You have full access to this open access article. HSβSPMEβGCβMS 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. 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.
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. Red-fleshed apples are popular due to their attractive color and high concentrations of potential health promoting poly phenols [ 1 ]. Apart from color and antioxidant properties, poly phenols contribute together with sugars and acids to aroma, taste, mouthfeel, and particularly astringency of fruits and derived juices [ 2 ].
In addition, the aroma is determined by volatiles generated from primary metabolites like fatty acids, amino acids or carbohydrates during ripening and postharvest storage as well as those altered during processing.
Noteworthy, the human olfactory system merely recognizes a limited proportion of the numerous apple volatiles [ 3 , 4 , 5 ]. Hereby, the aroma activity is determined by the concentration and odor threshold of the individual constituents [ 7 ]. Apple volatiles may be classified into aldehydes, alcohols, ketones, terpenes, and esters [ 4 , 5 ]. The typical apple juice aroma is mainly determined by esters and aldehydes, accounting for ca. Thus, oxygen plays an important role in the genesis of such aldehydes and alcohols via lipoxygenase and subsequent lyase-mediated cleavage of the intermediate fatty acid hydroperoxides, often being compounds with six carbon atoms [ 11 ].
