Department of Wine and Food Science, School of Agriculture, Food and Wine, The University of Adelaide, PMB 1 Glen Osmond SA 5064, Australia.
Molecules. 2018 Dec 26;24(1):73. doi: 10.3390/molecules24010073.
The colour of red wine is largely determined by the concentration of anthocyanins that are extracted from grape skins during fermentation. Because colour is a key parameter in determining the overall quality of the finished product, understanding the effect of processing variables on anthocyanin extraction is critical for producing a red wine with the desired sensorial characteristics. In this study, the effect of convective conditions (natural and forced) on the mass transfer properties of malvidin-3-glucoside (M3G) from pre-fermentative grape solids was explored at various liquid phase conditions representing stages of fermentation. A mathematical model that separates solid and liquid phase mass transfer parameters was applied to experimental extraction curves, and in all cases, provided a coefficient of determination exceeding 0.97. Calculated mass transfer coefficients indicated that under forced convective conditions, the extraction process was controlled by internal diffusion whereas under natural convection, both internal diffusion and liquid-phase mass transfer were relevant in determining the overall extraction rate. Predictive simulations of M3G extraction during active fermentation were accomplished by incorporating the current results with a previously developed fermentation model, providing insight into the effect of a dynamic liquid phase on anthocyanin extraction.
红葡萄酒的颜色在很大程度上取决于在发酵过程中从葡萄皮中提取的花色苷的浓度。由于颜色是确定成品整体质量的关键参数，因此了解加工变量对花色苷提取的影响对于生产具有所需感官特性的红葡萄酒至关重要。在这项研究中，在代表发酵各个阶段的不同液相条件下，探索了对流条件（自然和强制）对预发酵葡萄固体中矢车菊素-3-葡萄糖苷（M3G）传质特性的影响。应用了一个将固相与液相传质参数分开的数学模型来处理实验提取曲线，在所有情况下，其决定系数都超过 0.97。计算得出的传质系数表明，在强制对流条件下，提取过程受内扩散控制，而在自然对流条件下，内扩散和液相传质都与确定整体提取速率有关。通过将当前结果与先前开发的发酵模型相结合，对活性发酵过程中 M3G 提取进行了预测模拟，深入了解了动态液相对花色苷提取的影响。
