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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 drying and decontamination of rough rice using combined pulsed light and holding treatment

Author
item Wang, Bei - University Of California
item Khir, Ragab - University Of California
item Pan, Zhongli
item El-mashad, Hamed - University Of California
item Wood, Delilah - De
item Mahoney, Noreen
item Wu, Bengang - Jiangsu University
item Ma, Haile - Jiangsu University
item Xingrong, Liu - Jiangsu University

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2015
Publication Date: 10/13/2015
Citation: Wang, B., Khir, R., Pan, Z., El-Mashad, H., Wood, D.F., Mahoney, N.E., Wu, B., Ma, H., Xingrong, L. 2015. Simultaneous drying and decontamination of rough rice using combined pulsed light and holding treatment. Journal of the Science of Food and Agriculture. 96(8):2874–2881. doi: 10.1002/jsfa.7458.

Interpretive Summary: Rice as one of the most important staple foods worldwide can be easily infected with fungi in the field and during harvest. Chemical disinfection treatment (e.g., using calcium hypochlorite) is widely used in developing countries. However, shortcomings such as presence of chemical residue, insufficiency of disinfection and hazard to workers make an increasing demand to develop new methods to assure the food safety of rice. Generally, drying is the most common way to prevent the growth of fungal spores by reducing rice moisture content. The convective drying process is normally not able to inactivate the Aspergillus flavus (A. flavus) due to the relative low air temperature. Pulsed light (PL) technology has been proven effective in reducing the microbial population on food surface using intense light pulses with broad spectra. With the synergy of these spectra, the cell wall and nucleic acid structure of microorganisms are destroyed in a few seconds. However, thermal effect of PL is a limiting factor for its application. Appropriately use the thermal effect of PL may achieve a simultaneous disinfection and drying effect. The obtained results revealed that the combined PL and holding treatment had good potential for successful application in the rice industry to simultaneously achieve disinfection and drying.

Technical Abstract: Pulsed light (PL) technology has been proven effective in food disinfection. However, increasing the light intensity or treatment time could swiftly increase the temperature of the food product. Using the thermal effect in an appropriate way may achieve a simultaneous disinfection and drying effect. The objective of this study was to investigate the feasibility of simultaneous disinfection and drying of rough rice using PL and holding treatment. Freshly harvested rice samples were inoculated by Aspergillus flavus (A. flavus) and treated using PL under different intensities and durations followed by holding treatment. The PL treatment under intensity of 1.08Wcm-2 for 21 s led to a reduction of 0.29 log cfu/g on the population size of A. flavus spores. After holding treatment, a 5.2 log cfu/g reduction was achieved. The corresponding total moisture removal reached 3.3% points. No adverse effect on milling quality was detected after the treatment.