nutrition - food test
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8/7/2019 Nutrition - Food test
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� The test for the presence of proteins in food
samples is known as theMillons test.
� A red precipitate is formed when protein (such
as egg albumen) is heated together with
Millons reagent.
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Is a diet that contains all classes of food in the right
amount according to our body needs.
A balanced diet contain :
a) Carbohydrates (55% - 65%) and fats (20% - 35%)
to provide energy.
b) Proteins (10% - 15%) for the growth and repair
of damaged tissue.
c) Sufficient vitamins and minerals to maintaingood health.
d) Water and fibre to maintain liquid equilibrium
in the body and encourage peristalsis.
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� Individual who has a bigger body needs more
calories than an individual with a smaller body.
� An individual who is physically activeneeds more calories than an individual
who is inactive.
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� A healthy person requires less energy than a sick person.
� Sick person need to overcome infections, maintain body
temperature and to repair diseased body tissues.
� A person living in a cold country needsmore energy to maintain his body
temperature.
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� Males need more energy than females of the same age
group.
� The metabolic rate of males is higher than that of females.
� Children and adults need more energy
than babies as they are more active.
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What is calorie?It is the amount of energy stored in food.
What is Calorific value or energy
value?It is the amount of energy produced by one gram
of a particular type of food.
SI unit is joules (J) or calories (cal).
1 calories (cal) = 4.2 joules (J)1 kilojoules (kJ) = 1000 joules (J)
1 kilocalories (kcal) = 4200 joules (J)
= 1000 calories (cal)
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Class of food Energy value (kJ /g)
Carbohydrates 17
Proteins 18
Fats 39
Energy values of the main food classes
Food Energy
value
Food Energy
value
Rice 546 Bread and
butter
1400
Rice
Vermicelli
1474 Laksa 800
Chickenrice
2300 Nasi lemak 2500
Curry puff 360 Papaya 164
Energy values of some local food
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Food Calorific value
per 100g (kJ)
Tosei 154
Nasi Lemak 492
Orange juice 202
Meat Dumpling 235
Milk 276
Guava 290
Table 1
Meal A Meal B
100 g t s i 180 g at li g
150 g asi l ak 100 g ilk
200 g ra g j ic 120 g g ava
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Individual
� Newborn baby� Children
� Pregnant women
� Office worker
� Factory worker
Daily energyrequirement
� 2000� 7500
� 10000
� 11000
� 12500
Gender Age
Group
Suggested calorific value of
food for daily consumption
Males 15 ± 18 12 600
19 ± 24 12 180
Females 15 ± 18 9 240
19 ± 24 9 240
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Is necessary for :
a) Supplying the required energy.
b) Balanced body growth.
c) Maintain health of the body.
d) Repair and replace old or damaged tissues.
e) Preventing deficiency diseases such as
scurvy and rickets.
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� The food that we eat will be digested, absorbed into thebloodstream and transported throughout our body.
� Food consists of complex substances ( carbohydrates, protein
and fats)
� These substances are large and complex ;cannot be absorbedby body.
� So all these food need to be digested first before they can be
absorbed by the body.
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� Digestion : process breaking down food
molecules into smaller molecules readily
be absorbed by the body.
� Digestion is carried out by the digestive
system.
� Digestive system consists of :
i. The alimentary canal
ii. The accessory organs
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PHYSICAL DIGESTION
Big pieces of food are broken
down into smaller pieces by teeth.
CHEMICAL DIGESTION
Involves the action of enzymes on
the food.
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� Enzymes : proteins that speed up
the process of digestion.� AMYLASE ± help in the digestion of carbohydrates
� PROTEASES ± help in the digestion
of protein� LIPASE ± help in the digestion of
fats
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Characteristics
Required insmall quantity
only
Specific enzymesact only on specific
foods
Functions bestat body
temperature
Not destroyedat the end of
digestion
Specific enzymesact only in specificacidic or alkaline
conditions.
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� The bolus moves down
the oesophagus.
� The muscular wall of the
oesophagus contracts and
relaxes to produce a
wavelike movement.
� This movement is calledPERISTALSIS.
� Peristalsis pushes the
bolus from oesophagus to
stomach.
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Food is mixed with gastric juices .
Gastric juices contain :
:
a) Providing an acidic medium for the action of enzymes.
b) To kill bacteria that is found in food.
c) To stop the action of amylase enzyme.
Pepsin : Proteins peptones.
Rennin coagulates milk in stomach to help in the enzymic action of pepsin.
Partially digested food is called chyme.
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The first part of the small intestine.
Chyme is mixed with bile and pancreatic juice.
: greenish liquid produced by the liver and stored in the gall bladder.
:
a) Emulsifies fats into smaller oil droplets. Known as emulsification.
b) Does not contain enzyme.
c) Provides an alkaline medium for the action of enzymes.
Pancreatic juice contains amylase, protease and lipase.
Amilase : Starch Maltose
Lipase : Fat Fatty acid + glycerol
Protease : Protein Polipeptida
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Food that is digested in the duodenum enters ileum.
Food is mixed with intestinal juice.
Intestinal juice contains all the enzymes to complete the digestion of
carbohydrates, protein and fats.
Digestion of food ends in the small intestine.
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The end products of digestion are :
Class of food being digested End products
Carbohydrate Glucose
Proteins Amino acids
Fats Fatty acids and glycerol
The summary of the digestive processes in the alimentary canal :
Classes of
food
Part of alimentary canal
Mouth Stomach Duodenum Lower part of small
intestine
Carbohydrates / X / /
Proteins X / / /
Fats X X / /
Fibre X X X X
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The summary of process of chemical digestion in the human
alimentary canal :Part of
alimentary
canal
Rembesan Sifat-sifat
rembesan
Enzim Tindakan pencernaan
Mulut Air liur Beralkali Amilase Kanji ± Maltosa
Perut Jus gaster Berasid Protease Protein ± Pepton
Duodenum Jus
pancreas
Beralkali Lipase Lemak ± asid lemak +gliserol
Amilase Kanji ± maltosa
Protease Protein ± Pepton
Hempedu Beralkali Tiada
enzim
Lemak ± titisan lemak
Bahagian
bawah usus
kecil
Jus usus Beralkali Protease Polipeptida ± asid amino
Lipase Lemak - asid lemak + gliserol
Laktase Laktosa ± galaktosa + glukosa
Maltase Maltosa ± glukosa
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