Organic Acid Analyses of Sweet Carambola Pickling Brines by Reverse Phase High Performance Liquid Chromatography

• Main Authors: Pin-Kuang Chen, 陳品光
• Other Authors: Ming-Jen Sheu
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/84389160565499853104

碩士 === 國立臺灣大學 === 園藝學研究所 === 96 === We set up a qualification and quantification analytical method to test 8 organic acid in sweet carambola pickling brines, including acetic, lactic, succinic, malic, oxalic, fumaric, tartaric and citric acids. Malaysia and Red Dragon sweet carambola were pickled with 7% salt for 62 days; the exudates were taken and analyzed 20 times during the pickled process. The results showed that carambola has high content of oxalic acid，the pKa value is extremely low. The optimum analytical method of HPLC was 99% pH 2.70 phosphorus buffers as mobile phase and 1% methanol, and the analytical time was 12 min. We analyze real sample without purification found that strong matrix effect at UV210 nm, affect plurality of some peaks so we cannot detect tartaric, lactic, acetic, citric and succinic acids. Ascorbic acid also has high content in sweet carambola pickling brines; the retention time closed to lactic acid and covered the signal of lactic acid. After analyzed the organic acid in sweet carambola pickling brines during the pickled process; oxalic, malic, ascorbic and fumaric acids content of Malaysia carambola in the first day respectively is 1598 ppm, 1249 ppm, 87 ppm, 6 ppm. The highest content of organic acids in the 12th day respectively is 10301 ppm, 3800 ppm, 678 ppm, 26 ppm. The organic acids content decreased slowly to the 62th day respectively is 8580 ppm, 2912 ppm, 630 ppm, 18 ppm. Oxalic, malic, ascorbic and fumaric acids content of Red Dragon carambola in the first day respectively is 1813 ppm, 1197 ppm, 95 ppm, 3 ppm，. The highest content of organic acids in the 12th day respectively is 8149 ppm, 4771 ppm, 408 ppm, 29 ppm. The organic acids content decreased slowly to the 62th day respectively is 8132 ppm, 3969 ppm, 366 ppm, 28 ppm. We try to improve separation of tartaric, lactic, acetic, citric and succinic acid peaks by ion-pair method. The HPLC analytical method of ion-pair was 90% pH 7.00 phosphorus buffers as mobile phase and 10% organic phase (ACN : MeOH = 1 : 1), with 0.005 M TBA as counter ion. Detected organic acid at UV 210 nm, separation of acid peaks was improved by the ion-pair method. The proper ion-pair method in real sample needed the advanced testing.