Screening of Non-Saccharomyces for Citrus reticulata cv. ‘Dahongpao’ Fruit Wine and Volatile Organic Compounds Analyzed by Gas Chromatography–Ion Mobility Spectrometry

In recent years, there has been substantial global progress in screening yeasts for fermenting various specialty fruits, especially non-Saccharomyces species known for their contributions to aroma enhancement. This study focused on mature fruits and soil samples collected from orchards located in the main production region ofC. reticulatacv. ‘Dahongpao’ (CRCD) in China, with the objective of isolating specialized non-Saccharomycesyeasts suitable for producing CRCD fruit wine. After enrichment cultivation, seven characteristic yeast strains were isolated and purified. These isolates were identified asCandida parapsilosis,Meyerozyma caribbica,Candida quercitrusa, andMeyerozyma guilliermondiithrough a combination of microscopic morphology and molecular biology methods, which also includedPichia fermentans,Pichia kudriavzevii, andPichia kluyveri. The strains’ fermentation potential, ethanol production rates, and tolerance levels were assessed, leading to the selection ofCandida parapsilosis,Candida quercitrusa,Pichia fermentans,Pichia kudriavzevii, andPichia kluyverifor further fermentation experiments. The commercial yeast La-Ma was used as a control. Analysis of volatile organic compounds (VOCs) in the fruit wine samples was performed using Gas Chromatography–Ion Mobility Spectrometry (GC-IMS). A total of 42 different VOCs were identified, with esters being the most prevalent. The fingerprint profiles demonstrated notable differences between the fruit wine samples fermented with selected yeasts and those fermented with commercial yeasts. Principal component analysis (PCA) indicated thatPichia kluyveridisplayed the most significant divergence from both commercial and other selected yeasts. The samples contained notable VOCs such as 2-methyl-1-butanol, pentanal, 3-methyl-2-butenal, propyl acetate, butyl acetate, isobutyl acetate, isopentyl acetate, and 3-methyl-2-butenyl acetate, while the methanol production was observed to be lower compared to other samples. Consequently, this strain has the potential to produce distinctive fruit wine.