The flavor and quality of fermented foods are fundamentally influenced by microbial involvement. Microorganisms are the primary driving force behind the fermentation process, which is facilitated by microbial growth and reproduction, and especially by complex intra- and inter-species interactions, leading to the production of abundant nutritional components and unique flavor compounds. Numerous studies have been conducted on the community succession and individual contribution of microorganisms in fermented foods. In recent years, microbial interactions have gradually become the focus of research. This review delves into the core mechanisms by which microorganisms shape the flavor of fermented foods, with a focus on how quorum sensing (QS) regulates the metabolic activity and how group behavior of microorganisms and nutritional interactions promote the construction of microbial communities. It further examines the positive effects of different interaction types (mutualism, commensalism, amensalism, and competition) on the flavor profile of fermented foods. The review concludes by highlighting current problems and challenges, with the aim of providing insights for future research on microbial interactions and their impact on the flavor of fermented foods.

As the most widely used food flavor additive in the world, the production route of vanillin directly affects the flavor characteristics and market value of its products. Vanillin extracted from plants usually retains a variety of volatile compounds in vanilla pods, so it has rich flavor layers and complex aromas. In contrast, chemical synthesis lacks the flavor complexity of natural vanillin due to the limitations of raw materials and reaction conditions. In recent years, with the increase in consumer preference for natural foods, biosynthesis of vanillin has become a hot market concern due to its natural attributes and economy. By utilizing enzymes, genes and metabolic engineering, biosynthesis can effectively increase the yield of vanillin and has the capability to control the generation of by-products with natural characteristic flavors, which demonstrates a broad prospect for industrialization and flavor quality optimization. This review summarizes the major production methods of vanillin, analyzes the effects of different production methods on its flavor quality, and discusses the future development direction of vanillin, with a view to providing new technical support and ideas for the sustainable development of the vanillin industry.