Physicochemical Characteristics and Antioxidant Activity of Dutch Coffee Depending on Different Extraction Conditions and Storage

摘要

This study was designed to evaluate the changes in the physicochemical properties and antioxidant activity of Dutch coffee (cold brew) under different conditions of extraction and storage. Dutch coffee was extracted fi'om ground coffee soaked in waterat 4 or 20“C and stored for 8 weeks at 4 or 20"C. The storage temperature affected the decline in pH and increase in acidity compared to the extraction temperature. The total phenol content partly decreased during the storage period. As the extractiontemperature increased, the ABTS [2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)] and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activities also increased; in fact, DPPH radical-scavenging activity showed a general increase. As the storage time prolonged, the caffeine content decreased, but the contents of caffeic acid and chlorogenic acid increased. The results for all kinds of samples indicated that the general bacterial count was <1 CFU/mL, which indicated that the coffee can be stored for and consumed within 8 weeks.