Assessment of Metabolites in Noni Fruit Slurry Fermented With Four Non‐ <i>Saccharomyces</i> Yeasts

ABSTRACT Noni products often suffer from an unappealing flavor dominated by rancid, fatty‐acid‐like notes, which limits consumer acceptance and motivates sensory improvement efforts. In this study, dried noni fruit slurry (DNFS) underwent static fermentation at 20°C for 14 days with four non‐ Saccharomyces yeasts ( Metschnikowia pulcherrima Flavia, Pichia kluyveri Frootzen, Candida versatilis NCYC1433, and Williopsis saturnus NCYC22) to evaluate their potential to enhance flavor and nutritional quality. Among them, P. kluyveri Frootzen exhibited the most promising performance, with the peak cell count reaching ∼7.0 log CFU/mL from the initial ∼5.5 log CFU/mL during fermentation, whereas other strains either exhibited limited growth or a decline in viability. Notably, P. kluyveri Frootzen and W. saturnus NCYC22 enhanced the production of fruity and floral aroma compounds, such as isoamyl acetate (0 to 43.13 and 291.41 µg/L) and 2‐phenylethanol (16.89 to 316.78 and 689.69 µg/L, respectively), linked to banana‐like and floral notes, while reducing the off‐flavor compound n‐decanoic acid (1124.14 to 827.35 and 1067.20 µg/L, respectively). Furthermore, the fermentation process did not significantly alter the total phenolics, deacetylasperulosidic acid and asperulosidic acid contents, indicating the preservation of DNFS's antioxidant and bioactive properties. These findings highlight the potential of non ‐Saccharomyces yeasts, particularly P. kluyveri Frootzen, as the starter culture for improving the sensory qualities of fermented noni‐based products.