Food & Technology
FRUITS
Origin
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A fruit is the edible part of a plant that
contains a seed or the matured ovary of a
flower.
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Fruits are defined botanically as “the
matured ovaries of flowers”
Structure
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Fruits have 3 sections – the skin, the
flesh and the seeds.
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Fruit comes in a wide variety of colours, textures and
flavours and are generally sweet in taste.
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Colour – due to various pigments.
Green is due to chlorophyll
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Orange & Yellow are due to carotenoids
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Red & Blue due to anthocyanins
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The Process of photosynthesis
The green pigment in plants
(called chlorophyll) uses carbon
dioxide in the atmosphere, energy
from sunlight and water to
produce carbohydrates for energy
for growth. The carbohydrate is
stored in the fruits we eat.
Pectin
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This is a complex polysaccharide found in the cell
walls of many fruits.
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It forms a gel with sugar in acid conditions and is
responsible for the setting of jams. It can be
purchased commercially as Jamsetta or in Jam
setting sugar.
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Find images of jam, Jamsetta & jam setting sugar
Flavour
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Different flavours in fruits are due to complex mixtures of naturally occurring
chemicals.
They range from the subtle, slightly ‘perfumed’ flavour of a mango to the
strong citrus flavour of a lemon.
The acids each fruit contains determines the flavour.
Citric acid – oranges, lemons, grapefruit, limes
Malic acid - apples, pears, peaches, apricots
Oxalic acid - pineapples
Tartaric acid – grapes
Sweetness - is due to the sugars fruits contain. Fruit sugar is called
fructose and is a simple carbohydrate so provides quick, short bursts of
energy.
Texture - formed from a combination of different properties – the plant cell
shape and size, the amount of water in the fruit cells and the amount of
cellulose (fibre and starch) in the cells.
Nutrient content of fruit
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Fresh fruit is manly composed of water and carbohydrates.
Many are low in kilojoules.
The carbohydrate in ripe fruits is in the form of sugar such
as sucrose, fructose & glucose
Some carbohydrate is also present in the form of cellulose,
a polysaccharide. This is not easily digested and forms
dietary fibre.
Fruit is a valuable source of vitamins and the main source of
vitamin C
Vitamin A, in the form of carotene, is present in yellow and
orange fruits.
 Some fruits contain small amounts of minerals, such as
phosphorus, potassium and calcium.
When fruits ripen:
Pigments underneath and in the skin of fruit break
down, causing a colour change. An example is
where apples change colour.
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The edible pulp surrounding the seed becomes soft
and tender as the water content increases.
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The starch present converts to sugar, causing the
flavour to become sweeter
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A fuller and more distinctive aroma develops on
ripening
Classification of fruits
Fruits are grouped together in families according to how they grow & the physical properties of the fruit.
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POME FRUIT
Examples - Apple, pear, quince
 PROPERTIES
Physical - compartmented core that contains seeds. Core
surrounded by crisp, juicy flesh. Have an indentation in the core
end of the fruit.
Chemical - Acids present – citric and malic.
Apples are a good source of fibre & vitamin C
Sensory – Apples – firm, crisp texture, sweet flavour
Pears - soft, tender flesh, sweet flavour
Storage - store apples in the refrigerator to keep them crisp.
Keep them away from green vegetables which are sensitive to a
natural gas (ethylene) given off by the apples.
Classification of fruits
CITRUS FRUITS
Examples – oranges, grapefruit, lemons, cumquats, limes, mandarins
PROPERTIES
Physical – Firm, thick, lightly dimpled skin present in most varieties. Colours
range from green (limes) to orange (mandarin, orange) and yellow (grapefruit,
lemon. Internally, made up of juicy flesh that separates into membrane covered
segments.
Chemical - good source of vitamins (particularly Vit C) as well as minerals &
dietary fibre. Citric acid present.
Sensory – flavour can range from acidic to tangy and reasonably sweet,
depending on type of fruit.
Storage – Store at room temperature for about 5 days when the weather is cool to
mild but best to refrigerate in hot weather for extended storage time.
Classification of fruits
BERRIES
Examples – strawberries, raspberries, loganberries, blackberries
PROPERTIES
Physical – Some (eg raspberries) are clusters of a number of small fruits, each
tiny segment is a dupe or juice filled sac. With strawberries, what appear to be
seeds on the surface are actually individual fruits (achenes) containing a single
seed. Blueberries and cranberries are single fruits formed from the plant’s
ovaries.
Chemical - Berries are good sources of Vitamin C, potassium, iron and fibre.
Sensory – . Most have firm flesh and a sweet to slightly tart taste. Their flavour
is best when served at room temperature.
Storage – Store in the refrigerator , but wash them just before eating.
Classification of fruits
VINE FRUITS
Examples – Grapes, passionfruit, kiwi fruit
PROPERTIES - GRAPES
Physical – small, oval shaped fruit, most containing a seed. Colour ranges from green to
pale yellow and purple.
Chemical - Provide fibre, Vitamin C sugar, potassium & iron.
Sensory – sweet flavour. Texture is smooth, often crisp outer skin, smooth inside.
Storage – need to be stored in the refrigerator
PROPERTIES – PASSIONFRUIT
Physical – round or oval in shape, outer skin is leathery purple-brownish colour and
wrinkles when fruit is completely ripe. Inside contains translucent orange pulp and small
black seeds.
Chemical - contains Vitamins A & C, also a good source of fibre
Sensory – fragrant aroma, sour-sweet flavour
Storage – store at room temperature
Classification of fruits
STONE FRUIT Examples - peaches, nectarines, apricots, cherries, plums
PROPERTIES
Physical – round shaped fruit, size varies depending on type. All have juicy,
soft flesh surrounding a stone that contains a seed. Some (such as cherries,
nectarines & plums) have smooth skin while peaches and apricots have a
‘downy’ velvety skin. Colours range from red or blue to yellow or orange
depending on type.
Chemical - yellow types rich in Vitamin A and often C (eg. apricots)
Sensory – juicy flesh is generally sweet, plums are more acidic in flavour.
Flavour is best when served at room temperature.
Storage – place in the refrigerator for three to five days.
Classification of fruits
MELONS
Examples - cantaloupe, honeydew, watermelon
PROPERTIES
Physical - oval or ball shaped, all have a firm outer shell. Flesh comes in a
range of colours, depending on the type. Watermelon has a bright pink flesh
with medium black oval shaped seeds scattered throughout (unless a seedless
variety) cantaloupe has many small, pale coloured contained in the centre
surrounded by the orange flesh.
Chemical - cantaloupe are a good source of vitamin A, watermelon is low in
kilojoules and an excellent source of Vitamin C
Sensory – Flesh of most are firm and juicy. Sweet flavour. Subtle sweet aroma.
Storage – Can store at room temperature for several days.
Securely cover cantaloupe if placed in the fridge so the aroma doesn’t
contaminate other foods.
Classification of fruits
TROPICAL FRUITS
Examples – bananas, pineapples, mangoes,
PROPERTIES
Physical – vary greatly in shape, size & colour.
Chemical – Bananas – high starch content before they are ripe, after ripening
they are high sugar content. They are also a good source of potassium,
mangoes - rich in vitamins, particularly A & C
Sensory - most are aromatic, mangoes have a soft, almost buttery texture.
Sweet flavour and a distinctive perfume.
Storage- bananas best stored at room temperature. Pineapple are best eaten
soon after purchase and covered if they are put in the fridge due to their strong
flavour.
Selecting Fruit
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Select fruit that is in season
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It will be likely to be fresher, cheaper, have the best flavour and
have better nutrition content.
Chose fruit that is plump and quite heavy for its
size.
Avoid fruit that is damaged, bruised or wrinkled.
Buy only the quantity you will use within a few
days, as overripe fruit deteriorates very quickly.
If you are buying fruit in punnets, check the
condition of the ones at the bottom.
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Buy the best quality fruit you can afford.
Storage of Fruit
Store fruit in a cool, dry area with
adequate ventilation
 Refrigerator crisper is ideal
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 Fruit
will not continue to ripen in fridge. Therefore
make sure it is ripe when you put it in the fridge.
 Berries will deteriorate quickly. Purchase just
before use.
 Banana skins may discolour, but the flesh inside
will be consumable.
Functional properties of fruit
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Colour – fruit adds contrast to dishes and when used as a garnish
due to the variety of colours available.
Gelling properties - many fruits such as apples, quinces & citrus
fruits have a high pectin content which forms a gel when in the
presence of sugar and acid.
Texture - fruits provide a variety of textures depending on the
fruits used. This adds contrast to dishes like fruit salad.
Filling- fruits add bulk to the fillings of pies such as apple, apricot
or berries.
Flavour, sweetener- Apple is often combined with tart fruits to
give sweetness, or to fruit juice. It can also be used to replace cane
sugar in recipes like muffins.
Variety – because fruits come in a variety of flavours, textures and
colours, they add variety and interest to dishes and menus.
When fruits are cooked:
During cooking, the cell walls of the fruit become tender as water passes
through the cell membranes, causing the cell walls to swell and burst. As a
result, the fruit loses its shape and the pulp becomes soft
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If sugar is added when cooking, it strengthens the structure of the fruit and
helps to retain the shape.
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Applying heat causes some pigment changes and some loss of colour occurs
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Changes in flavour occur as the naturally occurring sugars in the fruit begin
to caramelise.
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The nutrient content is affected – for instance, vitamin C is lost due to its
sensitivity to heat and exposure to oxygen.
Origin (plant or animal)
Structure (images as well are really useful!)
Classification
Consideration s in food selection, including food quality and ethical
issues such as fair trade and intensive farming practices
Physical properties
Chemical properties
Sensory properties
Functional properties and their role in food preparation and
processing
Changes in the physical and sensory properties during preparation
and processing