Antioxidant efficacy of thymol and carvacrol in microencapsulated walnut oil triacylglycerols

Antioxidant efficiency of thymol and carvacrol in walnut oil triacylglycerols (WO-TAGs) was investigated. WO-TAGs alone or fortified with thymol/carvacrol were emulsified with sodium caseinate-lactose mixture. Oxidative stability of freeze dried emulsions was assessed via Rancimat and accelerated oven tests. Bulk WO-TAGs with and without thymol/carvacrol were also tested for comparison. Higher induction periods (IPs) were recorded for encapsulated and antioxidant fortified WO-TAGs compared to non-encapsulated and non-fortified counterparts. IP of thymol included and encapsulated WO-TAGs were found to be 1.5–2 fold higher than that of carvacrol at all concentrations (0.05–0.20%). IP of WO-TAGs was increased dose-dependent manner in the case of thymol and the highest protection was obtained with 0.20% thymol concentration (p < 0.05). Peroxide formation in bulk WO-TAGs fortified with carvacrol showed a slightly higher oxidative stability compared to thymol after 24 d of storage whereas thymol was a bit more effective in encapsulated WO-TAGs.