Effect of Potassium Bisulphite as a Food Preservative PDF

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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: Concentra tion  Time  Temperatu re

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.

CAN PRESERVATIVES BE NATURAL OR EASY? We

actually

'preserve' foods

fresh ourselves

every day, by storing foods in the fridge or freezer. 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 (249-

250) are also classified as preservatives. n our country, two chemical preservatives which are permitted 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 preservation of food materials. For the preservation of fruits, fruit juices, squashes and jams sodium 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 juice liberates Sulphur dioxide which is very effective in killing the harmful microorganisms present in food and thus prevents it from getting spoiled.

H+ + HSO3- → SO2 + H2O

The advantage of this method is that no harmful chemical is left in the food.

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

margarine,

breads, wine,

soft dried

drinks, fruit,

cheese, 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

gastrointestinal upsets.

EXPERIMENT The aim of this project is to study the effect of potassium bisulphite as food preservative. I. At different temperatures.

or

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.

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. 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 every day.

Observation Bottle number weight of

A

B

C

100gm

100gm

100gm

5gm

10gm

15gm

0.5gm

0.5gm

0.5gm

the jam taken Weight of the sugar added Weight of KHSO3

DAY 1

A

B

C

Colour

Dark

Dark

Dark

Odour

orange Pleasant

orange Pleasant

orange Pleasant

Fungus

smell Fungus

smell Fungus

smell Fungus not

not

not

formed

Colour

formed Dark

formed Orange

Light

Odour

orange Pleasant

Pleasant

orange Pleasant

Fungus

smell Fungus

smell Fungus

smell Fungus not

DAY 2 Colour

not

not

formed

formed Dark

formed Orange

Light

orange

DAY 3

orange

Odour

Pleasant

Pungent

Pungent

Fungus

smell Fungus

smell White

smell White

not

fungus is

fungus is

formed

formed

formed

Orange

Light

more in C Light

Odour

Pungent

orange Pungent

orange Pungent

Fungus

smell White

smell White

smell Fungus

fungus is

fungus

turned into

formed

has

greenish

Colour

DAY 4

increased colour Colour

Dark

Light

Yellow

Odour

orange Pungent

orange Pungent

colour Smells

smell

smell

ethanolic

DAY 5

Fungus

White

Fungus

Greenish

fungus

turned

colour

has

into

fungus has

increased greenish

increased

colour

DAY 6

Colour

Light

Yellow

Yellow

orange

colour

colour

Odour

Smells

Smells

fades Smells

Fungus

ethanolic Fungus

ethanolic Greenish

ethanolic Fungus

turned

colour

turned into

into

fungus

black

greenish

has

colour

colour Yellow

increased Yellow Yellow

colour

colour

colour

Odour

Smells

fades Smells

fades Smells

Fungus

ethanolic Greenish

ethanolic Fungus

ethanolic Spoilt

colour

turned

entirely

fungus

into black

Colour

DAY 7

colour

Result The increase in concentration of sugar causes deterioration of fruit jam due to growth of fungus.

Photos through the experiment.

(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. Bottle

Wt. of

Wt. of

Wt. of

Observation(days)

no

the jam

the

KHSO3

1

2

3

4

5

A

taken 100gms

sugar 5gms

1gms

no

no

no

fe

some

no no

w no no

few no

B C

100gms 100gms

5gms 5gms

1gms 1gms

no no

no no

(C) Effect of Temperature 1. Take 100 gm of Jam in three bottles labelled 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 (25˚C) and bottle No. III in a thermostat at 50˚C. Observe the changes taking place in the jam for 10 days.

Result: The increase in Temperature causes fast fermentation of jam. Bottl

Wt. of the jam

Wt. of the Wt. of KHSO3

e no

taken

sugar

A B C

100gms 100gms 100gms

5gms 10gms 15gms

1gms 1gms 1gms

Observation(days) 1

2

3

4

no no no

no no no

no no no no fermented fermente d

5 no fermented More fermentatio n

(D) Effect of time: – 1. Take three bottles and label them as I, II and 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. Bottle no A B C

7 NO NO NO

Observation(days) 14 21 ** ** Taste changes ** NO Unpleasant smell.

Result With increase of days, the quality of the jam deteriorates.

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.

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.

References: 1.

https://www.healthyfood.com/advice/what-arepreservatives/

2.

https://healthfully.com/308673-potassiumbisulphate-as-a-food-preservative.html

3.

https://www.sciencedirect.com/topics/foodscience/food-preservative

4.

https://en.wikipedia.org/wiki/Potassium_bisulfit e

5.

https://www.rwjbh.org/blog/2017/may/common -food-preservatives-and-their-purpose/

6.

https://www.unlockfood.ca/en/Articles/Foodtechnology/What-you-Need-to-Know-aboutPreservatives.aspx...