Decoding the Volatile Fingerprint of Fermented Underutilized Fruits and Citrus: A Multivariate Approach to Functional Beverage Design

The growing demand for functional beverages has driven the search for novel substrates rich in bioactive compounds and unique sensory profiles. This study explores the valorization of underutilized fruit and citrus biodiversity through controlled fermentation using selected Saccharomyces cerevisiae starter strains of oenological origin (respectively denoted NU32 and NC103). The primary objective of this invstigation was the evaluation of the interplay between distinct fruits and citrus genotypes and microbial metabolisms shape the final product. A comprehensive analysis of the volatile organic compounds (VOCs) profile using gas chromatography-mass spectrometry (GC-MS), combined with multivariate analysis, made it possible to identify the main volatile compounds responsible for the sensory characteristics and to assess the influence of individual variables and their interactions on the volatile profile of the beverages produced. This interaction had a statistically significant impact on the final aroma profiles, revealing significant changes between the different chemical classes and defining tailored aroma profiles. In detail, among minor fruit varieties examined, the Principal Component Analysis (PCA) coupled with the Cluster Heatmap showed that fruit matrix emerged as the dominant driver of volatile composition. On the other hand, the yeast-strain effects, although secondary, proved detectable and relevant in selected combinations, highlighting a fine-tuning role of microbial biodiversity. Interestingly, among citrus species studied, the Bergamotto (Citrus × bergamia (Risso)) juice emerged as the most aromatic substrate, systematically exhibiting the highest concentrations of terpenes, particularly when fermented with the NC103 strain. In conclusion, the recovery and characterization of autochthonous, neglected biodiversity, combined with tailored fermentation biotechnologies, represent a powerful strategy. This approach not only prevents genetic erosion but it actively drives the design of innovative, customized functional beverages with optimized, distinctive volatile fingerprints and elevated consumer appeal.