Although many organic molecules found commonly in the atmosphere are known to be surface-active in aqueous solutions, their effects on the mechanisms underlying haze formation remain unclear. In this paper, based on a...Although many organic molecules found commonly in the atmosphere are known to be surface-active in aqueous solutions, their effects on the mechanisms underlying haze formation remain unclear. In this paper, based on a simple thermodynamic analysis, we report that the adsorption of amphiphilic organics alone not only lowers the surface tension,but also unexpectedly stabilizes nanodroplets of specific size under water vapor supersaturation. Then we determine how various factors, including relative humidity, water activity effect due to dissolution of inorganic components as well as surface tension effect due to surface adsorption of organic components, cooperatively induce the stability of nanodroplets.The nanodroplet stability behaviors not captured in the current theory would change the formation mechanism of haze droplets, from the hygroscopic growth pathway to a nonclassical two-step nucleation pathway.展开更多
Protein haze was one of the main causes of the instability of white wines. Proteins that caused haze or precipitation in white wines mainly came from grape fruits, and their compositions and contents were affected by ...Protein haze was one of the main causes of the instability of white wines. Proteins that caused haze or precipitation in white wines mainly came from grape fruits, and their compositions and contents were affected by many factors such as fruit diseases, harvesting methods and water stress. Unstable wine proteins were usually pathogenesis-related(PR)proteins of grapes, mainly chitinases and thaumatin-like proteins(TLPs), which had lower isoelectric point(pI)and smaller molecular weight, and were highly resistant to the low pH values of wines and the protease hydrolysis during fermentation. At present, the technology of protein stabilization and clarification in white wines mainly included bentonite fining, heat treatment, enzymatic hydrolysis, polysaccharide treatment and ultrafiltration methods. Among them, the most commonly used method was bentonite treatment. In this paper, the research progresses of the origin, mechanism and influencing factors of the unstable proteins in white wines were summarized, and the applications, advantages and disadvantages of various clarification techniques were also concluded, in order to provide some support for the theoretical and technological research of the protein stability in white wines in the future.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21978007)。
文摘Although many organic molecules found commonly in the atmosphere are known to be surface-active in aqueous solutions, their effects on the mechanisms underlying haze formation remain unclear. In this paper, based on a simple thermodynamic analysis, we report that the adsorption of amphiphilic organics alone not only lowers the surface tension,but also unexpectedly stabilizes nanodroplets of specific size under water vapor supersaturation. Then we determine how various factors, including relative humidity, water activity effect due to dissolution of inorganic components as well as surface tension effect due to surface adsorption of organic components, cooperatively induce the stability of nanodroplets.The nanodroplet stability behaviors not captured in the current theory would change the formation mechanism of haze droplets, from the hygroscopic growth pathway to a nonclassical two-step nucleation pathway.
基金The financial support of this work was received from China Agriculture Research System for Grape Industry (CARS-29)。
文摘Protein haze was one of the main causes of the instability of white wines. Proteins that caused haze or precipitation in white wines mainly came from grape fruits, and their compositions and contents were affected by many factors such as fruit diseases, harvesting methods and water stress. Unstable wine proteins were usually pathogenesis-related(PR)proteins of grapes, mainly chitinases and thaumatin-like proteins(TLPs), which had lower isoelectric point(pI)and smaller molecular weight, and were highly resistant to the low pH values of wines and the protease hydrolysis during fermentation. At present, the technology of protein stabilization and clarification in white wines mainly included bentonite fining, heat treatment, enzymatic hydrolysis, polysaccharide treatment and ultrafiltration methods. Among them, the most commonly used method was bentonite treatment. In this paper, the research progresses of the origin, mechanism and influencing factors of the unstable proteins in white wines were summarized, and the applications, advantages and disadvantages of various clarification techniques were also concluded, in order to provide some support for the theoretical and technological research of the protein stability in white wines in the future.
