OXI-013: Evaluation of the Oxidative Stability of a Bigel System using Natural Antioxidants

Bigels are a new solid-like formulation produced from the combination of an oleogel and a hydrogel. They are semi-solid structured systems with a lipophilic phase and a hydrophilic phase. Interest in this type of system has increased due to its high potential to be a fat substitute in food. However, the bigel composition, mainly of polyunsaturated oil, can significantly affect oxidative stability during processing and storage. Therefore, this study aimed to evaluate the antioxidant effect of gallic acid, ascorbic acid, and astaxanthin on the oxidative stability of a bigel (oleogel/microcapsule) system. The bigel was prepared with an oleogel (beeswax/shellac waxed 70/30 (% w/w) and linseed oil) mixed with microcapsules (sodium alginate/shellac dewaxed 95/5 (% w/w) and sunflower seed oil) in a proportion of 80/20 (% w/w), respectively. Astaxanthin was incorporated into the lipid phase, and gallic acid and ascorbic acid into the hydrophilic phase of the microcapsules. The effect of each antioxidant on oxidative stability was evaluated using the Rancimat test (induction time) and lipid oxidation using the peroxide index. The oxidative stability of bigels reached 2.50±0.35 without antioxidants (control), 3.36 ± 0.19 h with astaxanthin, 2.76 ± 0.29 h with gallic acid, and 3.82 ± 0.13 h with ascorbic acid. The bigel with astaxanthin and ascorbic acid showed a significant difference (p<0.05) compared to the control, increasing the induction time by 0.86 h and 1.32 h, respectively. The peroxide index of the bigels was 4.750± 0.004 meq O2/kg for the control, 3.755 ± 0.004 meq O2/kg with astaxanthin, 1.361 ± 0.002 meq O2/kg with gallic acid, and 1.925 ± 0.056 meq O2/kg with ascorbic acid. All the antioxidants significantly reduced (p<0.05) the oxidation of the bigels during the manufacturing process. According to these preliminary results, hydrophilic antioxidants indicate promising applications in this novel structured oil based on oleogels and hydrogels as microcapsules with an antioxidant delivery system.