• Bigels based on multi-component gelatin-tragacanth hydrogel were successfully formed. • Higher gelatin content enhanced oil binding capacity up to 70% as well as apparent viscosity and viscoelastic properties. • Bigel with higher oleogel content exhibited superior viscoelastic behavior and thermal stability, but lower firmness and gumminess. • Bigels successfully protected both ascorbyl palmitate and ascorbic acid more than 85%, particularly at a higher oloegel content. • Ascorbyl palmitate presented more oxidation stability due to its greater exposure to the oil-water interface. This research focused on developing a novel edible bigel system based on a single-component oleogel and a multi-component gelatin-tragacanth hydrogel for the delivery of hydrophobic and hydrophilic antioxidants. Bigel characterization was first investigated as a function of different hydrogelator ratios (10:90 to 90:10 of gelatin gel to tragacanth gel) to find the best multi-component formulation of hydrogel fraction at a constant hydrogel:oleogel ratio. All bigels exhibited high oil holding capacity (> 65%), which was significantly enhanced as the gelatin gel content increased in the hydrogel phase. Moreover, the viscoelastic properties of the bigels in terms of apparent viscosity and elastic modulus increased at higher gelation gel content. Therefore, the gelatin gel-to-tragacanth gum gel ratio of 90:10 was selected as the hydrogel fraction for further analysis. In the second phase, the potential application of bigels containing 30% and 70% fractions of oleogel for delivery of ascorbic acid (AA) and ascorbyl palmitate (AP) was investigated. Our findings showed that an increase in the oleogel content increased solid-like behavior and ordered structure of the bigel but decreased firmness and gumminess. Bigel with higher oleogel content also presented a minor frequency-dependent behavior and superior thermal stability; however, its elasticity was more compromised at higher temperatures. Bigels successfully protected both AA and AP more than 85% against oxidation during storage, which was substantially enhanced at higher oleogel content. According to oxidative stability results, the more exposure of the oleogel fraction as the continuous phase to the oxygen in the O70:H30 bigel resulted in more oxidation. Additionally, AP was a more effective antioxidant in inhibiting lipid oxidation compared to AA due to its lipophilic nature, contributing to its greater accumulation at the oil-water interface. These findings confirmed the promising potential of bigels to encapsulate hydrophilic and hydrophobic antioxidants to extend food shelf life as well as develop functional foods with diverse textural properties.
Hojjatpanah et al. (2026) studied this question.