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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Functional Foods Research » Research » Publications at this Location » Publication #315345
Title: Differences in antioxidant activity between two rice protein concentrates in an oil-in-water emulsion

Author
item Bakota, Erica
item Moser, Jill

Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2017
Publication Date: 3/16/2017
Citation: Bakota, E.L., Winkler-Moser, J.K. 2017. Differences in antioxidant activity between two rice protein concentrates in an oil-in-water emulsion. European Journal of Lipid Science and Technology. doi: 10.1002/ejlt.201600421.

Interpretive Summary: Lipid oxidation is a problem that continues to plague the food and restaurant industries. Food lipids can occur in the bulk phase, such as in frying oils, or dispersed throughout a food product, as is the case in emulsions. Emulsions are particularly susceptible to lipid oxidation. This oxidation leads to measurable declines in product quality and ultimately, shorter product shelf lives. Rice is an important staple crop that represents approximately 25% of world grain production and is cultivated in over 100 countries worldwide. While rice is generally known for its high carbohydrate content, rice also contains 6-10% protein, depending upon the variety. In this work we show that rice protein fractions are capable of inhibiting lipid oxidation. The protein concentrates investigated here are produced by milling, heating, and treating brown rice with alpha-amylase, which breaks down many of the complex carbohydrates in rice. The insoluble rice proteins are then separated from the hydrolyzed starch by mechanical means, dried, and milled further to achieve the desired particle size. The protein concentrates examined here differ in protein content and degree of hydrolysis but are otherwise similar. One of the two protein concentrates was able to suppress lipid oxidation, which could potentially prolong the shelf life in foods.

Technical Abstract: Two formulations of rice protein concentrates (RPC) derived from brown rice were evaluated for their antioxidant activity in bulk oil and in oil-in-water emulsions. Bulk oils were mixed with RPC and heated to 180°C, and total polar compounds and triacylglycerol polymerization were measured. Minimal antioxidant activity was observed in the bulk oil phase. Rice protein concentrates were then incorporated into soybean oil-in-water emulsions, which were subjected to accelerated oxidation at 50°C for 8 days. Lipid oxidation in emulsions was assessed via peroxide values (PV), headspace oxygen levels, headspace volatile oxidation products, and fatty acid analysis. One of the RPC treatments showed the ability to suppress lipid oxidation in emulsions, suggesting that RPC could potentially be used as antioxidants to extend shelf life and preserve product quality.