Effect of starch gelatinization on the morphology, viscoelasticity, and water structure of candelilla wax–canola oil–starch hybrid gels

Abstract

Hybrid gels (HG) were prepared using candelilla wax (CW, 5 g), canola oil (CO, 100 g), and native corn starch (N), in 20:80, 40:60, and 60:40 weight ratio (CW), respectively, and water (W, 45:1 weight ratio with respect to N). In method M1, CW/CO/N were heated (90°C, 15 min) and then mixed with W. N gelatinization was incipient. In method M2, CW/CO and N/W dispersions were heated (90°C, 15 min) by separate, and then mixed. N was completely pre-gelatinized (P). Starch was mainly dispersed within the oily phase in the HGs made by M1, whereas it was dispersed in water when made by M2. In all HGs, the aqueous phase was dispersed in the oily continuous phase. Higher stability against phase separation was shown by HGs made with P than with N. FTIR analysis showed that CW esters interacted with water molecules providing interfacial stabilization. The HGs rheological properties were modulated by varying P contents. Practical applications Hybrid gels are complex multi-colloidal systems which potentially offer many advantages over other semi-solid formulations, including greater stability, use as carriers/controlled release systems for bioactives, and as saturated fat replacers in foods. This work provides the basis for formulating stable hybrid gels using GRAS materials (candelilla wax, corn starch, canola oil, and water) and a simple manufacturing procedure, where the physicochemical properties can be modulated by varying the relative amount of pre-gelatinized starch with respect to the other ingredients in the formulation.