Utilization of an innovative vegetable source (chickpea aquafaba) in the formation and stabilization of capsaicin encapsulation

Abstract: Aquafaba, the by-product of boiling chickpeas in water, is often seen as food waste. It contains heat-stable proteins, polysaccharides, and self-assembled nanoparticles, and could be a sustainable natural-coating agent as the potential replacement for animal-origin emulsifiers and/or synthetic surfactants. The use of aquafaba as an encapsulation and emulsifying agent for health-promoting bioactive compounds such as capsaicin, the active component of chili peppers, has not yet been demonstrated. This study aims to evaluate the feasibility of utilizing chickpea (British Kabuli) aquafaba to produce encapsulated capsaicin systems by assessing its stability and improving the in-vitro release and bioaccessibility of capsaicin. To this end, British Kabuli chickpeas were used to produce aquafaba following steps: soaking (16h.,~4°C, 1:4 chickpea:soaking water) followed by cooking (20min, ~113°C, 10PSIG, 1:5 chickpea:cooking water). The protein composition of aquafaba was 16.06±0.43% (dwb) and the total carbohydrate content was 81.42±4.43% (dwb). The monosaccharide composition was evaluated by ion-exchange chromatography, comprised of D-glucose and D-galactose. Capsaicin oleoresin-loaded oil-in-water emulsions (1% v/v oil phase) were prepared with three oleoresin types (capsicum 6%, chili bird’s eye, and chili ancho) by Panda homogenization at 600bar with 2 passes. The capsicum 6% oleoresin-loaded emulsions were the most stable during storage (particle diameter at day 0= 282.7±5.7nm and day 28= 310.0±5.0nm) while chili ancho oleoresin-loaded emulsions showed the lowest stability (at day 0= 564.9±36.0nm and day 28= 689.0±42.0nm). The zeta potential values varied within a narrow range between -23.8±1.0 (Day 0) and -25.8±0.6mV (Day 28). Our results provide evidence that aquafaba has the capacity to be used as a wall material for capsaicin encapsulation. This work contributes to the existing understanding of the use of plant-based functional ingredients as replacers for animal and conventional hydrocolloids. Future studies based on the present findings will expand into the in-vitro, bioactive, and sensory properties of the addressed system.