USE OF LYSOZYME AND OLIGOMERIC PROANTHOCYANIDIN TO REDUCE SULFUR DIOXIDE AND THE EVOLUTION OF VOLATILE COMPOUNDS IN ITALIAN RIESLING ICE WINE DURING AGING PROCESS

摘要

In order to reduce sulfur dioxide (SO_2) level in ice wine making, the effects of lowrnSO_2, lysozyme and oligomeric proanthocyanidin (OPC) on the volatile compoundsrnwere, respectively, studied during 1 year aging process. Based on the previousrnstudy, seven treatments of Italian Riesling ice wine were carried out forrnmonitoring the evolution of volatile compounds. Results of gas chromatographyrnmass spectrometry (GC-MS) showed that, about 180 mg/L SO_2 not onlyrnincreased total alcohols content in Italian Riesling ice wine, but also significantlyrncorrelated with certain higher alcohols during 1 year aging process. Meanwhile,rnthe final concentration of medium-chain fatty acid ethyl esters and the correspondingrnfatty acids were found highly related to lysozyme adding. Moreover,rnOPC played a positive role in stabilizing the total content of esters at a levelrnaround 200 mg/L, it mainly due to its excellent ability of free oxygen scavenging.rnFinally, principal components analysis (PCA) was conducted to reclassify majorrnvolatile compounds and 14 typical volatile components were defined.