| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 104 === (－)-Hydroxycitric acid [(2S, 3S)-HCA] exists mainly in Garcinia. It has been found to be an inhibitor of lipogenesis. Hibiscus sabdariffa L. also contains abundant of HCA with different structure, (2S, 3R)-HCA, which is able to inhibit the activities of pancreatic α-amylase and small intestine α-glucosidases. However, it has been reported that overintake of HCA might be hazardous to humans. Recently, more and more HCA containing health food appears in the market. However, study is still rare about the extraction and determination of hydroxycitric acid in health food. The purpose of this study is to investigate the best method for extracting HCA from health food by the use of ultrasonic extraction, microwave extraction, and water-bath extraction, as well as to establish a high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method for determining the content of HCA in health food. HCA was determined by using an InertSustain® C18 column along with UV detection under 210 nm. The mobile phase of 0.2% phosphoric acid solution was used to avoid the dissociation of HCA. The health food was extracted by using ultrasonic extraction (for 10, 20, 30, and 60 minutes), microwave extraction (with 100, 200, 400, 600, 800, and 1000 W for 1 and 2 minutes), and bath-water extraction (at 60 and 80℃ for 30 and 60 minutes), respectively. By using water-bath extraction at 60℃ under the ratio of 1：75 (g/mL) for 30 minutes,and using the best result for extraction was obtained 20% ammonia to clean up the sample at the solid phase extraction (SPE) stage. The limit of detection of HCA of health food was 0.57 μg/mL, and the recoveries were from 81 (± 20) to 101.2 (± 0.2)%.
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