Nitrogenous compounds and Chinese baijiu: a review

Baijiu is a traditional Chinese distilled beverage. There are twelve types of Chinese baijiu, each requiring different production technologies resulting in varying styles and characteristics. Proteins, peptides and amino acids are both sources of nitrogen for brewing microflora and precursors of flavour compounds. These compounds are the main non-volatile nitrogenous compounds in baijiu fermentation but are also present in the final product. Of the volatile nitrogenous compounds in baijiu, pyrazines dominate. This paper reviews the roles of nitrogenous compounds in baijiu production; systematically summarises the volatile and non-volatile nitrogenous compounds in baijiu and the relationships between production processes and nitrogenous compounds in Strong and Sauce flavour baijiu. Nitrogenous compounds are closely related to the quality of the baijiu. It is suggested that future work should focus on the role of nitrogenous compounds in the flavour and aroma of baijiu with particular regard to different production technologies, materials and regions.