Study On Cryo-Extraction Technology Of Wine

The quality of wine depends on raw material. The most important question of enology mainly displays in two aspects. One is to exhibit the potential quality of raw material economically and perfectly as much as possible at good raw materials. The other is to concealment quality defect and make relatively good wine at bad raw materials.The endemic element of wine mainly exist in the cells of pericarp and flesh. There were many special compositions in pericarp, therefore it was regarded as"noblest part"in all parts of grape. The lower epidermis cells were rich in aromatic substance, tannin and pigment. The quality of wine was determined by the contents of these beneficial substances. Thus the emphasis of modern enology is to extract the beneficial substances. In order to extract the beneficial substances of grape, people adopt the traditional methods of"soaking with CO2","normal steeping","heat steeping","cold steeping". The physicochemical properties of raw material were altered and the quality of wine was reduced by these methods.At five different temperatures: -15℃,-20℃,-25℃,-30℃,-32℃, Freezing effect on the structure of grape pericarp cells was studied using Chardonnay by electron microscope. Wine making experiment was conducted with Chardonnay at -20℃. We studied the physicochemical index and the sensory index of treated juice and wine. The extraction effect of the beneficial substances was studied in different steeping time at -3℃and normal temperature. Aroma components of juice was determined. All results were as followed:1. The untreated berry pericarp cell structure including the cell walls, the vacuoles and the cytoplasm were intact by electron microscope. However, the cells of treated berry were damaged at different degree. At -15℃and -20℃, the cells had been distorted, the structure had been damaged, the cell walls had been fractured. At -25℃, -30℃and -32℃, the most cells of grape berry were damaged badly. The cells had been distorted badly and it was hard to see intact cells.2. Wine making experiment was conducted with Chardonnay at -20℃and unprocessed berry using little vessel. We studied the physicochemical index of treated juice and wine. The content of tannin, total phenols, total nitrogen and trace element were higher than untreated and there was also much more the species of aromatic substance. The appearance, the aroma and the taste of wine which was made by freezed berry had changed. The fruity aroma was much more balanceable and the taste was much more salubrious.3. To investigate the distribution of polyphenol in cell wall at"normal steeping"and"cold steeping", we could found the phenomenon of the plasmolysis and with the elongation of treatment time, there was an intendance of increase for the phenomenon, and the structure was not resolved easily.