¹H-NMR and viscosity studies of hydrogen bonding of Chinese rice wine

Abstract

The viscosity of Chinese rice wine gradually increases with the maturing process, resulting in a better taste due to longer contact with the tongue. Herein, the structure of water-ethanol was detected by hydrogen nuclear magnetic resonance (1 H-NMR) and viscosity measurement to define the strength of hydrogen bonding. Through single-factor experiments, it can be seen that most of the flavors have a promoting effect on alcohol-water hydrogen bonding, with the exception of aldehydes. And the factors influencing hydrogen bonding in decreasing order were determined by Plackett-Burman (PB) test. The relationship between hydrogen bonding strength and flavor in Chinese rice wine with 18% (v/v) alcohol concentration was investigated through multiple regression analysis, with an adjusted R 2 of 0.925. The results of study provide important insight for the quality control and molecular mechanism of viscosity increasing during Chinese rice wine aging. 1 H-NMR y estudios de viscosidad del enlace de hidrógeno del vino de arroz chino RESUMEN La viscosidad del vino de arroz chino aumenta gradualmente durante su añejamiento, haciendo que su sabor sea más agradable debido a su contacto más prolongado con la lengua. El presente estudio detectó la estructura de agua-etanol empleando la resonancia magnética nuclear de hidrógeno (1 H-NMR) y la medición de la viscosidad para definir la fuerza de adhesión del hidrógeno. A través de experimentos de factor único se comprobó que la mayoría de los sabores promueve la adhesión del hidrógeno al alcohol-agua, excepción hecha de los aldehídos. La prueba Plackett-Burman (PB) determinó los factores que, en orden decreciente, inciden en la adhesión del hidrógeno. Utilizando un análisis de regresión múltiple, se investigó la relación existente entre la fuerza de adhesión del hidrógeno y el sabor del vino de arroz chino mediante la concentración de alcohol 18% v/v, con una R 2 ajustada de 0.925. Los resultados del estudio proporcionan importantes conocimientos para el control de calidad y el mecanismo molecular que provoca la creciente viscosidad del vino de arroz chino durante su añejamiento.

Whether the Research on Ethanol–Water Microstructure in Traditional Baijiu Should Be Strengthened?

“…Acids (H+ and HA: undissociated acids) and bases (OH– and A–: conjugate-base anions from weak acids) can strengthen the structure of the water–ethanol hydrogen bond [ 60 ]. The conclusion drawn by Cao et al [ 57 ] is consistent with the results by Nose, A. In addition, citric acid, malic acid, benzaldehyde, ethyl lactate, isoamyl alcohol, 2-phenylethyl and ethyl acetate are also considered factors affecting the strength of hydrogen bond from strong to weak.…”

“…Cao, J. et al [ 57 ] investigated the structure of ethanol–water, defined the strength of hydrogen bonding by 1 H-NMR and viscosity measurement and studied the relationship between hydrogen bond strength and flavor in Chinese rice wine. The results provide an essential theoretical basis for the molecular mechanism and quality control of increased viscosity during rice wine aging.…”

Flavor Formation in Chinese Rice Wine (Huangjiu): Impacts of the Flavor-Active Microorganisms, Raw Materials, and Fermentation Technology

“…Aging involves two processes: physical maturation and chemical maturation (Tao et al, 2014). During physical maturation, the hydrogen bonding among flavor compounds of Huangjiu and the volatilization of heterogeneous volatile compounds may contribute to the final flavor characteristic of Huangjiu (Cao et al, 2018;Wang et al, 2019). As for chemical maturation aging, a variety of chemical reactions, such as oxidation, esterification, and hydrolysis reactions, may affect the composition of flavor compounds, and thus are responsible for the flavor quality of Huangjiu.…”

Comprehensive two‐dimensional gas chromatography mass spectrometry‐based untargeted metabolomics to clarify the dynamic variations in the volatile composition of Huangjiu of different ages

“…Traditionally, newly brewed Huangjiu is aged in pottery jars at ambient temperature to develop a more harmonious aroma and a smoother mouth feel (Fan & Xu, 2012; Shen et al, 2012). The flavor quality of Huangjiu improves with age, owing to a series of chemical and physical reactions occurring during storage, such as esterification, oxidation, hydrolysis reactions, and alcohol–water hydrogen bonding (Cao et al., 2018; N. Wang et al., 2019). Therefore, the commercial value of Huangjiu is closely related to its age; as a result, Huangjiu is often labeled with its age as a measure of quality, which influences consumers’ choice (Chen et al., 2019; Y. Yang et al., 2019).…”