The document analyzes the effect of different storage temperatures (room temperature vs air conditioned) on wheat flour quality parameters over 8 weeks of short term storage. Key findings include: - Moisture, wet gluten, and gluten index were most affected by storage temperature, with moisture loss higher at room temperature. - Microbiological properties like bacterial and yeast/mold counts increased more with room temperature storage. - Most quality parameters declined slightly over time but were generally well preserved under air conditioned storage compared to room temperature storage. Proper temperature control is important to maximize wheat flour shelf life.

1. INFLUENCE OF DIFFERENT
STORAGE TEMPERATURES
ON WHEAT FLOUR QUALITY
PARAMETERS DURING
SHORT TERM STORAGE
BY
SUJITHA JESURAJAN
AS 1037

2. CONTENTS
• Introduction
• Objectives
• Materials and Methods
• Results and Discussions
• Conclusions
• Suggestions

3. INTRODUCTION
• Wheat ; A prominent cereal grain
• Wheat flour, A milled end product of wheat grain
• Wheat flour types: Soft flour and hard flour
• Blending of wheat flour
• Cooking purpose of wheat flour ˗ Cakes,Bread,String
hoppers,Muffins,Buns.etc
• Wheat flour chemistry

4. • Wheat flour quality as stated by quality of wheat grain
• Wheat flour quality parameters
 Physiochemical properties – Moisture, Wet gluten, Gluten
index, Falling number, Protein, Ash.
 Biological properties – Weevils count
 Microbiological properties – Aerial plate count, Yeast and
mold, Coliforms and E.coli
• Wheat flour storage
• Wheat flour deteriorating factors during storage

5. • Factors affecting wheat flour quality during storage
 Storage temperature
 Relative humidity
 Water activity
 Storage duration
• Wheat flour Aging
• Safe packaging of Wheat flour for long term use
• Shelf life of wheat flour

6. OBJECTIVES
1. To analyze the changes wheat flour quality parameters during
short term storage (8 weeks) under two different temperature
storage conditions(room temperature and a/c condition).
2. To study the rate of wheat flour maturation process occurring
under two different temperature storage conditions (room
temperature and a/c condition).
3. To evaluate the shelf life capacity of the wheat flour produced
in Prima Ceylon PVT Ltd.

7. BASIC EXPERIMENT CONCEPT
• 3 Different Wheat flour samples ˗ A,B and C (Varies in chemical
compositions)
• Done tests for physical, chemical, biological and microbiological
properties which determine the wheat flour quality
• Study Interval ˗ 2 weeks
• Study duration ˗ 9 weeks(Including fresh sample)
• Study Transactions ˗
1)Adjusting the stored air conditioned temperature to 27.5oC±0.5.
2)Adjusting the stored room temperature to 37oC±0.5.

8. PHYSIOCHEMICAL TESTS DONE FOR CHECKING WHEAT FLOUR
QUALITY CHANGES
• Moisture
 Long moisture test
 Moisture analyzer method
Long moisture test
1. Sample 10 gin moisture cans
2. Weighed(W1)
3. Oven heated
4. Weighed again(W2)
Moisture content % = W1/W2 ×100
Moisture analyzer
1. Moisture analyzer equipment
2. 5 g sample and heating
3. Results

9. • WET GLUTEN(Glutomatic method)
1. Test chambers were assembled.
2. Flour sample of 10 g taken.
3. 5 ml Sodium Chloride salt solution was added.
4. Allowed to wash in gluten machine(5 minutes).
5. Washed gluten was taken out.
6. Allowed for centrifugation(1 minute).
7. Centrifuged gluten was weighed.
Wet gluten(%) = Weight of washed gluten/Initial weight of the
sample ×100

10. • GLUTEN INDEX
1. Test chambers assembled.
2. Flour sample of 10 g.
3. NaCl salt solution 5 ml
4. Washing gluten machine.
5. Washed gluten.
6. centrifugation.
7. Separation of gluten
8. Weighing gluten
Gluten index=(Weight of total Gluten-Weight of leaked
gluten)/(Weight of total gluten) ×100

11. • FALLING NUMBER (Hagberg Perten Method)
1. Weight chart referring.
2. Collection of flour inside the viscometer tube
3. 25 ml Distilled water and stopper.
4. Shaken.
5. Stirrer fixing.
6. Perten machine with hot water bath and lid closed.
7. Readings.

12. • PROTEIN(Kjeldhal method)
 Digestion
1. Potassium disulphate powder 2.5g, 0.5 g selenium tablet, 1 g
wheat flour sample.
2. kjeldhal digestion flask.
3. 15 ml of 98% sulphuric acid and 2.5 ml of hydrogen peroxide
4. Protein digester and digestion for 40 minutes.
5. Clear yellow color: digestion stopped.
6. 75 ml cold water.

13.  Distillation
1. Distillation unit.
2. 60 ml Sodium Hydroxide.
3. Fixed 50 ml boric acid methyl red methyl blue solution in the
receiver end(Light purple color).
4. Distillation.
5. Distillation stopped; Purple turns green.
 Titration
1. Titration: 0.1 N Sulphuric acid.
Exact protein value = Titrated volume × Conventional factor

14. • ASH
1. Ash crucibles with known weight.
2. Wheat flour sample of 5 g in the crucibles.
3. Placed in electric muffle furnace; heated at 600oC for 6 hours.
4. Crucibles cooled in desiccator.
5. Weight was taken.
Ash content%=(Weight of burnt crucible-Weight of empty
crucible)/(Weight of sample) ×100

15. BIOLOGICAL TEST DONE FOR ASSESSING WHEAT
FLOUR QUALITY
• WEEVIL COUNTS
1. Done after microbiological and physiochemical tests.
2. Approximately 1 kg sample taken.
3. 250 micrometer pore sized sieve was selected.
4. Sieved.
5. Weevils retained in the sieve was noted.
Note ˗ 1 kg sample represents the whole wheat flour sample
packed in polypropylene bags.

16. MICROBIOLOGICAL TESTS DONE FOR ASSESSING WHEAT
FLOUR QUALITY
• E.COLI AND COLIFORM COUNT TEST
 Preparation of media and buffer solution
1. Media; Lauryl Sulfate Tryptose broth(LST) 35.6 g,1000 ml distilled
water.
2. Wet sterilized ˗ Media and other necessary reagents and containers.
3. buffer solution; 34 g Potassium Dihydrogen Phosphate 500 ml distilled
water.
4. Adjustment of Buffer solution.
5. Dilution of buffer solution.
 Preparation of test
1. 10 ml LST broth in durham tubes.
2. Buffer solution of 9.5 ml.
3. Wet sterilized.

17.  Inoculation
1. Done under laminar flow hood.
2. Surface sterilization of Laminar Flow Hood.
3. Gas burner
4. Stomacher bag; Wheat flour sample of 10 g + 90 ml Buffer
solution
5. Blending.
6. Poured in empty glass tube(10-1 dilution).
7. Addition of flour mixture to make dilutions.
8. incubated at 35.50C for 2 days.
9. Checked the tubes for the presence of air bubbles.
10.Gas positive tubes; Confirmation test

18. • AEROBIAL PLATE COUNTING
1. Media ˗ Plate Count Agar(PCA) 15.6 g in 400 ml distilled
water.
2. Wet sterilization.
3. Preparation of 10-1 , 10-2 , 10-3 aliquots.
4. Addition of 1 ml aliquot of 3 dilutions into different
petridishes.
5. Poured PCA media.
6. Rotation of Petridishes; Clockwise and Anti˗Clockwise.
7. Solidification of agar.
8. Incubation of Petridishes; 35oC for 2 days.
9. Colony Counter; Colonies counted.
Total bacterial count = Average count factor ×Dilution factor

19. • YEAST AND MOLD COUNT
1. Media ˗ Potato Dextrose Agar(PDA) 9.4 g in 400 ml distilled water.
2. Wet sterilization of media, petridishes and pipettes.
3. Preparation of 10-1 , 10-2 , 10-3 Diluted Flour samples with buffer
solution.
4. Addition of 1 ml aliquot of 3 dilutions into different petridishes.
5. Poured PDA media.
6. Rotation of Petridishes; Clockwise and Anticlockwise.
7. Allowed the agar to solidify.
8. Incubation of Petridishes; 25oC for 5 days.
9. Colony Counter; Colonies counted.
Total bacterial count = Average count factor ×Dilution factor

20. Sample A fresh 2 wks 4 wks 6 wks 8 wks
R/T 13.4 12.7 12.3 12.3 12
A/C 13.4 12.7 13.1 12.9 12.4
Sample B fresh 2 wks 4 wks 6 wks 8 wks
R/T 13.2 13 12.9 13.1 12.2
A/C 13.2 13 13.1 13 12.9
Sample C fresh 2 wks 4 wks 6 wks 8 wks
R/T 13.6 12.8 12.9 12.8 12.2
A/C 13.6 13.2 13.2 13.1 13
MOISTURE CONTENTS OF SAMPLES A,B AND C OVER 8 WEEKS

21. EFFECT OF STORAGE TEMPERATURE ON MOISTURE CONTENT OF
WHEAT FLOUR

22. Sample A Fresh 2Weeks 4weeks 6weeks 8weeks
R/T 33.5 33.3 33 33 32.6
A/C 33.5 33.6 32.9 33.1 33.2
Sample B Fresh 2weeks 4weeks 6weeks 8weeks
R/T 29.9 29.2 29.1 28.7 28.6
A/C 29.9 29.6 29.3 29 28.9
Sample C Fresh 2weeks 4weeks 6weeks 8weeks
R/T 39.5 39.2 39.1 38.3 38.8
A/C 39.5 39.3 38.7 38.5 39.2
WET GLUTEN(%) OF SAMPLES A,B AND C OVER 8 WEEKS

23. EFFECT OF STORAGE TEMPERATURE ON WET GLUTEN OF
WHEAT FLOUR

24. GLUTEN INDEX OF SAMPLES A,B AND C OVER 8 WEEKS
Sample A fresh 2weeks 4weeks 6weeks 8weeks
R/T 89.48 90.09 92.42 92.42 94.78
A/C 89.48 88.09 86.24 94.25 93.07
Sample B fresh 2weeks 4weeks 6weeks 8weeks
R/T 81.5 80.88 81.78 71.77 77.62
A/C 81.5 83.78 74.64 72.41 79.93
Sample C fresh 2weeks 4weeks 6weeks 8weeks
R/T 94.17 93.25 93.07 90.62 92.01
A/C 94.17 89.79 82.73 87.01 92.09

25. EFFECT OF STORAGE TEMPERATURE ON GLUTEN INDEX OF
WHEAT FLOUR

26. PROTEIN CONTENT OF SAMPLES A,B AND C OVER 8 WEEKS
Sample A fresh 2wks 4wks 6wks 8wks
R/T 11.66 11.63 11.76 11.64 11.51
A/C 11.66 11.63 11.52 11.68 11.66
Sample B
R/T 10.27 10.05 10.07 10.1 9.99
A/C 10.27 10.07 10.09 10.08 9.72
Sample C
R/T 13.49 13.47 13.32 13.44 13.34
A/C 13.49 13.34 13.34 13.33 13.31

27. EFFECT OF STORAGE TEMPERATURE ON PROTEIN CONTENT
OF WHEAT FLOUR

28. ASH CONTENT OF SAMPLES A,B AND C OVER 8 WEEKS
Sample A fresh 2wks 4wks 6wks 8wks
R/T 0.537 0.518 0.456 0.507 0.48
A/C 0.537 0.513 0.496 0.509 0.537
Sample B
R/T 0.501 0.494 0.471 0.506 0.479
A/C 0.501 0.508 0.491 0.512 0.502
Sample C
R/T 0.508 0.501 0.493 0.524 0.486
A/C 0.508 0.506 0.491 0.5 0.489

29. EFFECT OF STORAGE TEMPERATURE ON ASH CONTENT
OF WHEAT FLOUR

30. COLOR VALUES OF SAMPLES A,B AND C OVER 8 WEEKS
Sample A fresh 2wks 4wks 6wks 8wks
R/T 0.68 0.71 0.78 0.83 0.88
A/C 0.68 0.86 0.67 0.78 1.28
Sample B fresh 2wks 4wks 6wks 8wks
R/T 1.42 1.27 1.25 1.2 1.34
A/C 1.42 1.2 0.92 1 1.1
Sample C fresh 2wks 4wks 6wks 8wks
R/T 0.84 0.76 0.72 0.76 0.8
A/C 0.84 0.76 0.4 0.58 0.4

31. EFFECT OF STORAGE TEMPERATURE ON COLOR VALUE OF
WHEAT FLOUR

32. FALLING NUMBER OF SAMPLES A,B AND C OVER 8 WEEKS
Sample A fresh 2wks 4wks 6wks 8wks
R/T 412 402 440 411 451
A/C 412 383 396 384 394
Sample B fresh 2wks 4wks 6wks 8wks
R/T 357 359 367 349 376
A/C 357 349 361 341 356
Sample C fresh 2wks 4wks 6wks 8wks
R/T 446 470 512 509 507
A/C 446 439 395 403 427

33. EFFECT OF STORAGE TEMPERATURE ON FALLING NUMBER
OF WHEAT FLOUR

34. BACTERIAL COUNT OF SAMPLES A,B AND C OVER 8 WEEKS
Sample A fresh 2wks 4wks 6wks 8wks
R/T 470 410 580 610 500
A/c 470 870 530 640 750
Sample B fresh 2wks 4wks 6wks 8wks
R/T 980 610 790 600 600
A/C 980 610 630 650 660
Sample C fresh 2wks 4wks 6wks 8wks
R/T 270 245 220 200 190
A/C 270 180 460 370 340

35. EFFECT OF STORAGE TEMPERATURE ON BACTERIAL COUNT
OF WHEAT FLOUR

36. YEAST AND MOLD COUNTS OF SAMPLES A,B AND C OVER 8
WEEKS.
Sample A fresh 2wks 4wks 6wks 8wks
R/T 140 120 120 140 180
A/C 140 100 130 130 100
Sample B fresh 2wks 4wks 6wks 8wks
R/T 70 120 150 150 130
A/C 70 100 170 170 180
Sample C fresh 2wks 4wks 6wks 8wks
R/T 110 200 230 180 140
A/C 110 200 250 270 140

37. EFFECT OF STORAGE TEMPERATURE ON YEAST AND MOLD COUNT
OF WHEAT FLOUR

38. CONCLUSION
• The parameters which change quickly due to difference in storage
temperatures are, MOISTURE, WET GLUTEN AND GLUTEN INDEX,
FALLING NUMBER AND COLOR to a little extent.
• MOISTURE and WET GLUTEN shows visible changes due to storage
temperatures and the duration of storage.
• Moisture loss is high in room temperature which is favorable for storage
since low water availability attracts low weevils to the flour .But the moisture
content has to be kept optimum and too much moisture loss reduce the
baking quality.
• Gluten strengthens during high storage temperatures. But too much
temperature and long term storing deteriorates the gluten and directly
decreases the baking quality of the flour.
38

39. • High storage temperatures increases the falling number, which means low
yeast activity and this will produce bread with low volume. High falling
number value may be good for certain foods like cakes, muffins, rotti,
buns.etc which need low volume.
• Since the natural aging process is accelerated due to room temperature
storage, the color value decreases in minus due to natural bleaching. This is
a good thing about room temperature storage.
• But since the room temperature cannot be manipulated by humans and it is
always fluctuating, the deterioration of wheat flour occurs sooner than air
conditioned stored wheat flour samples.
• So it is recommended to store the wheat flour under air conditioned storage.
Regulation of relative humidity is a must since the flour is hygroscopic.
• Samples A,B and C differently affected by storage temperatures since their
chemical properties varies.
39

40. SUGGESTIONS
• Since the study was conducted for short time period, further study
should be carried out to evaluate the shelf life capacity of the wheat
flour produced by Prima Ceylon PVT Ltd.
• The flour maturation process has to be studied carefully under room
temperature conditions during long term storage.
• The measures have to be taken to pack the samples in paper bags
instead of polypropylene bags since the polypropylene bags can
allow the weevils to infest.
• The relative humidity of air conditioned storage should be
maintained constant and it should be regularly monitored. The
temperatures of wheat flours should be regularly monitored. The bio
security should be maintained and high sterile conditions should be
maintained when packing and storing the bags. 40

41. COST BENEFIT ANALYSIS
Cost Quantity
Price 2KG
(Rs)
Amount
(Rs)
Cost of Wheat flour 30 170/= 5100/=
Packing Material 30 20/= 600/=
Packing charge ˗ ˗ 500/=
Daily bus transport ˗ ˗ 1920/=
Food expenses ˗ ˗ 12,800/=
Electricity Cost ˗ ˗ 3000/=
Other(Charity and Donations) ˗ ˗ 1000/=
TOTAL COST (Rs) 24,920/=

42. REFERENCE
• Barton-Wright, E. C. (1938). Studies on the storage of wheaten flour. III.
Changes in the flora and the fats and the influence of these changes on
gluten character. Cereal Chem, 15, 521-541.
• Cenkowski, S., Dexter, J. E., & SVCANLON, M. (2000). Mechanical
compaction of flour: The effect of storage temperature.
• Chen, X., & Schofield, J. D. (1996). Changes in the glutathione content and
breadmaking performance of white wheat flour during short-term storage.
Cereal chemistry, 73(1), 1-4.
• Fisher, E. A., Halton, P., & Carter, R. H. (1937). Studies on the storage of
wheaten flour. 1. The influence of storage on the chemical composition and
baking quality of flour. Cereal Chemistry, 14, 135-161.
• Hruskova, M. and D. Machova. 2002. Changes of wheat flour properties
during short term storage. Czech Journal of Food Sci. 20: 125-130.
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