Integrated process optimization and microbial-flavor interactions during rapid Jiuyao–Zaopocu fermentation

Abstract

Zaopocu is traditionally produced using Jiuyao as a solid-state starter. However, rapid fermentation processes adopted in recent years often result in reduced aroma intensity and flavor complexity. In this study, a reproducible Jiuyao–Zaopocu fermentation workflow was established to clarify how starter culture affects downstream flavor formation under accelerated conditions. A temperature-controlled strategy was applied during Jiuyao production, and key factors were optimized using Plackett–Burman screening and Box–Behnken response surface methodology. The optimized conditions were identified as a mixing water temperature of 48 °C, Muqu addition of 1.9%, and high-enzyme-activity Jiuyao from Fangxian (FX) addition of 1.6%. Under these conditions, total acid (g/L) and ethanol (%) contents increased by 22.7% and 67.6%, respectively, compared with the basic process. Microbial and flavor analyses revealed a clear ecological transition from a mold-lactic acid bacteria co-dominated community (Rhizopus, Pediococcus) in Jiuyao to a Limosilactobacillus-dominated community during Zaopocu fermentation. Meanwhile, several aroma-active compounds enriched in Jiuyao, including 4-ethyl-2-methoxyphenol, ethyl tetradecanoate, and 3-methylbutyric acid, markedly decreased during rapid liquid fermentation, accompanied by a reduction in overall volatile diversity. Correlation analysis indicated that Rhizopus was positively associated with key aroma compounds, but its contribution weakened after the Jiuyao to Zaopocu transition. These findings suggest that part of the flavor potential generated during Jiuyao preparation is not fully retained under rapid Zaopocu fermentation. Therefore, front-end regulation of starter preparation and targeted retention of key functional microorganisms may help preserve aroma complexity under accelerated processing conditions.

Keywords

Zaopocu / Jiuyao / Box–Behnken response surface / Flavor substances / Microbial diversity

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Funding

National Natural Science Foundation of China(22422807)

RIGHTS & PERMISSIONS

Jiangnan University