Rice Science ›› 2015, Vol. 22 ›› Issue (5): 227-236.DOI: 10.1016/S1672-6308(14)60296-1

• Orginal Article • Previous Articles     Next Articles

Soaking Induced Changes in Chemical Composition, Glycemic Index and Starch Characteristics of Basmati Rice

J. Kale S.1(), K. Jha S.1, K. Jha G.2, P. Sinha J.3, B. Lal S.4   

  1. 1Division of Food Science and Post Harvest Technology, Indian Agricultural Research Institute, New Delhi 110012, India
    2Division of Agricultural Economics, Indian Agricultural Research Institute, New Delhi 110012, India
    3Division of Agricultural Engineering, Indian Agricultural Research Institute, New Delhi 110012, India
    4Division of Computer Applications, Indian Agricultural Research Institute, New Delhi 110012, India
  • Received:2014-09-10 Accepted:2015-04-23 Online:2015-05-15 Published:2015-07-24

Abstract:

An attempt was made to determine the qualitative changes in basmati rice (Pusa Basmati 1121, PB1121) during soaking at 40 °C to 80 °C. Soaking temperature had significant effect (α = 0.01) on chemical composition, glycemic index and starch characteristics of rice. Starch content, apparent amylose content, crude protein content and crude fat content in un-soaked rice were found to be 73.24%, 27.26%, 8.79% and 2.56%, respectively, but differences in these traits were observed after soaking. Amylose to amylopectin ratio (Am/Ap) decreased from 0.59 to 0.52 (soaked at 80 °C). Crude fibre and crude ash contents increased after soaking. The mineral composition (K, P, S, Ca, Mg, Mn, Fe, Cu and Zn) in soaked rice was found to be 16.46% higher than un-soaked rice at the same degree of polishing. Glycemic index of un-soaked rice was found to be 58.41, but decreased to 54.31 after soaking at 80 °C. Pasting properties, scanning electron microscope images, and X-ray diffractograms suggested partial gelatinization of starch in the temperature range of 60 °C to 80 °C. Based on qualitative changes in rice (apparent amylose content, Am/Ap ratio and crystallinity rate), it was concluded that intermediate soaking temperatures (60 °C to 70 °C) would be useful for soaking of PB1121.

Key words: basmati rice, soaking, glycemic index, starch characteristic, temperature, chemical composition, crystallinity