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STUDY OF EFFECT OF POTASSIUM BISULPHITE AS A
FOOD PRESERVATIVE
Submitted To: Indhumathy
Made By: Dhev Dharshan.S.S
Class: XII -BCD
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INDEX
1. Abstract
2. Introduction
3. Experiment
4. Materials
5. Procedure
6. Observation
7. Conclusions
8. Reference
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Abstract
The objective of this project is to Study of effect of
Potassium bisulphite as a food preservative under
various conditions
Condition:-
• Concentration
• Time
• Temperature
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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. Then
what should we add?
“PRESERVATIVES” Preservatives are natural or man-made
chemicals that are added to foods to stop them from spoiling.
Many packaged foods we buy need a preserving agent to
keep them from going 'off' and to protect us against
foodborne illnesses (food poisoning), which is why these
preservatives are used.
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CAN PRESERVATIVES BE NATURAL OR EASY?
We actually 'preserve' fresh foods ourselves
every day, by storing foods in the fridge or
freezer.
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Smoking fish or meats over burning wood or
coal are also methods
of preservat. Natural
preservatives that can
be added to foods
include salt and sugar.
CHEMICAL METHODS:-
Other preservatives that are commonly used in foods in small
amounts include sorbates, which can be identified by the
additive numbers 200203, benzoates (210-218), sulphites
(220-228) and propionates (280-283). Some nitrites (249250)
are also classified as preservatives. our country, two chemical
preservatives which are permitted for use are:
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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 preservation of food materials. For the
preservation of fruits, fruit juices, squashes and jams sodium
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benzoate is used as preservative because it is soluble in water
and hence easily mixes with the food product.
Potassium bisulphite is used for the preservation 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
reaction with acid of the
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juice liberates Sulphur dioxide which is very effective in
killing the harmful microorganisms present in food and
thus prevents it from getting spoiled.
H+ + HSO - → SO + H O
3 2 2
The advantage of this method is that no harmful chemical is
left in the food.
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Common questions asked:-
1) How do preservatives work?
To prevent spoilage of foods by moulds, yeast and
bacteria, preservatives have an acidic nature that makes
the organisms unable to grow in the food.
2) How can I tell which foods contain preservatives?
All 'additives', including preservatives, must be labelled on
food packages. You may commonly see the word
'preservative' followed by its additive number or name. For
example, preservative (220) or (sulphur dioxide). This
system makes it easy to identify preservatives in foods.
3) What foods contain preservatives?
You may be surprised at how many foods you commonly
eat contain preservatives. Items such as breads, soft
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drinks, cheese, margarine, wine, dried fruit, processed
drinks, cheese, margarine, wine, dried fruit, processed
meats, fruit juice and raw prawns may contain
preservatives.
4) Can preservatives cause reactions in sensitive people?
The body can react to all sorts of natural and artificial
chemicals found in the environment and in foods.
Particular preservatives may cause reactions in sensitive
people, with symptoms including skin rashes and itching,
breathing difficulty, sneezing or gastrointestinal upsets.
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EXPERIMENT
The aim of this project is to study the effect of potassium
bisulphite as food preservative. I. At different
temperatures.
II. At different concentrations and III.
For different intervals of time.
MATERIALS
I. Beaker, pestle and mortar, glass bottles, balance and
peeler.
II. Fresh fruits, potassium bisulphite and sugar.
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THEORY
Food materials undergo natural changes due to temperature,
time and enzymatic action and become unfit for
consumption. These changes may be checked by adding small
amounts of potassium bisulphite. The effectiveness of KHSO3
as preservative depends upon its concentration under
different conditions 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 matter.
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4. The material so obtained is fruit jam. It may be used to
study the effect of concentration of sugar and KHSO3,
temperature and time.
(A) Effect of concentration of Sugar: -
1. Take three wide mouthed reagent bottles labeled as A,B,C.
2. Put 100 gms of fruit jam in each bottle.
3. Add 5.0 gms, 10.0 gms and 15.0 gms of sugar to each
bottle respectively.
4. Add 0.5 gm of KHSO3 to each bottle.
5. Mix contents thoroughly with a stirring rod.
6. Close the bottle and allow them to stand for one week or
10 days at room temperature.
7. Observe the changes taking place in Jam everyday.
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OBSERVATION
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Result
The increase in concentration of sugar causes deterioration of
fruit jam due to growth of fungus.
Photos through the experiment.
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(B) Effect of concentration of KHSO3
1. Take bottles labeled as A,B,C.
2. Put 100 gm of Jam in each bottle.
3. Add 5.0 gm of sugar to each bottle.
4. Add 1.0 gm, 2.0 gm and 3.0 gm of KHSO3 to bottle
respectively.
5. Mix the contents thoroughly with a glass rod.
6. Keep all the bottles at room temperature for about 5 days
and observe the changes everyday.
Result
The increase in concentration of KHSO3 increase more time
of preservation.
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(C) Effect of Temperature
1. Take 100 gm of Jam in three bottles labeled as A,B,C.
2. Add 10.0 gm of sugar and 1.0 gm of KHSO3 to each
bottle.
3. Mix the contents thoroughly with a stirring rod.
4. Keep bottle No. I in the refrigerator at 0˚C, bottle No. II at
room temperature (25C˚) and bottle No. III in a
thermostat at 50C˚. Observe the changes taking place in
the jam for 10 days.
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Result:
The increase in Temperature causes fast fermentation of jam.
(D) Effect of time:–
1. Take three bottles and label them as I, II and
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III.
2. To each bottle add 25 g of Jam and 1 g of potassium
bisulphite.
3. Keep bottle A for 7 days, bottle B for 14 days and bottle C
for 21 days at room temperature.
4. Note the changes taking place in each bottle and record
the observations.
Result
With increase of days, the quality of the jam deteriorates.
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Conclusion:
Food containing more amount of sugar is not favorable to
keep for a long time , Potassium bisulphite is a good
preservative.
There are a number of uses for potassium bisulfite as a food
preservative. The Manitoba Agriculture, Food and Rural
Initiatives reports this product works to prevent the growth of
mold, yeast and bacteria in foods. It is also an additive for
homemade wine. Potassium bisulfate is found in some cold
drinks and fruit juice concentrates. Sulfites are common
preservatives in smoked or processed meats and dried fruits.
In spray form, it may help prevent foods from discoloring or
browning.
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Potassium bisulfite is primarily a commercial product. You
might find this chemical compound at meat processing plants.
Manufacturers of juice drinks and concentrate will use
potassium bisulfite to increase the shelf life of their products.
The preservative is also available for home use. Sulphites such
as potassium bisulfite can trigger an attack for those with
asthma. potassium bisulfite may cause lung irritation. People
must know merits and also the demerits of the additives used
in our day to day products. Anything in excess can be fatal
too. I hope this project helps people.
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References:
1. https://www.healthyfood.com/advice/whatarepreservatives/
2. https://www.sciencedirect.com/topics/foodscience/foodpres
ervative
3. https://en.wikipedia.org/wiki/Potassium bisulfite
4. https://www.rwjbh.org/blog/2017/may/common-
foodpreservatives-and-their-purpose/
5. https://www.unlockfood.ca/en/Articles/Foodtechnology/
What-you-need-to-know-about-Preservatives.aspx
