Stabilization of rice bran via different moving-bed drying methods

ABSTRACT

Stabilization of rice bran after milling is a necessary step to avoid subsequent oxidation of lipids in the bran. Selected moving-bed drying methods, i.e., hot-air fluidized bed drying (HAFBD), superheated-steam fluidized bed drying (SSFBD), and infrared vibrated bed drying (IRVD), were used to reduce the moisture content of the bran and, at the same time, inactivate deleterious enzymes, which are the cause of oxidation. Drying kinetics, oxidative stability parameters (i.e., lipase activity, free fatty acid content, and peroxide value), oil extraction yield, and contents of phenolic compounds and γ-oryzanol as well as color changes of the bran were determined. SSFBD could reduce the drying time by 8–22 and 76–79% in comparison with HAFBD and IRVD, respectively. Drying method significantly affected the total phenolic content (TPC) and total color changes but did not significantly affect the γ-oryzanol content of the bran. SSFBD resulted in the lowest levels of all oxidative stability parameters and to the highest TPC and oil extraction yield. SSFBD at 140°C resulted in the bran with the longest shelf life of 55 days and is suggested as an alternative method to shorten the stabilization process and maintain the stability of rice bran.

KEYWORDS:

• Bioactive compounds
• color
• enzyme inactivation
• infrared drying
• lipid oxidation
• phenolics
• superheated steam drying

Acknowledgment

Finally, the authors are grateful to Sahaphuedphon Thatum Partnership, Surin Province, Thailand for the rice processing information.