Sensomics-Based Characterization of Flavor Maturation and Enhanced Ester Accumulation in Sufu Fermented With Leuconostoc lactis C2/15.

Sufu, a traditional Chinese fermented soybean product, is known for its unique flavor, creamy texture, and rich nutrition, earning it the nickname "Oriental cheese" in the West. However, spontaneous fermentation often results in a monotonous flavor, insufficient floral/fruity volatile organic compounds (VOCs), and a tendency to develop off-flavors. Here, Leuconostoc lactis C2/15 was used as an auxiliary starter to investigate its role in flavor formation from a sensomics perspective. VOCs were characterized using headspace solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry (HS-SPME-GC-MS/MS), sensory evaluation, odor activity value (OAV) calculation, and aroma recombination and omission experiments. Inoculation with L. lactis C2/15 significantly promoted the accumulation of volatile compounds, resulting in a 2.2-fold increase in total VOCs at the 35d stage, with ethyl butyrate showing a 56-fold increase. Furthermore, 22 key VOCs (OAV > 1) were identified in the auxiliary group (including 13 newly emerged compounds, while 3 found in the spontaneous group were absent), compared to only 13 in the spontaneous group. Aroma recombination and omission experiments validated six VOCs as the core contributors to the overall aroma. Comprising primarily 1-octen-3-ol, phenethyl alcohol, ethyl 2-methylbutyrate, ethyl acetate, phenylacetaldehyde, and 2-pentylfuran, these odorants synergistically imparted rich fruity, floral, and roasted characteristics. The formation of these key volatiles was closely linked to carbohydrate metabolism, amino acid catabolism, lipid oxidation, and subsequent esterification. Overall, this sensomics-based study provides molecular-level insights into flavor regulation, offering a practical basis for deploying targeted starter cultures to standardize sufu production. PRACTICAL APPLICATIONS: Traditional spontaneously fermented sufu is appreciated for its characteristic traditional flavor; however, the formation of desirable fruity and floral aroma compounds can be limited during spontaneous fermentation. Using Leuconostoc lactis C2/15 as an auxiliary starter effectively enhanced the formation of ester and alcohol compounds, contributing to more pronounced fruity and floral notes. This starter enables manufacturers to produce sufu with an enhanced and differentiated aroma profile and strengthen market competitiveness.