Volatiles, descriptive sensory profiles as well as consumer acceptance and preference of juices from red-fleshed ‘Weirouge’ apples produced in 2019 and 2020 with three different dejuicing systems were assessed. HS–SPME–GC–MS analyses revealed differences in the profiles of volatiles in juices processed in an oxygen-reduced atmosphere with an innovative spiral filter press as compared to those obtained using conventional systems, i.e., horizontal filter press and decanter. A total of 49 volatiles was tentatively assigned and permitted a clustering of the samples according to vintage and processing technology by multivariate statistics. Tentative markers to differentiate the individual samples were deduced from the multivariate models. In both years, each three 1,3-dioxanes and C 6 alcohols were revealed as discriminative markers of horizontal filter pressed juices. Descriptive sensory analysis by trained panelists revealed higher intensity scores of ‘oxidized’ and ‘apple-like’ orthonasal odors in juices produced by horizontal filter press and decanter as compared to those obtained by spiral filter press. The visual appearance of the spiral filter pressed juices was significantly higher rated compared to those obtained by conventional pressing systems as revealed by an untrained consumer panel ( n = 65). In contrast, both odor and taste were lower rated, ultimately resulting in a clear-cut higher acceptance and preference of the decanter-made juices, followed by those obtained by horizontal and spiral filter press.

Blackcurrant juices were produced with an oxygen-excluding spiral filter press and two conventional pressing systems exerting common oxygen exposure at pilot plant scale (200 kg) in technological duplicate in two subsequent years ( n = 4). In contrast to findings on previously studied fruits, contents of total and individual anthocyanins were not significantly higher after spiral filter (1636–1872 mg/L) than after conventional pressing (1529–2083 mg/L). During storage for 52 weeks at 4, 20 and 37 °C, anthocyanin levels depended strongly on storage temperature, but not on the used pressing system (conventional vs. oxygen-reduced). Other juice quality parameters like ascorbic acid behaved likewise. Furthermore, a D-optimal design of experiments was used to study the influence and interactions of the factors oxygen, ascorbic acid, sugar and pH value on anthocyanin levels during a heat treatment in a model solution made with preparatively isolated blackcurrant anthocyanins. In agreement with our production trials at pilot plant scale, oxygen levels were only marginally important for the rate of anthocyanin degradation, but the influence of sugar content, ascorbic acid content and pH value was highly relevant as discussed in this report.

In this work, two vintages (2019 and 2020) of red-fleshed ‘Weirouge’ apples were processed with the innovative spiral filter press technology to investigate juice production in an oxygen-reduced atmosphere. After pressing, a more brilliant red color and appreciably higher amounts of oxidation-sensitive constituents (ascorbic acid, anthocyanins, and colorless (poly)phenols) were seen in spiral filter pressed juices compared to those produced with conventional systems (horizontal filter press and decanter). In a subsequent stability study (24 weeks storage at 4, 20, and 37 °C), the color and phenolic compounds were monitored and differences in the juices produced with the different pressing-systems were widely maintained during the storage period. The analyses of the anthocyanins and colorless (poly)phenols were conducted by UHPLC-DAD-ESI-QTOF-HR-MS/MS and UHPLC-DAD. The spiral filter press emerged as a promising technology for the production of juices with a more attractive color and a better retention of oxidation-sensitive constituents during processing and storage compared to conventional juices.