Chapter 9 Food Quality and Safety

Transcription

1 Chapter 9 Food Quality and Safety

2 Chapter 9 Food Quality and Safety Learning Objectives: 1) To discuss factors affecting meat quality and taste 2) To discuss factors affecting meat safety Bovine spongiform encephalopathy Salmonella E. coli Other food and waterborne pathogens 3) To discuss the use and safety of feed additives, hormones (skip), and contaminants DES Bovine growth hormone Hormone implants Dioxins Pesticides and other agricultural chemicals

3 Chapter Outline: I. MEAT QUALITY AND TASTE II. MEAT AND FOOD SAFETY III. FEED ADDITIVES, HORMONES, AND CHEMICALS (Skip) IV. ORGANIC VS. CONVENTIONALLY PRODUCED FOOD V. GLOBALIZATION OF AGRICULTURE AND FOOD SAFETY

4 I. MEAT QUALITY AND TASTE Issue: Common perceptions about modern food Taste and eating quality (organoleptic properties) are influenced by animal feeding (diet) and management. For example, in poultry meat the age of the bird is a factor. In general, younger animals are more tender but have less flavor. Today, broilers are harvested at only ~45 days of age. Which is more important to consumers: Cost or Taste? Free-range chicken eggs and meat are claimed to be more natural and have more flavor, and possibly be more healthy.

5 I. MEAT QUALITY AND TASTE Issue: Common perceptions about modern food Red Meat In the beef cattle industry, fat content is controlled by genetics, diet, feed additives, growth hormone, etc. Grass-fed beef is considered more costly. Why? Which is more important to consumers: Cost or Taste?

6 Food Safety is a major concern of American consumers Food scares are now a regular event and news stories (Alar in apples (a hoax) vs. Mad Cow Disease (very real). FDA considers microbial contamination as a MAJOR human health hazard There is overwhelming scientific evidence that feed additives, growth promotants, and other chemicals are both safe and effective (previously tested and approved by FDA).

7 Bovine Spongiform Encephalopathy (BSE) First occurred in 1980 s in Great Britain. BSE is a type of transmissible spongiform encephalopathy (TSE) disease 1. Extensive brain damage (degeneration of neurons leaving sponge-like lesions) 2. Belief that cattle fed meat meal from sheep infected by scrapies (TSE), although there is no evidence that scrapies is a problem in humans 3. BSE is similar to Kuru and Creutzfeldt-Jakob Disease (CJD) 4. Chronic Wasting Disease (CWD) in elk and deer is also a TSE (avoid eating meat from animals with CWD; Link) 5. Ban on Downer cows believed to possibly have BSE, but no evidence

8 Bovine Spongiform Encephalopathy (BSE) (Cont.) 6. BSE has a long incubation period. 7. Cause is believed to be due to a prion (highly resistant to heat, 600 C) 8. Once prion enters the body (food to GIT to brain) causes a chain reaction, converting normal proteins (PrP) to new prions, prionized 9. Later, nerve cells burst, leaving holes (Sponge-like cavities) Wikipedia - vine_spongiform_encephalopathy

9 Bovine Spongiform Encephalopathy (BSE) (Cont.) 10. In 1990 s, BSE became the #1 world-wide health issue 11. There is now compelling evidence that BSE in cattle is associated with CJD in humans involving a new variant strain 12. BSE all but wrecked the beef industry in Great Britain (tens of thousands of animals were euthanized and incinerated) 13. Present ban on feeding of all meat meals in feeds in many countries 14. In U.S., why is there a 30-months of age in cattle limit?

10 Food Safety is a major concern of American consumers Microbial contamination of Animal Food Products Salmonellosis Main concern with microbial contamination of meat and eggs (named after D.E. Salmon a USDA scientist over 100 years ago). Food poisoning signs: headache, fever, diarrhea, flu-like symptoms (3 to 5 days) Chicken meat (exposure during processing) and eggs (bacteria on or in eggs, especially raw egg products, like mayo)

11 Microbial contamination of Animal Food Products Salmonellosis (Cont.) Many strains with >2,000 serotypes known (new ones discovered each year) Several strains present in poultry manure S. enteritidis major problem in eggs, 0.5% of eggs laid by an infected hen Raw eggs should be pasteurized if used in recipes, else fully cook. Freerange eggs should never be consumed raw. All eggs should be sanitized and refrigerated ASAP

12 Microbial contamination of Animal Food Products Salmonellosis (Cont.) Irradiation (involving radioactive isotopes) of poultry meat kills Salmonella ( cold pasteurization ) Newly hatched chicks are highly susceptible to Salmonella What is Competitive Exclusion Free-range chickens added risk?

13 Microbial contamination of Animal Food Products Salmonellosis (Cont.) Antibiotic-resistant salmonella has been found in hamburger S. typhimurium DT 104 multi-drug resistant, mainly in cattle, avoiding drinking raw milk (diarrhea, fever, nausea, vomiting) Believed cause is long-term use of antibiotics in cattle Priority Rating for six beefborne pathogens Agent/Condition Priority Rating (max=90) E. coli O157:H7 65 Salmonella spp. 63 Listeria 61 Campylobacter 55 S. typhimurium DT Cysticercus bovis 40 Source: USDA

14 Microbial contamination of Animal Food Products Campylobacter contamination of poultry meat (food poisoning) Mainly C. jejuni commonly found in GIT of poultry C. jejuni responsible for majority of acute cases of human gastroenteritis (food poisoning) Contamination occurs during processing (shedding of bacteria) Quinolone-resistant C. jejun infections in humans are becoming an increasing problem because of use of flouroquinolone antibiotics in poultry (although is only used as a treatment, being prescribed by veterinarians)

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16 Food Safety is a major concern of American consumers Microbial contamination of Animal Food Products (cont.) Campylobacter contamination of poultry meat Increasing foreign travel ( traveler s diarrhea ) & internationalization of food trade makes the use of antibiotics a GLOBAL health issue Quinolones are widely used in the poultry industry in Mexico (poor human sanitation facilities) Livestock can acquire pathogens (salmonella and campylobacter) from humans Antibiotic-resistant bacteria found in soil and groundwater near swine waste lagoons

17 Microbial contamination of Animal Food Products Escherichia coli associated illnesses (E. coli common in GIT) E. coli 0157:H7 toxin-producing strain causing hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) HC abdominal cramps, watery diarrhea, and GI bleeding HUC acute kidney failure Most E. coli 0157:H7 outbreaks linked to raw milk and undercooked beef, also vegetables contaminated with animal excreta (livestock and wildlife) Beef Contamination of carcasses with fecal matter. Hamburger is the greatest risk. Why? Article Acid-resistant E. coli 0157:H7 in gut of grain fed cattle is a major concern (can by-pass human stomach!). One solution might be to feed hay to cattle before harvest.

18 Microbial contamination of Animal Food Products Escherichia coli associated illnesses (E. coli common in GIT) E. coli 0157:H7 toxin-producing strain causing hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS)

19 Food Safety is a major concern of American consumers Microbial contamination of Animal Food Products Other Concerns: Poor human sanitation (no toilets) in animal facilities have been reported to increase Salmonella infections in livestock Wild rodents have been found to have higher levels of antibiotic-resistant E. coli when raised near livestock operations Trichinosis (Trichinella spiralis) common in undercooked pork; presently only rare cases reported. Ban on feeding garbage and restaurant food wastes. However, over use of antibiotics in humans can lead to antibiotic-resistant bacteria, so the livestock industry cannot be entirely blamed Antibiotics may soon be banned for use in livestock, following the lead of several countries in Europe. The ban has been called for by the New England Journal of Medicine.

20 Waterborne Diseases in Humans Linked to Livestock: Protozoan parasites: Giardia lamblia and Cryptosporidium parvum ( crypto ) Oocytes in water that sporulate in GIT, invading intestinal cells, and later invading new tissues Linked to cattle feces in water supplies Human signs include severe diarrhea. In 1993, in Milwaukee some 400,000 people became infected (watery diarrhea). C. parvum was found, but source was not verified (cattle operations were suspected). Salmonella and E. coli These can also be waterborne from animal excreta Mycobacterium paratuberculosis (Johne s Disease and Crohn s Disease) and Listeria monocytogenes. Major risk is from CAFO s. WHY?

21 IV. ORGANIC VS. CONVENTIONALLY PRODUCED FOOD Organic Food: Is produced without human-made chemicals or fertilizers. Must be USDA certified to use in promotions. 1. No drugs 2. No antibiotics 3. No implants (GH) 4. No feed additives 5. No insecticidal chemicals Belief is that organic food is produced at a significantly higher cost. Is this true? Laura s beef USDA

22 IV. ORGANIC VS. CONVENTIONALLY PRODUCED FOOD Many foods contain deadly toxins as nature s herbicides and pesticides (carcinogens, mutagens, teratogens, clastogens, etc.; 99.99%; Ames et al., 1990a). Our ancestors had to cope daily with the real risk of being killed by what they ate! Plants have established a standing chemical and physical defense system ( Co-evolution ). Aflatoxin is produced by the mold, Aspergillus flavus. Only 1 ppb causes liver cancer!

23 IV. ORGANIC VS. CONVENTIONALLY PRODUCED FOOD Excessive concerns about chemical herbicides and pesticides can lead to over-regulation and higher food costs (EPA costs society about $140 billion per year; Ames and Gold, 1997). No known cases of human disease or pathology that can be linked to pesticide residues on food. The larger threat is natural toxins from health food stores. IPM program (page 317).

24 V. GLOBALIZATION OF AGRICULTURE AND FOOD SAFETY Waltner-Toews: We have less and less awareness of where our food comes from and what it is exposed to before it reaches our plates because of increasing globalization of the food industry. Contamination at one location can affect millions world-wide! Greatest food scares: 1. BSE and Asian Bird Flu (FAO) 2. Residues from pesticides used in other countries, even if banned in the U.S. 3. Fast-food restaurant chains E. coli 0157:H7 in hamburgers Armada of trucks on the North American highways Eating local could become more popular, especially if fossil fuel costs continue to rise Free trade?