Scientific Study

BACKGROUND: Changes in polyphenols have important effect on quality (especially color) and health benefits of dried apricots. SO2 concentration, storage and the activities of polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were the factors which had significant effects on polyphenols. Polyphenol profile and activities of PPO and PAL in sulfured dried apricots (SDAs, 0, 451, 832, 2112 and 3241 mg SO2 /kg) were monitored during storage at 4, 20 and 30 °C for 379 days for the first time. RESULTS: Even the lowest SO2 concentration (451 ​​mg/kg) was sufficient to inactivate PPO during entire storage period. However, while SO2 led to the increase in PAL activity of the samples (r = 0.767) before storage, PAL activities of SDAs decreased during storage. After 90 days of storage, PAL activity was determined in only non-sulfured dried apricots (NSDAs) and dried apricots containing 451 ​​mg SO2 /kg. Although major polyphenol in NSDAs was epicatechin (611.4 mg/kg), that in SDAs was chlorogenic acid (455-1508 mg/kg), followed by epicatechin (0-426.8 mg/kg), rutin (148.9-477.3 mg/kg), ferulic acid (23.3-55.3 mg/kg) and gallic acid (2.4-43.6 mg/kg). After storage at 30 °C for 379 days, the major polyphenol in SDAs was gallic acid (706-2324 mg/kg). However, the major polyphenol in NSDAs did not change after storage. The highest total polyphenol content was detected in SDAs containing 2112 mg SO2 /kg and stored at 30 °C. CONCLUSION: To produce dried apricots having high polyphenol content, ca. 2000 mg SO2 /kg should be used. Low storage temperature (<30 °C) was not necessary for the protection of polyphenols.