Comparison of anthocyanin and volatile organic compounds in juices and fruit wines made from blood oranges (Citrus sinensis L. Osbeck) at different maturity stages

The variation in profiles of anthocyanins and volatile organic compounds (VOCs) in juices and in the corresponding fruit wines made from blood oranges ripened at different maturity stages were investigated. The compositions of sugars and organic acids were monitored, as well. Original findings have been reported for the maturity effect on blood orange juices, while the impact of fruit ripening on wine is explored for the first time. Using UPLC-DAD-ESI-Q-TOF-MS, based on elution order, UV-vis spectra, fragmentation pattern, and authentic standards, thirteen individual anthocyanins were identified, nine common to unfermented and fermented blood orange samples, while four (identified as hydroxyphenyl-pyranoanthocyanins) generated from fermentation. The total anthocyanin content in unfermented blood orange juice showed dramatic increases during maturation, especially in the late maturity stage, while fermentation resulted in significant reductions. The monitoring of VOCs in blood orange and wines was provided via a combination approach of HS-GC-IMS and HS-SPME-GC-MS for the first time. Forty-five and ninety-one VOCs were identified by GC-IMS and GC-MS, respectively. The concentrations of alcohols, ketones, and terpenes decreased with maturity, while that of esters increased significantly during this period. Fermentation enhanced the complexity and intensity of VOCs, with all VOC categories except ketones showing 2.1-94.3 times increase after fermentation. This work improves the knowledge on the processing management of blood orange juice and wine in order to obtain superior quality products.