The crucial importance of soy sauce authenticity: global trade, adulteration risks, and analytical challenges

Background
Soy sauce, originating from China, has a long history in Asian countries. Recently, global production has markedly increased, and the consumer base is growing. The complex production process, involving various raw materials and multiple steps, poses multiple risks of fraud, some of which are related to food safety. Hence, soy sauce authentication is crucial.

Scope and approach
This review starts by investigating recent global production and trade volumes of soy sauce in major producing countries. It then outlines production standards and additive usage criteria in key countries. Building on this, it analyzes fraudulent activities observed in soy sauce over the past two decades. Finally, the review introduces principles, equipment, and data processing methods applied in analytical chemistry approaches for studying soy sauce authentication, considering both principles and applications.

Key findings and conclusions
In soy sauce production, soybean protein hydrolysis relies mainly on microbial fermentation, with an optional use of acid hydrolysis. The latter raises safety concerns, making fraudulent events in soy sauce production through these methods a significant concern. In recent years, soy sauce bottles have displayed various high-quality attribute labels, such as GM-free, organic, addictive-free, and handmade, etc. However, discerning the quality attributes in soy sauce through clear indicators is often very challenging. For the above issues, over the past decade or so, scientists have established a series of targeted and non-targeted analytical methods based on spectroscopy, mass spectrometry, and molecular biology techniques to verify the authenticity of soy sauce. Past research efforts are a good start, however, compared to other foods, the attention given to the authenticity analysis of soy sauce has not matched its importance. Future analytical approaches should focus on sample preparation, developing new rapid detection methods, and establishing chemical profile databases for diverse types of soy sauce. These efforts will further ensure the authenticity of soy sauce sold in many markets across the world.