Effect of natural fermentation on protein fractions and in vitro protein digestibility of rice


Changes in pH, titratable acidity, total soluble solids and protein of rice during natural fermentation at 37 °C up to 36 h were monitored. The pH of the fermenting material decreased sharply with a concomitant increase in the titratable acidity. Total soluble solids increased with progressive fermentation time. The crude protein content fluctuated during the first 24 h of fermentation but started to increase thereafter. Non-protein nitrogen was unchanged during the first 12 h of fermentation but increased sharply with progressive fermentation. The in vitro protein digestibility markedly increased as a result of fermentation. The increase in the globulin + albumin fractions constituted the most remarkable increase and were the major proteins in the 36 h fermented rice; the increase was up to 2.7 fold. The prolamin fraction, which was the minor fraction, the G1-glutelin and G2-glutelin fractions increased with progressive fermentation time. The G3-glutelin, which was the major protein fraction of unfermented rice, markedly decreased as a result of fermentation, while insoluble protein fluctuated during the fermentation process.

This is a preview of subscription content, log in to check access.


  1. 1.

    Ohtsubo K, Toyoshima H, Okadome H (1998) Quality assays of rice using traditional and novel tools. Cereal Foods World 43(4): 203–206.

    Google Scholar 

  2. 2.

    Juliano BO (1998) Varietal impact on rice quality. Cereal Foods World 43(4): 207–222.

    Google Scholar 

  3. 3.

    Kent NL (1980) Technology of Cereal, with Special Reference to Wheat, 2nd edn. England: Pergamon Press Ltd.

    Google Scholar 

  4. 4.

    Hettiarachchy NS, Qi M (1998) Rice protein nutrition, allergy and functionality. Cereal Foods World (Abstr) 43(7): 515.

    Google Scholar 

  5. 5.

    Medcalf DG (1998) Development of rice based medical and functional food. Cereal Foods World (Abstr.) 43(7): 514.

    Google Scholar 

  6. 6.

    Lookhart GL, Albers LD, Pameranz Y, Webb BD (1987) ldentification of US cultivars by high performance liquid chromatography. Cereal Chem 64(4): 199–206.

    Google Scholar 

  7. 7.

    Hamad AM, Fields ML (1979) Evaluation of the protein quality and available lysine of fermented cereals. J Food Sci 44: 456–459.

    Google Scholar 

  8. 8.

    AOAC (1975) Official Methods of Analysis, 12th edn. Washington DC: Association of Official Analytical Chemists

    Google Scholar 

  9. 9.

    Gheyasuddin S (1970) Studies of Sunflower Seed Proteins and Polyphenols. PhD Thesis, Texas A&M University.

  10. 10.

    Saunders RM, Connor MA, Booth AN, Bickoff EN, Kohler CO (1973) Measurement of digestibility of alfalfa protein concentrate by in vitro and in vivo methods. J Nut 103: 530–535.

    Google Scholar 

  11. 11.

    Joslyn AM (1970) Methods in Food Analysis, 2nd edn. New York: Academic Press.

    Google Scholar 

  12. 12.

    Landry J, Moureaux T (1970) Heterogeneity of the glutelins of the grain corn: Selective extraction and composition in amino acids of the three isolated fractions. Bull Soc Chem Biol 52: 1021–1037.

    Google Scholar 

  13. 13.

    Snedecor GW, Cochran WG (1987) Statistical Methods, 17th edn. Ames, IA: The Iowa State University Press, pp 221–222.

    Google Scholar 

  14. 14.

    Duncan DB (1955) Multiple range and multiple F-tests. Biometrics 11: 1–42.

    Google Scholar 

  15. 15.

    El Tinay AH, El Mahdi ZM, El Soubki A (1985) Supplementation of fermented sorghum kisra bread with legume protein. J Food Technol 20: 679–687.

    Google Scholar 

  16. 16.

    Padhye VW, Salunkhe DK (1979) Biochemical studies on black gram (Phaseolus mungo L.) III. Fermentation of black gram and rice blend and its influence on the in vitro protein digestibilities of proteins. J Food Biochem 2(4): 327–347.

    Google Scholar 

  17. 17.

    Cronk TC (1975) Biochemical studies of an Indonesian fermented rice food, tape ketan. Dissertation – Abstracts – International – B; 35 (11): 5473–5474.

    Google Scholar 

  18. 18.

    El Tinay AH, Abdel Gadir AM, El Hidai M (1979) Sorghum fermented kisra bread. 1. Nutritive value of kisra. J Sci Food Agric 30: 859–863.

    Google Scholar 

  19. 19.

    Palmiano EP, Almazon AM, Juliano BO (1968) Physicochemical properties of protein of developing and mature rice grain. Cereal Chem 45(1): 1–12.

    Google Scholar 

Download references

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

Yousif, N.E., El Tinay, A.H. Effect of natural fermentation on protein fractions and in vitro protein digestibility of rice. Plant Foods Hum Nutr 58, 1–8 (2003). https://doi.org/10.1023/B:QUAL.0000040347.82831.51

Download citation

  • Fermentation
  • In vitro protein digestibility
  • Protein fraction
  • Rice
  • Solubility