Microbiology - Meat Microbiology Meat Why study meat...

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Unformatted text preview: Meat Microbiology Meat Why study meat microbiology? Food Borne Diseases Food Spoilage Meat Quality Preservation Flavor Alteration Remember -- deep animal tissue is sterile. The main area of Remember deep The concern is any tissue near the surface of a carcass and whole muscle cuts. muscle Why is Meat is an Ideal Medium? Why High in moisture 70% water 18 – 20 % protein Rich in protein (nitrogenous food) Minerals necessary for growth Sufficient carbohydrates Favorable pH (~5.6) Sources of Contamination Sources Slaughter (Animal) Equipment Air Humans Microorganisms of Concern Microorganisms Cooked product should be bacteria free. Cooked bacteria Cooking kills 99% of the bacteria. Cooking 99% Three types of microorganisms of concern in meat: 1. Bacteria Goodteria Badteria 2. Yeast 3. Molds toxins Bacteria Reproduction Via binary fission--splitting into equal parts Bacteria Reproduction Reproduction If a bacteria’s generation time If is ~ 3 minutes, is in one hour 1 bacteria cell will in become one million (106). become Spoilage occurs at ~ 107. Stationary Log Death Lag Time Number Factors that affect microbial growth Factors 1. Temperature -- bacteria grow at temperatures from 32 to 150°F. However, no single bacteria will grow over this entire range. Therefore, they are classified according to the range of temperature at which they grow best. of Classification Range Optimum (° F) (° F) Psychrophiles 32-68 53 Mesophiles 68-113 90 120 Thermophiles 113-150 Factors that affect microbial growth growth Temperature cont’d A combined temperaturecombined temperature- Temperature abuse is Temperature the primary reason for meat spoilage. Therefore, never hold meat between 40 and 140°F. 140°F. time value must be reached to kill a microorganism with heat. Attaining a certain temperature to kill the organism is not enough. It must be held at a given temperature long enough to kill it. kill LIFE BEGINS @ 40 Temperature’s Effect on Bacteria Growth For every 10oF increase in storage temperature there is a doubling in growth rate For every 10oF decrease in storage temperature growth rate is cut in half. Factors that affect microbial growth 2. Moisture -- the water requirement for microbial growth is 2. Moisture defined in terms of water activity (aw) of the medium. water Fresh meat has an aw of 0.99 or higher The aw minimum for bacteria to grow is 0.90 aw reduction is a means of food preservation drying, salting, freezing Factors that affect microbial growth Factors 3. Oxygen availability -3. Oxygen Aerobic -- oxygen must be present to grow Aerobic psychrophiles are the most common Aerobic meat spoiler. meat Anaerobic -- cannot grow when oxygen is present present Facultative -- growth occurs both in the presence or absence of oxygen or Factors that affect microbial growth Factors 4. pH (acidity) -4. pH pH of 6.5 is normal for bacteria growth pH pH range for most pathogens to grow in is 4.8 to 7.0 5. Physical properties -Physical Surface area -- the more surface area Surface (large area exposed to oxygen) the more microbial growth microbial Curing Review of Growth Factors 1. Temperature 2. Moisture 3. Oxygen Availability 4. Acidity 5. Physical properties REVIEW PSYCHROPHILES MESOPHILES THERMOPHILES NEVER KEEP MEAT BETWEEN? BACTERIA ARE EVERY WHERE Foodborne Illness FBI Organisms of Concern Organisms Consumed microorganisms (foodborne microorganisms) Consumed may cause health problems either by intoxication or infection. infection Intoxication -- microbes produces a toxin, which when ingested by the host (human), triggers sickness sickness Infection -- organism is ingested by the host, then grows and by its presence it disrupts the normal functioning of the system normal Enterotoxins -- Organism grows in the GI tract and produces toxins and WHO ARE AT RISK? YOUNG CHILDREN Immune system kicks in after 1 yr. ELDERLY IMMUNOCOMPROMISED CANCER & AIDS 20% SUPRESSION IN IMMUNE SYSTEM PREGNANCY Incubation Period < 1 hour : usually chemical poisoning or alergic reaction 1 – 7 hours: indicates preformed toxin 8 – 14 hours: probable C. perfringens > 14 hours: other infectious or enterotoxins Can be up to 21 days. FBI -- Potential & Regulatory Activity CONTAMINATION OCCURS USDA FDA STATE HRI Consumer CITY MOM REGULATORY ACTIVITY 2% 5% Producer Manufacture 43% 50% Organisms of Concern Organisms Salmonella (infection) (infection) Source: animals or animal products Source: Poultry (100%) and Swine spread by direct contact with contaminated spread people or animals, and by handling during the manufacture and transportation of food and food ingredients and killed by pasteurization: 161 °F for 15 sec, 143 °F for 30 minutes key: avoid cross-contamination of cooked key: product with raw product product SALMONELLA CONT. 800,000 TO 4 Million cases per year 500 Deaths per year <1% up to 10% elderly Nausea, Vomiting, Abdominal cramps, Diarrhea, Fever, Headache Symptoms •On Set 6 To 72 Hours •Infective Dose As Few As 15-20 Cells •Last 4-7 days Escherichia coli E. coli is one of the most wide spread organisms in nature Most strands are goodteria E. coli 0157:H7 enterotoxin contamination occurs usually via improper slaughter procedures or improper and unsanitary handling of cooked product Produces a potent toxin that cause sever damage to the lining of the intestine + other damage E Coli O157:H 7 cont. Symptoms Severe cramping, watery diarrhea which becomes grossly bloody occasionally vomiting, low grade fever last 8 days Very young hemolytic uremic syndrome – renal failure As few as 10 organism Associated with undercooked hamburger, un-pasteurized fruit juices, dry-cured salami, lettuce, game meat, cheese, raw milk Mortality rate in elderly as high as 50% Campylobactor jejuni (infection) Campylobactor (infection) Leading cause of bacterial diarrheal illness Leading in U.S. in Not carried by healthy individuals but is Not isolated from healthy cattle, chickens, birds and flies. and will not grow at temperatures less than 86 °F, yet is destroyed by pasteurization yet key: avoid cross-contamination of cooked key: product with raw product product Campy cont. Campy Associated Foods Raw chicken 20 to 100% of retail chicken contaminated Raw milk Bacteria carried by flies Non chlorinated water Up to 4 million cases/year 1 death/1,000 cases Children under 5 and young adults most frequently afflicted Listeria monocytogenes (infection) Listeria (infection) Listeria is everywhere -- in soil, vegetation, Listeria all types of animals and water all Cold/Heat/Drying resistant Does not form spores Key: avoid post-cooking contamination Big concern in ready to eat (RTE) products Lunch meats, Hot Dogs, etc. Listeria cont. Listeria Associated foods: Raw milk Cheeses (soft-ripened varieties) Ice cream Raw vegetables Fermented raw meat sausages Raw and cooked poultry Raw meats Raw and smoked fish Clostridium botulinum Clostridium (anaerobic, intoxication) Potent, Heat labile Neurotoxin A few nanograms of toxin can cause illness 180F for 10 minutes Spores are heat resistant High mortality rate Associated with inadequately processed home Associated canned food canned Widely distributed in nature Clostridium botulinum Clostridium Associated foods Low acid canned foods Sausages Meat products Canned vegetables Seafood Almost any type of food that is not very acidic (pH > 4.6) can support growth and toxin production Trichinella spirillis Trichinella (not a bacteria) Microscopic parasite muscles of rats, dogs, cats, swine,horses, muscles wild game, humans wild Humans acquire by eating improperly Humans prepared meats of infected animals prepared Dosage of concern about 1,000 larvae 2% death rate Trichina Trichina Occurrence in commercial swine <1% 1940s 400 cases/yr ---- 1994 32/yr Garbage feeding Home freezer Cooking Cases associated with eating game increasing Bear, wild boar, walrus, cougar Trichina Trichina Control Cook to internal temperature of 144F Margin of safety 160F Curing such as for ham and some sausages Freezing retail cuts 5F -10F -20F 20 days 10 days 6 days Irradiation FDA approved REMEMBER REMEMBER KEEP IT COLD CLEAN DRY MOVING and COOK IT! ...
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This note was uploaded on 02/07/2011 for the course ANS 2002 taught by Professor Staff during the Spring '08 term at University of Florida.

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