Microbial diversity and flavor of Chinese rice wine (Huangjiu): an overview of current research and future prospects

The changes of microbial diversity and flavor compounds during the fermentation of millet Huangjiu, a traditional Chinese beverage

“…Glutinous rice was usually used as the brewing raw materials, such as Guyue Longshan rice wine in southern China. Non-glutinous rice, indica rice and glutinous rice mentioned earlier are three typical raw materials for traditional Huangjiu brewing, barleys and millet with prominent regional characteristics also beginning to emerge [ 2 , 3 ]. The key raw material in Northern Huangjiu is millet, the content of crude protein and starch in which is much higher than that of rice and wheat [ 4 , 5 ].…”

“…The aroma is the best characterized feature of Huangjiu, determined by diverse volatile flavor compounds, and over 900 different kinds of various volatile flavor compounds have been confirmed according Chen et al’s study, comprising primarily esters, alcohols, phenols, aldehydes, ketones and acids [ 14 , 15 ].Though the classification of Huangjiu varies according to region or aroma types, the production process could be generally divided into six major stages [ 3 , 15 – 17 ]: the pretreatment of raw materials (especially soaking in millet Northern Huangjiu, while glutinous rice steaming in Southern Huangjiu), sacccharification (primary fermentation), alcoholization (secondary fermentation), filtering, sterilizing and aging. In other words, almost all the aroma compounds have been achieved through the above complicated fermentation process with the help of raw materials and Qu (fermentation starter) [ 18 ], during which the microbial diversity plays the most critical and indispensable role [ 19 , 20 ].…”

Metabolomics Approaches for the Comprehensive Evaluation of Fermented Foods: A Review

“…The flavor of fermented foods is mostly generated through microbial metabolism and enzymatic biochemical reactions [111]. It is a key indicator of sensory qualities, which often directly determines acceptance by consumers [112]. Characterization of fermented food flavor also contributes to determining the maturity of a product and the differences among products obtained from different production locations or fermentation strains [112,113].…”

“…It is a key indicator of sensory qualities, which often directly determines acceptance by consumers [112]. Characterization of fermented food flavor also contributes to determining the maturity of a product and the differences among products obtained from different production locations or fermentation strains [112,113]. It mainly depends on the composition of volatile flavor compounds, which constitute a preferred flavor, or an unpleasant flavor based on different composition conditions.…”

“…Among them, white daqu has the most types of esters and alcohols, but the levels of esters and alcohols in yellow and black daqu were higher than in white daqu, which may be related to microbial metabolism during fermentation. The flavor of Chinese huangjiu from Shanxi, a yellow rice wine with zao-aroma, was also analyzed based on GC-MS and GColfactometry (GC-O) techniques, and ethyl cinnamate and ethyl 3-phenylpropionate were demonstrated to be key aroma compounds, which indicated differences from others such as Zhejiang Shaoxing and Fujian Hongqu huangjiu [112,115]. Pu-erh tea is a unique tea obtained from the fermentation of Monascus tea, and the understanding of the formation and evolution mechanism of its flavor-active compounds can improve its quality.…”