EXAM_3 Flashcards
Vinegar production probably started developing soon after
wine manufacturing began
The word Vinegar comes from from vin aigre (French); meaning
Sour wine;
A spoilage problem became one of the most widely used ingredients in foods
World-wide production of Vinegar
1 million liters/year
Vinegar was probably first developed as a means to:
preserve non-fermented, perishable foods, such as meats and vegetables.
The first biologically-produced preservative was
Vinegar
______ functions in pickling and flavor and is also used as a topical disinfectant, a cleaning agent, and as an industrial chemical
Vinegar
______ is found in hundres of processed foods; Salad dressings, mayonnaise, mustard, ketchup, bread and bakery products, picked foods, canned foods, and marinades and sauces
Vinegar
There is no U.S. standard of identity for _______, but there are guidelines
Vinegar
The guidelines for Vinegar in the U.S. are:
- Must be made from an ethanol-containing solution. (Most common starting materials are grape and rice wine, fermented grain and malt mashes, and fermented apple cider; distilled ethanol also permitted)
- Must have resulted from the “acetous fermentation”
- Must contain at least 4% acetic acid or at least 40 grains with the pH between 2.0 and 3.5
In making vinegar the most common starting materials for ethanol solutions are:
- grape and rice wine
- fermented grain and malt mashes
- fermented apple cider;
- distilled ethanol also permitted
The name of the vinegar is determined by:
the raw material
The predominate flavor in vinegar is the ____
acetate; source and ingredients also add flavors
The Two-step manufacturing process for Vinegar is:
- An ethanolic, anaerobic fermentation performed by yeasts
2. Acetogenic, aerobic process carried out by acetic acid bacteria
The genera of bacteria that can produce acetic acid as its primary metabolic end-product via oxidation of ethanol in the production of vinegar are:
Acetobacter
Gluconobacter
Gluconacetobacter (recently named)
Acidomonas
Acetobacter, Gluconobacter, Gluconacetobacter (recently named), and Acidomonas are all
gram-negative, obligately aerobic bacteria
Acetic acid bacteria are widely distributed in
plant materials rich in sugars (and alcohol-containing solutions)
Acetic acid bacteria commonly share environments with
ethanol-producing yeasts
Generally, Acetobacter grows better on _____ than _____ while, Gluconobacter grows better on _____ than _____
Ethanol, Glucose
Glucose, Ethanol
Generally, Acetobacter grows better on ethanol than glucose while Gluconobacter grows better on glucose than ethanol.
Acetobacter aceti long is considered
the primary industrial vinegar producer
Many vinegar fermentations use ______ or ______ cultures
mixed or wild cultures
In vinegar metabolism is
an incomplete oxidation
In vinegar metabolism oxidation isn’t down to ___ and ____ like the Krebs Cycle
CO2 and H2O
In vinegar metabolism ethanol is oxidized to
acetic acid; that’s it
The two main steps of metabolism in vinegar are
- Ethanol (CH3CH2OH) oxidized to acetaldehyde (CH3COH).
2. Acetaldehyde oxidized to acetic acid (CH3COOH).
In the production of vinegar both the substrate and product are _____, so there is a _____ of competitors in the process
toxic; lack
In vinegar acetic acid bacteria ______ ______ low pH and high levels of acetic acid
remarkably tolerate
To prevent further oxidation of acetic acid to breakdown products vinegar fermentation have historically been conducted in a
semi-continuous mode with a minimum amount of ethanol always present (EtOH represses synthesis of Krebs Cycle enzymes that would oxidize acetate).
(Vinegar) Spontaneous mutations of Acetobacter strains have caused _____ in several important functions
defects
(Vinegar) Acetobacter strain mutants have lost ability to
oxidize EtOH, tolerate acetic acid, and form surface films.
Most industrial strains of Acetobacter contain plasmids, but most plasmids are
cryptic
Methods for producing vinegar:
- Open vat method
- Trickling generator process
- Submerged fermentation process
In the production of vinegar the open vat process relies on _______________________ in vats, barrels, jars, or trays.
surface growth of acetic acid bacteria (AAB)
The _______ process was probably the first method developed to make vinegar
open vat process
In the open vat process of vinegar making the ___ only grow at the surface
AAB
In the open vat process of vinegar making a ____________________ forms on the surface
polysaccharide-containing film or pellicle
In the open vat process of vinegar making intact ______ is important; can take _________ to _____
pellicle
several weeks
months
Intact pellicle is important; can take several weeks to months.
The Orleans style open vat process for vinegar uses:
- Wooden barrels used; 60 to 70% full.
2. A pipe from outside top to inside bottom; air holes drilled along sides plugged with cheesecloth.
When complete the Orleans style open vat process for vinegar removes ________ and is __________
about two-thirds of the volume and is recharged to do again.
In the Orleans style open vat process for vinegar the film or pellicle is __________
Not disrupted
Balsamic vinegar is done using the ______________ process
The Orleans style open vat process
The Orleans style open vat process takes at least
2 to 3 weeks
What is the trickling generator process?
The presence and availability of oxygen and the surface area represented by the air-liquid interface critically affect production of acetic acid.
Optimizing the diffusion or transport of oxygen to the AAB cell surface.
Observations of Dutchman, Hermann Boerhaave, formed the basis for ____________
trickling generator processes
When and where was the trickling generator process first used?
1820s in Europe
What kind of vats were used for trickling generator processes in Europe during the 1820s
Used vats with inert packing materials, such as curled wood shavings, wood staves, or corn cobs.
I.e., Immobilized cells
The packing materials used in the trickling generator processes during the 1820s increased _______________
the surface area and degree of aeration
In the trickling generator processes _________ substrates are circulated or trickled through the cylindrical fermentation vessels from ________
Ethanolic
top to bottom
How many days are required to convert a 12% (v/v) ethanol solution to vinegar containing 10-12% acetic acid using the trickling generator processes
about three days
________ of the 1930s are still widely used
Frings generators; many modified to provide air in a counter-current direction along with a heat-exchange step so constant temperature can be maintained.
What is the newest technology employing modern industrial fermentors with rapid, high-throughput.
Submerged fermentation
“The Acetator”, “Cavitator”, “Bubble fermentor”, etc.
Stainless steel, easily cleaned and sanitized, can operate in batch, semi-continuous or continuous modes; computer-controlled.
What is submerged fermentation?
Delivering the oxygen via turbines that mix liquid with air or oxygen to deliver aeration at very high rates.
Bubbles kept small to increase surface area.
Aeration must be maintained at all times when in use with AAB.
Control of propeller speed (up to 1,750 rpm), nutrient feed, foam-handling, and temperature.
AAB activity is_________, so a means to control temperature important to maintain productivity.
exothermic
Large-scale acetators can produce _____ liters a day (about ____ gallons).
30,000 liters
7,500 gallons
Generally, starting material ethanol (grain) and acetic acid from a prior fermentation, water and yeast extract (nutrients) for a single cycle of 16 to 24 h to produce acetic acid of 7 to 12%.
About 50% removed from reactor and charged again.
In post-fermentation processing cell growth during a typical fermentation cycle is:
modest with only a single doubling of the initial population in a submerged fermentation.
Post-fermentation processing: Barrel-aged vinegar (Orleans) usually clear, does not require _______
filtration; submerged and trickling vinegars usually require elaborate filtration treatments prior to packaging.
In post-fermentation processing pasteurization is usually done to
inactivate any AAP, LAB or wild yeasts and molds (~80 degrees C/ ~30 seconds); there is usually a dilution with water to final concentration
What are the problems with post-fermentation regarding vinegar?
- Vinegar spoilage rare, but Moniliella acetoabutens (a mold), occasionally grows in raw vinegar.
- common problem is occasional contamination with mites and flies for open vat or trickling-type processes.
- The vinegar eel is a small worm (a nematode called Anguillula aceti), but seldom seen these days with submerged methods.
What role does phage play regarding vinegar?
- Phage infections occur; there are a lot of opportunities for infection; however, occurrence is apparently low in vinegar strains.
- Phage problems usually associated with trickling generator processes.
- Although submerged processes more sensitive to phage problems since they often rely on a single strain whose infection could conceivably result in a slow or failed fermentation.
What is the most frequently encountered problem with vinegar?
Oxidation of acetic acid by Acetobacter. Acetobacter have the capacity to oxidize acetic acid; they have Krebs Cycle enzymes, but oxidation is suppressed if the acetic acid concentration is below 6 to 7%.
Usually only under prolonged fermentations when EtOH is completely dissipated and acetic acid concentration is low does over-oxidation occur.
Is tea fermentation really fermentation?
No
What is coffee fermentation done for?
a means to remove the outer layers of the coffee bean
What is the tea plant?
an evergreen shrub, Camellia sinensis and Camellia assamica.
What is the choicest pluck on the tea plant?
the terminal bud and two youngest leaves of each branch.
Where is tea primarily produced?
in India, Sri Lanka, China, Indonesia and Japan.
Teas vary according to:
Age of leaf, season of plucking, and the altitude, soil and climatic conditions
What are the three major tea types?
Black tea, Green tea, and Oolong tea
How is black tea created?
Leaves are withered and rolled to break tissues and release juices which are held to undergo oxidative changes caused by enzymes in the leaves (called a fermentation, but not really so).
How is Green tea created?
Leaves first steamed to inactivate enzymes, then rolled and dried.
How is Oolong tea created?
Intermediate between black and green teas; the ‘fermentation’ period is kept short so that color and flavor are not as intense as with black tea.
Where is the coffee plant (Coffea arabica) native to?
native to Ethiopia; Brazil is now the #1 producer
How tall does the coffee plant grow to?
6 to 20 feet high (dependent on species, climate and extent of pruning – Coffea robusta resembles a shrub).
How many different varieties of coffee beans are there?
at least six different varieties of coffee beans; beans vary considerably depending on climate and soil where they’re grown.
How are the coffee beans prepared
- Spontaneous fermentation commonly used to remove skin, pulp and membranes from the bean.
- Green beans are sorted, graded and shipped to various markets (green beans can be stored for long periods of time).
- Roasting creates aromatic flavor compounds from components found in the green beans; roasting causes beans to expand, become more porous, and change to brown color.
- Carbon dioxide is formed during roasting; CO2 is desirable for keeping quality (preventing oxidative reactions) and retention of flavor and aroma substances.
Cocoa (chocolate) or rather the Theobroma cacao is cultivated only within ____ degrees of the equator
20 degrees
What are the largest producers of cocoa and chocolate?
West Africa is the largest producer, but Latin American countries are significant producers as well
Where is the Cocoa plant originally from?
Central America
How tall is the Cacao tree pruned to?
under 20ft tall so fruit can be harvested with a long stick
How many seeds does each fruit pod on a cacao tree have?
30-40 seeds
The fermentation of Cocoa is desirable because:
- Tight gelatinous pulp is digested away
- Plant embryo is killed by the heat generated in the fermentation (i.e., exothermic reaction)
- Desirable flavors are produced.
Cocoa fermentation is:
A true fermentation by natural microbial populations of plant
What is the purpose of bread fermentation?
Purpose is not to extend the shelf-life of the raw materials, but rather a means to convert the grain into a more functional and consumable form.
In bread fermentation do any of the primary fermentation end-products remain in the food product?
No
The history of bread-making parallels the history of ____________
human civilization
One of the earliest of all processed foods is
bread
What provided nourishment to the large labor force that built the pyramids in Egypt?
bread
What are the other non-wheat starting materials for bread?
rye, barley, oats, corn, sorghum and millet
What does gluten do?
Gluten gives bread its structure and elasticity and is necessary for the leavening process.
Bakers’ yeast is:
Saccharomyces cerevisiae
What two forms is bakers’ yeast used in?
Moist pressed cakes and dehydrated granules
What are Bakers’ yeast performance characteristics?
- Gassing power (i.e., rate of CO2 evolution)
- Produce good flavors
- Stable to drying
- Stable during storage
- Easy to dispense
- Ethanol-tolerant
- Cryotolerant
What are the bread manufacturing steps?
- Ingredients assembled and mixed into dough
- Bulk dough allowed to ferment
- Fermented dough is portioned and shaped (“punched down”)
- Given a second opportunity to ferment (re-disperses gas, forming smaller more regular gas cells).
- Baked, cooled, sliced and packaged.
What are the four basic ingredients in bread?
- Basic four ingredients are flour (60-70%), water (30-40%), salt (1-2%) and bakers’ yeast (1-2%).
- Salt toughens the gluten, controls the fermentation and gives a desirable flavor.
- Sugars: Sucrose or glucose usually added as an additional source of fermentable sugars; also for flavor and color.
- Enzymes: α- and β-amylases release glucose from amylose and amylopectin for more fermentable sugars and increase loaf volume. [Amylases should be heat-labile so bread doesn’t get soft and sticky.]
What are the non-basic ingredients in bread?
- Fat: Now using non-hydrogated oils to eliminate trans fatty acids; used as a shortening (tenderizing agent).
- Yeast nutrients: To enhance growth of yeasts – (nitrogen source) ammonium sulfate and other ammonium salts.
- Vitamins: There has been a flour and bread enrichment program in U.S. for >60 years (B vitamins and iron).
- Dough conditioners: To enhance dough elasticity (cysteine – weakens dough structure to decrease mixing times); ascorbic acid as an oxidizing agent.
- Biological preservatives: Mold inhibitors or weak organic acids such as potassium acetate and propionates (these are not inhibitory to bakers’ yeast).
- Emulsifiers: To increase water absorption and gas retention, to decrease proofing times, and reduce staling rate (mono- and diglycerates).
- Gluten: Dried gluten can be added to increase protein content, increase loaf volume and extend shelf-life.
What happens to oxygen in dough?
Oxygen in dough quickly used up and environment becomes anaerobic with evolution of CO2.
What do yeast utilize first?
Yeast utilize glucose first, when glucose exhausted then maltose and sucrose are consumed.
What role does C02 play in bread making?
CO2 causes gluten molecules to stretch; most of the gas is retained and trapped in the matrix.
What does a low pH do in bread making?
Low pH swells gluten making it more pliable.
What do yeasts in bread making produce?
Yeast also produces acids; sourdough breads feature active LAB as well to sour or flavor the dough.
What type ovens do modern commercial bakers use?
Most modern commercial bakers use continuous conveyer-type ovens, not batch ovens.
Temperature in these ovens is not constant, but increases in several stages.
During baking loaf volume expands due to heated CO2, EtOH is volatilized & lost, yeasts are killed, enzymes inactivated, starch swells & gelatinizes, gluten dehydrates/denatures and becomes rigid, crust forms (Maillard nonenzymatic browning), volatile flavor and aroma compounds are generated.
What is the history of Cachaca?
16th century - Portugal brought sugar cane to Brazil from Madeira Island
17th century – Distilled beverages
Sugars and molasses as raw material for alcoholic beverages
British colonies – Rum
France – Tafiá
Spain – Aguardiente de caña
Portugal/Brazil – Aguardente de cana and later “Cachaça”
Cachaca is the _______ most consumed spirit in the world
third
How many liters of cachaca does brazil produce?
1.5 billion liters
How many liters does Brazil export?
15 million liters
How many different registered brands of Cachaca are there in Brazil?
5 thousand
How long does is the fermentation in cachaca production?
generally 24h fermentation, with yeasts recycling
How many liters of fermented must does it take to produced one liter of cachaca?
6-10 liters
What is the alcoholic content of cachaca?
38-50 G/L
In cachaca production what determines the distillation cut?
the different boiling points of alcohol and water
What are the three distillation cuts in the cachaca production?
Head: first 10-20 minutes of distillation about 15% of total volume
Heart: Following fraction collected until the ethanol content reaches 38-40%
Tail: Last fraction containing ethanol content below 38%
What is cachaca aged in?
wooden barrels
What are the five major steps in cachaca production?
Sugar cane goes into
- Crusher
- Filtering
- Dilution
- Fermentation
- Distillation
What are the main microorganisms involved in cachaca production?
Bacteria and yeasts
What are the two phases in cachaca production?
Inoculum preparation: cell multiplication
Main fermentation: ethanol production
Characteristics of Saccharomyces cerevisiae for cachaca production
Efficient sugars utilization No production of excessive foam No production of acetic acid Aroma production Flocculation capacity Tolerance to high ethanol concentrations Initiate the fermentation quickly Low vitamins requirements Relative resistance to low pH values Polygalacturonase production
Types of yeast biomass production
Supply selected culture
Flask cultivation
Lab production of biomass
Yeast production in industrial scale
