High-pressure effect on the properties of onion was investigated. The dielectric properties of high-pressure treated onion were measured at 50 Hz- 5 MHz. Radius of Cole-Cole arcs of high-pressure treated samples were smaller than untreated. Radius of treated onion completely disappeared at 400 MPa. This indicated that cell structure would be damaged by high-pressure treatment. Next influences of high-pressure treatment on functional properties were analyzed. Antioxidative activities of high-pressure treated onion at 200 or 400 MPa were increased during storage at 25℃. The constituents of high-pressure treated onion were analyzed by HPLC. Scatter plot between high-pressure treated and untreated peak area ratio (sample peak area/internal standard peak area) were analyzed. Area ratios of untreated samples were plotted on x-axis and those of high-pressure treated were on y-axis according to the retention time. The slope with the retention time of 27.3 min was over 1.0. This indicated that the slope over 1.0 was positive-affected by high-pressure treatment. The ingredient with the retention time of 27.3 min was identified as quercetin. Scatter plot was a novel tool to extract the high-pressure effected substances from multiple and unidentified data. These changes of structural and functional properties of foodstuffs are defined as “High-Pressure Induced Transformation (Hi-Pit).”
Straight-through microchannel (MC) arrays consisting of numerous oblong straight-through holes are promising MC emulsification devices for producing monodisperse emulsions in large droplet-production scales. We investigated the effects of MC dimensions and velocity of a cross-flowing continuous phase on the production of soybean oil-in-water emulsions using straight-through MC arrays made of single-crystal silicon. The aspect ratio of oblong MCs with equivalent diameters of 21μm to 22μm significantly affected droplet generation and the sensitivity of droplet size to continuous-phase velocity. Uniform oil droplets with diameters of about 100μm and coefficients of variation of less than 3% were generated using large oblong MCs with equivalent diameters of 54μm to 55μm. Data analysis demonstrated that oblong MCs with aspect ratios exceeding a threshold of 3 were necessary to generate uniform oil droplets in a wide range of MC cross-sectional sizes. Moreover, the cross-flow of the continuous phase did not affect the size of the droplets generated using oblong MCs with a large aspect ratio.