การพัฒนาไมโครแคปซูลเก็บกักสารให้กลิ่นรสจากใบมะกรูดโดยวิธีโคอะเซอร์เวชันเชิงซ้อน

Abstract

Kaffir lime (Citrus hystrix DC.) leaves are one of the major ingredients in Thai food due to their good flavor and strong fragrance. The objectives of this study were to 1) optimize supercritical carbondioxide extraction of kaffir lime leaves 2) compare kaffir lime leaves extract among supercritical carbondioxide, steam distillation and solvent (hexane) extraction 3) develop microcapsules of kaffir lime leaves extract by complex coacervation technique and 4) evaluate shelflife

of microcapsule of kaffir lime leaves extract. Kaffir lime leaves extraction using supercritical carbondioxide with and without ethanol were conducted. A 2 2 factorial in completely randomized design with 2 center points was used to optimize the extraction temperature (40, 60°C) and extraction pressure (15, 25 MPa). Response surface methodology (RSM) was applied to study the effect of extraction conditions on yield of oil, the amount of citronellal, and odor liking scores. The optimum condition of both supercritical carbon dioxide extractions was extraction temperature at 40°C and extraction pressure at 25 MPa. When compare with conventional methods (steam distillation and solvent (hexane) extraction), the extract from supercritical carbondioxide extraction provided higher citronellal content than those of conventional methods. The extract from supercritical carbondioxide with ethanol extraction had higher citronellal content (11.13 mg/g of ground kaffir lime leaves), but lower yield (5.27%) and odor score (6.1) than those of without ethanol extraction (5.28% and 7.0). Therefore, supercritical carbondioxide without ethanol extraction was selected for the further study. There were 13 compounds found in the extract using GC-MS analysis. Citronellal was the most compound founded in crude oil from kaffir lime leaves extract. It was responded for the characteristic aroma of kaffir lime leaves. The olfactive notes of the major components of ground kaffir lime leaves oils are responsible for the fresh, green-citrusy, sweet and slightly woody notes with powerful citrus fragrance. Then, microcapsules of the extract from kaffir lime leaves was developed using complex coacervation technique and freeze-drying technique. A central composite design (CCD) was employed (microcapsule encapsulation condition as level of gelation at 10-30% and arabic gum at 2040%). The optimum condition was encapsulation with gelatin 20% and arabic gum 20% (1:1) and

was used as wall materials. These were mixed with 10% of extract in extra virgin olive oil as core

materials and the ratio of wall materials and core material was 2:1. L*, a*, b*, moisture content, water

activity,

encapsulation efficiency and citronellal were 65.29, -1.90, 51.09, 1.51, 0.250, 80.25 and 20.38 mg/g of microcapsule, respectively. The particle morphology by scanning electron microscopy (SEM) showed that microcapsules were irregular shape and various size. The shelf-life study of kaffir lime leaves extract encapsulated powder using moisture content as a shelf-life indicator was conducted. The shelf-life of kaffir lime leaves oil encapsulated powder, packed in aluminium foil pouch with 9 micrometer thick and kept at 35°C with 75.0% relative humidity was 1,281 days or 3 years and 186 days.