che 526 technology of food preservation - Department of Chemical ...

shamebagΒιοτεχνολογία

22 Φεβ 2013 (πριν από 4 χρόνια και 1 μήνα)

136 εμφανίσεις

CHE 425


TECHNOLOGY OF FOOD
PRESERVATION

Class Hours:

T
1 (KB 4
28
), T
h
1,2 (KB433),


Office:

M 11:30
-
12:30


Book:

Photocopies from different sources.


Grading:

2 midterms 2x30 = 60%


final exam : 40%


attendance bonus : 0.10 x %att.



WHY IS FOOD A DIFFERENT FIELD?


1.
Products

of
food

Industry

are

consumed

(not
used
)
by

human

beings

2.
Foods

are

living

systems



FACTORS OF SPECIAL IMPORTANCE
(competing)!

1.
SAFETY :
Since foods are living systems, biochemical and
microbiological changes take place continuously.


2.
NUTRITIVE VALUE:
Composition; carbohydrate, protein,

fat, vitamin, mineral etc. contents. Changes in these components
during processing, storage and other phases of food chain.


3.
ORGANOLEPTIC PROPERTIES:


*
Flavor (smell and taste)


*

Color


*

Texture (perceived mouth

feel
)

Food Industry

1.
Raw material production and acquisition ( maintenance of

raw material flow at optimum level, quality control)


2.
Processing (maintenance of adequate manufacturing pace,
quality assurance)


3.
Warehouse storage (proper storage conditions, quality
control)


4.
Transport and distribution (maintenance of steady, timely
distribution to consumer centers, quality control)


5.
Market storage and retail (quality control, shelf life)


Industries Supplying to Food Sector


1)
Packaging

: Cans, jars, pouches, plastics, cartons, papers,

wood, metal, laminates, printing houses etc.


2)
Chemical Industries:

Additives such as acidulants, preser
-

vatives, emulsifying agents, enzymes, stabilizers, coloring
materials
.

F
ertilizers, insecticides, sanitizing agents,

pesticides, various other chemical sprays.



3)
Machines, Maintenance and Repair Requirements:

Farming,
harvesting machinery, processing lines, distribution vehicles,

spare parts, lubricants etc.


% contributions to the total national
income of Turkey

Agriculture : 20.5%

Food : 16.6%

Petroleum Industry : 6.0%

Relative expenditures (%) for

various foods

Meats 29.6

Dairy products 18.1

Bakery and cereal products 15.4

Processed fruits and vegetables 10.6

Fresh Vegetables 6.7

Fresh fruits 4.2

Poultry 4.0

Fats and Oils 3.6

Eggs 3.2

Other 4.6

Typical Curricilum in Food
Engineering

1.
Food Chemistry (1 semester, 4 credits):


Basic composition, structure and properties of
foods and the chemistry of changes occuring
during processing and utilization.


1.
Food Analysis (1 semester, 4 credits):


Principles, methods and techniques of quantitative
physical and chemical analyses of foods and food
products, the analyses to be related to the
standards and regulations pertaining to food
processing and quality standards.

3.
Food Microbiology (1 semester 4 credits):


Relationship of habitat to the occurance of
microorganisms in foods; microbial action in relation to
food spoilage and food manufacture; physical, chemical and
biological destruction of microorganisms in foods; methods
for microbiological examination, public health and
sanitation.


3.
Food Engineering (2 or 3 semesters, 8
-
9 credits):


Engineering concepts and unit operations applicable to
food processing. Principles would include mechanics,
transfer and rate processes and process control
instrumentation. Unit operations would include fluid flow,
heat transfer, evaporation, drying, extraction,distillation,
filtration, mixing and material handling.

5.
Food Processing (2 semesters or 8 credits):


General characteristics of food raw materials;
harvesting, assembling and receiving of raw
materials, methods of food preservation; processing
objectives including factors influencing food
acceptability and preferences; packaging; water,
waste disposal and sanitation.


COURSE OUTLINE


A.
BIOLOGICAL, MICROBIOLOGICAL
BA
CKGROUND


1.
INTRODUCTION

( Defining Food Science, Magnitude,

Division and Interdependent Activities of the Food Industry,
Food and Man)

2.
CONSTITUENTS OF FOODS, PROPERTIES AND
SIGNIFICANCE


(
Water,
Carbohydrates, Proteins, Fats,
Other
Constituents)


3.
ENZYMES

4.
NUTRITIVE ASPECTS OF FOOD CONSTITUENTS



( Vitamins, Minerals,
Enzymes,
Other)

5.
FACTORS THAT INFLUENCE MICROBIAL ACTIVITY IN
FOODS

(Moisture, Water Activity, Oxidation
-
Reduction

P
otential,

Temperature, Acidity,

Inhibitors)

6.
TEMPERATURE IN MICROBIAL ACTIVITY IN FOODS

7.
FOOD SPOILAGE






COURSE OUTLINE

B.
PRESERVATION PRINCIPLES AND



OPERATIONS



1.
HEAT PROCESSING

2.
EVAPORATION

3.
DEHYDRATION

4.
CHILLING AND FREEZING

5.
IRRADIATION

6.
FERMENTATION AND PICKLING

7.
PRESERVATION AS SUGAR CONCENTRATES

8.
PRESERVATION WITH CHEMICAL ADDITIVES


9.
EMERGING PRESERVATION TECHNIQUES

Microorganisms (bacteria, yeasts,
moulds, algea, viruses)


Play an important
ecological
role in realizing
geochemical cycles
; convert reduced forms
of carbon, nitrogen and sulfur in dead plants
and animals to oxidized forms required by
plants which in turn are consumed by
animals




Nitrogen

Cycle


Plants have the ability to utilize energy from
sunlight for synthesis of carbohydrates using
CO
2

and H
2
O in the air
;

photosynthesis.




CO
2

+ H
2
O + (sunlight)


(CH
2
O)
n

+ O
2




Organisms consume carbohydrates and convert
them into energy through an enzymatic process
called
respiration.




C
6
H
12
O
6

+ 6O
2



6CO
2

+ 6H
2
O + 673 Kcal



Enzymes (enzyme systems)

Have well defined duties!



Some of them function regularly in daily
biochemical processes



Some of them are programmed to perform
duties in a later phase of the life cycle.

Typical life cycle of living tissues

Development
/
growth

(metabolic,biosynthetic reactions)



Maturation




Ripening



Senescence (catabolic, degradative reactions)



Deterioration

Rate of deterioration (spoilage) is subject
to various environmental influences:


Temperature


Humidity


Light


Composition of atmosphere w.r.t.
CO
2
, O
2
, ethylene and some other
volatiles


Composition of Foods

Composition of foods is
important in:


Spoilage and desirable changes
in foods


Processing


Preservation


Nutritive value


Organoleptic acceptance

Foods are generally water systems


Dissolved
:

water
-
soluble
carbohydrates (mono
-
, disaccharides),
some proteins, fatty acids, mineral
salts, vitamins, pigments, flavor
compounds.


Colloidal state
:
most proteins,
polysaccharides


Emulsion
:
fats

For survival, living entities
need to consume:


Hydrogen, carbon, oxygen, nitrogen,
calcium, phosphorus, sulfur, sodium,
potassium, iron, and some minor
elements

Typical plant and animal tissue
compositions


Constituent

Apple (%)

Meat (%)

Carbohydrates

16.0

2.0

Proteins

0.2

20.0

Fats

0.8

2.0

Ash (minerals)

2.0

2.0

Water

81.0

74.0

Water ( largest constituent of most foods)


Fruits and vegetables : 80
-
95%


Meat : 74%


Cheese : 37%


Cereals : 12
-
20%

Functions of water in living
cells and tissues

1.
It is a continuous matrix which holds the various food
constituents either in dissolved, in colloidal or in
emulsion form.


2.
It is a reactant in the photosynthesis reaction


3.
It is necessary for hydration, dehydration and
hydrolysis reactions.



Functions of water in living
cells and tissues

4.
Solvent properties of water are important for the
existance of chemical reactions, breakdown reactions,
reassimilation processes, ionization of chemical
species.


5.
It serves in the transport of nutrients, metabolites
and spent material into and out of the cells


6.
It takes part in many important biochemical reactions.


7.
It is necessary for the structural integrity of cells.