Volatile flavor characteristics and microbial fermentation differences of water kefir grains from different origins

Abstract

To assess the quality differences of water kefir (WK) grains from different regions, this study investigated the volatile flavor components and microbial composition of sugar-containing water kefir fermented beverages. Understanding these variations is crucial for optimizing fermentation conditions and developing starter cultures with distinct flavor profiles. The volatile components of water kefir beverages from eight regions were analyzed using an electronic nose (E-nose) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Partial least squares discriminant analysis (PLS-DA) effectively differentiated the flavor profiles of samples from different regions. GC-MS analysis identified 41 volatile compounds, eight of which were key differential compounds, including isoamyl acetate, ethyl octanoate, ethyl 4-hydroxymandelate, ethyl decanoate, Propan-1-ol, ethanol, acetic acid, and octanoic acid. High-throughput sequencing and correlation analysis revealed that specific microbial taxa, such as Pediococcus, Lactobacillaceae, and Novosphingobium resinovorum, were closely associated with the production of these key volatile compounds. Based on the obtained data, this study provides new insights into the relationship between microbial composition and volatile compounds during water kefir fermentation, which will facilitate the development of water kefir products with consistent and desirable flavor characteristics.