Microbiology Chapter 16: Food and Industrial Microbiology

Describe the process of fermentation in swiss cheese

As the cheese ages, first the lactic acid bacteria such as lactobacillus helveticus convert sugars to lactic acid. Then the propionic bacterium start to break down lactate further to acetate, propionate and CO2. The CO2 gas forms the bubbles or "eyes" of swiss cheese

Natto describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

It is from China and Japan It starts off with whole soybeans that are fermented The type of bacteria used is bacillus natto

Beer describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

It is from asia, Europe and Africa It starts off with Barely and hops which is then yeast fermented The type of bacteria used is saccharomyces

Why does a second stage of fermentation occur during wine making?

Malolactic fermentation is needed to decrease the acidity of malic acid found in grapes Both kinds of wine (white and red) undergo this process

What is an example of Semihard, ripened cheeses?

Muenster

What is one exception of cyanobacterium that can be eaten and why?

Spirulina This is because its purine content is low enough to include it as a modest part of the human diet

What are some examples of alcoholic fermentation

Wine (asia and europe) Beer (Asia, Europe and Africa)

Why are cheeses less susceptible than milk to general spoilage?

because of its solid structure and lowered water activity. However, cheeses can grow mold on their surfaces

CO2 causes bread to

rise

Several kinds of ____ are cultivated most notably in Japan

seaweed (marine algae) this is example of edible algae

Spirulina is classified as a form of ____

single celled protein

Acids

sour taste

How does seafood spoil?

spoil rapidly because of their unsaturated fatty acids rapidly oxidize Psychrotrophic bacteria reduce trimethylamine oxidase to the fishy smelling trimethylamine

Most classes of fermentation involve ____

the anaerobic fermentation of glucose or amino acids

lactic acid fermentation

the chemical breakdown of carbohydrates (ex. glucose) that produces lactic acid as the main end product

The hydrophobic portion of casein forms a curd that is ___ and results in ____

the hydrophobic portion forms a curd that is firm and results in the harder texture of solid cheese

Which part of the body detoxifies alcohol?

the liver

The preparation of all forms of yeast bread requires the _____ fundamental steps

the same fundamental steps

Why are the microbes that are used to ferment soybeans important?

they are important because they remove substances the decrease the nutritional value of soybeans. This would explain why it is better to eat fermented soybeans rather then unfermented soybeans

How do meat and poultry spoil?

they are putrefied by decarboxylating bacteria which produce amines with noxious odors More specifically: Meat in the slaughterhouse is easily contaminated with bacteria from hide, hooves, and intestinal contents Muscle tissue offers high water content which supports microbial growth The breakdown of peptides, and amino acids produced the undesirable odorants that defined spoilage Meat also contains fat or adipose tissues that commonly spoil abiotically by autooxidation (reaction with oxygen Finally, lactic acid bacteria and facultative anaerobes can generate short-chain fatty acids which taste sour

how can dairy products become spoiled?

they can become soured by excessive fermentation or made bitter by bacterial proteolysis More specifically in fresh milk lactose is available for microbial catabolism which supports anaerobic fermentation to sour milk. Under certain conditions, bitter flavors may be produced by bacterial degradation of proteins.

Rennet includes ___ of enzymes called

two types of enzymes known as chymosin and pepsin

The water soluble portion of casein forms _____ and is separated from the ____

whey and is separated from the curd (the curd separates from the liquid portion called whey

After the formation of curd this gel-like network generates the texture of ____

yogurt

What generates the special flavors in beer?

Secondary products, such as long-chain alcohols and esters.

Describe the basic process of bread making.

1. A starter culture of yeast is included into the dough. The yeast can be commercial baker's yeast or it can be a sourdough starter 2. The dough is kneaded to develop a fine network of air pockets 3. Let the dough sit to rise. the dough is able to rise due to the production of carbon dioxide gas 4. Then you can bake

Describe the basic overview of commercial cheese production. List the steps

1. milk is filtered, centrifuged and subjected to flash pasteruization 2. Fermenting microbes are added as starter culture 3. Renner is added for all BUT soft cheese 4. The solid curd is then cut or cheddared 5. Curd is then heat treated 6. Then the curd is pressed and shaped into a mold 7. Then the cheese is brined or ripened (aged)

What are the three successive stages of cocoa bean fermentation that occur to make chocolate?

Anaerobic fermentation by yeast Anaerobic fermentation by lactic acid Aerobic respiration by Acetobacter species

Practice question: Alkaline fermentation include which of the following

Answer is locust beans

What type of grain is used for beer?

Barely grains

Practice problem: Where does ethanolic fermentation mainly occur? A) Cheese production B) chocolate production C) Seaweed D) Bread and wine

Bread and wine

similarly to Beer, what type of yeast is used to make wine?

Brewer's yeast

What is an example of mold-ripened cheeses?

Brie and Camembert

Acid fermentation of dairy products include

Buttermilk (Asia, Europe) Yogurt (Asia, Europe) Kefir (russia) Sour cream (Asia, Europe) Cheese (asia, Europe)

Agaricus bisporus (mushroom) include

Button and portobello mushrooms

Practice Problem: True or false: the flavors of natto are generated by the side products of fermentation such as flavorful alcohols, esters and sulfur compounds?

False

Practice problem: True or False: the lyophilization of milk proteins results in the formation of curds?

False coagulation results in curds

Describe the process of wine making

First the grapes are crushed to release juicies. the grape sugar (from the juice) is fermented by yeast to make alcohol. While being stored a second stage of fermentation occurs known as malolactic fermentation by a type of bacteria called Oenococcus oeni.

Dawadawa describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From Africa It starts off with locust beans which are then fermented The type of bacteria used is Bacillus

Buttermilk: describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From Asia and Europe It starts off using bovine milk which is then lactic fermented It uses lactic fermentation by the lactococcus bacteria

Cheese describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From Asia and Europe Starts off with milk (either bovine, sheep or goat) then it is lactic fermented, coagulated and pressed. In some cases it is cooked or mold ripened If you are using Acid fermentation there are three types of bacteria that you could use: lactobacillus, streptococcus and propionibacterium If you are using mold ripening you would use: Penicillium

Yogurt: describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From Asia and Europe starts off using bovine milk which is then lactic fermented and coagulated The two types of bacteria that perform this is lactobacillus and streptococcus

Pidan describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From China and Japan It starts off with duck eggs that are coated in lime (Cao) and aged producing ammonia and sulfur odorants The type of bacteria used is Bacillus

sauerkraut describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From Europe Starts off with cabbage which is fermented, making lactic and acetic acids, ethanol and CO2 The type of bacteria used is leuconostoc, Pediococcus and lactobacillus

Kefir describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From Russia It starts off with either bovine or sheep's milk then it uses mixed fermentation, lactic acid with some alcoholic fermentation It uses three types of microorganisms including lactobacillus, streptococcus and yeast

Chocolate describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From South America Starts off with cocoa beans. It is then soaked and fermented before processing to chocolate It uses lactobacillus, bacillus and saccharomyces

Tempeh describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

From indonesia It starts off with soybean cakes then it goes through fungal fermentation The type of bacteria used is Rhizopus oligosporus

Why is gluten also important during the rising stage of bread making?

Gluten is a protein complex that forms a fine molecular network that supports the rising of the dough More gluten = more rising

Soy sauce: describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

If is from China Starts off with extract of soy and wheat, then it goes through fungal fermentation. Then it is brined and goes through bacterial fermentation The type of bacteria used is aspergillus followed by halotolerant bacteria and haloarchaea

What are the major classes of fermentation?

Homolactic acid Propionic acid Heterolactic acid fermentation Ethanolic fermentation Alkaline fermentation

Why is the fermentation of the cocoa bean (used to form chocolate) unique and complex?

In comparison to other forms of fermentation there hasn't been a starter cultures that has been identified or standardized

Why are very little bacteria edible as isolated organisms?

It is because their nucleic acids are too concentrated for food Uric acid production from purine cannot be metabolized and can lead to gout and kidney stones

Ogiri describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

It is from Africa Starts off with melon seed paste which is then fermented The type of bacteria used is bacillus

Wine describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

It is from Asia and Europe It starts off with grape juice which then goes through yeast fermentation followed by malolactic fermentation The type of bacteria used is saccharomyces and Oenococcus

Sour cream describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

It is from Asia and Europe Starts off with bovine cream then it is lactic fermented The bacteria used it lactococcus

Examples of alkaline fermentation includes:

Pidan (china and Japan) Natto (china and Japan) Dawadawa (Africa) Ogiri (Africa)

What type of yeast is used for beer?

Saccharomyces cerevisiae (brewer's yeast)

The most prominent yeast that performs ethanolic fermentation is

Saccharomyces cerevisiae known as baker's yeast or brewer's yeast

What is an example of Hard cheeses

Swiss cheese and cheedar

Acid fermentation of vegetables include

Tempeh (indonesia) Miso (japan) Soy sauce (China) Sauerkraut (europe) Chocolate (south America)

What type of poisonous mushroom produces toxins including the RNA polymerase inhibitor alpha-amantin

The amanita or destroying angel mushroom

Nori is best known for its use in wrapping rice, fish, and vegetables to form sushi. What is nori made out of?

The red alga Porphyra

Practice problem: Which of the following organisms or processes is not involved in the chocolate making processes?

Thermophilic bacteria

An extraordinary number of cheeses are divided into several categories based on ____ in their production. List the different variety of cheeses

These different types of cheeses are divided into several categories based on the particular steps in their production. The list includes: Soft unripened cheese Semihard, ripened cheeses Hard cheeses Brined cheeses Mold -ripened cheeses

How do we ferment cabbage, cucumbers and olives?

Through pickling which is a type of fermentation that uses a brine. A brine contains a high salt concentration The bacteria used for this process is leuconostoc mesenteroides

What is the purpose of food fermentation?

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

Practice problem: True or False: In all fermented foods, microbial metabolism generates by-products (secondary metabolites) the confer a characteristic aroma and flavor?

True

True/false: less than 1% of mushrooms are poisonous

True

Some types of mushrooms include

Underground truffles Agaricus bisporus

In Swiss cheese a ____ stage of _____ fermentation produces _____

a second stage of lactic acid fermentation produces propionic acid aka propionic acid fermentation

beer is derived from

alcoholic fermentation of grain

During the process of making beer, barely grains are ____ allowing enzymes to break down ____ into ____ for _____

barely grains are germinated allowing enzymes to break down the starch to maltose for yeast fermentation

Alkalinity

bitter taste

How is ethanol removed from bread?

by baking

What is an example of Soft unripened cheese

cottage cheese and ricotta

putrefaction

decomposition of proteins

Agaricus bisporus are a type of ______

edible fungi specifically mushrooms

Some of our most nutritionally significant and culturally important foods including bread and alcoholic beverages require _____ fermentation by ___

ethanolic fermentation by yeast fungi

What is an example of Brined cheeses?

feta and gouda

Miso describe the following: Its origin, Description, and Microbial genera (type of bacteria used)

from Japan Starts off with soy and rice past then it goes through fungal fermentation The type of bacteria used is Aspergillus

The fermentation of ____ gives rise to wine

fruit most commonly grapes

The finest textured bread are made from ___

gluten

Traditional fermented foods usually depend on ____ or _____

indigenous flora (which is found naturally in food) or Starter cultures (from previous fermentation

Glucose is fermented into ___. Where is this type of fermentation normally occur?

lactic acid (lactic acid fermentation) This fermentation occurs in cheeses and sausages

Which type of bacteria performs lactic acid fermentation?

lactic acid bacteria known as lactobacillus

Milk fermentation begins by _____ with _____

lactic acid fermentation with lactobacillus and streptococcus

Practice question: Sauerkraut, pickles and kimchi all use which type of bacteria?

leuconostoc mesenteroides

Fungal fruiting bodies are

multicellular reproductive structures that generate spores that are commonly known as mushrooms

Chymosin specifically cleaves casein into two parts including:

one which is charged and water soluble the other which is hydrophobic

Fermentation of the cocoa bean occurs...

outside of the bean within the fruit pulp

rancidity

oxidation of fats

In swiss cheese propionic acid fermentation is performed by what type of bacteria?

propionic bacterium called freudenreichii which generates the distinctive flavor of swiss cheese

In most kinds of cheese formation, an additional coagulation step during milk fermentation occurs following degradation of casein by ______ such as ____

proteases such as rennet

Mushrooms offer a source of ____ and _____

proteins and minerals

Acidification of milk during fermentation causes _____ especially _____ to denature and coagulate to form semisolid curd.

proteins especially caseins to denature and coagulate to form a semisolid curd. This gel-like network generates the texture of yogurt

Protein degradation in milk is most commonly caused by which type of bacteria?

psychrophiles

After the three successive stages of cocoa bean fermentation what occurs next?

pulp drainage, the beans are dried and then roasted

Ethanolic fermentation converts ....

pyruvate to ethanol and carbon dioxide

Food spoilage

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

Food contamination (food poisoning)

refers to the presence of human pathogens