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116 Cards in this Set
- Front
- Back
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Myoviridae |
contractile tail, small isometric head. |
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Siphoviridae |
Non-contractile log tail, small prolate heads |
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Podoviridae |
Non-contractile short tail, large prolate heads |
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Characteristics of Buttermilk |
pleasant aroma (from lactic acid)
strong butter flavour/aroma (diacetyl) slight effervescent (CO2) White, smooth, thick but pourable |
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Started culture for buttermilk |
Lactococcus species
(can be combined with Leuconostoc cremoris |
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Fermentation process for buttermilk |
1) skim milk and citrate (0.2%)-made up to 9% SNF
2)heat to 65C for 30minutes- kills bacterial cells 3)cool to 22C, add starter and agitate for 50mins 4)incubate at 22C for 12h (this will decrease pH to 4.6 and product 0.9% lactic acid 5) break gel and cool to 4.5C, salt |
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Why is aggravation required for buttermilk production? |
Leuconostop sp requires O2 to maintain diacetyl and prevent its conversion to aceton. Lactococcus sp required it for glycolysis of Lactose to glucose to pyruvate to produce L-lactic acid (homolytic) |
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Explain biochemistry of buttermilk production in terms of what converts to what |
Lactococcus: lactose--> glucose+ galactose. Glucose->-> pyruvate-> L-lactate. Galactose->tagatose-> pyruvate to L-lactic acid. (homolytic) Leuconostoc: Lactose--> glucose+ galactose. Glucose->-> D-lactic acid. Galactose-> glucose-> D-lactic acid or Acetate/ethanol and CO2 |
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Fermentation problems seen in buttermilk |
-too much acetylaldehyde-cause grreen yoghurt, from presence of Biovardiacetlactis -Slimy texture= contamination with slime producing bacteria (Lac. lactis) -yeast flavour:contamination with lactose fermenting yeast (Kluyvermyces maxlanus) -cheesy flavour: contamination with protelytic psychotrophs. |
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Characteristics of Yoghurt |
-semisolid: from coagulation of milk -sharp acid flavour: lactic acid -smooth mouth feel -walnuts flavour (90% acetaldehyde, lactate, deacetyl and acetate) |
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Start culture organisms which must be present to make a "yoghurt" |
Streptococcus thermophilus and Lactobacillus delbreuckii |
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Yoghurt Fermentation |
1) homogenise milk (12% TS) woth 1% stabiliser (prevent whey separation) 2) heat to 85C for 30minutes- cool to 43C 3)add starter and incubate at 43C until pH decreases to 4.3 4) cool to 30C in 30minutes 5)package and cool to 4.4C, hold for 24hours and pH will decrease to 4.3.. ready to consume |
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Why is both Streptococcus thermophilus and Lactobacillus delbreuckii required to make yoghurt? |
They are synergistic to one another. Streptococcus thermophilus products formate from amino acids which aids the growth of Lac. Lactobacillus breaks down casein/proteins to amino acids to aid Str with the production of Formate. -also Str readily converts glucose to pyruvate and Lac converts Threonine to Glycine which binds with pyruvate to form Acetaldehyde and then diacetyl for flavour |
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What does each yoghurt organism do to galactose? |
Lab- converts it to D-lactic acid or excretes it from the cell Str- cannot ferment galactose so excretes it and causes increased sweetness of yoghurt. |
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Biochemistry of yoghurt making |
Lactose in broken into galactose and glucose. Galactose is converted to glucose or excreted Glucose is converted to pryuvate through glycolysis. Pyruvate is converted to D-lactic acid (Lab) and L-lactic acid (Str) |
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Name 2 foodborne diseases caused by parasites |
Toxoplasmosis Trichinosis |
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5 algae toxin posionings |
Ciguatera Fish Poisoning, Paralytic, Neurotoxic, Diarrhetic, Amnesic Shellfish Poisoning |
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Ciguatera Fish Poisoning: organism, toxin and symptoms. |
Gambierdiscus toxicus (dino), Ciguatoxin. Neurological and gastrointestinal. |
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Paralytic Shellfish Poisoning: organism, toxin and symptoms. |
Gonuaulax catenella, Saxitoxins, neurological |
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Neurotoxic Shellfish Poisoning: organism, toxin and symptoms. |
Karenia brevis, brevetoxins, neurological (less sever than paralytic |
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Dirrahetic Shellfish Poisoning: organism, toxin and symptoms. |
Dinophysis fortii, dinophysistoxins, gastrointestinal |
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Amnesic Shellfish Poisoning: organism, toxin and symptoms. |
Pseudonitzschia multiseries, domonic acid, gast and neurological |
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Why is barley used for beer production? |
it is the principle cereal grain in beer production due to its husk which provides an excellent natural filter for clarification of the extracted water |
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What are the main ingredients of beer |
hops, barley, malt, yeast and wort |
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Species name for hops |
Humulus lupulus |
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Species name for barley |
Hordeum vulgare |
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3 main stages of malting in beer production and what occurs at these stages |
Steeping (stimulation of growth of embryo plant occurs within water for 24-48 hours) Germination (grains are transferred to malting beds and allowed to germinate for ~5 days. Temp, aeration and humidity are controlled. The cell walls degrade, starch granules released and enzymes make fermentable sugars Kilning (mositure removed from the green malt, dried using forced flow of hot air. Mositure content is reduced from >50% to <6% |
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What is the second stage of beer production and what occurs
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Milling/mashing
-Starch in barley is converted to fermentable sugars by amylases. -Wort is produced (a sugary solution) -milling- contents of grains are ground finely to maximized yield of carbohydrates. -in the mashing vessel the product is mixed with warm water and filtered through a bed of husk material to remove all of the solids before the next stage. |
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5 stages of beer production |
Malting, Milling/mashing, Wort boiling, Fermentation, Post-fermentation treatment. |
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What is the third stage of beer product and what occurs? |
Wort boiling: -boiling the wort with hops extracts flavour compounds in the hops and stabilizes and concentrates the wort. -wort is cooled to <20C -aerated to 6-8mg/L of O2, ready for fermentation |
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what is the role of hops in beer |
flavour and antimicrobial properties, also has resin for bitterness and aroma |
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Stage four of beer production |
Fermentation: -Saccharomyces cerevisiae is added to convert fermentable sugars to ethanol and CO2. -anaerobic conditions are mainly used- called pitching. |
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What occurs during beer fermentation |
formation of flavour and aroma compounds, ethanol, CO2. |
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What compounds contribute to what types of flavours in beer? |
-Esters: sweet -Carbonyl compounds: bitter greeny flavours -Higher alcohols: range of sweet and floral flavours |
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Stage 5 of beer production |
post-fermentation treatment -conditions -filtration -pasteurization -bottling and packaging |
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Main varieties of beer |
Stout: dark beer from roasted barley Ale: brewed from malted barley using brewers yeast Lagers: bottom fermenting yeast (S. pastoranus) Pilsner for example Wheat beers: larger proportion of wheat |
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What is distillation? |
A method of separating mixtures based on differences in boiling points -most volatile compounds are separated by heating the solution and condensing and collecting the vapour in a separate vessel. |
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Purpose of secondary distillation? |
to produce a higher strength ethanol solution and higher quality |
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Main ingredients of Whisky |
malted barley, water and yeast |
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Malting barely for whisky |
Steeping: increase water content of barley Germination: moisture and temp control to product green malt Kilning: use grate with anthracite or coke and peat burning. Stopping germination and adding flavour. |
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mashing in whisky production |
makes the malt soluble and dissolves the essential components of malt, produces wort (sugar solution). Water is then extracted at 68, 70, 88C. The high temperatures help to render the soluble starch particles which have not yet dissolved |
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fermentation of whisky |
using Sacch. cere |
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Distillation of whisky |
using copper pots, initially a 21% v/v alcohol is produced and then goes through a second distillation |
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Maturation of whisky |
must be matured for minimum of 3 years. Single malt must be >8yr |
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Brandy facts |
-burned wine -from 10%v/v white wine -heated to between 68-100C to evapourate the alcohol from wine -can be made from grapes, apples, blackberries, sugar cane, honey, milk, rice, wheat, corn, potatoes or rye |
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Congac information |
-best is made from white grapes -2 times distilled, >2yr maturation 40%v/v alcohol |
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Congac production |
-grapes picked in winter as more flavour -fermented to 10%v/v alcohol -1st distillation to 78.3-100C to 30% v/v and then again to 70% -1L Congac= 9L grape juice -maturation in oak barrels |
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Rum info |
-produced from sugarcane by products (molasses or sugarcane juice) - production similar to Congac or Brandy - maturation on wooden barrels |
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Vokda |
any starch/sugar rich material. Fruits/grains -distillate goes through extensive filtration through charcoal -honey, st johns wort as flavourings |
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Tequlia is made from... |
Blue agave (Agave azul) -takes 8-12 years to mature -use heart of plant- pinas -correct combination of altitude, soil, humidity, rain, temp and sun is required |
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How is tequlia made? |
-Pina are steamed for 24-36hours and juice extracted. -juice is fermented -2 times fermeted |
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Name 4 toxicoinfections |
Enteroheamorrhagic E.Coli Enteroaggergative E.Coli Clostridium perfingens Bacillus cerus |
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Enteroheamorrhagic E.Coli |
A toxicoinfection -produces veratoxin or shiga-like toxin -usually associated with cattle poop Mechanism: toxins aggervate intestinal wall Cause heamorrahagic diarhoea, hemolytic uremic syndome by destroying RBC and casuing kidney failure and also V+D |
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Enteroaggergative E.Coli |
A toxicoinfection blender virulence profile-shigalike and EAEC characteristics -it is resistant to 8 antibiotic classes |
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Bacillus cereus |
-10^5-10^8 -produces many toxins -g+ve, motile, sporeing, rod shaped, aerobic -cells sensitive to pasturization but spores are highly resistant Emetic toxin: similar to staphylococcus intoxication as stimulates vagus nerve Diarrheagenic toxin: toxin is produced in the GI tract and causes illness in 8-12 hours lasting for 12-24hr. Ab pain, V+D and N` |
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Clostridium perfingens |
-g+ve, motile rodes, spore-formers, anaerobic -cells sensitive to pasteurization but spores highly resistant -mainly found in protenatious foods -found in GI tract of animals -toxin- entrotoxin, Symptoms: causes gastroenteritis, require >5x10^5CFU/g of food to cause GE Usually associated with food which is held at a medium temp for long periods or slowly cooled (banquets) |
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5 foodborne infections |
Campylobacterosis Lysteriosis Enteroinvasive E.Coil Norovirus Salmonellosis |
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Campylobacteriosis |
-caused by C. jejuni and C. coil -G-ve, motile sprial. -Microareophillic- tolerate a small amount of O2 -survive fridge but freezes decreases survival -~500cells infectious dosage to cause V+D -ingest cells, migrate to intestinal cells and enter cells to cause damage and inflammation |
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Salmonellosis |
Salmonella -G-ve, motile rods, mesophillic -killed by pasturization -sensitive to low pH and aw but can frozen and dried foods -high density will not lower food quality -can cause typhoic or paratyphoid Symptoms: - >10^5 infectous dosage -adheres and invades mucosal cells of intestine causing imflammation and increasing production of prostoglandins, increasing cAMP levels and thus excretion of Cl- from cells leading to loss of water- diarrhoea |
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Norovirus |
-single stranded RNA -human is only reservior of it as it transfers human to human -mainly affects YOPI's How? it multiplies in the intestines causing gastroenteritis symptoms. can be fatal to YOPI's Symptoms: N, V, D, cramps and headache faeces contaminated water/seawater/shellfish |
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Listerosis |
Infection caused by listeria monocytogens -g+ve, nonsporing motile rod. -faculitative anaerobe, psychotroph thus resistant to freezing high salt and low pH Found in soil, poop, dead stuff, uncooked meat and fish and ready to eat Two types Febrile gastroenteritis: flu-like symptoms, fever. 10^8-10^10 cells Invasive infectious dose: mainly YOPI's, septocemia, endcarodsis, menengitis. 10^2-^3 How: ingestion of L.monocytogens causes adhesion-invasion and translocation of cells through GI tract and into blood circulation, this infections the liver, speen and lymphatic system and passes the blood brain barrier. |
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Staphylococcus aureus |
-Intoxication -G+ve coccus, highly resistant to low Aw, high salt and sugar, range of pH (4.2-9) and temp (7-48C) -faculitative anaerobe-rapid growth in O2 -entrotoxicogenic -only produce toxin if is higher 10^6 CFU/g food -the toxin is not destroyed by cooking Symptoms: stimulates the vagus nerve to cause vomiting. 0.5-8hour onsite, last for 1-2 days. 100-200ng/30g is infectious dose. |
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Entroinvasive E.coli |
infection by E coil -bind and invades epithelia cells in GI, moves cell to cell and spreads infection -requires 10^6 cells infectious dose -symptoms: similar to shigellosis, watery poos, blood in stool due to damage of cells, Ab cramps, flu like sysmptoms. -can carry cells for long time |
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Clostridium botulinum |
G+ve rods, -obligate anaerobe forms highly resistant spore 115C -produces neurotoxin during growth phase 6 types- only A,B,E,F are foodborne disease related -toxin is destroyed at 90C for 15 or 100C for 5min How? toxin blocks release of acetyl choline, preventing contraction of muscles thus casuing paralysis. initially causes GI symptoms and then absorbed into intestine and spreads to peripherial nerves causing tingling, difficulting breathing, blurred vision and eventually paralysis |
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Mycotoxins |
-no proteins or enteric toxins -interfer with cell signalling pathways and apoptosis -they are produced as secondary metabolites from fungi and moulds. Aspergillus flavus and A. parasiticum produce aflatoxins which are found in peanuts, tree nuts and contaminated animals -symptoms may not show for many months or years two types -Acute dose: hepatic necrosis, carcinoma of liver and coma -Chronic sublethal dose: mutations of DNA and liver tumors |
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Psychotropic organisms |
survive cooler temperatures. grow below 5C but optimal between 10-26C |
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Psychotropic aerobic bacteria |
Pseudomonas ssp |
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Psychotropic facilitative anaerobe |
Lactobacillus spp and Leuconstoc spp |
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Thermoduric bacteria |
Bacillus spp and Clostridium spp |
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Thermophilic bacteria survive |
grow in 40-90C but optimal is 55-65C |
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Thermophilic- sporing |
Bacillus spp and Clostridium spp |
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Aciduric bacteria |
grows rapidly at pH 4.6 or lower e.g. lactic acid bacteria (lactobacillus, lactococcus, Leuconostoc or Bifidobacterium) |
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3 ways of assessing storage partically |
storage studies, challenge studies and accelerated shelf life |
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Accelerated shelf life |
a method of determining a products shelf life, product is placed in an environment which is at a higher temperature than what is it normally stored as to decrease shelf life and then plotted the time taken to spoil to a specific amount and calculated shelf life using arrhenius equation |
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Challenged shelf life studies |
product is left to spoil in its normal/advised storage conditions with know specific spoilage organisms added. time take to spoilage is determined. faster than storage study quality is measured at regular intervals |
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Storage shelf life studies |
left food product in normal environment without specifically exposing to any SSO.
Takes a long time and no organisms may be present but gives an indication. quality is measured at regular intervals |
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mathmatical models for determining shelf life |
square root model: uses pH, water activity and temperature and growth rate sigmodal model: it takes into account the different phases of microorganism growth |
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What is food shelf life? |
It is a guide for the consumers of the period of tie that food can be kept before it starts to deteriorate, provided any stated storage instructions have been followed. -shelf life begins when the food is first manufactured and depends on its intrinsic/extrinsic factors. -during shelf life a food must remain safe to eat, keep appearance, odour, texture and flavour and meet any nutritional claims stated |
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What affects shelf life? |
microbial growth and non-microbial spoilage |
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Levels of microbial safety: Level 1 |
all components of food are cooked during manufacture and microbial count is low Satisfactory: <10^4 Marginal <10^4 Unsatisfactory: >10^5 |
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Levels of microbial safety: Level 2 |
components have been cooked and further handelled (stroed, sliced or mixed) or NO cooking process was used Satisfactory: <10^6 Marginal <10^7 Unsatisfactory: >10^7 |
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Levels of microbial safety: Level 3 |
Fresh fruit and vegetables and fermented food. Specific plate count is no applicable because microbial counts will be inherently high due to normal microbiological flora present
Satisfactory: N/A Marginal: N/A Unsatisfactory: N/A |
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What is the safe level allowed for campylobacter spp? |
None must be detected in 25 grams of food |
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What is the safe level allowed for salmonella spp? |
None must be detected in 25 grams of food |
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What is the safe level allowed for Listeria monocytogens? |
None must be detected in 25 grams of food. but a marginal level can detect <10^2 |
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What is the best way to extend shelf life? |
reduce microbial growth rate reduce initial microbial load reduce time allowed... but typically want to extend shelf life thus want to do things to allow a longer time |
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Sources of microbial contamination |
indigenous (natural to the foods) -GI tract from animal, air, sewage, water, soil Introduced (during processing) -air, processing plant, humans, food ingredients and water |
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Intrinsic growth factors determine microbial growth |
nutrients, pH, organic acids, reducing potential and water activity |
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Extrinsic growth factors determine microbial growth |
Relative humidity, temperature, gaseous environment and radiation |
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Microbial growth factors determine microbial growth |
cell-cell component integrity, metabolic capability, growth rate, synergism or antagonism and commensalism |
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Processing factors determine microbial growth |
pasteurization, irradiation, washing, slicing and packaging |
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What important things to consider when suppressing microbial growth? |
what organisms are present -range of metabolic capabilities, resistances, growth requirements, and range of spoilage attributes and potential to spoil |
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explain hurdle technology |
It is a method of extending shelf life but maintaining fresh characteristics of the food product. It is performed by making one or more barrier which a micro-organisms must survive in order to survive in the product. It uses knowledge of an organism optimal growth conditions and uses multiple sublethal stresses upon the micro.org to decrease survival. Each hurdle works synergistically |
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Why is hurdle technologies effective? |
It alters homoeostasis, causing metabolic exhaustion, a stress response thus causing cellular death. Homoeostasis required energy from the cell to maintain cell viability, pH, fluidity and solute concentration- any condidtion imposed onto an organism which deoptmises its growth will cause the cell to use more energy to maintain homoeostasis Microbial exhaustion occurs as it requires more energy to survive at suboptimal conditions. It is much more difficult to overcome simultaneous stresses/hurdles and thus cell is more likely to reach exhaustion and more than one shock protein is required. |
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What id NZFSA main role.. their mandate? |
"to protect consumers by providing an effective food regulatory programme covering food produced and consumed in NZ as well as imported and exported food products... In pursuing this mandate the overriding priority will always be to protect consumers" |
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Ranks of business in New Food Act 2014 |
High risk: prepare, sell meat, raw meat and seafood. Must have a food control plan (HACCP) Medium risk: not producing foods but follow written requirements for keeping the sold food safe and ensuring a clean selling/storage environment Low risk: fundraising, sausage sizzle, bake sales, school fairs etc. Only rule is that food must be safe to consume |
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7 principles of HACCP |
1- identify hazards, assess risks, list controls 2- determine critical control points 3- specify criteria to ensure control 4- establish monitoring system for CP and CCP's 5- Take corrective action if monitoring indicates a criteria has not been met 6- verify that system is working as planned 7- keep thorough documentation |
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What is a food safety plan/programme? |
it is designed to identify and control food safety risk factors in order to establish and maintain food safety |
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What must an owner systematically identify according to the Food Act 2014? |
Identifying: - hazards involved with preparation on premise or vehicles -how the hazard is monitored -how hazards are controlled -systematic supervision or controls Training and skills: -what food prep tasks or categories of tasks are required -what skills are required for the tasks - people or categories which carry out the tasks -training and instruction which is required -regular maintaince task which must be carried out Data: -set out appropriate documentation for regular audits |
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Define the food safety grades |
Gold: very high compliance, consistently demonstrate best practise A: high level of compliance and consistently demonstrate best practise B: good level of compliance with regulations (can be dropped from an A if manager does not have a food safety qulification D: not satisfactory and/or repeated failures E: serious deficiencies causing closure. |
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Microbiological safety monitoring methods |
-Culture and specific biochemical reactions - immunological (antibody based): detection of toxins and confirmation of cultures -emerging methods which are most commonly DNA based |
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Direct Enumeration: Plate counts |
a differential media can be used to find coliforms present or specific types of organisms. but plates are biased as not all microbes are able to grow in culture (VBNC) -use selective media -or differential and selective media |
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eDetermining bacterial growth in foods |
using first order kinetics can model bacterial growth: Nt= N0 ^e*rate*t |
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Microorganisms most commonly found in red meat |
Lactobacillus curvatus Enterobacter spp Serratia spp Hafnia spp Proteus spp Shewanella putrefaciens |
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What happens to shelf life with an 1C temp increase? |
Shelf life will decrease by 10% for every 1C above the 1.5 up or down of 5C |
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What is a Specific Spoilage Organism? |
SSO are micro-organisms which contribute to food spoilage. They product a metabolite which is associated with spoilage and is often hard to detect which organism is present as must link the metabolite with the organism. |
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For microbial spoilage to occur... |
-microorganisms must contact food -food environment must be favourable for growth of it -food must be stored at a temperature which allows 1 or more organisms to multiply -food must be stored under said conditions for long enough to allow growth to sufficiently high numbers in order to cause spoilage effects |
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Examples of intrinsic factors which affect microbial growth |
Aw, pH, MC, redox potential, nutrients, osmotic pressure, antimicrobial agents, protective strucutres |
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Extrinsic factors which affect growth |
environment, temp, humidity, light, packaging, pressure |
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Factors which affect growth of Microorganisms in red meat and associated products |
Rich in amino acids, pepties and proteins, low carbs. high Aw and acidic pH (5.5-5.8) stored in fridge, areobic and anaerobic micro-environments, mesophiles inhibited by refrigeration Psychrotrophs can readily utilise glycogen, peptides, amino acids, metals and phosphorus |
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Factors which affect growth of Microorganisms in fish |
High levels amino acids and proteins, very little carbs. pH>6. |
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Spoilage indicators |
sensory, microbiological, chemcial |
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What is a foodborne intoxication? |
Ingestion of preformed toxin, it must be present in the food before consumption in the active form. Viable cells are not required during consumption to cause illness. only the active toxin is |
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What is a foodborn infection? |
ingestion of viable enteropathogenic bacteria/virus. Live pathogens establish and proliferate in the digestive tract causing illness |
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What is a food borne toxicoinfection? |
ingestion of a large number of viable pathogenic bacteria which releases toxins into the body to cause illness. Often hard to differentiate from an infection. Toxin is not produced until bacteria is already in the body |
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What is the types of symptoms that a toxicoinfection can cause? |
Enteric symptoms: due to cell damage or entrotoxin producted locally causing pain, diarrhoea, vomiting and fever Non-enteric symptoms: when pathogens or toxin pass beyond intestines and invade or damage other organs/tissues |
