Extending shelf life of brown rice using infrared heating

Authors: VENKITASAMY, CHANRASEKAR - University Of California; Pan, Zhongli

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 5/10/2019
Publication Date: 9/15/2017
Citation: Venkitasamy, C., Pan, Z. 2017. Extending shelf life of brown rice using infrared heating. In: Manickavasagan, A., Santhakumar, C., Venkatachalapathy, N., editors. Brown Rice. Cham, Switzerland: Springer. p. 217-244. https://doi.org/10.1007/978-3-319-59011-0
DOI: https://doi.org/10.1007/978-3-319-59011-0

Interpretive Summary: Rice is the most widely consumed staple food and most of the rough rice produced is consumed as white (milled) rice. Recently, there has been an increasing trend in the consumption of brown (unmilled) rice due to its higher nutrition value than that of white rice. The short shelf life of brown rice has been a significant concern for its storage. The effective and economic way to extend the shelf life of brown rice is to inactivate the lipase enzyme to minimize the lipid oxidation, which cannot be achieved by currently used hot air drying. Infrared (IR) drying has been reported that it effectively inactivated the lipase enzymes during rough rice drying. This chapter summarizes the mechanism of IR heating, IR emitter types, advantages of IR drying and investigations performed on IR drying of rough rice and parboiled rice, and its influence on the milling yield, quality and storage characteristics of rough rice, brown rice and rice bran. The IR drying resulted in high drying rate, good milling quality, effective disinfestation and disinfection of rough rice and improvement in shelf life of both rough and brown rice due to partial lipase inactivation in the bran layer. IR dried rice can be stored in brown rice form at ambient temperature with even longer shelf life than that of rough rice dried with ambient and hot air. The rice bran from milling of IR dried rice has sufficient shelf life for further value-added utilization without need for additional stabilizing treatment.

Technical Abstract: The consumption of brown rice has been increasing due to its higher nutrition value, nutty flavor and rich texture compared to white rice. At the same time, there is a strong demand in storing rice as brown rice instead of rough rice for saving space and energy before milling. However, the short shelf life of brown rice has been a significant concern. The effective and economic way to extend the shelf life of brown rice is to inactivate the lipase enzyme to minimize the lipid oxidation, which cannot be achieved by currently used hot air drying. Infrared (IR) drying has been reported that it effectively inactivated the lipase enzymes during rough rice drying. This chapter summarizes the mechanism of IR heating, IR emitter types, advantages of IR drying and investigations performed on IR drying of rough rice and parboiled rice, and its influence on the milling yield, quality and storage characteristics of rough rice, brown rice and rice bran. The IR drying resulted in high drying rate, good milling quality, effective disinfestation and disinfection of rough rice and improvement in shelf life of both rough and brown rice due to partial lipase inactivation in the bran layer. IR dried rice can be stored in brown rice form at ambient temperature with even longer shelf life than that of rough rice dried with ambient and hot air. The rice bran from milling of IR dried rice has sufficient shelf life for further value-added utilization without need for additional stabilizing treatment.