Biochemical Analysis of Flour

[ps2id id=’background’ target=”/]

BACKGROUND

One of the versatile cereal is flour used all over the world. It is one of the staple food of large number of peoples used as important breakfast items, food ingredients.

The present experiment is to study the various biochemical properties of flour.

[ps2id id=’requirements’ target=”/]

REQUIREMENTS

Sample:              Flour

Chemicals:        Copper sulphate

Potassium sulphate

Sulphuric acid

40% NaOH

Boric acid

0.1% HCl

Petroleum ether

Ethanol

Benzene

[ps2id id=’procedure’ target=”/]

PROCEDURE

Biochemical analysis for various constituents

Protein

By following Micro Kjeldhal method (AOAC, 1980) protein is analyzed by determining the availability of nitrogen in the sample. Take flour (1 g) and digest it in 20 ml sulphuric acid at a temperature 420^oC by utilizing a catalyst mixture. The catalyst mixture consists of copper sulphate and potassium sulphate. Then distill this digested mixture by utilizing 40% NaOH. Then by using excess amount of 4% boric acid absorb ammonia and then perform titration with a standard acid like 0.1% HCl for estimation of protein content.¹ The protein content can be estimated by using the following calculation formula.

Protein (%) = 6.25 × Nitrogen content %

Nitrogen content % = Sample titre – Blank titre × Normality of HCl × 14 × 100 / weight of sample flour × 1000.

Crude fat

Take 5 g flour sample in a readymade thimble and then extract oil from it in a beaker by utilizing petroleum ether in SOCS PLUS for duration of 2.5 to 3 hours. Then evaporate the petroleum ether by keeping it in a hot air oven. Then determine the final weight of the beaker that gives the total amount of crude fat content in the sample.² The following formula can be used for determine the crude fat (%) content

Crude fat (%) = weight of fat in grams / weight of sample in gram × 100

Free fatty acids

Take flour sample (1 g) and add 50 ml petroleum ether and mix it properly by stirring for about 1 hour and then filter the mixture. Then wash it properly 2 more times with petroleum ether 5 ml. Then at a very low temperature evaporate the final reaction mixture. Make a mixture of ethanol and benzene in a ratio 3:1 and take 25 ml of this mixture and add in the final reaction mixture. From this take 10 ml in a separate flask and titrate it against a standard alkali along with addition of few drops of pH indicator.² With the help of following equation, the free fatty acid percentage was determined.

Free fatty acid (%) = weight of fat/weight of the sample × 100

Starch

In a clean test tube take about 1 gm of flour sample. Then to the test tube add about 10 ml of distilled water. For about 5 minutes boil the test tubes and then allow it to cool down. Now with the help of a filter paper, filter the contents of the test tube. Then test the filtrate for the amount of starch present by taking about 2 ml of the filtrate in a test tube and adding few drops of iodine to it.⁴ If a dark blue black colour appears, indicates the presence of starch.

[ps2id id=’conclusion’ target=”/]

CONCLUSION

Perfect biochemical analysis of flour can be utilized for quality control purposes.

[ps2id id=’references’ target=”/][ps2id id=’1′ target=”/]

REFERENCES

1. AOAC (1980). Official Methods of Analysis, 11^th edn. Washington, DC: Association of official analytical chemists.
   
2. Butt, M. S., Nasir, M., Akhtar, S. & Sharif, K. (2004). Effect of moisture and packaging on the shelf life of wheat flour. Journal of Food Safety, 5, 1–6.
   
3. Chakravarty, A. (1988). Post-harvest technology of cereals, pulses and oilseeds. India: Oxford & IBH publication (p. 177).
   
4. Hruškova, M. & Machova, D. (2002). Changes of wheat flour properties during short term storage. Czech Journal of Food Science, 20, 125–130.
   
5. https://nebraskawheat.com/wp-content/uploads/2014/01/WheatFlourTestingMethods.pdf. Accessed on 25 April 2018.