,Cross Contamination from Raw Animal Food,Raw Food Contaminated at Source,