FST 403:FRIUTS AND VEGETABLE TECHNOLOGY FIRST SEMESTER:

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FST 403:FRIUTS AND
VEGETABLE
TECHNOLOGY
FIRST SEMESTER:
20111/2012
Lecturer: Prof. F.O.Henshaw
E-mail:[email protected]
:[email protected]
Mobile phone: +234 8034056311
COURSE OBJECTIVES
• FST 403: A compulsory core course for the B.Sc
Food Science and Technology programme
• At the end of the course students should have:
– Acquired an understanding of the nature and properties
of the food commodity class, Fruits and vegetables
– Acquired an understanding of the post harvest
physiological changes in fruits and vegetables
– Been exposed to various processing and preservation
technologies appropriate for fruit and vegetables
– Acquired the required skills in post harvest handling and
storage of different fruits and vegetables
– Developed critical thinking in relating post harvest
handling to quality of fresh and processed fruits and
vegetable products
COURSE OUTLINE
1
2
3
4
5
6
Classification of Fruits and Vegetable
Structure of Fruits and Vegetables
Chemical Composition
Post harvest Physiology
Storage of fresh fruits and vegetable
*Controlled Atmosphere
*Modified Atmosphere
Pretreatment methods: Blanching,sulphiting
7
8
Preservation Technologies
Freezing
Canning
Dehydration
sun drying
mechanical drying
Osmo dehydration
Fruit and Vegetable Products
Fruit juice and Drinks
Fruit leather
9 Sugar Preserves
jam, jellies and marmalade
10 Fermented vegetables
Pickles,
COURSE
REQUIREMENTS
• 75% attendance of Lectures
condition to qualify to seat for final
examination.
Distribution of course grade
Take home assignment
10%
In Class Quiz
20%
Final Examination
70%
CLASSIFICATION
• FRUITS: Botanically, are mature
ovaries and seed bearing parts of
plants
• Include: grains, legumes, nuts
Cucumbers, olives , mangoes,
peppers, tomatoes, citrus, bananas
grapes, strawberry, pineapple,
• The course however does not include
fruits of the grass family such as
Cereals, nor the Legumes and nuts
• The succulent, high moisture and
generally sweet fruits and consumed
raw as dessert rather than main
meals.
• Vegetables: are all other parts of
plant which are edible
• Include; roots, stems, tubers , leaves
etc
• These are generally consumed,
processed in one form or the other
and part of main meal.
• This course does not include the
starchy roots and tubers
• This class of commodity (Fruits and
Vegetable) have the following
characteristics:
high moisture content
highly perishable
• Post harvest changes in Fruits and
vegetable can be desirable e.g
Ripening of fruits, which leads to
changes necessary for optimum
eating quality, colour change, taste
and flavour development
Structure of Fruits and
vegetables
• Fruits and Vegetables are made of
Simple and Complex cells
– Simple cells
• Dermal tissue
• Parenchyma tissue
Dermal tissue is the single layer outside
surface of leaves, stem, roots, etc
• Parenchyma tissue form majority of
the plant tissue and is where the
basic molecular activity take place:
• Synthesis
– Storage of carbohydrate
(Photosynthesis) occur.
Chemical composition
•
•
•
•
•
•
•
•
Water
Carbohydrates
Organic acid
Fiber
Pigments
Vitamins
Minerals
Pectic substances
Food
Cereals
wheat flour, white
rice, milled, white
maize, whole grain
Earth vegetables
potatoes, white
sweet potatoes
Vegetables
carrots
radishes
asparagus
beans, snap, green
peas, fresh
lettuce
Fruit
banana
orange
apple
strawberries
Carbohy Protein
drate
Fat
Ash
Water
73.9
78.9
72.9
10.5
6.7
9.5
1.9
0.7
4.3
1.7
0.7
1.3
12
13
12
18.9
27.3
2.0
1.3
0.1
0.4
1.0
1.0
78
70
9.1
4.2
4.1
7.6
17.0
2.8
1.1
1.1
2.1
2.4
6.7
1.3
0.2
0.1
0.2
0.2
0.4
0.2
1.0
0.9
0.7
0.7
0.9
0.9
88.6
93.7
92.9
89.1
75.0
94.8
24.0
11.3
15.0
8.3
1.3
0.9
0.3
0.8
0.4
0.2
0.4
0.5
0.8
0.5
0.3
0.5
73.5
87.1
84.0
• Phytochemicals: non nutrient plant
chemicals
• Beneficial in disease prevention
• Subject of Scientific research on
effects on human health
Structure of
chlorophyll
• Chlorophyll –green pigment in plant found
in the chloroplast, it is responsible for
photosynthesis
• Fat soluble
• Structurally a porphyrin ring containing
magnesium at the center
• Displacement of magnesium from the
center leads to irreversible pigment
change
• Change to a gray-green called pheophytin
• conversion to pheophytin is favoured by
acid Phbut does not occur easily under
alkaline condition
• Other factors that can cause colour
change;
– Heat of cooking
– Change in pH
– Minerals ( zinc and copper)
Carotenoids
– Red, orange, and yellow pigments in fruits and
vegetables
– Occur in chloroplast along with
chlorophyll,where the chlorophyll dominates
– Also in chromoplasts without chlorophyll
• Carotenoids are responsible or the colour
of tomatoes, peppers, citrus , carrots.
• E.g beta –carotene- orange colour,
structurally an unsaturated hydrocarbon,
the conjugated double bonds are
responsible for the colour
• Beta-carotene is a precursor of vitamin A
(retinol), cleaved by enzyme in the
intestinal mucosa to yeild vitamin A
• Lycopene- red-orange colour of tomatoes
and water melon,
• Xanthophylls: yellow orange colour
• Derivatives of carotene
• Reponsible for colour of yellow maize
(cryptoxanthin)
• Are vitamin A precursor
• Carotenoids are fairly stable , resistant to
to heat, pH changes, water leaching since
they are fat soluble
carotenoids may undergo autoxidation due
to large nos of double bonds
• Can lead to off-flavour
• Antioxidants are usually applied to prevent
oxidative changes
Structure of carotenoids
• Flavonoids:- group of compounds,
pigments and colour precursors
– Water soluble
– E.g; Anthocyanins: red, blue-red, purple
pigments such as in blueberries,
cherries, raspberries, plums and grapes
– structrally
Structure of
Anthocyanin
Structure of e.gs of
Anthoxanthin
Harvesting, handling and
Postharvest changes
• Different harvest regimes for Fruits and
vegetables
• Appropriate maturity stage required for
optimum quality
• Respiration continue after harvest i.e
taking in O2 and giving off CO2, heat and
moisture
• mechanical damage during harvesting
hastens respiration rate and spoilage
• Ripening: major
post harvest
change in fruits
• Ripening pattern
vary , 2 categories
– Climacteric ripen
after harvest
– Non Climacteric
ripen before
harvest
Climacteric NonClimacteric
Apples
Banana
Mango
Peach
Plum
Pawpaw
avocado
Citrus
Cherry
Pineapple
melon
strawberry
• Ripening involves biochemical changes
• Enzymic, hormonal
• Leading to colour changes, flavour
development and optimum eating
quality
• Storage of fresh produce must seek
to control post harvest changes
• Controlled storage conditions ca
extend the shelf life of produce
– Modified atmosphere packaging:
Principle is to replace the internal
atmosphere of fresh produce by
flushing with nitrogen or carbon dioxide
and this will lead to extension of shelf
life
• After flushing the material is sealed
in a package to prevent oxygen entry
• Normal air composition (78%,
Nitrogen; 20% oxygen and 0.03%
carbon dioxide) is modififed within
the package to:
– Reduces respiration
– Retards growth of aerobic organisms
• Controlled atmosphere storage:
• Principle is similar to MA storage
involve modification of the gas
composition. Reducing oxygen and
increasing carbon dioxide in the
store
• Combined with low temperature.
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