Food Biotechnology

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20 Φεβ 2013 (πριν από 4 χρόνια και 3 μήνες)

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Food Biotechnology

Food

Food is anything that is eaten or drunk as a
source of nutrients

Nutrients are used for growth, maintenance,
and reproduction

Biotechnology is being used increasingly to
provide food


use of technological innovations in
manipulating food production and processing.

Some forms of biotech have been used for
hundreds of years in food preservation and
production

Food Biotech


Food biotech deals with cellular and
subcellular manipulation of organisms

focus on rDNA techniques in genetic
engineering

study of the substances that humans eat

food makeup

nutritional content

ways of making food more available and
appealing

Food Science

Food Chemistry

study of substances that make up food

cellular structures formed by living organisms
used as food sources

structures consist of chemical elements that
may form proteins, carbohydrates, fats, water
and other nutrients

Nutrient


a nutrient is a substance in food that supports
life processes


Six basic nutrients

Water

Fats/Lipids

Protein

Carbohydrate

Vitamins

Minerals

Water

many foods contain a high percentage of
water

three states of water
-

solid, liquid, gas; have a
big impact on food science

these states are involved in all aspects of food
production, processing and preparation

regulating the amount of water influences the
quality of the food

pH


acidity or alkalinity

Milk
-

pH of 6.2
-
7.3

lemon juice
-

pH of 2.2
-
2.4

pH can be used in preservation to inhibit the
growth of microbes

Food Physics

study of the physical characteristics of food

relationship between food constituents and
heat

The way most foods are affected by heat
involves the water found in the food

attraction of water molecules to themselves
and to other materials creates a kind of
tension in food

This tension relates to other physical
processes that occur in foods

Osmosis
-

flow of water from areas of high
concentration to low concentration

influences the quality of the food

effects of water on food

freezing for preservation

while frozen, water molecules are not
available to microbes that cause decay

removing water prevents decay

focuses on characteristics of living organisms
and their products that are used for food

it includes how food products are kept
wholesome and prepared for consumption

focus on microbiology of foods

microbes that are in or on foods

Food Biology

how organisms can be used to improve foods
or produce other foods as well as how these
organisms cause food to become unfit

quality and availability of food on earth varies

Food from plants provides 80% of the protein
and 88% of the calories in the human diet

Most is provided by 15 species of plants

Foods from animals are less important
worldwide but more important in the US

Food Supply

Consumption

use of food substances

per capita consumption of food in the US

potatoes
-

136#

veggies
-

244#

red meat
-

163#

chicken/turkey
-

61#


eggs
-

30#

fish and shellfish
-

15#

milk
-

dairy products
-

244#

fresh fruit
-

124#

grains
-

189#

Some food products are more nutritionally
adequate than others

income, cultural preference and other factors
determine consumption patterns

Quality

not spoiled

not contaminated

safe to eat


Processing

preparation for consumption

primarily preparing the product to be
purchased by the consumer

canning, freezing, pickling, salting, drying,
irradiating, and refrigerating

purpose is to extend the shelf life of the
product and prevent spoilage

Spoilage

makes food unsafe to eat

spoilage is most obvious as food decays

spoiled foods can cause food poisoning
resulting in disease or death

Botulism is likely the best
-
known poisoning
from food

spoiled food may have a changed appearance
or odor

Spoilage agents

microorganisms
-

grow in or on food

insects
-

burrowing in or eating produce

chemical contamination
-

pesticide residue

purity
-

food products mixing with other food
products, weed seeds, foreign material

undesirable growth
-

sprouting in storge

Storage and
Transportation

Shelf life
-

length of time food can be stored
and be safe to eat

create new products with a longer shelf life

biotech is used to help create conditions that
promote longer shelf life

Genetic engineering
-

used to produce the
Flavr Savr Tomato, released in 1994, longer
shelf life

Food Microbiology


microbes

cause spoilage

cause illness or death if ingested

serve useful roles in fermentation; produce
highly desired food products

Useful Microbes

alter taste, texture, or other characteristics into
forms that are more desirable

Yogurt
-

two species of bacteria are added to
milk to cause coagulation

Lactobacillus bulgaricus

Streptococcus thermophilus

Likely that first occurrence of yogurt was by
accident

some portion of the product was likely saved
as a starter culture for future use

bacteria convert lactose to into lactic acid

acid gives yogurt it’s flavor and curtails growth
of spoilage microbes

yogurt is refrigerated to extend shelf life

cause food to decay and become unfit for
human consumption

if consumed, the food may cause disease or
death

Escherichia Coli
-

E. coli

Most E. coli contamination is from manure
coming into contact with food

Harmful Microbes

food
-
borne illness: disease people contract
from food they eat

food poisoning

symptoms range from mild discomfort to upset
stomach, fever, and in severe cases, death.

May result from improper preparation, storing
or handling

Food
-
borne Illness:

two major types of food
-
borne illnesses

infection and intoxication

infection
-

caused by ingesting a harmful
microbe

intoxication
-

ingesting toxins produced by
microbes

examples of toxins
-

Botulism
-

extremely
dangerous. May affect the nervous system,
cause double vision, make speech and
swallowing difficult, cause respiratory
paralysis, and result in death.

A day or more may be required for the disease
to develop. If caught early, treatment with an
antitoxin is successful.

the alteration of the rate at which chemical
reactions occur

refers to chemical reactions in foods

some changes cause food to deteriorate,
others cause an improvement of quality

ripening fruit is an example. As fruit ripens the
sugar content increases

Catalysis

once the fruit is ripe, decay may occur if
proper storage or preservation methods are
not used.

we can alter the processes that control
changes in foods

this requires the use of catalysts

a catalyst is a chemical that increases or
decreases the rate of change

the rate of natural ripening, decay, and other
changes can be regulated using catalysts.

a catalyst is not used up or changed the the
reaction.

Enzyme
-

protein or substance produced by
living cells

many enzymes are found in foods

comprise a group of proteins that regulate
organism growth and life processes.

Enzymes act as catalysts in chemical changes
that result in foods having desirable or
undesirable qualities

Enzymes in food

enzymes require substrate molecules to work

substrate
-

substance on which a specific
enzyme reacts

substrates are consumed by microbes when
food decays

some enzymes can be used on substrates so
microbes do not readily consume the
substrate
-
this prevents decay

Food Scientists have learned how to control
and promote enzyme activity in most foods

some enzymes cause desirable changes in
foods, some do not

classified by the types of substances they
affect

Lipases
-

lipids

Proteases
-

proteins

Carbohydrases
-

carbs

Changes by enzymes

amylase
-

used to prevent bread from
becoming stale

peroxidase
-

causes un
-
blanched vegetables
to soften


influenced by:

Temperature

pH

presence of other substances

Enzyme activity

warm temperatures tend to increase enzyme
activity while cold or hot temperatures may
stop enzyme activity.

optimum temperature
-

point where enzyme
activity is at its maximum

generally enzyme activity is doubled for every
50
°

F until the point is reached where enzyme
activity stops

In processing fresh vegetables blanching is
used before freezing to inactivate enzymes

Fresh fruit is refrigerated to prevent browning
and rot that would result from enzyme activity
at room temperature