Moldy oranges

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Food Spoilage (Contd)
Moldy oranges
Moldy cheese

Potato blight
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Causes of spoilage microbiological bacteria,
molds (fungi) non-microbiological)
hydration / dehydration (texture, glass
transition, Aw) discoloration
e.g. meat oxidizes from myoglobin (dark red)
to oxymyoglobin (bright red) to metmyoblobin
(brown) oxidative rancidity
(lipids / fats) antioxidants needed -
odor enzymatic degradation
(rancidity, softening) others?
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Food is more likely to spoil if its?
Damp Keep food in well-ventilated places to
avoid build-up of moisture
Warm Do not keep food at warm temperatures
Low acid Make sure pickles or foods preserved in
acid (vinegar, acetic acid) have sufficient
acid added during processing and are used
within a reasonable time.
Low in sugar Adding sugar to food will preserve
them, e.g. jam.  However they should be used
within a reasonable time.
Damaged Check food on delivery and do not accept
damaged stock
Old Rotate food using a first in-first out
policy.
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Conditions for growth Moisture Heat Nutrien
ts pH /- Oxygen
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Water Activity Aw
Water in food which is not bound to food
molecules can support the growth of bacteria,
yeasts and moulds (fungi). The term water
activity (aw) refers to this unbound water. The
water activity of a food is NOT the same thing as
its moisture content. Although moist foods are
likely to have greater water activity than are
dry foods, this is not always so in fact a
variety of foods may have exactly the same
moisture content and yet have quite different
water activities.
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The water activity scale extends from 0 (bone
dry) to 1.0 (pure water) 0.2 for very dry
foods 0.99 for moist fresh foods. Water
activity is usually measured as equilibrium
relative humidity (ERH) The water activity (aw)
represents the ratio of the water vapour pressure
of the food to the water vapour pressure of pure
water under the same conditions and it is
expressed as a fraction. If we multiply this
ratio by 100, we obtain the equilibrium relative
humidity (ERH) that the foodstuff would produce
if enclosed with air in a sealed container at
constant temperature. Thus a food with a water
activity (aw) of 0.7 would produce an ERH of 70.
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FoodPreservation
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A substantial amount of processing activities are
designed to preserve foods in an edible,
nutritious, safe, and appealing state e.g.
canning specialized bottles and
containers e.g. pigmented (brown, green)
sterilization / pasteurization
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Heat Treatments

• Blanching Heat to deactivate enzymes
• Pasteurization Heat to kill pathogenic bacteria
  
• Sterilization Heat to kill all bacteria and
  other organisms

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Typical Pasteurization Regulations Milk 63 C
for not less than 30 min.,72 C for not less
than 16 sec., (test for microbes and
enzymes) Frozen dairy dessert mix (ice cream or
ice milk, egg nog) at least 69 C for not less
than 30 minat least 80 C for not less than 25
secother time temperature combinations must be
approved (e.g. 83 C/16 sec). Milk based
products- with 10 mf or higher, or added sugar
(cream, chocolate milk, etc)66 C/30 min, 75
C/16 sec
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Others.. freezing drying oxygen
barriers additives smoking Examples of
products in each category?
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Low Temperature

• Refrigeration -
• Freezing - 0 F

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Food can be made safe to store by lowering the
water activity to a point that will not allow
dangerous pathogens such as Clostridium botulinum
and Staphylococcus aureus to grow in it.
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Lowering Water Activity

• Dehydration
• Concentration
• Salt
• Addition of Sugar

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Chemical Preservation
Food Additives

Food additives are any substitute that
becomes part of a food product either directly or
indirectly during processing, storing or
packaging.
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• Preservatives Additives that keep food fresh
  and reduce spoilage. Control bacteria, mold,
  fungi, and yeast.
• Benzoates
• BHT, BHA (antioxidants)
• Calcium Propionate (inhibits molds)
• Sodium Bisulfate
• Sodium Nitrate

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Irradiation

• Food approved in the US
• Pork
• Chicken
• Beef
• Fruits and Vegetables
• Grain
• Many other foods approved in other countries
  

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Some Useful Food Spoilage Web Sites USA
http//vm.cfsan.fda.gov/mow/intro.html CANADA
http//www.inspection.gc.ca/english/toc/centree.sh
tml UK http//130.88.13.171/browse/cabi/943ec832
97aa96e868af334112ab12af.html NZ
http//www.ccc.govt.nz/Health/foods3.asp
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Food-borne (or water-borne) illness Any
illness caused by contaminated food or water.
The most common food-borne illness is food
poisoning. But note also BSE (prion - Mad
Cow) Avian Flu (virus)
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Causes of food-borne illness

• Bacteria
• Leading cause
• Viruses
• Parasites
• Fungi
• Food can taste good, look good and smell good but
  still give you food poisoning - bacteria cannot
  be seen with the human eye.
• Bacteria grow and multiply very quickly. After
  two hours, there can be enough bacteria to cause
  food poisoning.

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Some bacteria produce spores or
toxins Spores not killed by normal heating,
so may be present in some cooked foods.
Spores, unlike bacteria, can survive in soil just
resting for many years. Only when they have
enough food, moisture, warmth and time will
they hatch out of their coats into
bacteria. Toxins some bacteria produce toxins
(poisons) while they grow. the toxins from
these bacteria that cause food poisoning.
Normal cooking often does not destroy
toxins. Anaerobic bacteria grow in absence
of air (facultative or obligate) always keep
vacuum-packed food in the refrigerator use by
the "use by" date anaerobic bacteria will not
grow in the refrigerator.
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Who is at risk for food-borne illness?

• EVERYONE is potentially at risk for food-borne
  illness, but the following groups are at higher
  risk than others
• Children
• Pregnant women
• Seniors
• Individuals with compromised immune systems
• Medications that weaken natural immunity

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Some of the conditions that accelerate spoilage,
such as inappropriate temperature and moisture
control, also encourage the growth of pathogenic
microorganisms that cause foodborne illness.
Consequently, spoiled food is not just an issue
of quality, it is also often a question of food
safety. Mold Yeast Corn, nuts, breads, meat,
cheeses, fruits and vegetables are all affected
by mold. Do not try to salvage cheese that shows
visible mold by cutting it away, unless of course
it is a natural part of the cheese (i.e. bleu
cheese, Brie, or Camembert). Mold forms a network
of microscopic strands that extend into the foods
which could cause allergic reactions or illness,
so discarding them is the safest option. Most
cheeses do not improve with age. Deli meats are
the same. Yeast can cause discoloration, slime,
and odors on sweet, acidic refrigerated foods or
jams/jellies. Bacteria Some spoilage bacteria
are also pathogenic (disease causing). For
example, Clostridium perfringens (a common cause
of spoilage in meat poultry) and Bacillus
cereus (spoils milk cream) are also responsible
for causing foodborne illness. Most foods are
subject to bacterial growth. Enzymes Enzymes
are naturally present in the cells of
microorganisms that break down animal and plant
foods. Breakdown continues until blanching or
cooking inactivates the enzymes. Other causes of
spoilage include 1) the bruising or piercing of
vegetables, fruits or vacuum packaged food by
rough handling 2) oxidation (changes the taste
or texture when exposed to oxygen) or freezer
burn 3) pest infestation as a result of poor
receiving control, storage, rotation or cleaning
4) adulteration through addition of leftover,
inferior or undesirable food or ingredients to
fresh food. Detecting spoilage relies on being
aware of the typical indicators, such as
appearance (discoloration or slime), texture,
smell or taste (obviously not recommended if any
of the others are present). Bottom line
prevention - When in doubt, throw it out. Food
spoilage affects your bottom line in food waste
dollars. Prevention includes good receiving
inspection practices, following the
manufacturer's instructions, unfailing
temperature recording and control, being
observant and of course good sanitation and
personal hygiene by food handlers. However,
there are a few things we can do that will have a
positive effect on the shelf life and safety of
our food. Some preservation is done at the food
manufacturing level and some occurs naturally,
but a better understanding of the processes may
help you extend the shelf life. Preservation
methods and storage conditions must be designed
to reduce the rate of decomposition and protect
the safety, appearance and taste of our food.
The "Bad Bug Book" This handbook provides basic
facts regarding foodborne pathogenic
microorganisms and natural toxins. It brings
together in one place information from the Food
Drug Administration, the Centers for Disease
Control Prevention, the USDA Food Safety
Inspection Service, and the National Institutes
of Health. Some technical terms have been linked
to the National Library of Medicine's Entrez
glossary. Recent articles from Morbidity and
Mortality Weekly Reports have been added to
selected chapters to update the handbook with
information on later outbreaks or incidents of
foodborne disease. At the end of selected
chapters on pathogenic microorganisms, hypertext
links are included to relevant Entrez abstracts
and GenBank genetic loci. A more complete
description of the handbook may be found in the
Preface.
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PATHOGENIC BACTERIA Salmonella spp. Clostridium
botulinum Staphylococcus aureus Campylobacter
jejuni Yersinia enterocolitica and Yersinia
pseudotuberculosis Listeria monocytogenes
Vibrio cholerae O1 Vibrio cholerae non-O1
Vibrio parahaemolyticus and other vibrios
Vibrio vulnificus Clostridium perfringens
Bacillus cereus Aeromonas hydrophila and other
spp. Plesiomonas shigelloides Shigella spp.
Miscellaneous enterics Streptococcus
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Salmonella - 50,000 cases/year in US In poultry
and swine, water, soil, insects, factory
surfaces, kitchen surfaces, animal feces, raw
meats, raw poultry, and raw seafoods Nausea,
vomiting, abdominal cramps, diarrhea, fever, and
headache. Chronic consequences -- arthritic
symptoms may follow 3-4 weeks after onset of
acute symptoms. Onset time -- 6-48 hours.
Infective dose -- As few as 15-20 cells Raw
meats, poultry, eggs, milk and dairy products,
fish, shrimp, frog legs, yeast, coconut, sauces
and salad dressing, cake mixes, cream-filled
desserts and toppings, dried gelatin, peanut
butter, cocoa, and chocolate
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Staphylococcal food poisoning
(staphyloenterotoxicosis staphyloenterotoxemia)
is the name of the condition caused by
enterotoxins which some strains of S. aureus
produce Onset of staphylococcal food poisoning
usually rapid and often acute Common symptoms
are nausea, vomiting, retching, abdominal
cramping. Recovery generally takes two
days Foods include meat and meat
products poultry and egg products salads such
as egg, tuna, chicken, potato, and
macaroni bakery products such as cream-filled
pastries, cream pies, and chocolate eclairs
sandwich fillings milk and dairy products.
Foods that require considerable handling
during preparation and that are kept at slightly
elevated temperatures after preparation are
frequently involved in staphylococcal food
poisoning. Frequency variable and often unknown
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Listeriosis is the name of the general group of
disorders caused by Listeria monocytogenes.
1-10 of humans may be intestinal carriers of
L. monocytogenes found in at least 37 mammalian
species and 17 birds isolated from soil, silage,
raw or supposedly pasteurized milk hardy and
resists the deleterious effects of freezing,
drying, and heat Most L. monocytogenes are
pathogenic to some degree. Listeriosis is
clinically defined when the organism is isolated
from blood, cerebrospinal fluid, or an otherwise
normally sterile site (e.g. placenta,
fetus) septicemia, meningitis,encephalitis, and
cervical infections in pregnant women, which may
result in spontaneous abortion (2nd/3rd
trimester) or stillbirth. fewer than 1,000
total organisms may cause disease. L.
monocytogenes may invade the gastrointestinal
epithelium.
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ENTEROVIRULENT ESCHERICHIA COLI GROUP (EEC
Group) Escherichia coli - enterotoxigenic (ETEC)
Escherichia coli - enteropathogenic (EPEC)
Escherichia coli O157H7 enterohemorrhagic
(EHEC) Escherichia coli - enteroinvasive (EIEC)
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PARASITIC PROTOZOA and WORMS

• Giardia lamblia
• Entamoeba histolytica
• Cryptosporidium parvum
• Cyclospora cayetanensis
• Anisakis sp. and related worms
• Diphyllobothrium spp
• Nanophyetus spp
• Eustrongylides sp
• Acanthamoeba and other free-living amoebae
• Ascaris lubricoides and Trichuris trichuria

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VIRUSES Hepatitis A virus Hepatitis E virus
Rotavirus Norwalk virus group Other viral
agents
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NATURAL TOXINS Ciguatera poisoning Shellfish
toxins (PSP, DSP, NSP, ASP) Scombroid poisoning
Tetrodotoxin (Pufferfish) Mushroom toxins
Aflatoxins Pyrrolizidine alkaloids
Phytohaemagglutinin (Red kidney bean poisoning)
Grayanotoxin (Honey intoxication)
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OTHER PATHOGENIC AGENTS Prions APPENDICES Infect
ive dose Epidemiology summary table Factors
affecting microbial growth in foods Foodborne
Disease Outbreaks, United States 1988-1992
Additional Foodborne Disease Outbreak Articles
and Databases.
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Food poisoning This is an illness, which can
start one hour after eating contaminated food,
or it may take as long as 48 hours to develop.
Usually includes either vomiting or diarrhea,
or both. Food poisoning usually occurs when
bacteria have been allowed to grow and multiply
in the food. Due primarily to toxins produced
by microorganisms