Importance of Microbes in Foods

Question 1

What is food microbiology?

Answer 1

The study of the microorganisms which inhabit, create or contaminate food.

It involves the study of microorganisms causing food spoilage or foodbourne diseases.

Involves the study of bacteria, viruses and fungi.

Question 2

What are the areas of food microbiology?

Answer 2

• Food Safety
• Food Spoilage
• Food Preservation
• Food Fermentation

Question 3

(T/F) - The term food microbiology is not restricted to pathogenic organisms.

Answer 3

True - In fact, the presence of various non-pathogenic bacteria and fungi in cheeses and wines are included in the concept of food microbiology.

Question 4

What are the primary sources of microorganisms/microbes in food?

Answer 4

• Natural Sources
• External Sources

Question 5

What are some examples of natural sources of microbes in food?

Answer 5

• Two categories: Plant and Animal Sources
• Plant Sources: Surface of fruits, vegetables and grains; Damaged tissues and pores of some tubers
• Animal Sources: Skin, Hair, Feathers, Gastrointestinal tract, Urinogenital tract, Respiratory tract, Milk ducts

Question 6

What are some examples of external sources of microbes in foods?

Answer 6

Some external sources:
1. Air
2. Soil
3. Sewage
4. Water
5. Feeds
6. Humans/other animals
7. Food ingredients
8. Equipment/Utensils
9. Packaging
10. Insects

Question 7

The microbial flora of food consists of:

Answer 7

• those microbes associated with raw materials
• those microbes introduced during harvesting, handling and processing
• those microbes that survived any preservation treatment and storage.

Question 8

What are some beneficial properties of microbes in foods?

Answer 8

• Used in food production
• maintaining normal health of the gastrointestinal tract of humans
• controlling spoilage and pathogenic bacteria in food (Biopreservation)

Question 9

What are some good of microbes?

Answer 9

• Food Production/Supplements
• Food Preservation
• Beneficial Bacteria
• Biopreservation

Question 10

How are microbes used in food production.

Answer 10

• Microbes are used to produce desirable flavours and textures
• Microbes inhibit pathogen organisms
• Fermentation: makes food more nutritious, tastier or easier to digest

Question 11

What are some other benefits of fermentation?

Answer 11

• Enhances food safety because it helps to preserve food and increase its shelf life thus reducing the need for refrigeration or other energy intensive preservation methods.

Question 12

What are the four categories of fermented foods?

Answer 12

1. Fermented meat products - such as sausages, salami and pepperoni
2. Fermented dairy products - yogurt, cheese
3. Fermented vegetables and fruits - pickles, sauerkraut, soy sauce
4. Fermented beverages - wines, beer, rum

Question 13

What are the most common forms of fermentation bacteria and what are their role?

Answer 13

-Streptococcus
- Lactobacillus
-Leuconostoc
- Pediococcus
- Micrococcus

These bacteria preserve food by converting the sugars needed by competing microbes to lactic acid. It also inhibits the growth of organisms

Question 14

Name the bacteria that are used in the following:
a) the production of vinegar
b) the production of ethanol and CO2 and is used in the baking and brewing processes.

Answer 14

A. Acetobacter & Gluconobacter
B. Yeasts (Saccharomyces)

Question 15

List some food supplements that benefit from the effects of microorganisms.

Answer 15

• Vitamins ( such as vitamin B12 and riboflavin)
• Amino acids (such as glutamic acid, aspartic acid, phenylalanine and lysine)
• Probiotics

Question 16

What are probiotics?

Answer 16

Probiotics are products containing living microorganisms, which on ingestion in certain numbers exert health benefits beyond inherent general nutrition.

Question 17

Name the benefits of probiotics to the gastrointestinal tract (GI).

Answer 17

1. Provides protection against enteric pathogens.
2. Supplying enzymes to help metabolize foods.
3. Detoxify harmful food components and metabolites that can cause cancers
4. Stimulate intestinal immune systems
5. Improves intestinal peristaltic activity.

Question 18

What is bioperservation and how do microorganisms contribute to the process?

Answer 18

• Biopreservation refers to techniques of extending the shelf life of food by using natural or controlled microbiota.
• Microorganisms can provide antimicrobial compounds (against pathogenic microbes)
• Microbes can have certain properties (bacteriostatic, bacteriocidal, fungastatic, fungicidal) that may kill organisms involved in food spoilage.
• The microbes used are safe so they can be used as preservatives.

Question 19

What are some of the ways microorganisms are important in the agricultural industry?

Answer 19

1. Biological control and bioinsecticides : this prevents infection of plant
2. Contributes to the fertility of soil and symbiotic associations with plants. (Eg. Rhizobium and Mycorrhizaea)
3. Ruminant animals: these animals depend on microorganisms to aid in digestion.
4. Cycling of nutrients: responsible for the cycling of important nutrients like carbon, nitrogen and sulphur

Question 20

What are some of the traditional pathogenic bacteria associated with food-related illnesses?

Answer 20

1. Salmonella and Shigella,
2. Clostridium botulinum,
3. Clostridium perfringens,
4. Bacillus cereus,
5. Staphylococcus aureus

Question 21

List the emerging pathogens causing food-related illnesses.

Answer 21

1. Yersinia enterocolitica,
2. Escherichia coli,
3. Listeria monocytogens, 4. Campylobacter jejuni

Question 22

Why do viruses not reproduce in food?

Answer 22

Because the food only acts as a carrier

Question 23

Why would one expect the incidence of food related illnesses to be significantly low?

Answer 23

1. Increased public awareness of bacterial food-borne illnesses,
2. Regulations and technologies geared towards food safety,
3. Increased sanitation

Question 24

What are some reasons why foodborne illnesses are not being reduced?

Answer 24

1. Controlled food processing preceded by uncontrolled food production, mishandling, distribution or sale
2. Increased volumes of products from a single manufacturing sources,
3. Canning being partially replaced by freezing.
4. The worldwide distribution of food, serves unintentionally to spread food-bourne microbes.
5. Pre-processed and street vended meals enhances the chance of infection (in underdeveloped countries) and increased consumer preference for fresh undercooked or raw foods have the same the effects (in industrial countries)
6. There is a lag in transferring new testing technologies into the regulatory chain.
7. Animal husbandry has been markedly more intensive over the years. Animal to animal and a higher proportion becomes asymptomatic carriers of human enteric pathogens
8. Public is still not sufficiently informed or concerned to be able to distinguish bad from good practices.

Question 25

What are the major disadvantages of food spoilage?

Answer 25

1. Economic loss,
2. Loss of Consumable foods,
3. Food spoilage can adversely affect the availability of food