Research Progress on Closed Solid-State Fermentation System and Its Application in Vinegar Brewing

The brewing of solid vinegar is traditionally carried out in an open solid-state fermentation system, which is susceptible to environmental factors, leading to unstable flavor quality, low degree of mechanization and low labor productivity. Compared with the traditional open solid-state fermentation system, the closed solid-state fermentation system is not disturbed by external environmental factors, and allows mechanized and automated vinegar brewing, which is beneficial for stabilizing product quality, improving labor productivity, and promoting the modernization of the vinegar industry. In recent years, the closed solid-state fermentation system has been widely used in the field of vinegar brewing, which has brought significant improvement to the production efficiency of solid-state fermented vinegar. This article introduces the structure, characteristics, and regulatory measures of common closed solid-state fermentation systems. Besides, the factors affecting the fermentation performance of the closed solid-state fermentation system are summarized, the application of the closed solid-state fermentation system in vinegar brewing is briefly discussed, and an outlook on future trends in the development of an automatic and intelligent closed solid-state fermentation system is given. We hope that this review can provide a reference for the development of a new closed solid-state vinegar system in the future.