Molecular Microbiology Research, 2025, Vol.15, No.2, 45-58 http://microbescipublisher.com/index.php/mmr 51 with modern biotechnology, factories can choose fermentation mode according to product needs: for quick brewing soy sauce, inoculation + temperature control + stirring can be used; for high-end soy sauce, long-term static fermentation is adhered to, supplemented by excellent bacterial strains, the products of the two will differ in indicators such as amino acid nitrogen and aroma substances. 5.2 Artificial intervention strategies for microecosystems in fermentation environments In the era of Industry 4.0, intelligent control technology has gradually been applied to the traditional fermentation industry, and soy sauce brewing has also begun to explore digital and automated production paths. Traditional soy sauce gardens rely on the experience of brewing masters to judge the fermentation status, such as distinguishing the aroma of the mash through smell, visual observation of bacterial film and liquid color, and judging the heating nodes by hand touching the temperature. Although these experiences are valuable, they are subjective and difficult to standardize. To this end, modern factories have introduced various sensors and online analytical instruments to monitor fermentation parameters in real time to judge microbial fermentation activity. When an abnormality is detected, such as excessive temperature, Aspergillus may autolysis or lactic acid bacteria may die from overheating, the system can automatically alarm and start the corresponding adjustment device (such as starting the cooling water cycle or stopping heating). Through the Internet of Things (IoT), traditional sauce jars can also be connected to digital systems to realize remote data collection and control (Chen, 2013). Another intelligent direction is applied machine learning and big data analysis. Enterprises can collect multi-dimensional data (temperature, bacterial phase, chemical composition, etc.) of different batches of soy sauce during the fermentation process, and combine the final quality evaluation results to train the prediction model. Some large soy sauce factories in Japan have partially realized automation: from raw material cooking, koji stirring, fermentation and stirring to pressing, sterilization and packaging, all links are performed by programmable controllers (PLCs) and robots, achieving stable mass production. However, for brands such as Yuyue, which adhere to the ancient method, dual monitoring of artificial sensors and instruments will still be adopted during the key flavor formation stage, and adjustments will be made with caution. In intelligent transformation, how to avoid destroying traditional flavors is an important consideration. For example, the introduction of automatic opening and closing sheds in the open-air sunlight process can control sunshine and rainfall, which can ensure the flavor while reducing the pollution of mixed bacteria and fermentation stagnation caused by the weather. For example, if the use of electronic nose and electronic tongue devices to evaluate the aroma and taste of the fermentation broth in real time, it can be used to automatically determine the fermentation progress and coordinate the temperature stirring and other parameter adjustments. The application of these intelligent equipment makes traditional experience digital, which is conducive to the inheritance of skills and training of newcomers. 5.3 Integration of microbial process modeling and brewing intelligent control system In addition to microbial and control technologies, some emerging processing technologies are also trying to integrate into the soy sauce process in order to improve quality or develop new varieties. Physical technologies such as ultrasonic processing and high-pressure processing have been studied to accelerate certain enzyme reactions or sterilization (Higuchi et al., 2024), but the impact on flavor needs to be carefully evaluated. The development of enzyme engineering has enabled industrial enzyme preparations to supplement Aspergillus enzymes and added to fermentation mash to improve protein decomposition rate, thereby obtaining soy sauce with high amino acid nitrogen content in a shorter time. However, excessive reliance on exogenous enzymes may lead to monotonous flavor and must be used reasonably. On the other hand, biotechnical means such as metabolic engineering are being used to customize fermentation strains. With advances in synthetic biology, it may even be possible in the future to "synthese" key flavor complexes of soy sauces by engineering microorganisms, thereby significantly shortening fermentation times. However, pure chemical or biological rapid production is currently difficult to reproduce the round and comprehensive flavor given by traditional fermentation. Therefore, the more realistic path at present is the combination of innovation in
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