Differences in volatility and organoleptic characteristics of mixed and sequential fermentation of mulberry fruit juices by Weissella confusa and Pichia kudriavzevii using metabolomics analysis

Abstract

Mulberries (Morus alba L. cv. Longsang 1), rich in various nutrients and bioactive compounds. Fermentation can improve the nutritional value of fruit juice processed from mulberries, making it easier to absorb, and can also improve the taste and aroma, thus promoting further development. This study investigates the differences in aroma and sensory attributes between Pichia kudriavzevii and Weissella confusa mixed bacterial fermentation (PWF) and sequentially fermented (MLF) mulberry juices. Headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis was employed to examine the volatile metabolites in fermentation juice, while high performance liquid chromatography (HPLC)-MS analysis quantified the free amino acid and organic acid content. Additionally, electronic nose and electronic tongue technologies were utilized for sensory evaluation. Results from HS-SPME-GC-MS analysis revealed a notable 61.06% increase in esters in MLF juice, imparting fruity and floral aromas. HPLC-MS analysis indicated a 52.69% increase in sour amino acids in MLF juice, with umami amino acids being 2.23 times higher compared to PWF, resulting in a more pronounced taste profile. Additionally, succinic acid, citric acid, lactic acid, tartaric acid, and malic acid exhibited reductions of 20%, 50%, 12.66%, 75%, and 43.18%, respectively. Electronic tongue and electronic nose analyses demonstrated elevated response values for aromatic components and decreased astringency and bitterness in MLF juice. This research presents a novel fermentation approach to enhance the sensory attributes of fermented mulberry juice.