Effects of High Pressure Processing and Ultrasound-Assisted Extraction on Physicochemical Properties, Antioxidant Activity and Flavor Compounds of Cold Brew Citri Reticulatae Pericarpium Beverage

High pressure processing (HPP) and ultrasound-assisted extraction (UAE) can effectively shorten extraction time and increase extraction efficiency of the cold brew (CB) process. However, their application in CB citri reticulatae pericarpium (CRP) and the underlying mechanisms of flavor modulation remain poorly understood. In this study, CB-CRP beverage was prepared with HPP-assisted, UAE-assisted, and HPP+UAE-assisted extraction from 1, 3, 5, and 10 years CRP. Results revealed that the total soluble solids (TSS), total sugars, flavonoids, polyphenols, and volatile organic compounds (VOCs) and antioxidant activity of CB-CRP increased after assisted extraction. The combined application of HPP and HPP+UAE-assisted extraction exhibited the most pronounced effects. The kinds and total content of VOCs of CB beverages prepared from 10-year-aged CRP increased from 45 to 81, and from 2.44 to 5.98 μg/mL, respectively. Moreover, the combined HPP+UAE extraction promoted the enrichment of fatty and woody aroma-related compounds, which drove a shift in the flavor profile from fresh to a richer woody type. And this endowed the CB-CRP water with a more complex and multidimensional aroma profile.