Thesis (M.Sc.)--Chulalongkorn University, 2013

This research was aimed to develop microcapsules from mulberry leaf extract using polymer-polymer interaction method. Firstly, the extraction of antioxidants from mulberry leaves was determined using 4 concentrations of ethanol (50%, 60%, 70% and 95% v/v). It was found that 60% ethanol extract (60EM) had total phenolics content of 122.21 mg GAE/g dried leaves and antioxidant properties (using FRAP and DPPH) of 51.83 and 10.45 mmol trolox/g dried leaves, respectively. These values were significantly higher than those in other extracts. In determination of type of flavonoids using LC-MS, it was found that mulberry leaves extract contained rutin, quercetin, isoquercetin, quercetin glucoside, quercitrin and astragalin. The suitable core material in encapsulation process by polymer-polymer interaction method was then determined. Coating materials were a combination of soy protein isolate (SPI) and low methoxyl pectin and core materials were 60EM and 95EM. The result presented that encapsulation efficiency and total phenolics content of microcapsules from 60EM and 95EM was not significantly different (p > 0.05). Therefore, both extracts were used for study the suitable final pH of mixed solution (3.5, 4.0 and 4.5) in polymer-polymer interaction process. It was found that microcapsules from 60EM with pH adjusted to 4.0 showed 50.29% encapsulation yield with 13.55% encapsulation efficiency. Total phenolics content was 57.04 mg GAE/g microcapsules, antioxidant properties was 25.20 mmol trolox/g microcapsules (FRAP) and 12.68 mmol trolox/g microcapsules (DPPH). Amount of rutin and quercetin was 0.49 and 6.24 × 10-3 mg/g microcapsules, respectively. The antioxidant activities of this condition were significantly higher than those in microcapsules produced using other conditions (p ≤ 0.05). This condition was used for study the suitable concentration of coating materials (SPI and pectin) in microcapsules production. The concentration of SPI and pectin was varied in 3 values (2.5, 5.0 and 7.5% w/v) at a 1:1 ratio. It was found that microcapsules produced by using 7.5% w/v of SPI and 7.5% w/v pectin gave encapsulation yield of 69.52%, encapsulation efficiency of 15.22%, total phenolics content of 73.37 mg GAE/g microcapsules. Antioxidant activities was 27.71 mg trolox/g microcapsules, for FRAP and 20.13 mg trolox/g microcapsules, for DPPH. The antioxidant activities of this condition were significantly higher than those in microcapsules produced using other concentrations of coating materials (p ≤ 0.05).