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1 Food Biotechnology 1 Food Biotechnology

1 Food Biotechnology - PowerPoint Presentation

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1 Food Biotechnology - PPT Presentation

Dr Kamal E M Elkahlout Food Microbiology 2 Sources of microorganisms in food amp Important Bacterial Groups in Foods 2 Sources of microorganisms in foods 3 The internal ID: 617358

bacteria foods food microorganisms foods bacteria microorganisms food sources clostridium processing bacillus air acid micrococcus lactobacillus soil water produce pathogens spp pseudomonas

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Slide1

1

Food Biotechnology

Dr.

Kamal

E. M.

Elkahlout

Food Microbiology

2

Sources of microorganisms in food

&

Important Bacterial Groups in FoodsSlide2

2

Sources of microorganisms in foods

Slide3

3

The

internal

tissues of healthy plants (fruits and vegetables) and animals (meat) are essentially sterile.

Raw and processed (except sterile) foods contain different types of molds, yeasts, bacteria and viruses.

Microorganisms get into food from natural sources and external sources. Slide4

4

Natural sources for foods of plant origin

Surfaces of fruits, vegetables and grains and damaged tissues and pores in some tubers (e.g. radish and tubers).

Natural sources for foods

of

animal origin

Skin, hair, feathers, gastrointestinal tracts, urinogenital tract, respiratory tracts and milk ducts (teat canals) in animals producing animals.Slide5

5

An understanding of the sources of microorganisms in food is important to:

develop methods to control access of some microbes in food.

develop processing methods to kill them in food.

Determine the microbiological quality of foods.

Setup microbiological standards and specifications of food and food ingredients.Slide6

6

Pre dominant microorganisms in plants (fruits and vegetables).

Internal tissues are sterile except for few porous vegetables and leafy vegetables.

Some plants produce natural antimicrobial metabolites that limit the presence of microorganisms.

Fruits and vegetables harbour microbes on their surfaces and microbe presence depends on their type, soil condition, water used and air quality. Slide7

7

Molds and yeasts

Lactic acid bacteria

Bacteria from the genera:

Pseudomonas, Alcaligenes, Micrococcus, Erwina, Bacillus, Clostridium and Enterobactor.

Pathogens especially of enteric types (

Salmonella, Escherichia coli, Campylobacter, Shigella, Cyclospora, Giardia

can be present if the soil is contaminated with untreated sewage. Slide8

8

Factors contributing to increase in microbial numbers

Diseases of the plants.

Damage of the surface before (during and after harvest).

Long delays between harvesting and washing.

Unfavorable storage and transport conditions after harvesting and before processing can greatly increase the microbial numbers.Slide9

9

Reducing microbial loads in foods of plant origin

Proper methods used during growing (such as use of treated sewage or other types of fertilizers).

Damage reduction during harvesting.

Quick washing with good quality water to remove soil and dirt.

Storage at low temperature before and after processing. Slide10

10

Are carriers and can carry pathogens such as

Salmonella

spp., pathogenic

Escherichia coli,

Campylobacter jejuni, Yersinia enterocolitica

and

Listeria monocytogenes

Laying birds – suspect of carrying

Salmonella enteritidis

in ovaries and contaminating yolk during ovulation.

Fish and shellfish carry normal microflora in the scales, skin and digestive tracts. Carry pathogens such as

Vibrio parahaemolyticus, Vib vulnifus.

Pre dorminant microroganisms in animals birds, fish and shellfishSlide11

11

Contamination of foods of animal origin during production and processing:

Milk – contaminated with fecal materials on the udder surface

Egg shells – contaminated with fecal material

Meat- contaminated with the intestinal contents during slaughtering

Enteric pathogens from fecal materials common are

Staphylococcus

aureus

, Micrococcus

spp

, moulds and yeasts.Slide12

12

Reduction in microbial load – foods of animal origin

Effective use of husbandry of live animals and birds:

- good housing

- avoid overcrowding

- supply of uncontaminated water

Testing animals and birds for pathogens and culling the carriers-to reduce the incidence of pathogenic microorganisms in food.

Cleansing carcasses with good quality water.

Careful hair, feather removal and digestive, urinogenital and respiratory organs.

Proper sanitation during slaughtering and processing.

Proper cleaning of the udder before milking and after milking.

Eggs should be collected soon after laying and washed and stored as per recommended procedures.

Fish and marine products should be harvested from unpolluted waters. Observe proper sanitation during processing. Use ice for storage

.Slide13

13

Sources of microorganisms

Air

Microorganisms are present in dust in air

Do not grow in dust but are transient and variable depending upon the environment

Their level is controlled by the degree of

humidity, size and level of dust particles,

temperature and air velocity and resistance of microorganisms to dryingSlide14

14

Dry air with low dust content and higher temperature has a low microbial level.

Predorminant microbes in air include spores of

Bacillus spp. Clostridium spp.,

mold and Gram-positive bacteria (

Micrococcus spp and Sarcina

).

Microbial contamination in the air can be reduced by

removing the potential sources,

controlling dust particles in the air (using filtered air) using positive air pressure,

reducing the humidity level and installing UV light.Slide15

15

Soil

Soil contains several varieties of microorganisms

Microorganisms multiply in soil, their numbers can be very high (billions/ g)

Moulds, yeasts and bacteria genera (

Enterobacter, Pseudomonas, Proteus, Micrococcus, Enterococcus, Bacillus

and

Clostridium

) can get into foods from the soil.Slide16

16

Soil contaminated with fecal materials can be source of enteric pathogenic bacteria

Sediments where fish and marine foods are harvested can also be a source of microorganisms in those foods

Prevention - removal of soil (and sediments) and avoiding soil contamination are used to reduce microorganisms in foods

Slide17

17

Sewage

Sewage when used as fertilizer in crops can contaminate food with microorganisms.

Predominant types include enteropathogenic bacteria and viruses.

Major concern with organically grown foods and many imported fruits and vegetables where untreated sewage may be used as fertilizers.

Prevention

not to use sewage as fertilizers, or should be efficiently treated to kill the pathogens.

Wash foods following harvesting is importantSlide18

18

Water

Is used to produce, process and in some cases store foods.

Used for irrigation of crops, drinking by food animals.

Raising fishery and marine products.

washing foods, processing (pasteurization canning and cooling of heated foods).

washing and sanitation of equipment , processing and transportation facilitiesSlide19

19

Water is used as an ingredient in many processed foods thus can greatly influence the microbial quality of foods.

Wastewater can be recycled for irrigation

Chlorine-treated potable water should be used in processing, washing, sanitation and as an ingredient.

Although potable water does not contain coliforms and pathogens. It can contain other bacteria capable of causing food spoilage (including

Pseudomonas, Alcaligenes

and

Flavobacterium)

Improperly treated water can contain pathogen and spoilage microorganismsSlide20

20

Humans

Between production and consumption foods come in contact with people handling the foods.

people working in a food processing plant, handling foods at restaurants, catering services, retail stores and at home.

Improperly cleaned hand, lack of aesthetic sense and personal hygiene, dirty clothes and hair can be a major sources of microbial contamination in foods.

Pathogens such as

Staphylococcus

aureus

, Salmonella spp.

Shigella

spp.

Pathogenic

E. Coli

and hepatitis A can be human sources.

Slide21

21

Food ingredients

prepared or fabricated foods many ingredients or additives are included in different quantities.

Many ingredients can be a source of both spoilage and pathogenic microorganisms

various spices can possess very high populations of mold and bacterial spores.

Starch, sugar and flour might have spores of thermophilic bacteria. Slide22

22

ingredients should be produced under sanitary conditions.

and given antimicrobial treatments.

Setting up acceptable microbial specifications for the ingredients will be important in reducing microorganisms in foods from this sourceSlide23

23

Equipments

wide variety of equipment are used in

harvesting, transportation,

processing and storage of foods

microorganisms from air, raw foods, water and personnel can get into the equipment and contaminate foods.

Depending on environment and time,

microbes can multiply from low initial population to reach high level and contaminate large volumes of foodsSlide24

24

processing used continuously for a long period of time,

microorganisms resent initially can multiply and act as a continuous source of contamination in the product.

small parts, inaccessible sections and certain materials may not be efficiently cleaned and sanitized therefore can serve as sources of both pathogenic and spoilage microorganisms in foodSlide25

25

Small equipments such as cutting boards, knives, spoons due to improper cleaning can be source of cross-contamination

Salmonella, Listeria, Escherichia, Enterococcus, Micrococcus, Pseudomonas, Lactobacillus, Listeria

and yeasts and moulds can get into food from equipment

Proper cleaning and sanitation of equipment at prescribed intervals are importantSlide26

26

Miscellaneous sources

Several other sources of food contamination include :

Many types of packaging materials are used in food. (wrapping materials, containers).

Flies, birds, house pets and rodents.

proper microbiological standards (or specifications) for packaging materials are necessarySlide27

Important Bacterial Groups in FoodsSlide28

Lactic Acid bacteria

produce relatively large quantities of lactic acid from CHO's.

Lactoccus, Leuconostoc, Pediococcus, Lactobacillus

and

Streptococcus thermopillus

Lactococcus

LeuconostocSlide29

Lactic Acid bacteria

Pediococcus

Lactobacillus

Streptococcus thermopilusSlide30

Acetic acid bacteria

bacteria that produce acetic acid.

Acetobacter aceti

.Slide31

Propionic

acid bacteria

bacteria that produce propionic acid and are used in dairy fermentation.

Propionibacterium freudenreichii

.Slide32

Butyric acid bacteria

bacteria that produce butyric acid in relatively large amounts.

Some

Clostridium spp

such as

Clostridium butyricum

.Slide33

Proteolytic

bacteria

those that are capable of hydrolyzing proteins, due to production of extracellular proteinases.

Species in genera

Micrococcus, Staphylococcus, Bacillus, Clostridium, Pseudomonas, Alteromonas,

and

Flavobacterium.Slide34

Proteolytic

bacteria

Staphylococcus

Micrococcus

Bacillus

Pseudomonas

Clostridium

FlavobacteriumSlide35

Lipolytic

bacteria

able to hydrolyze triglycerides due to production of extracellular lipases.

Species in genera

Micrococcus, Staphylococcus, Pseudomonas, Alteromonas

and

Flavobacterium.

AlteromonasSlide36

Saccharolytic

bacteria

able to hydrolyze complex CHO's.

Bacillus, Clostridium, Aeromonas, Pseudomonas

and

Enterobacter.

Aeromonas

EnterobacterSlide37

Thermophilic

bacteria

able to grow at 50°C and above.

Include some species from genera

Bacillus, Clostridium, Pediococcus, Streptococcus

and

Lactobacillus

.

PediococcusSlide38

Psychrotrophic

bacteria

able to grow at refrigerated temperatures (

5°C).

Pseudomonas, Alteromonas, Alcaligenes, Flavobacterium, Serratia, Bacillus, Clostridium, Lactobacillus, Leuconostoc, Carnobacterium, Brochothrix, Listeria,

Yersinia

and

Aeromonas

.

Alcaligenes

Serratia

ListeriaSlide39

Thermoduric

bacteria

able to survive pasteurization temperature treatment.

Include some species from

Micrococcus, Enterococcus, Lactobacillus, Pediococcus

,

Bacillus

(spores) and

Clostridium

(spores).

EnterococcusSlide40

Halotolerant

Bacteria

able to survive high salt concentrations (

10%).

Bacillus, Micrococcus, Staphyloccus, Pediococcus, Vibrio

and

Corynebacterium

.

VibrioSlide41

Aciduric Bacteria

:

able to survive at low pH (below 4.0).

Lactobacillus, Pediococcus, Lactococcus, Enterococcus

and Streptococcus

.

Osmophilic bacteria

:

can grow in a relatively higher osmotic environment than other bacteria.

Some species from genera

Staphylococcus, Leuconostoc

and

Lactobacillus

are included. They are much less osmophilic than yeasts and molds Slide42

Gas-producing bacteria

produce gas (CO

2

, H

2

, H

2

S) during metabolism of nutrients.

Leuconostoc, Lactobacillus, Propionibacterium, Escherichia, Enterobacter,

Clostridium

and

Desulfotomaculum

.

EscherichiaSlide43

Slime Producers

:

produce slime due to synthesis of polysaccharides.

Xanthomonas, Leuconostoc, Alcaligenes, Enterobacter, Lactococcus

and

Lactobacillus.Slide44

Sporeformers:

ability to produce spores.

Bacillus, Clostridium

and

Desulfotoaculum

spp.

They are divided into

aerobic sporeformers,

anaerobic sporeformers,

flat sour sporeformers,

thermophilic sporeformers

sulfide-producing sporeformers.Slide45

Coliforms:

includes species of

Escherichia, Enterobacter, Citrobacter

and Klebsiella and used as index of sanitation.

Fecal Coliforms:

mainly

Escherichia coli

. Also used as index of sanitation.Slide46

Enteric Pathogens:

includes pathogenic

Salmonella, Shigella, Campylobacter, Yersinia, Escherichia, Vibrio, Listeria

,

hepatitis A and others that can cause gastrointestinal infection.