【作者】 张斌；

【导师】 曾新安；

【作者基本信息】 华南理工大学 ， 制糖工程， 2012， 博士

【摘要】 作为深受消费者喜爱的白兰地酒需在橡木桶里进行贮藏陈酿，通过橡木与酒之间缓慢的反应为酒添色增香，使酒色泽金黄透明、口味醇厚。但是白兰地一般需在橡木桶中贮藏多年，如特级白兰地(X.O)在橡木桶中至少要存放六年以上，一些著名品牌的特级白兰地存放达15年以上。因此为了提高白兰地橡木桶陈酿速率，节省世界有限的橡木资源，降低生产成本，缩短陈酿周期，提高生产效率，白兰地陈酿方法的研究越来越受到人们的重视。目前工业化生产所用橡木桶容积一般为225L或者更大，为了能够在较短时间内探明电场作用于橡木桶对白兰地有无影响及产生影响的好坏，本论文研究选择了容积相对较小的经中度烘烤的5L和2L法国橡木桶进行实验。于橡木桶两端施加50kV的电压，5L橡木桶中白兰地的实际电场强度约为1kV/cm，2L橡木桶中白兰地的实际电场强度约为1.1kV/cm，连续处理15个月，每天电场处理12h，处理室温度控制在15℃20℃，相对湿度控制在65%72%。并自然陈酿的白兰地进行了对比，全面分析了白兰地陈酿15个月过程中各种物质的含量变化，主要涉及多酚类物质、醛类、酸类、酯类、醇类物质，及色度、pH、溶解氧、氧化还原电位等指标，并与工业化生产的225L橡木桶中陈酿的白兰地酒进行了对比。主要研究内容和结果如下：各陈酿样在5L及2L橡木桶中白兰地的酚类物质、酯类物质及β苯乙醇含量随贮存时间均呈现递增的趋势，但电场处理样的各物质含量均高于同期同容积的自然陈酿样。例如，陈酿6个月时，在5L橡木桶中，电场处理样的总单宁、缩合单宁、总酚、辛酸乙酯及β苯乙醇含量比自然陈酿样分别提高了31.6%、68.2%、7.5%、6.6%和1.6%；在2L橡木桶中，陈酿6个月时，以上各指标分别提高了43.3%、60.3%、3.1%、10.8%和1.4%。橡木桶容积的大小决定了与酒体接触内比表面积的大小，容积越小则内比表面积越大。实验表明，2L橡木桶中白兰地的酚类物质、酯类物质及β苯乙醇含量比同期5L橡木桶的含量要高。例如，自然陈酿6个月时，2L陈酿样的单宁、缩合单宁、总酚、辛酸乙酯及β苯乙醇含量比5L陈酿样的分别高62.8%、83.8%、22.7%、2.6%和1.0%；电场处理6个月时，分别高77.2%、67.6%、17.6%、6.7%和0.4%。与工业化生产所用225L橡木桶陈酿白兰地12个月时的酚类物质及酯类物质含量相比，5L电场处理样的单宁、缩合单宁、总酚及辛酸乙酯含量在78个月时超过其值，2L电场处理样则更提前了12个月超过其值。说明了电场处理能够促进橡木桶中酚类物质的溶出，促进酯类物质的合成。随着陈酿时间的延长，乙醛、乙缩醛、糠醛含量呈现先降低后升高的趋势；乙酸、辛酸、癸酸均呈现递增的趋势，但是电场处理样的增幅要小于同期同容积的自然陈酿样；甲醇及杂醇油含量均呈逐渐降低的趋势，且电场处理样的甲醇及杂醇油含量要低于同期同容积的自然陈酿样。例如，在5L橡木桶中电场处理样的杂醇油及甲醇含量比自然陈酿样在6个月时分别降低了8.26mg/L和4.34mg/L；2L橡木桶中，分别降低了14.04mg/L和6.97mg/L。实验还选取了橡木粉、橡木片、橡木丁及橡木块进行陈酿实验，发现无论自然陈酿样还是电场处理样，白兰地的单宁、总酚及易挥发酚类物质含量随贮存时间的增加均呈现递增的趋势，但是电场处理样的含量均要高于同期对照样，4种橡木制品的酚类物质溶出速率大小为橡木粉＞橡木片＞橡木丁＞橡木块。通过对没食子酸、原儿茶酸及香草醛等10种酚类物质，乙酸乙酯和乳酸乙酯等5种酯类物质的含量变化趋势分别进行聚类分析，发现了其在白兰地酒陈酿过程中的内在关联性，酚类物质可聚类分为三大类，酯类物质可聚类分为二大类，其中4甲基愈创木酚及乙酸乙酯都单列一类，且电场处理样的含量明显高于同期同容积的自然陈酿样。例如，在5L橡木桶中，电场处理样的4甲基愈创木酚和乙酸乙酯的含量比自然陈酿样在6月时的含量分别提高了66.7%、16.6%；2L橡木桶中分别提高了75.0%和17.5%。通过建立电场对酚类物质作用的数学模型，发现对于每一种酚类物质扩散系数的回归方程，电场强度E的系数均比橡木桶体积V的系数要大，这充分说明电场作用与橡木桶体积大小相比，电场的作用对酚类物质的含量影响要大，同时电场E的系数均为正数，说明电场作用对扩散系数及酚类物质的含量起到积极地促进作用。在外加电场的作用下，白兰地中溶质分子的跃迁频率和激活熵被提高，增大了扩散过程中分子的自由度,加快了分子的扩散过程，同时活化能降低，扩散系数增大，从而促进了白兰地酒对橡木成分的提取。外加电场加速了分子运动速度和化学反应速度，电场提供能量，促使分子的电离，降低了反应所需的活化能，活性提高的同时，处于动态平衡的化学反应都加快，提高了分子间的有效碰撞，加速了酯化反应、缔合反应、氧化还原反应等的进行，同时促进了低沸点物质的挥发。更多还原

【Abstract】 Brandy should be stored in oak barrel for many years in order to obtain attractive color,complex aroma as well as harmonious and comfortable mouth feel by slow reactions betweenoak and wine. For example, special brandy (X.O) should be stored in oak barrels for at leastsix years, some famous brandy were stored for more than15years. Natural aging processnormally takes a long time (over many years), resulting in the low production efficiency andhigh cost. In order to shorten the aging time, save the limited oak resources, reduceproduction costs, speed up the turnover ratio, and improve economic benefit, research shouldbe conducted to accelerate the aging process.In the brandy industry, the most common used oak barrel is225L, which is far largerthan the5L and2L barrels used in the current research. The reason of using smaller barrelsis to firstly test and verify the concept and effectiveness of using electric field to acceleratethe aging process of brandy. Once the feasibility of the technique is confirmed, furtherexperiments can then be conducted for larger barrels. When a voltage of50kV is applied, thereal electric field strength in the brandy is about1kV/cm in5L oak barrels, and it is a about1.1kV/cm in2L oak barrels. A voltage of50kV was applied between two electrodes insideof the cellar every12hours (normally treatment time was from8AM to8PM everyday) forcontinuously15months. The cellar temperature was controlled at15℃20℃, and the relativehumidity was controlled at65%72%.The influence of applying an electric field treatment onbrandy stored in oak barrels to simulate the industry application during15months wasinvestigated.The compositions in the EF treated and control brandy samples including phenols,aldehydes, acids, alcoholics, esters, chroma, pH, dissolved oxygen as well as oxidationreduction potential were analyzed. It was demonstrated that the application of electric fieldtreatment directly on oak barrel is a promising and feasible technology to accelerate brandymaturation. The main contents and results were as follows:The content of phenolic compounds, esters and β phenethyl alcohol in both barrelsincreased gradually with aging time. Meanwhile, the EF treatment significantly enhanced theincrement of the compounds. For example, concentration of tannins, condensed tannins, totalphenols, ethyl caprylate as well as β phenethyl alcohol in brandy treated by EF was31.6%,68.2%,7.5%,6.6%,1.6%higher than those of the control brandy after6months ofmaturation in5L oak barrels, and43.3%,60.3%,3.1%,10.8%,1.4%higher than those of thecontrol brandy in2L oak barrels, respectively. The specific surface area was determined by the volume of oak barrel, the smallervolume the larger specific surface area. Results showed that the concentration of phenoliccompounds, esters and β phenethyl alcohol of brandy stored in2L oak barrels were higherthan stored in5L oak barrels. For example, concentration of tannins, condensed tannins, totalphenols, ethyl caprylate as well as β phenethyl alcohol of brandy stored in2L oak barrelswere62.8%,83.8%,22.7%,2.6%,1.0%higher than stored in5L oak barrels after6monthsof natural maturation, and77.2%,67.6%,17.6%,6.7%,0.4%higher than those treated by EF,respectively.Compared with the industrial production value of brandy in225L oak barrels duringaged for12months, the concentration of tannins, condensed tannins, total phenols as well asethyl caprylate in brandy were exceeded after78months stored in5L oak barrels treated byEF, and were exceeded even more12months stored in2L oak barrels treated by EF,respectively. Results showed that after being treated by EF, more beneficial phenols wereextracted from oak barrel. On the other hand, the synthesis of esters was promoted.It was observed that the content of the acetaldehyde, acetal and furfural first decreasedand then increased with aging time. Movever, the content of acetic acid, caprylic acid andcapric acid in both barrels increased gradually with aging time, and the content of thosecompounds in brandy stored in oak barrels treated by EF were lower than the natural agedones. The content of methanol and fusel oils in both barrels decreased gradually with agingtime, and the content of those compounds in brandy stored in oak barrels treated by EF waslower than the natural aged ones. For example, the concentration of fusel oils and methanol inbrandy treated by EF was8.26mg/L,4.34mg/L lower than control ones after6monthsmaturation in5L oak barrels, and14.04mg/L,6.97mg/L lower than those in2L oak barrels,respectively.The effect of electric field treatment on brandy by adding oak powder, oak chip, oak bit,oak block were also studied in this paper. Results showed that the content of tannins, totalphenols and volatile compounds in all brandy samples increased gradually with aging time.Meanwhile, the EF treatment significantly enhanced the increment of these benificialcompounds. Take phenols for examples, the extraction efficiency under EF fits the followingorder: oak powder, oak chip, oak bit, oak block, respectively.The internal relevance of10kinds of phenols and5kinds of esters was revealed bycluster analysis. The phenols and esters was divided into3,2groups, respectively. Meanwhile,the EF treatment significantly enhanced the increment of the compounds. For example,concentration of4methyl guaiacol and ethyl acetate in brandy treated by EF was66.7%, 16.6%higher than those of the control brandy after6months of maturation in5L oak barrels,and75.0%,17.5%higher than those in2L oak barrels, respectively.It was indicated that the electric field strength coefficient was larger than the volumecoefficient by regression equation of mathematical model. This implies that the effect of EF ismore significant than the volume of oak barrels. Meanwhile, it was explored that the electricfield strength coefficient was positive which implied the effect is positive. When it wastreated by EF, transition frequency and activation entropy of the solute molecule wereelevated, degree of freedom of molecules diffusion was improved, meanwhile, the activationenergy was reduced, molecular diffusion coefficient depends on the activation energy ofsolvent, less activation energy, greater diffusion coefficient, under the condition of constanttemperature, the molecular diffusion processes was accelerated, so the chemicals extractionfrom the wood was promoted. The speed of molecular motion and reaction speed wasaccelerated by EF, as the electric field power, the ionization of molecules was promoted, thereaction activation energy was reduced, the dynamic equilibrium of chemical reactions wasspeeded up, and effective collision between molecules was also increased. So theesterification reactions, associative reactions, as well as oxidation reduction reaction wereaccelerated, while the volatilizing of low boiling substances was also strengthened.更多还原