Dupin I V, McKinnon B M, Ryan C, Boulay M, Markides A J, Jones G P, Williams P J, Waters E J
The Australian Wine Research Institute, Glen Osmond, South Australia, Australia.
J Agric Food Chem. 2000 Aug;48(8):3098-105. doi: 10.1021/jf0002443.
A fraction containing the mannoproteins released during fermentation from the winemaking strain of Saccharomyces cerevisiae, Maurivin PDM, was able to reduce the visible protein haze in white wine. This fraction of haze protective mannoprotein material (HPM) could be recovered by either ultrafiltration or ethanol precipitation. The kinetics of the release of both mannose- and glucose-containing polymers during the growth cycle of PDM were determined as a guide to the release of HPM. Active HPM was first detected in the culture supernatant when the cells were exponentially growing. HPM was also released into the medium under an environment simulating winemaking conditions by PDM cells during fermentation as well as during storage on yeast lees. Since the amounts of HPM released during fermentation are greater than those subsequently extracted from the cell wall, fermentation would be a more viable procedure than extraction from yeast cells for the commercial production of HPM. Yeast invertase, a mannoprotein with haze protective activity, was used as a model substrate to investigate the mechanism of haze protection. Invertase was found to reduce visible turbidity but not prevent protein precipitation. Invertase itself did not precipitate but remained soluble in the wine. On the basis of these observations, we propose that the mechanism of haze protection may be one of competition between HPM and wine proteins for unknown wine component(s), the latter being required for the formation of large insoluble aggregates of denatured protein. As the available concentration of these components decreases, due to the presence of HPM, the particle size of the haze decreases and thus visible turbidity declines.
一种含有在发酵过程中从酿酒酵母（Saccharomyces cerevisiae）的酿酒菌株中释放出来的甘露糖蛋白的组分，Maurivin PDM，能够减少白葡萄酒中可见的蛋白质浑浊。这种具有浑浊保护作用的甘露糖蛋白物质（HPM）组分可以通过超滤或乙醇沉淀回收。测定了PDM生长周期中含甘露糖和葡萄糖聚合物的释放动力学，以此作为HPM释放的指导。当细胞呈指数生长时，在培养上清液中首次检测到活性HPM。在模拟酿酒条件的环境下，PDM细胞在发酵过程以及在酵母酒泥上储存期间，HPM也会释放到培养基中。由于发酵过程中释放的HPM量大于随后从细胞壁中提取的量，对于HPM的商业生产而言, 发酵比从酵母细胞中提取是更可行的方法。酵母转化酶是一种具有浑浊保护活性的甘露糖蛋白，用作模型底物来研究浑浊保护机制。发现转化酶可降低可见浊度，但不能防止蛋白质沉淀。转化酶本身不会沉淀，而是保持溶解在葡萄酒中。基于这些观察结果，我们提出浑浊保护机制可能是HPM与葡萄酒蛋白质之间竞争未知葡萄酒成分的机制之一，后者是变性蛋白质形成大的不溶性聚集体所必需的。由于这些成分的有效浓度因HPM的存在而降低，浑浊的粒径减小，因此可见浊度下降。
