Exam (elaborations)
FSC 211 Exam 3 – Questions/Answers
FSC 211 Exam 3 – Questions/Answers
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FSC 211 Exam 3 – Questions/AnswersFood fermentations ✔️Ans - Historic means of preserving food
Selective fermentations ✔️Ans - enhance the shelf life stability of raw
ingredients
provide unique products of distinctive flavor, color and texture
Fermentation process ✔️Ans - Substrate "Feed Stock" --> organic
metabolism --> end products
cucumbers pickles (dill, sour, salt, stock)
olives green, ripe
cabbage, lettuce kraut
coffee cherries coffee beans
vanilla beans vanilla
meats fermented sausages
sour milk drinks yogurt, buttermilk
butter sour cream, cultured butter
cheese unripened-cottage,pot, cream, whey-ricotta, mysost, ripened-
cheddar, Edam, American ✔️Ans - lactic acid fermentations
vegetables soya sauce, tempeh
cheese Roquefort, Brie, bleu ✔️Ans - lactic acid bacteria with fungi
(mold)
beans vermicelli
ginger plant ginger beer
cereals sour dough products, rye bread, pancakes ✔️Ans - lactic acid
bacteria with yeast
alcoholic fermentation ✔️Ans - Transformation of organic substrates
into specialty foods
Organic compounds are transformed through metabolism
higher energy products are converted to products of lesser energy
subsequent release of energy in the form of heat
This is an oxidation-reduction reaction including:
Addition of O2
,Removal of H2
alcoholic fermentation reaction ✔️Ans - Glucose --> (yeast) Ethanol
Carbon Dioxide
alcoholic yields ✔️Ans - Quality & Quantity of alcohol
CO2 formed
By-products (type & concentration) vary
Strain of yeast
Composition of stock
Temperature
Extent of aeration
Acetic Acid fermentation example ✔️Ans - Vinegar
Lactic Acid fermentation examples ✔️Ans - Kraut
Pickles
Alcoholic (ethanol) fermentation examples ✔️Ans - Malt beverages
Wine
vinegar ✔️Ans - a condiment made from plant starches fermented
through alcohol to acetic acid
Vinegar = acetic acid
vinegar: two fermentations ✔️Ans - Alcoholic by yeast (anaerobic)
Conversion of sugars to alcohol
Oxidation of the alcohol leads to acetic acid (aerobic)
acetic acid bacteria Acetobacter - genius s. aceti
Technically an oxidation process
Acetobacter is a major contaminant in an alcoholic operation
Typically only done on an alternate dedicated site
Wine fermentation process (anaerobic) ✔️Ans - glucose --> (yeast)
Alcohol
Acetic oxidation process (aerobic) ✔️Ans - alcohol --> (acetobacter)
Acetic Acid/Vinegar
,Home vinegar process "natural" ✔️Ans - Slow process
Wild cultures
yeast - alcohol
wild aceto bacteria (low vinegar species/strains)
Limited control - poor yield
low alcohol content
acetic acid
Barrel "Orleans process" ✔️Ans - Previous run has 1/3 of barrel serves
as inoculum
Alcoholic liquid is added to the barrel and then barrel rotated
Aeration
Latice work inside barrel to support aceto bacteria
Increased surface area
Prevents settling for the biomass
70-85°F several weeks
Continuous method: "Vinegar generator" ✔️Ans - Continuous flow -
rapid
High surface area
Packer column reactor:
Beech wood
Wood chips
Corn cobs
Temperature 85°F
Control temperature because of heat liberated
Single pass or recycle to increase acidity
Finishing
Clarification similar to wine procedures
Adjustment of acidity
Distillation (white)
lactic fermentation ✔️Ans - Lactic Acid Producing Bacteria
Tolerant of moderate salt concentrations (8-10%)
Most spoilage organisms tolerate only 2.5%
Salt plus tissue water produces anaerobic conditions and yield lactic acid
, Salt and acid provides flavor, texture, and preservative effect
sauerkraut ✔️Ans - Clean, sound product of characteristic flavor
obtained by full fermentation, chiefly lactic, of properly prepared and
shredded cabbage in presence of not less than 2% nor more than 3% salt.
Lactic acid bacteria
Osmotic pressure of salt reduces turgor pressure and draws cell sap to
produce brine
Wilted cabbage + brine are tightly packed
Anaerobic conditions develop by CO2 of respiration
Kraut contains natural flora of cabbage plus contaminants from soil and
water
3 Stage Fermentation: principle of "feedback inhibition" Lactic-acid-
producing bacteria divided into three types: ✔️Ans - Gas producing
cocci
Non gas producing rods
Gas producing rods
Gas producing cocci ✔️Ans - 1. Gas producing cocci
Leuconostoc mesenteroides
Attack sugars and produce lactic and acetic acids, ethanol, mannitol, and
CO2.
Produce the least amount of change in protein and cellular structure of
sauerkraut
When acid content increases to 0.7 - 1.0%, they are destroyed
Non gas producing rods ✔️Ans - 2. Non-gas producing rods
Lactobacillus cucumeris, and Lactobacillus plantarum.
Produce lactic acid in large quantities from a portion of unchanged sugar
and mannitol
Destroyed by their own lack of resistance to the acid they produce
Gas producing rods ✔️Ans - Gas producing rods
Lactobacillus brevis.
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