枸杞果酒发酵过程中黄酮与多糖含量的变化动力学及其发酵条件优化

枸杞果酒发酵过程中黄酮与多糖含量的变化动力学及其发酵条件优化摘要枸杞是我国传统的药食同源植物之一，含有枸杞黄酮、枸杞多糖等多种生物活性物质。枸杞酒是枸杞传统的食用方式之一，其中发酵法制得枸杞果酒因其风味良好、能保留较多活性物质而深受人们青睐。为探讨枸杞果酒发酵过程中生物活性物质的变化机理、优化枸杞果酒发酵条件，本论文以宁夏枸杞为原料，采用不同发酵条件酿造枸杞果酒，对枸杞果酒发酵过程中的黄酮、枸杞多糖等物质进行了测定，考察了发酵温度、糖浓度、酵母接种量及pH等发酵条件对发酵后枸杞果酒中总黄酮含量和枸杞多糖含量的影响规律，获得了以下主要结论：（1）发酵过程中各因素的变化趋势表现为：发酵液pH值在发酵前期表现为轻微下降，下降至一定值以后基本保持不变，酒精体积分数不断增大至最大值后基本保持不变，总黄酮含量持续增加至最大值后基本保持不变，多糖含量先增大后减小，最后维持在最低水平基本保持不变；发酵过程中发酵液中的总黄酮含量和枸杞多糖含量均与酒精体积分数之间呈现很好的二次相关性。（2）响应面分析法优化得出能够枸杞果酒中总黄酮含量最大时的最佳发酵条件为：发酵温度21.9℃，酵母接种量0.29g/L，糖浓度220.0g/L，pH4.3，此条件下黄酮含量的预测值为0.2404g/L，实测值为0.2337±0.0043g/L。表明所得方程适用性好。（3）响应面分析法优化得出能够枸杞果酒中枸杞多糖含量最大时的最佳发酵条件为：发酵温度21.9℃、酵母接种量0.31g/L、糖浓度297.3g/L，pH3.8，此条件下的多糖含量的预测值为1017.48mg/L，实测值为1009.52±7.56mg/L。表明所得方程适用性好。（4）用固相微萃取提取枸杞果酒中的香气成分，通过气相色谱-质谱联用技术对香气成分进行分析鉴定，并应用内标法测定各成分的相对含量。在枸杞果酒中共检测定性出31种挥发性成分，其中主要是酯类、醇类、有机酸、酮和少量其他香气物质；辛酸已酯、己酸乙酯、乙酸乙酯、癸酸乙酯、醋酸苯乙酯、苯乙醇、辛酸等成分含量较高，是形成枸杞果酒特征香气的主要组分。关键词：宁夏枸杞；多糖；黄酮；果酒；发酵；优化KINETICOFTHECHANGEOFFLAVONOIDANDPOLYSACCHARIDECONTENTDURINGTHEFERMENTATIONOFLYCIUMBARBARUML.WINEANDOPTIMIZATIONOFTHEFERMENTATIONCONDITIONSABSTRACTLyciumchinenseisafamousfruithasbeentraditionallyusedbothasfoodandmedicineinChina.TheberryofLyciumchinenseisrichinfunctionalcomponents,mainlyflavonoid,andLyciumBarbarumpolysaccharides(LBP).WineofLyciumbarbarumL.wassupposedtokeepthemainfunctionalcomponentsintheberries,sincedippingtheberriesinalcoholisawidelyacceptedwaytousetheberryinChineseherbalmedicine.Inordertoproducehighactivecomponentscontentwine,influenceofthefermentationconditionsontheresultswasstudiedandoptimized.Fourfactorsoffermentationtemperature,yeastinoculumsize,sugarconcentrationandpHwereinvestigated.Box-BehnkendesignandResponseSurfaceMethodology(RSM)wereusedtoarrangetheexperimentsanddataanalysis.Themainlyobtainedresultswerelistedasthefollowing,(1)Duringthefermentation,pHvaluedecreasedslightlyatthefirststageandthenkeptatastableleveluntiltheend.Thetotalflavonoidcontentkeptincreasingtoapeakvalueandthenchangedslightly,similartoofthevariationtrendofalcoholcontent.Thepolysaccharidecontent(LBP)increasedfirstlyandthendeclinedtoaminimumvalue.Quadraticregressionmodelsweredevelopedtoshowthechangeofflavoniodcontent,polysaccharidecontentandalcoholconcentration,respectively.(2)AccordingtheRSManalysisonthedataofBox-Behnkendesign,theoptimalfermentationconditionsforthehighestflavoniodcontentinLyciumBarbarumL.wineweresetatfermentationtemperatureof21.9℃,yeastinoculumsizeof0.29g/L,sugarcontentof220.0g/LandpH4.3.Undertheoptimalconditions,flavoniodcontentinthewinecouldreachtothehighestvalueof0.2404g/Lpredictedbythemodeland0.2337±0.0043g/Lintherealverificationtest.Theconstructedmodelshowedgoodfitnesstotheexperimentaldata.(3)AccordingtheRSManalysisonthedataofBox-Behnkendesign,theoptimalfermentationconditionsforthehighestpolysaccharidecontentinLyciumBarbarumL.winewerefermentationtemperatureof21.9℃,yeastinoculumsizeof0.31g/L,sugarcontentof297.3g/LandpH3.8.Undertheoptimalconditions,thehighestpolysaccharidecontentwaspredictedas0.2404g/Land0.2337±0.0043g/Lintheverificationtest.(4)AccordingtotheGC/MSanalysis,31componentswereidentifiedinthearomaofLyciumBarbarumL.wine.Theimportantaromacomponentswereidentifiedasester,alcohol,organicacid,ketoneandsmallamountofothercomponents.Sevenkindofcomponents,includingoctanoicacidethylester,hexanoicacidethylester,ethylacetate,decanoicacidethylester,aceticacid2-phenylethylester,phenylethylalcoholandoctanoicacid,showedrelativelyhighercontentamongthearomacomponents,andweresupposedasthemainaromecomponentsinLyciumBarbarumL.wine.KEYWORDS:LyciumBarbarumL.,Polysaccharide,Flavonoid,Wine,Fermentation,Optimization目录第一章文献综述..............................................................................................................11.1枸杞资源.............................................................................................................11.2枸杞的营养价值.................................................................................................11.2.1黄酮类化合物..............................................................................................21.2.2枸杞多糖......................................................................................................31.2.3其他功能成分..............................................................................................51.3枸杞果酒.............................................................................................................51.4响应曲面法.........................................................................................................61.5本文研究内容、目的意义和技术路线.............................................................71.5.1研究内容......................................................................................................71.5.2目的和意义..................................................................................................71.5.3研究技术路线..............................................................................................7第二章枸杞果酒发酵过程中黄酮和枸杞多糖含量的变化动力学..............................92.1材料与方法..................................................................