Inhibition of lipase activity in commercial rice bran of coarse, fine, and superfine cultivars

Abstract

Lipase activity of commercially produced rice bran was inhibited with an aim of multiple product recovery. The initial values of free fatty acid were 8.72, 1.89, and 4.41% in bran from coarse, fine, and superfine cultivars which increased to 60.11, 51.70, and 75.33% level, respectively, after 40 days of ambient storage conditions. Storage temperature of −20°C and hydrochloric acid at 5% were found to be effective in controlling the lipase activity. Sodium hydroxide was less effective in controlling the lipase activity even at 10%. Hydrogen peroxide (30%) did not inhibit the activity but promoted oil degradation in rice bran. The initial peroxide value varied from 2.74 to 4.76 meq O₂ per kg of oil which increased to 10.19–14.15 meq O₂ per kg in untreated, while HCl-treated samples varied from 6.22 to 7.98 meq O₂ per kg at 5% level after 40 days.

Keywords:

• rice bran
• lipase
• alkali
• hydrochloric acid
• hydrogen peroxide
• free fatty acids

Public Interest Statement

Rice bran has highly nutritious oil and proteins. Rice bran shows high lipase activity after processing due to which rice bran oil is hydrolyzed into free fatty acids. Most of the industries inactivate lipase using high heat treatment mainly extrusion, but high temperature negatively affects rice bran protein isolation and its functional properties. So, chemical or low-temperature treatment was used to inhibit lipase activity which prevented hydrolysis of rice bran lipids and also enabled rice bran for better protein isolation.

Competing interests

The authors declare no competing interest.

Additional information

Funding

Funding. The authors received no direct funding for this research.

Notes on contributors

Tajendra Pal Singh

Tajendra Pal Singh is a PhD scholar in Department of Food Science and Technology, Guru Nanak Dev University, Amritsar, India and working on the utilization of major rice by-product: Bran.

Research reported in the paper of Inhibition of lipase activity in commercial rice bran of coarse, fine, and superfine cultivars: Low economy level technique used to increase shelf life of rice bran without any negative effect on rice bran. So, we use treated rice bran for further processing such as oil and protein extraction.

Dalbir Singh Sogi

Tajendra Pal Singh is a PhD scholar in Department of Food Science and Technology, Guru Nanak Dev University, Amritsar, India and working on the utilization of major rice by-product: Bran.

Research reported in the paper of Inhibition of lipase activity in commercial rice bran of coarse, fine, and superfine cultivars: Low economy level technique used to increase shelf life of rice bran without any negative effect on rice bran. So, we use treated rice bran for further processing such as oil and protein extraction.