Why is food-grade acetic acid not suitable as a substitute for brewed vinegar?

Industrial acetic acid, even at high purity, is not equivalent to food-grade brewed vinegar. The dominant production route—methanol carbonylation, pioneered by Monsanto—uses feedstocks and catalysts that leave trace impurities potentially harmful to human health. Unlike edible alcohol, there is no established process for producing food-grade pure acetic acid. Major Chinese producers including Huayi Group, Jiangsu SOPO, and Hualu Hengsheng all use this industrial route. Regulatory authorities have fined and even pursued criminal charges against vinegar makers who blended industrial acetic acid into 'brewed' vinegar products. The distinction matters commercially: brewed vinegar carries cultural and quality value in China, while industrial acetic acid is a commodity chemical priced for manufacturing use, not consumption.