Transcript Food & Beverages - Belle Vernon Area School District

Food & Beverages
I. All foods have Microorganisms on their surface.
II. Microorganisms take food for metabolism and turns it into
acids, alcohols, & gas.
III. Sometimes desirable – pleasant tastes & textures.
IV.
– foods altered by the careful controlled
growth of microorganisms
A.
– sour cream & blue cheese.
B.
– Spoilage, sour milk, molded
bread does not change the quality of food but may lead
to illness
V. Factors Influencing the growth of organisms on foods
A.
(aW)
1. Bacteria - .9 or higher for growth
2. Fungi – lower aW
B.
Most are inhibited by acidic conditions.
C.
Low temperatures slow down enzymatic
activities.
D.
1. Nutrients
2. Coverings
3. Antimicrobials
VI. Production of foods & beverages
A.
BC Sumerians & Babylonians
B.
BC Egyptians – bread & beer
C. Milk
1.
from cow but
leads to
contamination.
2. Lactic Acid –
3. Yogurts
a
to eliminate undesirable spoilage.
b. Inoculated with Streptococcus thermophiles
or Lactobacillus bulgaricus.
c. Incubated at 40C.
d. Produces lactic acid, pH drops causing
of milk protein which changes
texture.
e. Conditions are controlled so only certain
bacteria can grow.
f. ½ million pounds of yogurt is sold in US, yearly
4. Cheese
a.
yrs ago – Asia
b. Steps
1. Milk inoculated with
starter culture (Lactic
Acid bacteria).
2. Incubated until
fermentation of milk
sugars
3.
(enzyme) is
added to
milk proteins (CURD).
4.
(CURD) is
separated from liquid
(WHEY).
5.
– cottage
cheese,
Cheese
c. Types of cheeses
1.
– White fungus, Pencillium caseisolon
2.
– Bacteria, Brevibacterium linen
3.
– Bacteria, Propionibacterium sp.
a. Produces propionic acid & CO2.
4. Cheeses
a. very hard, semi, soft
content
D. Pickled Vegetables & Olives
1. Made with
bacteria
E. Sauerkraut
1. Cabbage is shredded & layered
with
.
2. Salt
prevent
growth.
out cabbage to
bacteria
3. Permits
bacterial
growth (Lactobacillus
plantarian) in 2- 4 weeks.
4.
tangy
taste
pH levels results in
F. Soy Sauce
1. soy bean &
Aspergillus oryzae.
2. Mix salt, soy bean, & wheat =
3. Let sit for 3 days
4. Carbohydrates are broken down to produce
fermentable sugars.
5. Mixed with 18%
& bacterium
(Pediococcous soyae & saccharomyces rouxi) for 8 –
12 months.
6. Liquid is drained for soy sauce
G. Breads – Bakers Yeast
1. Leavened Bread.
2. Mixture of flour,
sugar, milk, water,
yeasts (Saccharomyces
cerevisiae), butter or oil.
3.
ferments
carbohydrates from
sugar to
&
.
4. Produces ethanol gas
which is
in
baking.
5. CO2 causes bread to
.
H. Alcohols
1. From fruits.
2. 10 million yeast cells on grapes.
3. Fruit sits for days at room temperature and begins to
bubble as juices ferment.
4. Weeks – mixture alcohol
5. Wine
a. Crush selected grapes –
solids & juices –
.
b. Red wine
1. Red grapes
2. Entire grape
c.
red grapes
– Only juice from
d.
– red for a day
then only juices ferments.
e. S. cerevisicae for growth.
f.
, controlled
temperature for days to weeks.
g. Sugar
Ethyl alcohol & CO2.
Less than 14% alcohol
6. Beer
a. Fermentation of sugars from grain by
Saccharamyces.
b.
– starch to sugars
1.
(germinating grain) is
soaked in water to yield an
extracting enzyme (wort) – sugars
& nutrients for yeast growth.
c.
is boiled to destroy enzyme &
most microorganisms.
d.
are added for flavor & inhibited
unwanted bacterial growth.
e. Brewers’ Yeast
alcohol.
f. Sits in vats to settle out solids including
yeast & microorganims & flavoring.
g.
S carlsbergensis – 6
– 12 C 8-14 days (American beer).
h.
S cereviside – 14-23 C 5
– 7 days, carried to top by CO2. Stouts.
7. Distilled Spirits
a. Similar to beer except
b.
boiled.
continues during fermentation.
c. Alcohol is separated by
.
d.
– sugar cane or molasses.
e.
barrels.
– barley & aged in oak or cherry
8. Vinegar
a. Product of oxidation of ethyl alcohol by acetic acid
bacteria.
b. 4% acetic acid.
VI. Food Spoilage
A. Growth of
an undesirable change.
B.
microorganism
on or in food that produces
of food determines the type of
.
C. Bacteria commonly involved in food spoilage
1. Gram Negative
a.
.
Wide range of food &
temp.
b.
.
Degrade fruits &
vegetables.
c.
.
ethyl alcohol to acetic acid
d.
.
degrade cottage cheese
2. Gram positive
a. Streptococcus, Leuconstoc & Lactobacillus –
b. Bacillus & Clostridium –
.
c. B. coagulans & Strearothermophils = sour spoilage
of some
.
D. Fungus
1. Rhizopus sp. =
2. Aspergillus –
VII. Food Borne illness
A.
1. Hours
2. Consumption of a toxin produced by a microorganism
growing on a food product.
ex. Staphylococcus aureus – ham, pasteries, salads
nausea & vomiting.
B.
1. Neurotoxin by Clostidium botulinea (Gram positive)
2. Errors in canning with endospore contamination.
ex canned food – bulging
C.
- Salmonella & E. Coli
1. Infection after ingestion in the small intestines by a living
organisms.
2. Up to 24 hrs to feel effects resulting in diherrhea
3. Prevention
a. Thoroughly cook food.
b. Wash cutting board to prevent cross contamination.
IX. Food Preservation
A. Drying –
B. High Temperatures –
C. Low Temperatures –
D. Irradaition –
E. Sugar –
F. Smoked –
G. Pasteurization
1. High temp –
2. Low temp –
3. Ultra high