Food
quality:
Quality of foods and
food products may be defined as the degree of excellence and includes such
things as taste , appearance and nutritional content, evaluation of food
quality for consumer acceptance is based on the use of sensory organs or by the
use of appropriate instruments,
Sensory
evaluation of food quality:
Sensory evaluation of
foods may be carried out by human operators or by automated instruments.
Sensory evaluation includes three factors
1.
Appearance
2.
Texture
3.
Flavors
Appearance
factors include such things as size, shape, different forms
of damage, color, transparency and consistency.
Textural
factors include various physical factors such as softness,
hardness, firmness, juiciness felt by the consumer when consumer handled the food with fingers (hand
feel) or with the tongue, teeth (mouth feel)
Flavor
factors depends the sense of smell as well as the sense of
taste as experience by a consumer. Flavor characteristics may be evaluated by
instrumented methods as well by panels
of judge.
Quality
factor for consumer safety:
1.
Nutritional quality
2.
Sanitary quality
3.
Keeping (storage) quality
Nutritional
quality: Evaluated by specific analysis such as protein, vitamins,
minerals and other nutrients. Chemical instrumental methods are used for
evaluating the nutritional quality.
Sanitary
quality: Evaluation of sanitary quality of food is based on
determining the microbial load. Reduction of microbial load and prevention of
recontamination right from the raw material stage through various processing
steps to the final product is absolutely essential.
Two newer concepts in
product quality and safety have been developed and widely adopted in recent
years. Total quality management (TQM) and Hazard analysis and critical control
point (HACCP)
TQM is a management
system which strives to continuously improve the quality of products by making
small but incremental changes in a product ingredient, manufacture, storage
which result in overall improvement.
HACCP is applied in
food-chain from primary producer to final consumer. HACCP is a preventive food
safety system in which a process for manufacturing, storing and distribution a
food product is carefully analyzed step-by-step. Points at which light control
of the process will result in elimination of a potential hazard are identified
and appropriate control measure taken before a problem occurs.
Keeping
quality of foods:
The storage stability
or keeping quality of foods may be determined by accelerated tests simulating
the conditions under which the product is expected to be handled and stored
before it reaches the consumers.
Beverage
Beverage are consumed
for their food value, (e.g. milk) thirst quenching and stimulating effects or
simply because consumption is pleasurable and drinks are considerable
healthful.
Three groups of
beverage are commonly consumed.
1.
Carbonated non-alcoholic beverage or
soft drink
2.
Non-carbonated non-alcoholic stimulating
beverage such as coffee and tea, cocoa
3.
Alcoholic beverage-wine, beer
Carbonated
non-alcoholic beverage are generally sweetened, flavored,
acidified, colored, artificially carbonated and sometimes chemically preserved.
The carbonated beverage may contain artificial flavor or natural fruit juice.
The major ingredients
of carbonated soft drink beverages in addition to water and carbon dioxide are
sugar, flavorings, colors and acids; water constitutes the largest component to
the extent of 92-93%. It must be free from suspended matter, coloring matter
and minerals which may interfere with the flavor and color of the soft drink.
Sucrose is the most commonly used sweetener. Sodium benzoate is the most
commonly used preservative. Pure carbon dioxide gas enhances the flavor and
extends the life of the drink.
Carbonated soft drinks
are packaged in glass or polyethylene terephthalate (PET) bottles or cans.
Stimulated
beverage:
Both coffee and tea
have no food value but are consumed entirely for their refreshing and
stimulating beverage characteristics due to the presence of caffeine to the
extent of about 1% in coffee and about 4% in tea.
Tea:
Tea is the beverage
made when the processed leaves of the tea plants are infused with boiling
water. Its leaves contain the chemicals caffeine and tannin.
Types of tea include
fermented (black), unfermented (green) and partially fermented (oolong)
Processing:
1.
Leaves are hand plucked by experience
worker. Only the smallest, youngest
leaves are used to produce tea.
2.
Harvested leaves are spread on withering
racks to dry
3.
Leaves become soft and pliable and are
then roller crushed to break the cell walls and release the enzyme. This
process gives the tea its flavors. After rolling the lumps of tea are broken
and spread in a fermentation room to oxidize, which turns the leaves to a
copper color.
4.
The leaves are finally hot air dried in
a process that stops fermentation and turns the leaves black
5.
After the tea is processed, it is sieved
to produce tea leaves of a uniform size
Steps:
Withering, rolling,
fermentation, drying, grading and packing
1.
Leaves are hand plucked by experience workers.
Only the smallest, youngest leaves are used to produce tea.
2.
Harvested leaves are spread thin and
withered in trays or drying racks in drying rooms. During this withering step
which lasts over 4 to 18 hr. partial drying of leaves occurs reducing the
moisture content of the fresh leaves from about 75% to about 60-65%
3.
The leaves become soft and pliable and
are then roller crushed to break the cell walls and release the enzyme. After
rolling the leaves are spread out thinly in layers of 5-7cm thick and fermentation
occurs over about 1-4 hours at 35-40oC. During fermentation the enzymes,
particularly polyphenol oxidase, resulting in a change of color from green to a
copper color.
4.
Heating the fermented leaves in over at
85-95oC for about 20 minutes stop the fermentation process.
5.
The dried tea is cleaned and graded into
various commercial varieties according to the quality.
6.
Tea is generally blended and packed into
aluminum foil lined wooden boxes or paper cartons of smaller sizes.
Green
tea is made similar to the black tea without involving the withering and
fermentation steps. Green tea is a light yellow-green.
Oolong
tea
is an intermediate between black and green tea in color and taste, and is
obtained by partial withering and light fermentation steps before drying the
leaf.
Coffee:
Coffee beans or
cherries come from a small tree of the genus coffee. Three species of coffee
are of commercial importance, coffea Arabica best quality, coffea robusta and
coffea liberiaca lower quality. Ripe fruits are referred to as cherries.
The steps involved
include:
I.
Coffee processing
II.
Roasting
III.
Grinding
IV.
Brewing the decoction
The processing steps
involves removal of the skin, pulp around the beans removed. Two methods used
dry and wet method. In the dry method of curing, the cherries are hulled and
air-dried in the sun on artificially. In the wet or washed-coffee method, the
cherries after removal of the outer skin are soaked in water and passed through
pulping machines to separate the pulp from the rest of the bean. The dry and
wet methods of preparation produce distinctive flavors in the beans.
Roasting:
During roasting the
characteristics flavor of coffee is developed. Both and continuous-roasting
equipment is available. Roasting is typically carried out at about 260oC
for about 5 minutes when the bean temperature reaches about 200o.
Grinding:
The roasted beans are
cooled and ground to a size depending upon its intended end use such as home brewing,
vacuum extraction, percolator or vending machine.
Brewing:
Freshly ground coffee
is contacted with hot water in suitable vessels to extract the soluble caffeine
and flavoring materials. Brewing coffee to the correct strength and flavor
depends on several variables. These include the ratio of coffee to water,
particle size of the ground coffee, temperature of the water, mixing action in
the brewer and time.
Cocoa:
Cocoa is consumed as a
suspension in water and in large amounts to get the stimulating effect in
contrast to a clear extract as in the case of coffee and tea. The primary
stimulants in cocoa products are the alkaloids, particularly the bromine. Cocoa
products provide nutrients such as carbohydrates, fats and proteins
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