freezing of okra
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Transcript of freezing of okra
FREEZING OF OKRA
اشراف الدكتور سليمان اللوصي
سائد محمود زبيدات محمد ناصر زبيدات
الزبيدات بامية اخوان
OUTLINE
1. Food
2. Food preservation
3. Freezing
4. Okra
5. Food deterioration
6. Blanching
7. Frying
8. Experimental Work
9. Discussion
10. Conclusion
Known food, where
every item has a taste
acceptable and easily
chewed & digested, and
absorbed in the blood, in
order to obtain a
balanced food and a
good nutritional value.
FOOD PRESERVATION
Methods of food preservation
Acidification
Drying
Canning
Freezing
FREEZING
A food preservation method used for increasing
the shelf-life of the product, by decreasing the
temperature and stop the microbial growth.
Some unit operations are applied before
freezing.
Our project is talking about freezing of Okra
and the study of the morphology of Okra.
FREEZING
Two methods of freezing are known: slow
freezing & rapid freezing
Rapid freezing
1. Small ice crystals
2. Both extra and ultra cellular ice crystals
3. Better quality
4. Produce freezing burn less than slow freezing
FREEZING
Slow freezing
1- Large ice crystals are formed
2- Ice crystal formation in extra cellular formation
3- low quality of product
4- Freezing burn occurs
EXAMPLE OF FREEZING VEGETABLE
Broccoli
Cabbage
Cucumber
Potatoes
Okra
TYPE OF OKRA
OKRA
Okra in French (Gombo) (lady’s finger) is a plant floral eaten off the green.
Scientific name: Abelmoschus esculentus, kind annual or with grown in one season
Plant height up to 2 meters and more. Securities petition reaches a length between 10 to 20 cm.
Okra have a high nutritional value and health benefits
OKRA PRODUCTION
Okra is produced in many warm-weather countries e.g. India, Pakistan, Turkey, Iran, Nigeria, Ghana, Greece, and southern USA,and is considered one of the most important vegetables in Egypt, because of its nutritional content and medicinal potentials against inflammation.
It is one of the major products concerning al-Zubeidat Company.
MICROBIAL ACTIVITY & ENZYMATIC BROWNING
1. Microbial activity: Microorganisms, such as
bacteria, yeast & mold are omnipresent and
may have good or bad effect on our food.
2. Enzymatic browning : Fruits and vegetables
contain enzymes, which accelerate damage of
its tissue and loss of texture and color.
ENZYMATIC BROWNING
Enzymatic browning is a biochemical process in
which plant (fruit or vegetable) tissues take on
a brown color when exposed to oxygen.
Other types of browning in foods include
Maillard browning (proteins and sugars at high
temperatures), carmelization (sugars at high
temperatures).
ENZYMATIC BROWNING
Enzymatic browning occurs when plant tissue is
exposed to air resulting in a brown colored
pigment, being produced as a result of a series
of biochemical reactions. Phenolases which are
enzymes found outside the cell wall come in
contact with colorless phenols which are found
inside the cell causing the brown color to
appear.
HOW TO PREVENT ENZYMATIC OXIDATION
The polyphenol oxidase enzyme can be
inactivated by:
1. certain organic acids; such as ascorbic acid
and citric acid that are commonly used in food
industry to prevent browning of fruits and
vegetables.
2. Heat treatment such as blanching.
BLANCHING
Blanching is the exposure of the vegetables to boiling water or steam for a brief period of time to inactivate enzymes. Practically every vegetable needs to be blanched and promptly cooled prior to freezing, since heating slows or stops the enzyme action.
Enzymes can cause loss in quality, flavor, color, texture, and nutrients. If vegetables are not heated sufficiently, the enzymes will continue to be active during frozen storage
BLANCHING
Blanching may be done by using:
Hot water….. at a temperature of 85°C/4 min.
Steam …..at a temperature of 100°C/6 min.
EFFICIENCY OF BLANCHING AND HOW IS DETERMINED?
After freezing is finished some test use to
determine efficiency of blanching this test :
1.Catalase
2. Peroxidase
3. Sensorial properties.
PEROXIDES TEST& CATALASE TEST :
If color changes, it means the presence of enzyme.
Peroxidase test
Pink color colorless
+ve -ve
Inefficient efficient
Catalase test
Formation of gas bubbles is an indicator of
enzyme activity.
FRYING
Main Purpose of frying: altering of organoleptic
quality (color, flavor & texture…)
Secondary purpose
1. Inactivation of enzymes and microorganisms
2. Reduce moisture content.
FLOWCHART OF FREEZING
Preparation Cleaning/washing ,cutting, slicing,
dicing)
Blanching Frying at 145ºC for 4min Hot water
at 85ºC for
4 min
Steam at
120ºC
for 4min
Draining
Vacuum packaging
Freezing at
-18ºC
PREPARATION
BLANCHING 85C/4MIN &COOLING
DRAINING
PACKAGING
Proper packaging of frozen food is important to
protect the product from contamination and
damage while in transit from the manufacturer
to the consumer, as well as to preserve food
value, flavor, color, and texture. There are
several factors considered in designing a
suitable package for a frozen food
POLYETHYLENE
Polyethylene bags have a variety of uses. They are flexible, transparent and have a perfect resistance to low temperatures and impermeability to water vapor. An important advantage is that these bags can be easily heat-sealed. Utilization is in forms of sheets and bags.
VACUUM PACKAGING
STEAMING 100C/6MIN
FRYING 145C/4 MIN DEEP
VACUUM PACKAGING
PREPARATION OF SOLUTION
Sensorial test PeroxidaseCatalase
Texture Color
SoftGoodNo color changeAbsence of gasHot water
GoodGoodNo color changeAbsence of gasSteam
Very softGoodNo color changeAbsence of gasPartial Frying
RESULT
RESULT
DISCUSSION
The best way to inactivate enzymes is by blanching (hot water).
Mucilage is suitable for medicinal and industrial applications. It has been used medically.
The pods must be removed by cutting to prevent browning.
In steam, the pods must be mixed to allow the steam to reach all parts of okra evenly.
CONCLUSION
Our experimental part was conducted very late
because okra was unavailable.
After blanching, mucilage still appears but by
frying mucilage is lost.
We choose the study of Okra and one of its
preservation methods, because it is one of the
most important products at al-Zubeidat Co.
Palestine investment fund promised our Company
to fund a project of freezing of vegetables.