Transcript Fermentation Preservation

FermentationPreservation
Lucy Allan
Delaney Ryan
Abbi Radous
2015
What is Fermentation?
An enzymatically controlled change in a food product brought on by the
action of microorganisms.
-manufacturers add microbes to cause fermentation
-what it does: changes the chemical environment of a food
*promotes the growth of bacteria, yeasts, and mold
-Types of fermentation
a. alcoholic
b. bacterial
c. mold
d. two-step
Fermentation Process Video…
https://www.youtube.com/watch?v=Tp-oQUJEIzM
(0:00-4:20)
Back to the types of fermentation…
 Alcoholic: Yeast  Bread
 Yeast uses oxygen
 Oxygen is used up
 CO2 is produced
 Small air sacs in the dough  bread rises
 Alcohol evaporates
Formula:
Pyruvic acid + NADH
alcohol + CO2 + NAD+
Types of fermentation (continued)…
 Bacterial
 “Lactic Acid Fermentation” refers to the fact that the major by-product is lactic
acid
 Where it occurs
 Muscle cells: O2 is needed to produce ATP. During intense exercise, the body produces a large
amount of lactic acid because the body doesn’t have enough oxygen.
 Yogurt
Formula:
Pyruvic acid + NADH
lactic acid + NAD+
Types of fermentation (continued…)
 Mold
 Creates a wide range of by-products
 Antibiotics
 Flavor compounds
 Enzymes
Examples: soy sauce, and tempeh (Asian soybean cake)
Types of fermentation (continued…)
 Two-step fermentation
 May require different types of microbes
 Types:
 Lactic Acid plus other microbes
 Cheese
 Sourdough bread
 Acetic Acid Fermentation
 Vinegar  red wine vinegar
 Cacao beans  chocolate
 Candied citron  fruitcake
So, which types of foods does
fermentation impact?
 Yogurt
 Cheese
 Wine
 Cider
 Bread
 Sauerkraut
 Flavorings
 Candy
 Fruit juice
 Silage
 Beer
So does it impact non-food items?
 Answer: Yes
 Antibiotics
 Laundry detergent
 Insulin
 Growth hormone
 Cellulose
 Monoclonal antibodies
 Compost
 Sno-max
 Ice-minus
 Medicine to dissolve tumors
 Medicine to clot blood
Why do we need fermentation?
 Increase shelf life of foods
 Improve dough handling characteristics of bread
 Enhance the texture, flavor and odor of foods
 Safely store food
 Creates a variety of flavors, textures, colors and appearances
 New energy sources
 Increased vitamin content
 Improved digestibility
 Decreased toxicity
 Decreased ailments
Are there any disadvantages of
fermentation?
 Answer: Yes.
 The product may become unfit for consumption
 Acid and gas
 Unfavorable conditions for microorganisms
Can other factors impact
fermentation?
 Answer: Yes.
 Fermentation time
 pH levels of 4.0-8.5
 Carbonic acid
 Calcium carbonate
 Presence of air
 Temperature
 Salts
 Water
 Concentration of sugar
 Contaminating organisms
A cheesy video…
https://www.youtube.com/watch?v=y9wLhRrj5Ug
Labs that we’ll be doing…
 Yogurt Lab (2/25-2/27)
 Root Beer Lab (2/27)
Yogurt Production
COMPOSITION OF YOGURT
What Is Yogurt?
• A fermented dairy product whereby milk is inoculated with bacteria
cultures
• Fermentation - a slow decomposition process of organic
substances induced by microoroganisms or enzymes
Producing Yogurt
• Lactose (compound sugar found in milk shown as lactin or milk
sugar) is fermented by two differen species of bacterai:
Lactobacillus and Streptococcus
• Commercially produced by adding milk to 2-4% nonfat dry milk
powder that has been inoculated with a 5% combinatin of
Lactobacillus bulgaricus and Streptococcus thermophilus(1:1 ratio)
• Milk mixture is then indubated at 45oC/113oF foor 3-6 hours.
Product must be chilled immediately.
Composition of Yogurt
• Product of fermentation
• food fermentation - study of microbial activity usually anaerobic,
on suitable substrates under controlled or uncontrolled conditions
• Lactose is fermented
• Lactic acid - end product of anaerobic metabolism of glucose
provides tart flavor of yogurt, as well as the formation of a gel
structure
• Major flavor components - carbonyl compounds - acetaldehyde is
most important and gives yogurt is green apple or nutty flavor
Yogurt Composition Etc.
• Quality is based on color, appearance, body, texture, flavor
• Ropy (slime-producing) lactic acid bacteria produce
polysaccharides that are released into yogurts where they
increase viscosity and improve water retention
• Milk SNf (solids-not-fat) cotent varies 9-16%
• can be increased by adding milk powder
• increased levels needed to increase protein content, helps to
increase viscosity to desired levels
Role of Bacteria in Yogurt Production
• Lactic acid bacteria produce polysaccharides that increase
viscosity and water retention
• High moisturer content 85%
• Reaches desired acidity (ph of 4.25-4.5), bacterial fermentation is
stopped by cooling yogurt
• Cooled yogurt should have between 0.9% and 1.2% lactic acid
Sour Taste in Yogurt
• Enzymes released by bacteria convert lactose into lactic acid
• Acis have sour taste, yogurts is a sour tasting dairy product
• Some yogurt contains live bacteria and others have been
fermented but pasteurized, heated to kill microorganisms, after
fermentation
Gel Texture of Yogurt
• Milk proteins curdle
• Each milk gel consists of protein matrix, which is modified by
lactic acid to produce smooth yogurt product
• Heating milk cases casein micelles to interconnect to form a gel
matrix - destroyes undesirable microorganisms
• Lactic acid bacteria produces polysaccharides that decrease
"flowability"
Root Beer Experiment
History
 Made by soaking Sassafras root in water, and adding sugar in yeast
 Early 1900s, scientists discovered that safrole, chemical in Sassafras root,
was a carcinogen
Background
 2 respiration types: aerobic and anaerobic
 Yeast cells obtain energy from glucose through fermentation
Alcoholic Fermentation
 Begins after glucose diffuses into the yeast cell. Glucose is broken down into
ATP for yeast cell.
 2 3-carbon molecules called pyruvate are made..
 Yeats cell converts pyruvate into CO2 and ethanol.
 Equation for anaerobic alcohol fermentation:
C6H12O6  2C3H4O3 (pyruvate) + 4H+  2CO2 + 2CH3CH2OH (ethanol)
 First 2 days – yeast will use aerobic respiration to grow/reproduce
 Oxygen supply is depleted, yeast cells shift to anaerobic respiration to obtain
energy
 Supplies root beer with carbon dioxide (“fizz”) and gives it a unique flavor due to
small amount of ethanol produced
Fermentation in Food Products
 Beer, wine, bread, cheese, sauerkraut, baked goods
 Carbon dioxide in root beer gives it it’s “fizz”
 Fizz produced artificially in store bought root beer, without aid of yeast cells