This study investigated the effect of hydrothermal pre-treatment on ferulic acid content and antioxidant activities of corn hydrolysate. The low-grade corn was treated by hot water and autoclaving process at different temperatures and times. The highest phenolic content (471.7±7.4μg FA.mL-1, p＜0.05) was obtained by autoclaving at 121℃ for 90 min. High performance liquid chromatography (HPLC) revealed 277.3±3.2μg.mL-1 of FA, which was 2.05 times higher than that of the control (unheated sample). The high yield of FA obtained here may be due to high-temperature autoclaving eliminating the FA-lignin and FA-polysaccharide bonds. Furthermore, the optimal hydrothermal pre-treatment at 121℃ for 90 min improved the DPPH and ABTS radical scavenging activities by 1.3 and 1.5 fold, respectively, compared to the control. On the other hand, the dextrose equivalent (DE) values obtained from corn hydrolysate at the different heat treatments in this study were in the range of 23.2±0.7 to 28.7±0.9. These results illustrated that autoclaving method showed a promising pre-treatment process to add value of corn hydrolysate product.
The aim of this study was to investigate the effects of salt on the kinetic parameters of thermal protein denaturation of egg constituents. Egg whites and yolks containing different quantities of added salt were analyzed using differential scanning calorimetry (DSC) and dynamic viscoelastic oscillatory measurements. DSC measurements revealed an increase in the denaturation temperatures of the second peaks of egg whites and yolks in the presence of elevated salt concentrations. Given that the activation energy values obtained from the kinetic analysis of egg proteins using dynamic DSC were comparable, we suggest that salt affects not the denaturation rate of the egg protein, but the temperature of denaturation. Dynamic viscoelastic oscillatory measurements revealed that the gel-point temperatures increased with increasing salt concentrations. The elevated gel-point temperatures coincided with the temperature of the maximum denaturation rate calculated using the kinetic parameters.