Kinetics of chemical deteriorations over the frying protected by gallic acid and methyl gallate

The present work shows the possibility of use of gallic acid (GA) and methyl gallate (MG) as natural antioxidants replacing the powerful synthetic antioxidant TBHQ in frying process. Oxidative stability index (OSI) and the kinetics of change in lipid-peroxidation conjugated dienes (LCD), carbonyls (LCO), and acid value were adopted for the evaluation purposes. GA alone (1.2 mM) and in combination with MG (75:25) provided OSI values comparable to that of TBHQ (18.5–19.0 h). The GA/MG 75:25 exerted a frying performance quite better than TBHQ (r(n) = 0.1351 vs. 0.1784 h(−1)) in preventing the LCD formation. From the LCO formation standpoint, the GA/MG 75:25 (r(n) = 0.0758 h(−1)) and then MG (r(n) = 0.1004 h(−1)) provided better performances than TBHQ (r(n) = 0.1216 h(−1)). Lipid hydrolysis was also inhibited well by GA (AV(m) = 8.6) and GA/MG 75:25 (AV(m) = 7.9), respectively (AV(m) = 9.2 for TBHQ).