Current situation, trend, and prospects of research on functional components from by-products of baijiu production: A review

Recent Advances in Resource Utilization of Huangshui from Baijiu Production

“…In addition to containing a large amount of flavor components such as alcohols, aldehydes, acids, and esters, Huangshui also contains some nutrients such as sugars, amino acids, humus, yeast autolysates, and a certain number of live functional microbes. Due to the influence of raw materials used in Chinese Baijiu fermentation and their proportion, pit quality, pit age, and operational factors, the chemical composition of Huangshui produced by each pit or distillery is quite different, and its chemical component and content are described in Table 1 [4,[10][11][12]. Generally, Huangshui is constituted of complex ingredients and includes a large number of organic substances and microbes with 25,000-40,000 mg/L COD Cr and 25,000-30,000 mg/L five-day biochemical oxygen demand (BOD 5 ) [12].…”

“…Huangshui has various functional microbes, organic acids, carbohydrates, nitrogencontaining matters, alcohols, and flavor substances (e.g., ethyl acetate and ethyl butanoate) [5,10]. In addition to microbial use, Huangshui can also be utilized in a variety of uses, which is acted as a raw material for secondary fermentation, extraction of proteins, soluble starches, organic acids, polysaccharides, tannins, and pigments [9,35].…”

“…In addition to microbial use, Huangshui can also be utilized in a variety of uses, which is acted as a raw material for secondary fermentation, extraction of proteins, soluble starches, organic acids, polysaccharides, tannins, and pigments [9,35]. Huangshui is simply treated, which can be utilized to blend Baijiu, produce calcium lactate, extract flavor components, culture the artificial pit mud, make solid and liquid feed, prepare vinegar and polysaccharides, and preserve food [10,18]. Huangshui, as the main by-product of Baijiu brewing, contains rich aromatic substances and nutrients [3].…”

“…They found that the total ester concentration increased from 4.86 to 7.31 g/L under the optimal conditions (10% alcohol and pH 3.5) after esterification for 16 days [37]. Moreover, Huangshui is enriched with aromatic substances, which can be used to produce biological functional blending liquid or other essence to improve Baijiu flavor and quality [10]. The supercritical CO 2 fluid extraction potentially promotes esterification reactions to form aromatic compounds such as ethyl butyrate and ethyl hexanoate [45].…”

“…Nonetheless, there are few reviews on studies associated with Huangshui. Jiang et al [10] only briefly introduced the complex components contained in Huangshui and their application areas, thus existing reports require more systematic elaboration. This review focuses on the advances of Huangshui recycling in nutrition, energy, and materials.…”