Week 7-3 Fermented Foods

Food spoilage

- refers to microbial changes that render a product obviously unfit or unpalatable for consumption.

Swiss cheese and cheddar

-Hard cheeses (_________) -aged for many months, even several years.

Muenster

-Semi-hard, ripened cheeses (___________) -aged for several months.

cottage cheese and ricotta

-Soft, unripened cheeses (__________) -whey is partly drained

Semi-hard, ripened

-____, ______ cheeses (Muenster) -aged for several months.

Brined

-_____ cheeses (feta cheese) -permeated with brine (concentrated salt)

Soft, unripened

-_____, _____ cheeses (cottage cheese and ricotta) -whey is partly drained

Hard

-______ cheeses (Swiss cheese and cheddar) -aged for many months, even several years.

Listeria monocytogenes; intestinal epithelium

-_______ _________, a psychotrophic bacterium that invades the cells of the ______ _________ -Causes listeriosis

Mold-ripened

-_________ cheeses (Camembert and Roquefort)

pickling

-fermentation in brine (high salt)

b. Propionibacterium

1.The genus _______ is responsible for the flavor of Swiss cheese. ● a. Lactobacillus b. Propionibacterium c. Saccharomyces d. Leuconostoc e. Penicillium

Ethanolic fermentation

A fermentation reaction yielding 2 ethanol and 2 CO2 as products.

ethanol

Acetic acid results from the reduction of:

proteins

Alkaline fermentations raise pH through the catabolism of:

alkaline fermentation

Bacterial fermentation in conjunction with proteolysis and amino acid catabolism that generates ammonia in amounts that raise pH. ex: thousand year egg, brie cheese

grains

Beer is derived from alcoholic fermentation of ____

malolactic ; Oenococcus oeni

Both kinds of wine usually undergo _____ fermentation by ___________ bacteria

CO2

Bread Dough is Leavened by Microbial ____

Esters

Chemical means of food preservation: _____: -Fatty acid esters and benzoic acid esters

Other organic compounds

Chemical means of food preservation: ______: -Cinnamon contains the benzene derivative eugenol (a potent antimicrobial agent)

Organic acids

Chemical means of food preservation: _______: -Benzoic acid, sorbic acid, and propionic acid

Inorganic compounds

Chemical means of food preservation: ________: -Salts such as phosphates, nitrates, and sulfites

fermentation; proteolysis

Dairy products can be soured by excessive _______ or made bitter by bacterial ______.

hydrolases

During mashing in beer making, stepwise heating activates what enzymes to break down carbohydrates and proteins?

ethanol and carbon dioxide -C3H4O3 → CH3CH2OH + CO2

Ethanolic fermentation converts pyruvate to _____ and _____

-Agaricus bisporus

Farming of __________ mushrooms on horse manure compost,

true

Fermentation gives chocolate its flavor. true or false

nucleic acids

Few bacteria are edible as isolated organisms because they have a high content of:

-Acids = sour taste -Oxidation of fats = rancidity -Decomposition of proteins = putrefaction -Alkalinity = bitter taste

Food spoilage: -_____ = sour taste -_______ of____ = rancidity -Decomposition of _____ = putrefaction -______ = bitter taste

white

For (red/white) wine the skin is removed.

8; Bacillus

For alkaline fermented foods, microbes consume part of the food then produce alkaline byproduct.. The pH is usually ~___ -when the pH is higher than this number, fermentation prevents microbial growth. -The only microorganism that grows at this pH is _________.

-The pH change is unlikely to be reversed. -Animal or plant bodies grown at near-neutral pH are unlikely to support growth of acidophiles or alkaliphiles, which grow at extreme pH conditions.

How is an acid or base used as an effective preservative?

bc many microorganisms will not grow in acidic or alkaline conditions

How is food preserved by fermentation?

germination

In beer making, malting involves __________ of the grain to induce the expression of hydrolase enzymes.

maltose

In beer production, yeast ferment ______.

TCA cycle

In production of alcohol by ethanolic fermentation, if there were to be some air present, then some of the pyruvate would enter _____ via aerobic respiration. This would produce a lot of intermediates such as aldehydes. Many aldehydes makes beer taste bad, while alot of esters make beer taste good.

citrate to alcohol.; sugar to lactate.; acteic acid; ethanol to CO2

In production of chocolate: 1. Yeast ferments _____ to _____. 2. Lactic acid converts ____ to_____. 3. With aeration, ______ bacteria oxidize ______ to _____

glucose

In wine production, yeast ferments ______ to alcohol.

cabbage

Kimchi is a fermented Korean food made primarily from which substance?

psychotroph

Listeria is a common _____ which spoils food at cold temperatures -common cause of food poisoning -survives at cold temp and causes disease in humans

putrefied; amines

Meat and poultry are ________(proteins decomposed) by decarboxylating bacteria, which produce _______ with noxious odors.

fermentation

Mold ripening refers to the secondary __________ stage of cheese production.

Bacillus

Only a few microorganisms can grow at alkaline pH, one being _____ which ferments soybean (natto), locust beans (dawadawa), and the century egg (pidan)

lyophilization

Physical means of preservation -Dehydration and ___________-(freeze-drying) -Refrigeration and freezing -Controlled or modified atmosphere -Pasteurization -Canning -Ionizing radiation

bacteria or molds; Pathogens

Plant foods spoil by excess growth of ____ or _____. -______destroy food crops before harvest.

Saccharomyces cerevisiae; lactobacilli; gluten

Process of making bread: 1. A starter culture of baker's yeast (_______), and/or ________. 2. The dough is kneaded to develop a fine network of air pockets. 3. CO2 causes bread to rise. - More _____ → more rise

1)To preserve food: by limiting microbial growth 2)To improve digestibility: by breaking down fibers 3)To add nutrients (such as vitamins) and flavor molecules (such as esters and sulfur compounds)

Purposes of fermentation in the past:

Secondary

Saccharomyces cerevisiae: Brewer's yeast -Beer derives from alcoholic fermentation of grain. -Barley grains are germinated, break down starch to maltose and glucose. -Yeast ferment maltose. -________products, such as long-chain alcohols and esters, generate the special flavors of beer.

unsaturated fatty acids

Seafoods spoil rapidly because their ________ ______rapidly oxidize.

B12; Porphyra; Spirulina

Single celled microbes can be consumed as an alternative source of Vit _____, which can not be acquired from plant only sources.

Rhizopus; Aspergillus

Soybeans -Microbes remove harmful elements when fermentation occurs -Mold: _____—tempeh(a mold fermented soy product) -Mold: ______—miso, soy sauce

lactic acid; lactate

Swiss cheese production involves two fermentation stages: -Stage 1: Lactobacillus ferments lactose into _____ -Stage 2: Propionibacterium converts ______ to propionate, acetate, and CO2

alkaline;

The Chinese century egg is made by being treated with an _____ solution and create tiny holes for microorganisms to enter the egg and ferment it

amino acids

The biosynthesis of ______ generates by-products that contribute both desirable flavors (long-chain alcohols) and off-flavors (acetaldehyde and diacetyl) in beer and wine.

propionic acid fermentation

The fermentation of lactic acid to propionic acid by Propionibacterium species; used in the production of Swiss cheese.

CO2; heterolactic; Propionibacteria; propionate

The holes in swiss cheese are caused by release of ____ by _____ fermentation (involves Lactic acid bacteria, Lactobacillus) The flavor is given by a second fermentation with _______, so the flavor of the swiss cheese is actually _______.

toxin

The most dangerous consequence of infection by food-borne pathogens is ____ production

1. Anaerobic fermentation by yeast (lowers pH to 4.2) 2. Anaerobic fermentation by lactic acid bacteria 3. Aerobic respiration by Acetobacter species (Polyphenol oxidation gives brown color of cocoa)

There is no starting culture for making chocolate, no ready made microorganism. Every fermentation of chocolate and coffee must be done where the cocoa beans are planted. The fermentation is done by the indigenous microorganisms (cannot be grown in a plate) They involve three metabolisms:

recycle NADH to NAD+

To the microorganism, the main purpose of fermentation is to...

indigenous flora; starter cultures

Traditional fermented foods usually depend on _______ (found naturally in the food) or _________(from a previous fermentation).

acid

Vegetables like kimchi, pickles, sauerkraut, soybeans, and olives are prepared by ______ fermentation

pasteurize it(killing of microorganisms), boil it, keep in a sheep's stomach

Ways to preserve milk?

fungi, algae, bacteria

What are some edible microbes?

Bacterium Leuconostoc

What bacterium is used in fermentation of sauerkraut, pickles, and kimchi?

fruit, usually grapes

Wine is derived from alcoholic fermentation of ____

Alkali

____-fermented foods include natto (soy), dawadawa (locust beans), and pidan (eggs).

Casein; peptides and amino acids; volatile alcohols and esters; methanethiol

_____ catabolism generates flavor molecules (highlighted). Extracellular enzymes break down casein into _____ and ____, which are taken into the bacterial cell by membrane transporters. The amino acids are fermented to ____ and ____. In some cases, they combine with sulfur to form _______ and other sulfur-containing odorants characteristic of cheese.

Polyphenol oxidation (a result of Aerobic respiration by Acetobacter

_____ gives brown color of cocoa

Clostridium botulinum; muscle

_____ toxin inhibits synaptic vesicle fusion, thus preventing activation of ____ cells. -contains endospores -Causes flaccid paralysis

Acid

_____-fermented foods include tempeh (soybeans), sauerkraut (cabbage), kimchi, and pickles.

Bleu

______ cheese is fermented twice. Once by bacteria and once by molds.

Injera; Injera; Candida

______: "edible tablecloth" -A prolonged (3-day) fermentation of Ethiopian/Eritrean bread called _____. -Made from teff and other grains -Makes an edible "tablecloth" -Fermentation dominated by the yeast _____

feti; brining

_______ cheese is salty because after fermentation, it goes through _____ -submerged in salty water to stop fermentation and make food more nutritious

Button; portobello

__________ mushrooms and __________ mushrooms are both cultures of Agaricus bisporus that are harvested at different stages.

Malolactic Fermentation ; lactic

a process in winemaking in which tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting _____ acid

ethanolic; Saccharomyces cerevisiae

bread and alcoholic beverages are a result of ____ fermentation by a single microorganism, a yeast called _____.(baker's yeast or brewer's yeast)

ethanolic

bread and wine are made by _____ fermentation

fermented food

cheese, chocolate, bread, beer, wine, even beef

true

coffee is partially fermented. true or false

spores ex: Clostridium botulinum

drying, smoking, and canning are ways of preserving food, but they may have ____ survive in them and germinate

Food contamination

or food poisoning, refers to the presence of human pathogens

Heterolactic acid fermentation

produce mainly lactic acid, but also produce ethanol and CO2 ex. sauerkraut, pickles, buttermilk, involved in food spoilage also

homolactic acid fermentation

pyruvate is converted directly to lactic acid, using electrons from reduced NAD

Clostridium botulinum

spores are found in honey, this microorganism is called ________, it is also responsible for botox in cosmetic surgeries. When these spores germinate, they release neurotoxins which make people look younger but can also paralyze them.

flaccid paralysis

§Clostridium botulinum toxin inhibits synaptic vesicle fusion, thus preventing activation of muscle cells. -contains endospores -Causes ______ _______

lactic acid

§Dairy products typically undergo _______ fermentation. -Yogurt and the numerous varieties of cheese

Spirulina.

§Many microbes are edible, including mushrooms, algae, and the bacterium _______