Quality change during high pressure processing and thermal processing of cloudy apple juice

This work evaluates the impact of high pressure processing (HPP; 600 MPa, 3 min) on apple (Pink Lady, Granny Smith and Jonagold) juice quality changes compared to thermal processing (TP; P8.3°C 85°C =5min). This comparative study was performed by integrating both an untargeted headspace-GC-MS fingerprinting and targeted approach to analyze the volatile fraction and a priori selected quality attributes (color, sugars, acids and enzymes) respectively. A significant higher total color difference (ΔE* >6.0) was determined for thermally treated juice. Polyphenol oxidase and peroxidase can be inactivated below detection limits by TP, while residual activity (>50%) was detected after HPP. Sugars and acids were almost not affected nor by HPP nor by TP. Using the untargeted fingerprinting approach, aldehydes, alcohols, ketones and organosulfur were detected in higher amounts after TP compared to untreated and HPP treated samples, which could be linked to the Maillard reaction and oxidative reactions. In general, the overall quality of HP treated apple juices is much more comparable to that of the fresh juice, in particular HPP results in lower amount of thermally induced compounds that are related to cooked notes of pasteurized apple juices.