Development and characterization of a novel bigel system based on candelilla wax oleogel and guar gum hydrogel for heat-triggered release properties

This study introduces an innovative approach for the encapsulation and heat-triggered release of natural pigment, paprika oleoresin (PO) as a model pigment, by formulating oleogel-in-hydrogel bigels incorporating candelilla wax (CW). By varying the CW concentrations, the impact on the critical physicochemical properties of bigels was investigated. Increasing CW concentration from 2 to 8% elevated the sol-gel transition temperature (Tg) of the oleogels significantly, ranging from 45.83 ± 0.83 to 61.38 ± 0.51 °C (p < 0.05). Across all CW concentrations, high encapsulation efficiency over 95% was consistently observed. Conversely, reducing CW concentration increased droplet size within the bigels, varying from 13.19 ± 2.97 to 2.97 ± 0.60 μm (p < 0.05). Notably, these bigels exhibited distinct heat-triggered pigment release characteristics. In specific, the amount of released PO decreased with increased CW concentration, resulting in a lower ΔE* value. Correlation analysis highlighted CW's positive correlation with the Tg of the oleogel and bigel lightness, and its negative correlation with droplet size, cumulative pigment release content, release rate constant, redness, yellowness, and ΔE* of the bigel. These results indicate that controlling pigment release through CW-based bigels with thermoresponsive properties can enhance color stability and preserve the integrity of pigment during heat processing. This novel bigel system with heat-triggered release properties holds promise for wider application in the food industry. Overall, it addresses the critical need to stabilize and precisely regulate natural pigment release, which is important for both product quality and consumer satisfaction in the food industry.