Bioscience Methods 2025, Vol.16, No.3, 154-161 http://bioscipublisher.com/index.php/bm 156 amino nitrogen continue to rise. Especially, the aging process significantly increases the levels of total phenols and flavonoids. These substances are directly related to the antioxidant capacity and quality characteristics of vinegar (Figure 1) (An et al., 2011). Figure 1 Antioxidant contribution of main phenolic compounds during the aging process of ZAV (Adopted from Duan et al., 2019) Image caption: Antioxidant activities of phenolic compounds mixture were detected by DPPH assay (A), ABTS assay (B), and FRAP assay (C) during the AP of ZAV (Adopted from Duan et al., 2019) 3.2 The influence mechanism of solid-state fermentation on the formation of flavor substances Solid-state natural fermentation, as the core of traditional techniques, cultivates stable and diverse microbial communities, driving the synthesis of flavor substances and functional components. This process promotes the natural enrichment of beneficial microorganisms such as bacteria and fungi, and their metabolic networks jointly construct the unique aroma and nutritional system of traditional vinegar (Jiang et al., 2019; Yu et al., 2022). This process significantly enhances the generation efficiency of volatile substances such as acids and esters, and promotes the accumulation of active components such as phenolic acids. The microbial diversity jointly shaped by the characteristics of raw materials and the fermentation environment plays a decisive role in substrate transformation, the formation of flavor substances and the synthesis of healthy components (Liu et al., 2024). 3.3 Inheritance and innovation of the craftsmanship of Yuyue orange vinegar Based on the multi-stage fermentation and aging technology, it creatively combines the unique attributes of the citrus raw materials in the production area. Its process framework is benchmarking against the production standards of traditional famous vinegar to ensure that the unique active components and aroma substances of citrus raw materials are optimized and retained during the biotransformation process (Duan et al., 2019). Through the meticulous control of the entire solid-state fermentation process, not only is the essence of traditional craftsmanship carried forward, but also the characteristics of raw materials are fully exploited. This combination of techniques not only retains the classic flavor and health benefits of traditional vinegar, but also creates products with both distinctive taste and functional advantages through the unique properties of citrus raw materials (Nie et al., 2012). 4 Optimization Paths and Technical Systems for Brewing Processes 4.1 Strain optimization strategy: functional bacteria screening and construction of a synergistic system The key to strain optimization lies in screening highly efficient functional strains to drive core biochemical reactions and enhance product quality and process stability. Intelligent modeling and process control systems can precisely identify suitable strains and enhance the controllability and reproducibility of the fermentation process (Романов et al., 2015). The key screening of dominant strains can precisely regulate the synthesis of target metabolites and effectively inhibit the generation of odor by-products. Establishing a collaborative system of complex microbiota can integrate the metabolic characteristics of multiple strains and enhance the biosynthesis of functional components. This method, through the synergistic effect of enzyme systems among bacterial communities, can not only construct multi-level flavor profiles but also enhance the enrichment effect of active components. Directional regulation of the microbiota combined with the production process can also reduce energy and raw material input and improve the overall efficiency of the production line (Ruarte et al., 2024).
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