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50 Cards in this Set
- Front
- Back
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What are the 5 main factors of food spoilage?
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Moisture
Temp pH Oxygen Chemical Composition |
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How does the preparation of Distilled Alcoholic beverages differ from beer?
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No hops added, different grain used
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What is a_w?
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availability/ activity of water
calculated by: a-w= vapor pressure of air over food / vapor pressure of air over pure water |
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What has a a_w of greater than 9.5 and what microorganisms can grow?
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Fresh foods
all can grow |
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What can grow at a_w less than 0.9?
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many molds
most bacteria and yeast unable to grow |
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What can grow at a_w less than 0.8?
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only specialized organisms can grow
ex halophiles, Osmophiles, and Xerophiles |
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Osmophiles
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able to survive in high osmolarity and sugar conditions
able to grow at a_w below .8 |
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Xerophiles
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Able to survive in dry environments with low osmolarity
a_w less than 0.8 |
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Psycophiles
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ideally grow at low temp
usually non-pathogenic because unable to grow at 37.5 |
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Psychrotrophs
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able to grow at low temp, but is not optimum temperature
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What are three pathogens that can grow at 4.5 degrees C?
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Yersinia enterocolitica
Listeria monoytogenes Clostridiu botilium |
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What the downfall of refrigeration?
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microorganisms not killed even after an extended period of time
able to resume growth with temperature increase |
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What is the pH of most food?
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Neutral or Acidic
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What are the pH limitations of most bacteria? exceptions?
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Most unable to grow below pH 5
Lactic acid bacteria can grow down to pH 4 Very few can grow below pH 4 |
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What are the pH limitations of mold and Yeast?
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any can grow in pH 4 and below
are the main spoilage organism in acidic food |
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How does the oxygen availability effect spoilage?
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Is required for molds and many aerobic bacteria and yeast
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What are mechanisms to limit available oxygen? and signs it went wrong...
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Vacuum packing, canning and modified atmosphere
(Yeast and bacteria that can grow anaerobically causing swelling of package) |
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How does the chemical composition effect spoilage?
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nutrients available dictate microorganisms because organisms must have enzymes to degrade nutrients present
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What do microorganisms require to break down meat products? What are theses organisms called?
what are the mains groups present |
proteases (called proteolytic)
lipases (called lipolytic) Bacteria and Mold can grow |
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What are vegetibles and fruits high in?
What do organisms require to grow? What are the main groups able to grow? |
Vegetables are high in starch, cellulose, and pectin
Fruits are high in sugars and pectin microbes require saccharase, cellulase and pectinase Bacteria, yeast and molds can grow |
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Tell me about Food Poisoning/intoxication
Give two examples |
Toxin alone causes disease and symptoms appear quickly
exotoxin is present on food BEFORE injection Ex. Botulism and Staphylococcal |
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How is Scotch Made?
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Out of a barley brew but wort is not boiled so it becomes contaminated with other bacteria creating a mixed fermentation
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Tell me about Food Infection
Give two examples |
Organisms is injected and multiplies in host
Symptoms take longer to develope Illness due to tissue invasion and/or production of exotoxin INSIDE HOST Ex. Salmonella enterica and E.Coli O157:h7 |
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What are the symptoms of Botulism?
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Flaccid paralysis, respiratory or cardiac failure, difficulty swallowing and breathing and double visions
caused by ingestion of neurotoxin produced by Clostridium botulinum germinated spores |
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What are the risk factors and how can it be prevented?
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Risk factors == Home canning with insufficient heat applied and Processed foods that are not reheated
Without proper heating spores germinate, grow and produce toxin Prevent by cooking food -- cooking may only destroy toxin but not organism (but organisms is fine to ingest, toxin causes symptoms) |
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Tell me about staphylococcal?
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Most common food poisoning ( 40% of cases)
Caused by enterotoxin (exo-) produced by certain serovars/strains of Stacphylococcal auries Sypmtoms appear quickly: nausia, vomitting, diarrhea Toxin is relatively HEAT STABLE, Halotolerent and can grow at low temp 20-30% of humans are colonized (skin and upper respiratory) therefore easily transferred but many organisms are needed to produce toxic dose |
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Salmonella enterica
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Food Infection of mammals, birds and reptiles
bacteria Grows in intestines and destroys epithelium cells (causes bloody diarhea) use injectisome to inject proteins into cells Host ranges are both specific and broad -- up to 2000 serovars--- only fraction bad for humans Common Human Strains = Enteritids and typhimurium Cooking food kills bacteria |
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E. coli O157:H7
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Food Infection
Fecal coliform BUT DOESNT GROW AT 44.5 C -- escapes detection Attaches and grows on epithelium cells Produce Shiga-like AB exotoxins that inhibit protein synthesis Toxin can travel in blood stream and destroys cells of kidneys -- causes HUS hemolytic uremic syndrome that leads to renal failure |
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Hemolytic Uremic Syndrome
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Cause when AB toxins of E. Coli O157:H7 travels in blood stream to kidneys and destroys cells
Leads to renal failure |
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What are the three goals of Food processing
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1) Prevent or delay decomposition by microbe
2) Destroy pathogens or inhibit growth 3) Prevent/ Delay self-decomposition by natural enzymes in food |
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What are 7 methods of food preservation?
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Refrigeration
Freezing Pasteurization Canning Reduction of Water Availablility Irradiation Chemcicals |
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What are the aims of Refrigeration and Freezing? Problems?
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Aim: slow/inhibit growth of microbes
During freezing a_w is reduced to bellow 0.82 Problems: organisms may not be killed and can resume growth when heated Freeze/thaw cycle may effect quality of food due to crystal formation -- best to fast freeze and fast thaw |
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What is the aim of Pasturization? Problems?
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Aim: reduce number of organisms and delay spoilage
problems: Not sterile May change taste |
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What are the three methods of Milk pasteurization?
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LTLT (Low temp Long Time)= Cause bad taste
HTST (High temp slow time) = used for drinkable milk, cost $$$$$$$$ UHT (UltraHigh Temp) = sterile, increase shelf life temp and time required are affected by amount of fat, sugar, and protein |
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What are the Aims of Canning? Promlems?
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Aim: Seal food and heat container to kill most to all organisms
Temp varies based on acidity 100 C for acidic and 120 C for less acidic Problem: Have to balance between safety, nutrition, and taste |
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What is the 12D process?
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temp and time sufficient enough to kill 10^12 spores of Clostridium botulism
Method of quality control |
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What are the aims of reducing a_w? Methods? Problems?
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Aim: prevent microorganisms from growing
Methods: Drying (sun, hot air, and lyophilization) Adding salt and sugars to increase osmotic strength Problems : Doesn't KILLLL |
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Describe Aims, methods and concerns of irradiation
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Aim: reduce contamination of pathogens and spoilage organisms on FRESH PRODUCTS surface
Methods: Radappertization ( kill all) Radicidation (kill some) Radurization (reduce contamination) Concerns: Radioactive contaminants toxic/carcinogenic compounds altered nutrition off-flavor |
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What are aims of chemical food treatment? what are GRAS? name three
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Aim: control growth of microorganisms (usually selected microorganism)
GRAS = chemicals GENERALLY recognized as safe Nitrate- prevent C. botulinum Sulfites- inhibit wild yeast in wine Nisin- bacteriocin produced by Lactococcus lactis |
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What is Bacteriophage preparation?
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FDA approved cocktail to use against Listeria monocytogens
Used in cheese production to target special bacterial cells |
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Define Industrial Microbiology?
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Use of microbes to produce large quantities of useful compounds
From either first or secondary metabolites |
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What are primary metabolites?
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produced by microorganisms during exponential stage
ie alcohol |
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What are secondary metabolites?
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produced at the end of the exponential phase near or in stationary stage
Produced when under stress Ex. Antibiotics |
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What are Fermentors?
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Vessel used for industrial growth of organisms
Similar to Chemostat -- can control temp, nutrients, pH and oxygen level Mass industrial growth of microbes is called fermentation, even in aerobic conditions (Silly engineers) |
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What types of organisms are used in industrial microbiology?
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Spontaneous mutants that overproduce desired metabolite (used especially in a.a. production)
GMO bacteria and yeast with inserted desired gene Wild-types usually not stable enough |
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Radappertization
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Irradiation that kills all mirobes
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Radicidation
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irradiation that kills some microbes
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Radurization
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irradiation that reduces contamination
similar to pasteurization |
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Can yeast degrade meat?
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NOOOO
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Are LTLT and HTST equal?
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YES
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