Biotechnology in Food Science

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22 Οκτ 2013 (πριν από 3 χρόνια και 11 μήνες)

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Biotechnology in Food Science

Biotechnology 2

Common Food Bourne Pathogens

Bacteria

Salmonella enteriditus

Campylobacter jejuni

Many, many others

Fungi

Some are used in food production

Other are contaminants or even toxic

Salmonella

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

Campylobacter

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
-
contamination

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
-
making
process


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
°
C
-

60
°
C

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

Enzymes

Fermentation

Yeasts


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


Intolerant

The live active cultures create
lactase
, the enzyme
lactose
-
intolerant people lack, and another enzyme
contained in some yogurts (beta
-
galactosidase) also
helps improve lactose absorption in lactase
-
deficient
persons. Bacterial enzymes created by the culturing
process, partially digest the milk protein
casein
, 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.

Enzymes

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


Fermentation

Or as Homer Simpson says
-

“Hmmm….Beer”

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
Ethanol

Carried out by yeasts.

Zymology

The study of fermentation processes used in:

Bread making

Wine making

Beer production

Etc


Yeast


Important microorganism in the production of
several types of foods

Yeast are NOT BACTERIA

So what are they….

They are fungi


Factors affecting Yeast Function

pH

Extreme pH will kill the yeast

Temperature

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.

Fermentation

Pickling

Dehydration

Freezing

Irradiation

Steam Sterilization

Heating

Freezing


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
thawing

Irradiation

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
products

Creates an inhospitable environment for
microorganisms

Highly effective for meats and other foods

Changes taste and texture drastically

In ancient history it was the only effective
method storing food

Pickling

Using a vinegar
-
based solution to soak foods

Creates an environment where bacteria may not
survive

Drastically alters taste

The environment must be acidic enough to be
effective


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
bacteria

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
recognizable

Potential Applications of
Biotechnology in Food Science

Genetic Engineering of Crops and Animals

Simplify Production of Foods

Others

Reasons to use Genetic Engineering

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

Drought

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
storage


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

??????