Evaluation of sampling and extraction procedures for the analysis of ascorbic acid from pear fruit tissue

A suitable method of extraction of ascorbic acid (AA) and dehydroascorbic acid (DHAA) from Conference pears during storage was developed. Analytes determination was carried out by HPLC with UV detection at 254 nm. Three sampling procedures from fresh fruit and three extraction procedures from frozen tissue were tested. Recovery data were achieved by running at the same time the sample with and without addition of an ascorbic acid standard solution. Results showed that improper sampling procedure from fresh fruit and a storage temperature of frozen samples prior to extraction of -20 degreesC led to AA degradation in pears. Furthermore, small variations in temperature and light exposure during extraction significantly affected ascorbic acid recovery. The final set up procedure, comprising a specific sampling from fresh fruit, a storage temperature of frozen samples of -80 degreesC, and an extraction with 6% meta-phosphoric acid on ice, under reduced light and in a cold room at 2 degreesC, gave the highest AA recoveries. It was easy to perform and had high extraction rates. (C) 2002 Elsevier Science Ltd. All rights reserved.