Biotechnology in Food Science


22 Οκτ 2013 (πριν από 4 χρόνια και 7 μήνες)

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Biotechnology in Food Science

Biotechnology 2

Common Food Bourne Pathogens


Salmonella enteriditus

Campylobacter jejuni

Many, many others


Some are used in food production

Other are contaminants or even toxic


Salmonella is very common and causes:

Food Poisoning

Digestive ailments

Salmonella is transmitted via:

Contact with infected animals

Ingestion of raw or undercooked egg that has
contacted contaminated shells


Found in:

Undercooked meats

Unpasteurized milk

Other contaminated foods

Causes ~10% of all diarrhea in the US

Spread of Bacteria

Bacteria are usually spread by:

Physical contact

Ingestion of contaminated liquid or solid

Moral of the story

Be careful of cross

Good Fungi

Fungi are used in the production of many foods,
especially cheeses and yogurt.

Blue Cheese, Brie, Munster, etc

These are made by injecting cheeses with specific
fungi at some point during the cheese

Bad Fungi

While some fungi are used for food production
others are considered to be contaminants.

Some can even be toxic

Signs of a Bad Fungus…..

Fungi often appear on breads with high moisture
and sugar content as well as fruits and grains.

A typical fungus might appear as a fuzzy, blue
growth or as fuzzy, white spots.

Fungi usually spread via airborne spores.

Preventing Food Bourne Pathogens

The optimal range for the growth of harmful
bacteria is 4


Low temperatures (below 4
C ) usually cause
dormancy in bacteria

High temperatures (above 60
C ) can deactivate or
even destroy bacteria

Role of Biotechnology Applications




Enzyme Activities

Proteins that act as catalysts to speed up
chemical reactions in organisms or compounds

Enzymes are incredibly important in processes
as diverse as

digestion (break down compounds)

Respiration (conversion of sugars to ATP)

Fermentation (….?….)

Yogurt and the Lactose


The live active cultures create
, the enzyme
intolerant people lack, and another enzyme
contained in some yogurts (beta
galactosidase) also
helps improve lactose absorption in lactase
persons. Bacterial enzymes created by the culturing
process, partially digest the milk protein
, making
it easier to absorb and less allergenic. While the amount
varies among brands of yogurt, in general, yogurt has
less lactose than milk. The culturing process breaks
down the milk sugar lactose into glucose and galactose,
two sugars that are easily absorbed by lactose
intolerant persons.


There are lots of enzymes, Tabe 12
1 on page
293 lists those manufactured using GE bacteria
and fungi.

What do you notice about most of the names?

Almost all enzymes end in “ase”

The most important enzymes (as far as we care
concerned) are:

Amylase, protease, lipase


Or as Homer Simpson says


Actually fermentation is used to make more than
just alcoholic beverages.

More about Fermentation

Fermentation is the anaerobic conversion of sugars in
plant materials to simple chemical compounds

Actually alcoholic fermentation is the most common
type and the most important on biotechnology.

Breaking down of sugars creates Carbon Dioxide and

Carried out by yeasts.


The study of fermentation processes used in:

Bread making

Wine making

Beer production



Important microorganism in the production of
several types of foods


So what are they….

They are fungi

Factors affecting Yeast Function


Extreme pH will kill the yeast


High temperatures (over say 40
C) will kill yeast

Food Science Techniques

Most “technologies” and techniques associated with
Biotechnology and Food Science deal with, or are the
result of, the preservation of food.






Steam Sterilization



Increases the shelf life of many foods indefinitely
with varying impacts on food quality

Will NOT KILL most common bacteria

Only makes them dormant

Most foods should NOT BE REFROZEN after


Treatment of food products with low levels of
ionizing radiation to kill microorganisms in food

Not dangerous for human consumption

Does not alter food quality and taste

Least invasive method of sterilization for many food
products including meats

Dehydration / Salting

These methods remove water from food

Creates an inhospitable environment for

Highly effective for meats and other foods

Changes taste and texture drastically

In ancient history it was the only effective
method storing food


Using a vinegar
based solution to soak foods

Creates an environment where bacteria may not

Drastically alters taste

The environment must be acidic enough to be

Steam Sterilization

Using super heated water to kill surface bacteria

Often used in the processing of meats

Oven / Microwave (Heating)

Physically cooking foods to proper internal
temperatures ensures the destruction of harmful

This is the reason most restaurants will not serve
rare hamburger

Ensuring Safety

Food containers and process are
specifically designed to ensure food safety

The presence of a raised center on the lid of
home canned vegetables or store purchased
foods indicates likely bacterial contamination

Botulism is an example of a toxic bacteria often
occurring in such instances

Abnormal visual growths or smells are
often an indication of the presence of
fungal or bacterial contamination

Many contaminants are not easily

Potential Applications of
Biotechnology in Food Science

Genetic Engineering of Crops and Animals

Simplify Production of Foods


Reasons to use Genetic Engineering

Crops can be engineered to survive harsh
environmental conditions such as:


Poor Soils

Soils with high levels of salts

GE can lead to longer storage life

The removal of genes coding for ethylene production
in fruit would prevent decay (rotting)

GE and Increased Nutrition

Golden Rice is an example of a crop that has
already been developed to contain higher levels
of nutrients

Other crops could be designed to address
nutritional deficiencies by using genes from
microorganisms or animals to produce more
vitamins or other beneficial compounds

GE and Insect Resistance

This could lead to reduced use of pesticides that
leave toxic residues on crops

Bt crops have already led to decreased use and
have decreased overall insect damage

A byproduct of this has been a reduction in the
occurrence of fungal damage during long term crop

Fungal pathogens often occur in the wounds or around
the waste of plant insect pests

GE and Caffeine

An enzyme used in caffeine production in coffee
(synthase) has already been removed and the
gene cloned in research trials in Japan and
Scotland (2000).

Other “harmful” products could be engineered
out of plants and animals

Simplifying Production

The prime example is rennin (used in cheese
production), once collected from the digestive
system of cattle

Rennin (ChyMax) is now produced in unlimited
quantities in GE bacteria, which requires very little
energy, care, or processing

What other applications can you think of related
to simplifying production?

Other Applications?

More efficient yeasts for fermentation