Microencapsulation of glutathione through water/oil emulsification and complex coacervation: Improved encapsulation efficiency, physicochemical stability, and sustained release effect.

The feasibility of preparing microcapsules of water-soluble ingredient via complex coacervation was explored. Gelatin and gum arabic were used as wall materials to encapsulate glutathione (GSH) through water in oil (W/O) emulsion. Soy lecithin at a concentration of 3 % (w/w) was used as an emulsifier, and the aqueous phase containing 15 % GSH (w/w) was emulsified with soybean oil at a ratio of 5:5 (w/w), which resulted in a stable W/O emulsion. Furthermore, GSH microcapsules produced under optimal conditions, core/wall ratio 1:1, wall material content 1 % (gelatin: gum arabic = 1:1), stirring rate 400 r/min, added 0.25 g glutamine transaminase (TGases) per gram of gelatin, exhibited good morphology, high encapsulation efficiency and yield, which being 92.88 % and 92.10 %, respectively. After comparing the effects of four different oil emulsions on the microencapsulation of GSH, it was found that all had excellent encapsulation efficiency, indicating that no specific oil phase was required for emulsions preparation. GSH microencapsulation by complex coacervation significantly enhanced its stability, reduced the loss ratio of GSH by 23.5 % when capsules were heated at 150 °C for 2 h. Moreover, GSH microencapsulation increased its retention by 23.25 % and 43.88 % during capsules storage at 40 °C and under light exposure, respectively. In addition, GSH microcapsules effectively prevented its degradation during simulated gastrointestinal digestion induced by salivary amylase, pepsin and acidic environments, while rapidly released GSH under trypsin and alkaline environments. This study provided new insights into water-soluble ingredients microencapsulation and its efficient application in the food and nutraceutical industries.