Research On The Fermentation Technology,Aging Method And Volatile Components Of Kiwi Fruit Brandy

In this paper, the study on the processing technology of kiwi fruit brandy was done. First, the brewing process conditions of kiwi brandy were optimized and the optimal brewing process conditions were obtained. Then, the nature aging of kiwi brandy and artificial aging of kiwi brandy were compared. And on this basis, the special flavor compounds, sensory evaluation and physic-chemistry properities in kiwi brandy were investigated, which could provide the basis for the industrial production and the development of new products. The conclusions obtained in this thesis are listed as follows.Firstly, by comparing the results of fruit pulp fermentation with fruit juice fermentation, it was concluded that the fermentation effect of kiwi fruit pulp were better.Based on the results of single factor test and the response surface experiment,the best fermentation technical parameters of Kiwi spirit were determined, which was pH 3.55,the soluble solids (TSS) 22.84%, addition of yeast 0.49%. Under these conditions, a verification experiment were conducted.The results showed that the alcohol content and the methanol content were 11.12%vol and 181mg/L, which were similar to the predicted values 11.24%vol and 172.6mg/L. Prove that this model was effective.Secondly,effects of alcohol, sugar content, TSS, pH, methanol content during the processes of kiwi fermentation for brandy production were investigated.It was founded that, in the fermentation of the kiwi brandy, the alcoholic strength and methanol content gradually increasedand concentrations of sugar and TSS decreased,meanwhile, the pH value of the fermentation medium first decreased, then went up. The 5-9 days of fermentation was the yeast exuberant stage. And after 10 days of fermentation, the indicators tend to be stable, the alcohol content is 11.14%vol, the total sugar content is 4.9 g/L, TSS is 8.2%, the pH is 3.43, the methanol content is 175 mg/L.Thirdly, according to the optimization of fermentation technology of kiwi fruit wine, the kiwi through 12 days fermentation and 30 days after fermentation, became the kiwifruit wine with the alcohol degree of 11.2%vol. And using the method of second distillation, got the original brandy with the alcohol degree of 66%vol.Fourthly, by monitoring the changes of physical-chemical properities in the natural aging process of kiwi brandy, it was founded that the alcohol content, the methanol content and the pH in the aging process continued to decline, the total phenol content in the unceasing increase. ORP was on the rise, and the rate of increase was gradually slowing down. The conditions of microwave aging were optimized and founded that the best condition for the microwave treatment was microwave power 200 W and treatment 4 min. And in this time, the total phenolic content was 329.3 mg/L, the methanol content was 646 mg/L, and the sensory score was 86. The high temperature treatment and microwave treatment of brandy aging for three months compared with the brandy with natural aging for three months. It has been founded that the use of artificial aging on kiwifruit brandy physico-chemical indexes have improved obviously. Artificial aging can quickly reach the effect of the old wine, the kiwi brandy had a typical style in a short period of time.Fifthly, to study the influence of aging on the aroma components in thekiwi brandy, the solid-phase micro extraction (SPME) and the gas chromatography-mass spectrometry (GC-MS) were adopted to identify the aroma components in different aging period and high temperature aging and microwave aging.And the relative content of each component was calculated by area normalization method.134 kinds of volatile compounds were identified. Among them, there were 41 compounds with a relative content of more than 1%, which accounted for the total peak area 90.1%,84.69%,90.47%,84.35%,87.25%,89.17%, 88.95%,93.29% respectively.The types and relative contents of volatile components of all showed a different trend in different aging time and different aging methods.The changing trend of the whole was the decreasing of the content of alcohols and carbonyl compounds. And aromatic esters, terpenes, heterocyclic content was on the rise.