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74 Cards in this Set
- Front
- Back
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what do food spoilage organisms affect?
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the QUALITY of food
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what intrinsic factors affect the growth of microorganisms in food?
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pH moisture (aw) oxidation- reduction potential (Eh) nutrient composition antimicrobial constituents biological structures |
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what extrinsic factors affect the growth of microorganisms in food?
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temp of storage humidity gaseous atmosphere presence of other microorganisms |
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what are the three types of microorganisms in reference to temperature?
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PHYSCHROTROPHIC MESOPHILIC THERMOPHILIC |
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what temps do physchrotrophs grow best at? what temps can they still grow at? example?
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optimum= 20-30 can grow at less than 7 so can grow in your fridge pseudomonas |
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what temps do mesophils grow best at? examples?
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optimum=30-40 can grow from 10-40. coliform bacteria can spoil food stored incorrectly or in excess of 5 |
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what temps do thermophils grow best at? examples?
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above 45, optimum=55-65 clostridium and bacillus canned food where high temps used |
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what are the two types of food contamination?
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external- by environmental bacteria- slime, off odours and green colours. internal- internal tissue usually sterile from microorganisms in healthy animal. gas, dark cuts, bone taint and sours. |
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what is an example of a gram negative non enteric bacilli that causes food spoilage?
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PSEUDOMONAS= most common spoiltage organism. |
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what temps does pseudomonas grow best at?
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phychrotrophic- can grow at refrigeration temperature below 7. optimum= 20-30 so can be destroyed by heat. |
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what does pseudomonas need for survival and how can this be manipulated to prevent food spoilage?
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oxygen- it is an obligate aerobe. use vacuum packs to prevent growth. |
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what characteristic odour does pseudomonas have?
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fruity- metabolises glucose
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give some examples of gram negative enteric bacilli that cause food spoilage?
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citrobacter enterobacter proteus |
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where are citrobacter, enterobacter and proteus distributed and how can contamination occur?
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widely distributed in environment and part of normal intestinal flora in mammals. contamination via faecal contamination of animal carcases or from environmental sources. |
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what type of microorganisms are citrobacter, enterobacter and proteus?
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mesophilic- grow slowly at refrigeration temps, can grow 10-40
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why would vacuum packed foods not prevent growth of citrobacter, enterbacter and proteus?
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facultive anaerobes
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what sort of spoilage do citrobacter, enterobacter and proteus cause?
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gas production, off flavours , odours and slime
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what are some examples of gram positive microorganisms that can cause food spoilage?
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bacillus clostridium these are spore formers and thermophils |
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what sort of food do bacillus and clostridium commonly cause spoilage in?
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canned and pasteurised- these are heated during processing. spores allow the bacteria to survive heating. heat treatment also removes other competitive bacteria- gram negatives. |
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what is bacillus cereus responsible for the spoilage of?
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sweet curding and bitty cream in milk
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where might you find clostridium?
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large rounds of hard cheese cause of bone taint in animal carcases clostridium= anaerobe |
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how does PM glycolysis have an inhibitory affect on some microorganisms?
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production of lactic acid decreased pH- most bacteria like a neutral pH to grow.
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what bacteria commonly cause spoilage of red meat?
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pseudomonas
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if red meat stored at high temperature what bacteria can cause spoilage?
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enteric bacilli
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if vacuum packed with high pH, what bacteria can spoil red meat?
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shewanella
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if vacuum packed and low pH (red wine marinade), what bacteria can spoil red meat?
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bronchothrix
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what bacteria commonly cause spoilage of poultry meat?
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pseudomonas
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how can you detect food spoilage?
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sensory tests- odour, visual, taste. chemical detection- changed in pH (lactic acid bacteria), detection of specific microbial metabolites. microbiological detection- total viable count, specific spoilage organisms detection. |
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what is the shelf life?
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length of time during which quality of product is maintained and considered fit for consumption.
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what is the most common presentation for food borne disease?
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enteric disease
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what species of campylobacter causes 80% human enteric illness?
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campylobacter jejuni
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campylobacter is microaerophilic, what does this mean?
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grow at reduced oxygen tension
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what are the symptoms of campylobacteriosis in humans?
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mild diarrheoa lasting 24 hours to severe illness of over 1 wk. persistent colicky abdo pain vomiting is uncommon can cause IBS |
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what are 80% of human infections due to campylobacter jejuni due to eating?
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poultry meat
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what are risk factors for campylobacter colonisation of poultry?
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season of year- increased incidence in summer. age of birds- no colonisation up to 3 wks (MDAs) insects. thinning of flock. biosecurity. farm environment- increased in free range. carry over from previous flock. |
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how can you control campylobacter infection on the farm?
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improve biosecurity and hygiene. decrease slaughter age. discontinue thinning. organic acid in feed and water. vaccination. breed genetically resistant birds. |
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how can you control campylobacter infection during transport?
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minimise time and distance. feed and water withdrawal. less than 12 hour journey. clean and disinfect lorries. |
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how can you control campylobacter infection at processing?
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good hygiene- HACCP. accurate evisceration. identify positive flocks and slaughter last. chemical decontamination or irradiation. heat treatment or freeze final product. flash surface freezing of carcase in liquid nitrogen vapour. |
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how can you control campylobacter infection at consumer level?
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don't wash chicken before cooking. avoid uncooked and undercooked meat. keep raw meat separate. |
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where can you find E.coli in animal?
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lower intestinal tract
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which strain of E.coli can infect humans?
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E.coli 0157:H7 VTEC |
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what symptoms does E.coli 0157:H7 infection cause in humans?
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it is bacterial toxin induced. mild diarrhoea to haemorrhagic colitis, haemolytic uraemic syndrome, thrombocytopenia and purpura. |
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describe epidemiology of VTEC?
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cattle are reservoirs (asymptomatic) super shedders are targets for control. spread between animals by contamination feed or water, hide, wild animals and birds. |
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how can carcase be contaminated with VTEC?
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during processing dehiding and evisceration further processing- mincing non meat foods: environmental contamination handlers |
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what is the most important control for VTEC infection?
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ONLY SEND CLEAN CATTLE FOR SLAUGHTER |
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how can you control VTEC infection on the farm?
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vaccination. good hygiene. identify super shedders and target. decrease pests. biosecurity. fresh/clean water and feed. |
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how can you control VTEC contamination at processing?
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good hygiene and HACCP. only slaughter clean cattle care dehiding- don't touch carcase. care evisceration carcass washing don't mix batches of product |
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what sort of foods is listeria monocytogenes associated with?
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ready to eat refrigerated foods
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how could listeria be hard to control?
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survives long in environment, on food, in fridge, in processing plant.
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symptoms of listeriosis in humans?
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most often affects immunocompromised individuals. most often affects pregnant uterus, CNS, or bloodstream. acute febrile gastroenteritis. bacteraemia, septicaemia, meningitis, encephalitis, miscarriage, neonatal disease, premature birth, stillbirth. |
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how can you control listeria monocytogenes contaminating food?
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reformulation of product- alter parameters so food no longer supports growth. (susceptible to pasteurisation) strict control of temp- ready to eat foods should never exceed 6. shorten duration of product shelf life. good hygiene. |
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which animals especially is salmonella widespread in?
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poultry and pigs
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which serovars of salmonella cause most disease in humans?
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typhimurium enteritidis newport |
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what symptoms do most cases of salmonellosis cause in humans?
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gastrointestinal disease acute disease- nausea, vomiting, abdo cramps, diarrhoea, fever, headache. |
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what could infection with S. Typhimurium cause in humans?
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septicaemia, typhoid or typhoid like fever
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what foods are associated with salmonella infection?
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raw meats, poultry, eggs, milk, dairy products, fish, shellfish.
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how can salmonellosis be controlled?
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vaccine for laying hens red lion code |
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what is a common food borne virus?
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norovirus
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how do viruses cause food born illness?
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food just acts as vehicle for the virus, virus doesn't multiply or produce any toxins in the food. recycling of human viruses back to humans. |
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what is the microbiological criteria for foodstuffs?
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defined limits on presence or numbers of microbes or metabolites in food. necessary to interpret results of tests, ensure food safe and produced hygienically. cant guarantee food safety, hence HACCP. but microbiological testing verifies HACCP procedures. |
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who is responsible for microbiological criteria?
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FBO OV responsible for compliance |
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name the 3 categories of microbiological criteria?
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process hygiene criteria. food safety criteria. meat and working surface testing. |
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what is process hygiene criteria?
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provide indication of performance and control of slaughter, dressing and production hygienic process at time of sampling. applies to carcasses, minced meat, meat preparation and mechanically separated meat. |
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what are the four criteria that demonstrate compliance with process hygiene criteria?
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aerobic colony count and enterobacteriaceae- cattle, sheep, goats, horses, pigs. salmonella- cattle, sheep, goats, horses, pigs, broilers, turkeys. aerobic colony count and E.coli- minced meat, mechanically separated meat. E.coli- meat preparations |
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what does food safety criteria monitor?
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efficacy of HACCP implementation.
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what meat is food safety criteria set for?
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fresh poultry meat, minced meat, meat preparations, meat products, mechanically separated meat.
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on food safety criteria, if a batch exceeds the limit, what happens to the food?
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unsatisfactory- not placed on market
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which 3 pathogens does food safety criteria require monitoring of?
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E.coli salmonella listeria |
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which 2 pathogens do you need total absence of in the particular food product?
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salmonella and listeria
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in which foods should salmonella be absent in?
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minced meat meat preparations to eat raw and cooked. mechanically separated meat. meat products intended to eat raw. meat products from poultry to eat cooked fresh poultry meat |
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in which foods should listeria be absent in?
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RTE foods for infants RTE foods able to support growth other than for infants. RTE foods unable to support growth other than for infants. |
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what should the levels of enterobacteriaceae and specific E.coli counts be at?
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below specific threshold
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what does the meat and working surface testing verify?
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HACCP
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when might meat and working surface testing not be a legal requirement ?
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in cutting plant if FBO can provide other forms of verification of cleaning procedures if don't produce RTE foods |
