Preparation and characterization of succinic acid deamidated wheat gluten microspheres for encapsulation of fish oil

Succinic acid deamidated wheat gluten (SDWG) microspheres for encapsulation of fish oil (FO) via O/W/O double-emulsion followed by heat-polymerization of emulsified SDWG was reported. Different SWDG concentrations (16.8–67.2 mg/ml) and FO/SDWG ratios (1:3–4:3, w/w) were studied. To optimize the process, particle size and Zeta potential of SDWG–FO emulsion and encapsulation efficiency (EE) of FO were analyzed. The most efficient condition was obtained at 50.4 mg/ml for SDWG and 3:3 (w/w) for FO/SDWG ratio, with an EE of 81.8%. In this condition, confocal microscopy showed FO well encapsulated in SDWG microspheres. Scanning electron microscope (SEM) showed sunken pores and fractures inside microspheres after FO was extracted, confirming the presence of FO in microspheres. FTIR and electrophoresis showed during microspheres formation dramatically elevated SWDG aggregation resulted in intermolecular-crosslinking and enhanced interactions (hydrogen bonds and hydrophobic interactions) between SDWG and FO. In the evaluations of in vitro experiments in simulated gastric fluid and oxidation stability during storage, results indicated that SDWG matrix protected it from both oxygen and gastric fluid, resulting in improved storage stability and release property. Therefore, it is foreseen that SDWG can be used to encapsulate FO or other sensitive nutraceuticals in the applications of supplementation and functional foods.