Microbial food spoilage:“first come – first serve”
due to production of volatile endcompounds
pigment production or oxidation
softening due to the breakdown ofpectin in vegetables or the tissues byproteinases
Accumulation of gas
CO2, H2 or H2S2
due to the production ofdextrans and/or amount of microorganisms
Caused by preformedtoxin in the food; organism may or may notbe alive and growing; Clostridium botulinumand Staphylococcus aureus
Live cells delivered bycontaminated food; organism multiply oncefood is ingested; Salmonella
Gr+, non-motile,asporogenous cocci• “grape-like” clusters• enterotoxin• effective at 1ug/kg• protein of 239 aminoacids• serological types: A, B, C,D, F
Staphylococcus aureusFOOD POISONING SYNDROME
• onset: 0.5 to 6 hours• recovery: 24 to 72 hrs• major symptoms: vomiting, diarrhea• other symptoms: nausea, salivation,cramps, retching,prostration
consumption of honey that iscontaminated by spores (0 - 2 months)• Treatment: antitoxin and ventilation
Botulism and Temperature Abused Pot Pie
Patient: 56 year old diabetic woman• Symptoms: diplopia, weakness, difficultybreathing, chest pain, respiratory arrest.• Scenario: Son prepared pot pie for mother.Father brought home take-out hamburgers.Mother left pot pie out on shelf (in California, inAugust), and ate it two and one-half days laterwithout reheating.• Illness: next day. Type A botulinum toxin wasisolated from the left-over food and patient'sserum.
C. perfringens produces cpe gene productas paracrystalline inclusionbody released during sporulation. Alsomakes beta-toxin (necrotic).
Gram negative enteric bacterium; all strains arepathogenic; transmission is from sources (eggs, meats)and by food handlers
(most commonly by S. typhimurium): 105 - 108viable cells; disease onset within 8 - 48 hrs; headaches, chills,vomiting, diarrhea and fever (2-3 days); continuous shading oforganism for months/years; treatment - non
Salmonellosis Typhoid fever
(Salmonella enterica serovar Typhi ): Septicemialeading to high fever that can last for several weeks; mortality is15% if untreated; antibiotics
Some strains of E. coli; diarrhea and urinary tractinfection; classification of pathogens is based on toxinand diseases
colonization of thesmall intestine and verotxin production -> hemorrhagicdiarrhea and kidney infection; uncooked andundercooked ground meat; occasional epidemics
Travelers diarrhea) - heat labile toxin;water and produce in developing countries; immunity
diarrhea that afflicts young children
invasive colon infection; bloodydiarrhea; survival in phagosomes; in developing countries
Treatment and prevention: diseases are self-containedbut antibiotics help.
Campylobacter jejuni Characteristics
High morbidity, low mortality– Sensitive to freezing– Survives in refrigerated foods– will not grow at <30◦C– Microaerophilic– Fragile organism, sensitive to drying,heat, acidic conditions, and disinfectants-
Disease–Onset 48-82 h followingingestion–Profuse diarrhea– Invasive–Survives phagocytosis
FSIS inspectors no longer mark cattle tested for BSE as "inspected andpassed" until confirmation is received
Advanced Meat Recovery
FSIS expanded a prior prohibition on spinal cord from being allowed inproduct– Prohibits dorsal root ganglia, clusters of nerve cells connected to the spinalcord
FSIS banned the practice of air-injection stunning
Specified Risk Material
Skull, brain, trigeminal ganglia, eyes, vertebral column, spinal cord and dorsalroot ganglia– 30 months of age or older and the small intestine of all cattle are specified riskmaterials that are prohibited in the human food supply.– Tonsils from all cattle are also not allowed in the human food supply.
Additional Bans and Regulations Downer Cattle
Banned from human food chain– A hidden camera investigation by the Humane Society at the Hallmark/Westland MeatPacking company in Chino, California– Recall involved 143 million pounds of raw and frozen meat
Banned from human food chain
Specific changes in FDA’s present animal feed rule
Mammalian blood and blood products to be fed to other ruminants as a protein source.– Use of “poultry litter” as a feed ingredient for ruminant animals• Bedding, spilled feed, feathers, and fecal matter that are collected from living quarters wherepoultry is raised.– Plate waste as a feed ingredient for ruminants– Requires equipment, facilities or production lines to be dedicated to non-ruminant animalfeeds if they use protein that is prohibited in ruminant feed
Why do "new" pathogens emerge?
CHANGES IN EATING HABITS: fresh, organic• CHANGES IN AWARENESS: computer databases• CHANGES IN DEMOGRAPHICS: larger sensitivepopulations• CHANGES IN PRIMARY FOOD PRODUCTION: scaleof operation, global production• CHANGES IN FOOD PROCESSING TECHNOLOGY:chill, vacuum packaging• CHANGES IN HANDLING AND PREPARATION:homerefrigeration, microwave• CHANGES IN THE MICROORGANISMS:plasmid
FDA DEFINITION OF A CHEMICAL PRESERVATIVEFDA-CFR TITLE 21, p. 101.22 (A)
“Any chemical that when added to food, tends toprevent or retard deterioration, but does not(A)include common salt, sugars, vinegars, spices,or oils extracted from spices, substances addedto food by direct exposure to wood smoke, orchemicals applied for their insecticidal orherbicidal properties.”
Bacteriocins are defined as ribosomally-producedproteinaceous substances of bacterial origin thatexhibit antimicrobial activity.They kill sensitive cells by formingpores in the membrane causingthe leakage of cellular materials,and the depletion oftransmembrane potential(Δψ) and/or the pH gradient.