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Research Project: New Sustainable Processing Technologies to Produce Healthy, Value-Added Foods from Specialty Crops

Location: Healthy Processed Foods Research

Title: Simultaneous rough rice drying and rice bran stabilization using infrared radiation heating

item WANG, TIANXIN - University Of California
item KHIR, RAGAB - University Of California
item Pan, Zhongli
item YUAN, QIPENG - Beijing University Of Chemical Technology

Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2016
Publication Date: 12/24/2016
Citation: Wang, T., Khir, R., Pan, Z., Yuan, Q. 2016. Simultaneous rough rice drying and rice bran stabilization using infrared radiation heating. LWT - Food Science and Technology. 78:281-288. doi:10.1016/j.lwt.2016.12.041.

Interpretive Summary: The research indicates that the IR heating and tempering treatments showed a promising potential to achieve an effective stabilization for rice bran during storage after milling. The IR heating of rough rice to 60 'C followed by tempering treatment for 4 or 5 h resulted in significant reduction in lipase activity, particularly for rice with high initial MC. Consequently, the storage time of stabilized rice bran with free fat acid concentration of less than 10% could be extended to 38 days under two-pass drying compared to 7 days for the control. The new drying method should bring significant economic benefit to the rice industry when it is applied.

Technical Abstract: The objective of this study was to develop a new rice drying method by using IR heating followed by tempering. Freshly harvested medium grain rice (M206) samples with different initial moisture contents (IMCs) were used in this study. The samples were dried for one- and two-passes by using a catalytic IR emitter to reach a rice surface temperature of 60 ºC. After IR heating, the samples were tempered in an incubator at 60 ºC for different durations ranging from 1 to 5 h. The effects of new drying method on moisture removal, total rice yield (TRY), head rice yield (HRY), whiteness index (WI), and shelf life of rice bran were evaluated. Results showed that high heating and drying rates and good milling quality of rough rice were achieved. It took only 55 s to heat the rice samples to 60 ºC. For one-pass drying and 4 h tempering treatment, the total moisture removals were 3.33%, 3.78% and 5.89% points for samples with initial moisture contents of 20.06%, 25.53% and 32.50% (d.b.), respectively. The total moisture removal by two-pass drying was 12.2% points for samples with an IMC of 32.50%. IR heating did not generate adverse effects on TRY and HRY. Importantly, the storage stability of rice bran from the new drying method was extended to 38 days compared to 7 days based on the current drying practice.