INDEX
Aim of the project
Introduction
Experiment
1.Effect of temperature
2.Effect of concentra on
3.Effect of me
Conclusion
Bibliography
AIM OF THE PROJECT
To study the effect of potassium bisulphite as
a food preserva ve under various condi ons
[temperature, concentra on and me.]
INTRODUCTION
Growth of microorganisms in a food material can
be inhibited by adding certain chemical
substances. However, the chemical substances
should not be harmful to the human beings.
Such chemical substances which are added to
food materials to prevent their spoilage are
known as chemical preserva ves.
In our country, two chemical preserva ves which
are permi ed for use are:
1. Benzoic acid (or sodium benzoate)
2. Sulphur dioxide (or potassium bisulphite)
Benzoic acid or its sodium salt, sodium benzoate
is commonly used for the preserva on of food
materials. For the preserva on of fruits, fruit
juices, squashes and jams sodium benzoate is
used as preserva ve because it is soluble in water
and hence easily mixes with the food product.
Potassium hydrogen sulphite or potassium
bisulphite is a chemical compound with the
chemical formula KHSO3. It is used during the
produc on of alcoholic beverages as a sterilising
agent.
It is made by the reac on of sulphur dioxide and
potassium carbonate. The sulphur dioxide is
passed through a solu on of the potassium
carbonate un l no more carbon dioxide is given
off. The solu on is concentrated and then allowed
to crystallize.
Potassium bisulphite is used for the preserva on
of colourless food materials such as fruit juices,
squashes, apples and raw mango chutney. This is
not used for preserving coloured food materials
because Sulphur dioxide produced from this
chemical is a bleaching powder.
Potassium bisulphite on reac on with acid of the
juice liberates Sulphur dioxide which is very
effec ve in killing the harmful micro-organisms
present in food and thus prevents it from ge ng
spoiled.
HSO3-(aq) + H+(aq) ------------> H2O (l) +SO2(g)
The advantage of this method is that no harmful
chemical is le in the food. The aim of this project
is to study the effect of potassium bisulphite as
food preserva ve.
i. At different temperatures.
ii. At different concentra ons
iii. For different intervals of me.
EXPERIMENT
TO STUDY THE EFFECT OF POTASSIUM
BISULPHITE AS A FOOD PRESERVATIVE UNDER
VARIOUS CONDITIONS.
EXPERIMENT
AIM: To study the effect of potassium bisulphite
as a food preserva ve under various condi ons
(temperature, concentra on and me.)
APPARATUS: Beaker, pestle and mortar, glass
bo les, balance and peeler.
CHEMICALS: Fresh fruits, potassium bisulphite,
and sugar.
THEORY: Food materials undergo natural changes
due to temperature, me and enzyma c ac on
and become unfit for consump on. These changes
may be checked by adding small amounts of
potassium bisulphite. The effec veness of KHSO3
as preserva ve depends upon its concentra on
under different condi ons which may be
determined experimentally.
PROCEDURE:
1. Take fresh fruits, wash them thoroughly with
water and peel off their outer cover.
2. Grind it to a paste in the mortar with a pestle.
3. Mix with sugar and colouring ma er.
4. The material so obtained is fruit jam. It may be
used to study the effect of concentra on of sugar
and KHSO3, temperature and me.
[A] EFFECT OF TEMPERATURE:
1. Take 100 gm of Jam in three bo les labelled as
A, B and C.
2. Add 10.0 gm of sugar and 1.0 gm of KHSO3 to
each bo le.
3. Mix the contents thoroughly with a s rring rod.
4. Keep bo le No. A in the refrigerator at 0°C,
bo le No. B at room temperature (25°C) and
bo le No. C in a thermostat at 50°C. Observe the
changes taking place in the jam for 10 days.
RECORD:
Bo le No. Weight of Weight of Weight of
the jam the sugar KHSO3
taken
A 100 g 5g 1g
B 100 g 10 g 1g
C 100 g 15 g 1g
OBSERVATION:
Day 1 Day 2 Day 3 Day 4 Day 5
no no no No no
no no No No Fermented
no no Fermented fermented More
fermenta on
RESULT:
The increase in temperature causes fast
fermenta on of jam.
[B] EFFECT OF CONCENTRATION OF KHSO3
1. Take bo les labelled as A, B, C.
2. Put 100 gm of Jam in each bo le.
3. Add 5.0 gm of sugar to each bo le.
4. Add 1.0 gm, 2.0 gm and 3.0 gm of KHSO3 to
bo le No. A, B and C respec vely.
5. Mix the contents thoroughly with a glass rod.
6. Keep all the bo les at room temperature for
about 10 days and observe the changes everyday.
RECORD:
Bo le no. Weight of Weight of Weight of
jam taken the sugar KHSO3
A 100 g 5g 1g
B 100 g 5g 1g
C 100 g 5g 1g
OBSERVATION:
Day 1 Day 2 Day 3 Day 4 Day 4
No No No Few Some
No No No no Few
no No no No no
RESULT: The increase in concentra on of KHSO3
increase more me of preserva on.
[C] EFFECT OF TIME:
1. Take three bo les and label them as A, B and C.
2. To each bo le add 25 g of Jam and 1 g of
potassium bisulphite.
3. Keep bo le A for 7 days, bo le B for 14 days and
bo le C for 21 days at room temperature.
4. Note the changes taking place in each bo le and
record the observa ons.
OBSERVATION:
Bo le no. Day 7 Day 14 Day 21
A NO ---- -----
B NO Taste -------
changes
C NO No Unpleasant
smell
RESULT: With increase in days, the quality of the
jam deteriorates.
CONCLUSION
Food containing more amount of sugar is not
favourable to keep for a long me Potassium
bisulphite is a good preserva ve.
Uses
There are a number of uses for potassium
bisulphite as a food preserva ve. The Manitoba
Agriculture, Food and Rural Ini a ves reports this
product works to prevent the growth of mold,
yeast and bacteria in foods. It is also an addi ve for
homemade wine.
Potassium bisulphate is found in some cold drinks
and fruit juice concentrates. Sulphites are common
preserva ves in smoked or processed meats and
dried fruits. In spray form, it may help prevent
foods from discolouring or browning.
Availability
Potassium bisulphite is primarily a commercial
product. You might find this chemical compound at
meat processing plants. Manufacturers of juice
drinks and concentrate will use potassium
bisulphite to increase the shelf life of their
products. The preserva ve is also available for
home use.
Allergies
Sulphites such as potassium bisulphite can trigger
an a ack for those with asthma. Potassium
bisulphite may cause lung irrita on.
BIBLIOGRAPHY
www.google.com
www.wikipedia.com
www.slideshare.net
www.gneet.com
