ACE Inhibitory Rate, Bitterness and Stability of Microencapsulated Extracts of Ginger, Chinese Wolfberry and Gardenia jasminoides

This study obtained mixed alcohol extracts of ginger, Chinese wolfberry, and Gardenia jasminoides by pulverization and ultrasound. Maltodextrin, modified starch, and a mixture of both with gelatin as the composite embedding wall material, and spray dried into microcapsules. The embedding rate, ACE(angiotensin-convertion enzyme) inhibition rate, hygroscopicity, total phenol content(TPC), bitterness degree were determined, and infrared spectroscopy(FTIR), scanning electron microscope(SEM), thermogravimetric analyzer(TGA) were used to study the structure and thermal stability of microencapsulated particles. The results showed that the best wall material of the microcapsules was a 1:1 mixture of maltodextrin and modified starch. At this time, the embedding rate was 75.24%(P<0.05). The infrared spectrum analysis showed that the extract was successfully embedded by the wall material, and forming a starch/dextrin-phenol-gelatin polymers. Compared with non-embedded and single maltodextrin, modified starch embedding, the bitterness of the microcapsules embedded with a 1:1 mixture of maltodextrin and modified starch as the wall material was significantly reduced(P<0.05), and the hygroscopicity was reduced from 52.83 to 16.04 g/(100 g). The release rate of phenols in the microcapsules after gastrointestinal digestion was 69.64%, and the ACE inhibition rate was 49.64%(P<0.05). Thus, modified starch and maltodextrin in weight ratio 1:1 mixing, as the microencapsulated medicinal and food homologous extract of the wall material, could significantly reduce bitterness and improve product stability. After storage at room temperature for seven days, the ACE inhibition rate was still as high as 22.36%.