Microbiology of Fermented Foods

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Questions and Answers

What determines the flavors of different cheeses?

The type of milk used

The color of the cheese

The use of different starter cultures (correct)

The shape of the cheese curd

What happens during the ripening process of cheese?

The curds are hardened by heat

The curds are dissolved in water

The curds are frozen

The curds are softened by enzymes (correct)

What is used to promote the growth of specific microorganisms during cheese ripening?

Radioactive isotopes

High temperatures

Low pressures

Various temperatures (correct)

What is used to encourage the growth of specific bacteria and fungal populations during cheese ripening?

Brine Signup and view all the answers

What type of fermentation is involved in Swiss cheese formation?

Late propionic acid fermentation Signup and view all the answers

Which fungus is used in the ripening of Blue cheese?

Penicillium sp Signup and view all the answers

What is the primary fermentation microorganism used in the production of yogurt?

Streptococcus thermophilus Signup and view all the answers

What is the primary function of the lactic acid bacteria used in yogurt production?

To produce lactic acid and acetaldehyde Signup and view all the answers

What temperature is used for incubation during yogurt production?

40-45°C Signup and view all the answers

What is the purpose of pasteurizing the milk before adding the starter culture in yogurt production?

To kill any remaining pathogens Signup and view all the answers

What is the approximate annual sales of yogurt in the United States (in pints)?

3 billion Signup and view all the answers

How does lactic acid contribute to the texture of yogurt?

By coagulating proteins and lowering the pH Signup and view all the answers

Which of the following is NOT a microorganism used in dairy product production?

Escherichia coli Signup and view all the answers

What is the primary microorganism responsible for the production of Swiss cheese?

Propionibacterium Signup and view all the answers

What is the principal yeast used in bread making?

Saccharomyces cerevisiae Signup and view all the answers

What type of cheese undergoes little or no ripening?

Mozzarella Signup and view all the answers

Which of these microorganisms is NOT involved in the production of sauerkraut?

Saccharomyces cerevisiae Signup and view all the answers

What is the primary role of Lactobacillus helveticus in cheese production?

Adding a sweet flavor Signup and view all the answers

Which type of cheese is classified as 'very hard'?

Parmesan Signup and view all the answers

Which of these microorganisms is involved in the production of cocoa?

Candida krusei Signup and view all the answers

What is the main product of yeast fermentation in bread making?

Carbon dioxide Signup and view all the answers

What is the primary difference between soft cheeses and hard cheeses?

The length of ripening and water removal Signup and view all the answers

What is the ideal temperature range for cooling milk before adding starter cultures?

40-45°C Signup and view all the answers

What is the purpose of pasteurizing milk in yogurt processing?

To eliminate harmful bacteria Signup and view all the answers

What is achieved by holding the inoculated milk at 40-45°C until a pH of 4.5 is reached?

It transforms the milk into a soft gel Signup and view all the answers

During cheese production, which enzyme is primarily responsible for curdling milk?

Rennin Signup and view all the answers

Which of the following microorganisms are commonly used as starter cultures in cheese production?

Streptococcus and Lactobacillus species Signup and view all the answers

What happens to yogurt after fermentation is complete?

It is cooled to stop the fermentation process Signup and view all the answers

In making set-style yogurt, where is the fruit usually added?

At the bottom of the cup before pouring yogurt Signup and view all the answers

Which step in yogurt processing immediately follows the inoculation with starter cultures?

Holding for fermentation Signup and view all the answers

Which of the following is NOT a type of wine produced through fermentation?

Distilled wine Signup and view all the answers

What is the primary role of yeast in wine production?

To break down sugars into alcohol and carbon dioxide Signup and view all the answers

Which of the following statements accurately describes the difference between white and red wine production?

The fermentation process for white wine is carried out with the grape skins, while red wine fermentation excludes the skins. Signup and view all the answers

Which of the following beverages is produced through the fermentation of malted grains?

Beer Signup and view all the answers

What is the purpose of aging wine?

To remove tart compounds and soften the flavor of the wine. Signup and view all the answers

Which of the following is a characteristic of a fortified wine?

It has a high sugar content. Signup and view all the answers

Which type of wine is produced through fermentation in a closed bottle, resulting in the presence of carbon dioxide?

Sparkling wine Signup and view all the answers

What is the role of Saccharomyces ellipsoideus in wine production?

To ferment sugars in grape juice into alcohol and carbon dioxide Signup and view all the answers

Study Notes

Fermented Foods Overview

Fermentation involves the conversion of sugars into acids, gases, or alcohol by microorganisms.
Key fermented foods include dairy products (yogurt, cheese), pickled vegetables, and alcoholic beverages.

Microorganisms in Dairy Products

Common microorganisms in dairy fermentation include:
- Yogurt: Streptococcus sp., Lactobacillus sp.
- Cheddar Cheese: Streptococcus, Lactococcus.
- Sour Cream & Cottage Cheese: Streptococcus sp.
- Swiss Cheese: Propionibacterium.
- Cultured Buttermilk: Streptococcus sp., Leuconostoc sp.

Yogurt Production Steps

Pasteurization: Milk is heated to eliminate spoilage bacteria.
Inoculation: Starter cultures (Lactobacillus bulgaricus & Streptococcus thermophilus) are added.
Incubation: Mixture is kept at 40ºC for several hours to ferment lactose, producing lactic acid.
Cooling: Yogurt is cooled to 7ºC to stop fermentation.
Flavoring: Fruits and flavors may be added before packaging.

Cheese Production Process

Cheese is made by curdling milk using enzymes like rennin and lactic acid bacteria.
Various starter cultures influence the flavor, including different species of Streptococcus and Lactobacillus.
Cheese varieties are classified by texture and hardness:
- Soft: Cottage, Cream, Brie.
- Semi-soft: Monterey Jack, Fontina.
- Hard: Cheddar, Swiss.
- Very Hard: Parmesan, Asiago.

Cheese Aging/Ripening

Involves transformations by proteolytic enzymes, affecting taste and aroma.
Specific ripening techniques include:
- Use of brine to promote bacteria/fungi growth.
- Varied temperatures to encourage specific microorganism growth.
Types of cheeses with distinctive molds:
- Blue Cheese: Penicillium sp.
- Brie/Camembert: P.candidum.

Bread Fermentation

Bread is produced by fermenting sugars using Saccharomyces cerevisiae (baker’s yeast).
Yeast fermentation results in CO2 production, essential for bread rise.

Other Fermented Foods

Common fermented foods include:
- Cocoa: Candida krusei & lactic acid bacteria.
- Pickles: Lactobacillus plantarum.
- Sauerkraut: Enterobacter cloacae.
- Soy Sauce: Aspergillus oryzae.

Fermented Beverages

Produced by yeasts of the Saccharomyces genus.
Types of alcoholic beverages:
- Beer: Fermentation of malted grains.
- Wine: Fermentation of fruit juice.
- Distilled Drinks: Whiskey, brandy, and rum through distillation.

Wine Production Steps

Wine starts from pressing grapes to produce juice (must).
Red wine fermentation occurs with grape skins; white wine fermentations are skin-free.
The wine undergoes aging, filtration, and bottling.

Summary of Wine Types

Dry Wine: All sugars fermented (e.g., Chardonnay).
Sweet Wine: Some sugar remains (e.g., Moscato).
Fortified Wine: Distilled beverage added (e.g., Port).
Sparkling Wine: Contains CO2 from fermentation (e.g., Champagne).

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Description

This quiz covers the primary fermentation microorganisms involved in the production of fermented foods. It explores the role of microorganisms in fermentation processes and their impact on food products. Test your knowledge of fermented foods and their microorganisms!