This article presents the results of numerical simulation and experimental study of a multi-pin electrohydrodynamic (EHD) dryer. Combined effect of EHD flow and the external air cross-flow on drying performance was investigated with 3-D numerical model, which accounts for electric field, electric charge transport, external air cross-flow and material-gas moisture transport. Effect of cross-flow air stream on drying was positive in the range of low velocities, changing to negative at high velocities due to counteracting with EHD flow. Numerical simulation predicted previously unknown effect of EHD flow on the cross-flow air stream, which was quantified as an increase of airway resistance. This prediction was fully validated by experiments. Both numerical simulation and experiment proved that for given intensity of EHD flow there is an optimum value of the cross-flow, resulting in maximum drying performance. The numerical model can be applied to determine the optimal operating parameters for multi-pin EHD dryer.

The trypsin inhibitor (TI) is one of the most important anti-nutritive elements in soybeans. As a new nonthermal technology, dielectric-barrier discharge (DBD) cold plasma has attracted increasing attention in food processing. In this research, we investigated the effect of dielectric-barrier discharge (DBD) plasma treatment on soybean trypsin inhibitor content and its structure, evaluated TI toxicity and the safety of its degradation products after treatment with DBD technology in vitro and in vivo, and applied the technology to soybean milk, which was analyzed for quality. Using the statistical analysis of Student’s t-test, the results demonstrated that DBD plasma treatment significantly decreased the content of TI (33.8 kV at 1, 3, or 5 min, p < 0.05, p < 0.01, p < 0.001) and destroyed the secondary and tertiary structures of TI. TI was toxic to Caco-2 cells and could inhibit body weight gain, damage liver and kidney functions, and cause moderate or severe lesions in mouse organ tissues, whereas these phenomena were alleviated in mice treated with degradation products of TI after DBD plasma treatment under the optimal condition (33.8 kV at 5 min). The content of TI in DBD-treated soymilk was also significantly reduced (p < 0.001), while the acidity, alkalinity, conductivity, color, and amino acid composition of soymilk were not affected, and there were no statistical differences (p > 0.05). In summary, DBD plasma is a promising non-thermal processing technology used to eliminate TI from soybean products.

The disinfection of recirculating nutrient solution is essential to avoid disasters due to the dispersal of pathogens in closed soilless culture systems. This work presents the development of a new technique to perform disinfection, based on pulsed electric field (PEF) treatment. Hoagland solution inoculated with Fusarium oxysporum was selected as the specimen to verify the effectiveness of PEF treatment. The results indicate that PEF deactivated most of Fusarium oxysporum in nutrient solution within a few seconds with the maximum disinfection efficiency achieved being 99.84%. The disinfection efficiency became higher with the extending of treatment time or the increase of PEF strength, while the initial microbial density was proven to play no role. Temperature rise indicates that PEF treatment played the dominant role in the process of disinfection. The energy-efficiency depends mainly on treatment time and electric-field-intensity. The optimal operating conditions were found to be: treatment time less than 10 seconds and electric field strength around 5 kV/cm. This investigation imply that, in the future, the PEF treatment has the potential to be applied to disinfect nutrient solution.