Radiant heat treatments for corn drying and decontamination

Abstract

Freshly harvested corn at moisture content of 24% wet basis (w.b.) was intermittently dried with infrared (IR) at intensities 2.39, 3.78, and 5.55 kW/m2 for 30, 50, and 180 s to safe storage‐moisture content of 13% (w.b). Microbial load reduction, energy use and corn sensory and pasting qualities were evaluated. Experiments were carried out at product‐to‐emitter gap size of 450 mm. Increasing IR intensity from 2.39 to 5.55 kW/m2 resulted in average microbial load reductions of 2.6 and 2.9 log CFU/g at 180 and 30 s of intermittent IR heating, respectively. IR treatments reduced corn paste viscosity and stress cracks (p < .05), but insignificantly impacted corn color (p > .05). Drying corn to storage‐moisture content with IR intensities 2.39 and 5.55 kW/m2, required 7.5 and 15.0 MJ/kg of water removed, respectively. Accelerated, Scaled‐up IR drying and decontamination was achieved without affecting the corn quality; optimized treatments could potentially improve throughput and energy efficiency. Practical applications Freshly harvested, high moisture content corn must be dried within short duration to about 12–14% (w. b.) to prevent mold growth and preserve the overall corn quality. This research presents the following practical applications: Scaled up infrared (IR) treatment of corn with efficacy to significantly reduce drying time (9 to 22 min depending on infrared intensity and intermittent IR drying duration to dry freshly harvested corn at moisture content 23–13% wet basis). Capability of using intermittent IR heating to combine corn drying and decontamination in a single step while maintaining the quality of finished product. Potential of IR heating to inactivate heat resistant, mycotoxin‐producing mold spores that are liable to survive conventional drying methods.

Impacts of broadband and selected infrared wavelength treatments on inactivation of microbes on rough rice

“…Likewise, low intensities of the selected IR wavelengths showed significant reduction in mold load after incorporating a tempering step. In agreement with the current result, Wilson, Okeyo, et al (2017) reported that IR treatment of corn followed by tempering at 50 C for 4 hr resulted in 3.8-4.5 log CFU/g of mold reduction. However, statistical analysis showed that there was no interaction effect (p > .05) between intensity of both broadband and selected IR after incorporating a tempering step.…”

“…IR heating has been linked with the merits of higher energy transfer rate, shorter duration of drying, milder environmental footprints, and better or comparable product quality than convective heated air treatments (Wang et al, ). In addition, IR heating has the potential to simultaneously dry and inactivate microbes and their spores on grains (Khir, Pan, Salim, Hartsough, & Mohamed, ; Pan et al, ; Tanaka et al, ; Wang et al, ; Wilson, Okeyo, Olatunde, & Atungulu, ; Yang et al, ). For industrial application purposes, IR energy emission can be realized through design of IR emitters such as catalytic or ceramic emitters.…”

“…Although many previous studies have mainly employed the use of broadband IR wavelength (wavelength that ranges between a specific limit), there is possibility that not all the wavelengths will be effective in inactivating microbes. It may be beneficial to use a narrower IR waveband in order to increase the potency of IR to inactivate microbes and also to save energy (Wilson, Atungulu, & Olatunde, ; Wilson, Okeyo, et al, ).…”

“…IR heating supplies a high heat flux to the surface of treated product. For grains treatment, the IR heat dissipated on the surface of the grain may lead to case hardening, surface discoloration, or even burning before maximum moisture removal is achieved (Wilson, Atungulu, & Olatunde, ; Wilson, Okeyo, et al, ). These problems may be alleviated by including tempering steps after the IR heating treatment.…”

Physical and Chemical Methods for the Reduction of Biological Hazards in Animal Feeds

“…Irradiation using gamma, ultraviolet (UV), or electron beam radiation has been demonstrated to reduce PEDV load by 3-log (Trudeau et al, 2016). Wilson et al (2015Wilson et al ( , 2016 demonstrated the feasibility of using infrared radiation to decontaminate raw pet food ingredients; depending on initial moisture content of the ingredients, infrared heating intensity, and tempering duration, up to 3-log of mycotoxigenic fungi was reduced.…”