CERTIFICATE
This is to certify that Raunak Pal of class XII
A has successfully completed the practical
file work under the guidance of Mr. Vipin
during the session 2024-2025.
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Teacher’s Sign
Examiner’s Sign
ACKNOWLEDGEMENT
Primarily I would like to thank God for being
able to complete this project with success.
Then I would like to thank my principal
MR.K.K .Sharma and Chemistry Teacher MR.
Vipin whose valuable guidance has been
the ones that helped me patch this project
and make it full proof success. His
suggestions and his instructions have
served as the major contributor towards the
completion of this project.
Then I would like to thank my parents and
friends who have helped me with their
valuable suggestions and guidance in
various phases of completion of the project.
Last but not the least I would like to thank
my class mates who have helped me a lot.
Table of Contents
1. Introduction
2. Objectives
3. Hypothesis
4. Materials Required
5. Theory
6. Experimental Procedure
7. Observations
8. Results and Discussion
9. Future Scope
Introduction
Food preservation has been an essential
part of human life since ancient times.
Among the modern methods, chemical
preservatives play a significant role in
inhibiting spoilage caused by
microorganisms. Potassium bisulphate
(KHSO₃) is one such preservative widely
used in fruit juices, syrups, and canned
foods. It works by releasing sulfur dioxide
(SO₂), which has antimicrobial properties
and prevents the growth of bacteria, Molds,
and yeasts.
Potassium bisulphate (KHSO₃)
The objective of this project is to
systematically study the effect of potassium
bisulphate under various conditions of
temperature, concentration, and time to
determine its efficiency as a food
preservative.
Objectives
1. To evaluate the preservative effect of
potassium bisulphate on perishable food
items.
2. To study how variations in temperature
influence its effectiveness.
3. To understand the relationship between
concentration and preservative efficiency.
4. To assess the role of time in food spoilage
prevention.
5. To identify optimal conditions for using
potassium bisulphate.
Hypothesis
Potassium bisulphate effectively prevents
spoilage in food samples. Its efficiency is
expected to vary with temperature,
concentration, and time.
Materials Required
1. Potassium bisulphate (KHSO₃) powder
2. Perishable food samples (e.g., orange
juice, tomato juice, cut fruits like apples or
bananas)
3. Glass beakers/test tubes
4. Distilled water
5. Measuring cylinders and droppers
6. Refrigerator and incubator/water bath
7. Stopwatch/timer
8. pH meter or universal pH paper
9. Microscope and nutrient agar plates (for
microbiological testing)
10. Labels, markers, and graph paper
11. Protective gloves and goggles
Theory
Potassium bisulphate decomposes in
aqueous solutions to release sulfur dioxide
(SO₂), which acts as the primary
antimicrobial agent. It inhibits the activity of
spoilage organisms by lowering the pH and
interfering with their metabolic processes.
However, factors like temperature and
exposure time can influence the stability of
SO₂, affecting its preservative properties.
The reaction can be represented as:
KHSO₃ + H₂O → K⁺ + HSO₄⁻ + SO₂ (aq)
Experimental Procedure
1. Preparation of Food Samples:
- Select fresh food samples such as orange
juice, tomato juice, or fresh-cut fruits.
- Divide each sample into several portions
for testing under different conditions.
2. Preparation of Potassium Bisulphate
Solutions:
- Prepare solutions of potassium bisulphate
with varying concentrations, such as 0.1%,
0.3%, 0.5%, and 1%.
- Label these solutions accurately.
3. Experimental Setup:
- Add different concentrations of potassium
bisulphate solution to each food sample.
- Keep a control sample without any
preservative for comparison.
4. Variation of Conditions:
- Temperature: Store samples at room
temperature, refrigeration, and higher
temperatures (~40°C) using an incubator or
water bath.
- Time: Observe and record changes at
regular intervals (e.g., every 24 hours for up
to a week).
5. Observation Parameters:
- Physical Changes: Colour, Odor, and
texture of food samples.
- Chemical Changes: Measure pH changes
using a pH meter or universal indicator
paper.
- Microbiological Analysis: Test for microbial
growth by culturing samples on nutrient
agar plates.
6. Record Observations:
- Create tables to document the results
systematically for each condition.
Observations
Results and Discussion
1. Effect of Concentration:
Higher concentrations of potassium
bisulphate (e.g., 0.5% or 1%) were more
effective in preserving food samples
compared to lower concentrations.
2. Effect of Temperature:
Samples stored in refrigeration exhibited
slower spoilage rates than those stored at
room temperature or higher temperatures.
3. Effect of Time:
The preservative effect weakened over
time, especially in samples stored at higher
temperatures.
4. Control Sample:
Spoilage occurred rapidly in the untreated
samples, confirming the role of potassium
bisulphate in preventing microbial growth.
Conclusion
Potassium bisulphate is an effective
preservative for perishable food items, with
its efficiency increasing at higher
concentrations and lower storage
temperatures. However, its preservative
action diminishes over time and at elevated
temperatures. The study highlights the
importance of optimizing concentration and
storage conditions for its practical
application.
Precautions
1. Handle potassium bisulphate with care, as
it may cause irritation.
2. Use clean and sterile equipment to avoid
contamination.
3. Dispose of spoiled samples and chemical
waste responsibly.
Future Scope
1. Study the effect of potassium bisulphate
on a wider range of food products.
2. Compare its efficiency with other
chemical preservatives.
3. Investigate its long-term effects on food
quality and safety.
Bibliography
1. NCERT Chemistry Class XII textbook.
2. Internet resources on food preservation
techniques.
3. Laboratory manuals and guides.
