Protective effect of gallic acid on the thermal oxidation of corn and soybean oils during high temperature heating

Improving the physicochemical quality and oxidative stability of deep-fried pork meatballs by coating with chitosan grafted gallic acid

The objective of this research was to examine the effectiveness of chitosan (CH)-gallic acid (GA) conjugate (CH-g-GA) as an edible coating in improving the physicochemical properties and oxidative stability of deep-fat fried pork meatballs. The meatballs were coated with either CH alone, a combination of CH and GA, or CH-g-GA before being fried at 180 °C for 5 min. The viscosity of the coating solutions influenced the amount of coating picked up by the meatballs, with higher viscosity coatings showing increased pickup. The application of chitosan-based coatings in deep-fried meatballs resulted in a decrease in moisture loss and oil uptake, as well as decreased b* values and hardness, while maintaining consistent cooking yield. Furthermore, compared to the control group, the chitosan-based coatings treatment significantly increased the ratio of immobilized water and decreased the ratio of free water (P < 0.05), as well as effectively inhibited lipid oxidation in deep-fried meatballs (P < 0.05). Among the different coatings tested, CH-g-GA coating exhibited the highest effectiveness. The research findings suggest that the CH-g-GA edible coating has significant potential in enhancing the overall quality of deep-fried meatballs.

Frying Performance of Gallic Acid and/or Methyl Gallate Accompanied by Phosphatidylcholine

This study shows the possibility of using gallic acid (GA) and/or methyl gallate (MG) accompanied by phosphatidylcholine (PC) instead of tert-butylhydoquinone (TBHQ) for frying purposes. The antioxidants and PC were added in the concentrations of 1.2 mM and 500-2000 mg/kg, respectively. Oxidative stability index (OSI) and the kinetics of change in conjugated dienes (LCD), carbonyls (LCO), and acid value (AV) were used to assess the antioxidative treatments. GA alone and GA/MG (50:50) plus PC at 2000 mg/kg yielded the same OSI as that of TBHQ (18.4 h). The latter was of the highest frying performance in preventing the formation of LCD (rn = 0.0517/h and tT = 10.6 h vs. rn = 0.0976/h and tT = 4.5 h for TBHQ), LCO (rn = 0.0411/h and tT = 12.7 h vs. rn = 0.15/h and tT = 4.3 h for TBHQ), and hydrolytic products (AVm = 37.8 vs. 24.0 for TBHQ); rn: normalized the maximum rate of LCD/LCO accumulation; tT: the time at which the rate of LCD/LCO accumulation is maximized; AVm: quantitative measure of hydrolytic stability.