Study On The Flavor Formation And Control Of Ethyl Carbamate Of Silver Rum

Rum is a kind of spirit made from sugarcane juice or molasses.The aroma ingredients are important factors in determining the characteristics and quality of Rum,as well affecting its style and type.Ethyl carbamate is a by-product of alcoholic beverages such as rum and alcohol,which has significant carcinogenic properties,and thus it is particularly important to strictly control the content of ethyl carbamate in Rum.Therefore,finding an effective way to reduce the content of ethyl carbamate in rum and to regulate the aroma components,and improving the aroma quality of rum is the research focus and hotspot of enterprises and scientific researchers.Based on the changes of chemical composition and volatile aroma substances in the fermentation process of sugarcane juice and rum,the composition was monitored from the aspects of sugarcane varieties,fermentation process,dynamic changes of aroma components and strains of Saccharomyces cerevisiae.The change of aroma material during the fermentation process of sugarcane juice,and the correlation between aroma of each stage,so as to promote the research on the aroma composition of rum.The material qualitative and quantitative analysis of rum flavor so as to provide scientific data for the the establishment of a quantitative evaluation system.Moreover,the flavor materials of rum were qualitative and quantitative analyzed,and expected to provide some scientific data for the establishment of a quantitative evaluation system.The main research contents and conclusions were as follows:(1)The volatile composition of six Chinese sugarcane varieties has been analyzed by headspace solid-phase microextraction(HS-SPME)method coupled with gas chromatography-mass spectrometry(GC-MS).It was found that the sugarcane juice from Daheixiong and Gui 00122 varieties contained the highest amount of alcohols and esters,whereas 94128 and Yue 00236 were rich in acid substances and monoterpenes,respectively.The Tai 22 variety has the highest level of aldehydes and ketones.After comparing the aroma components of the rum fermented with six kinds of sugarcane juice,it was found that acetal diethanol,3-ethyl-2-heptanol,propanol,n-butanol,1-amyl alcohol,isobutanol,isoamyl alcohol,Isoamyl acetate,ethyl hexanoate,diethyl succinate,ethyl decanoate,ethyl 9-decenoate,ethyl laurate,ethyl pentadecanoate,ethyl palmitate and 1,2,3,4-tetrahydro-1,1,6-trimethylf fumarate are the main components of six rum.Among them,the flavor ingredients of Rum brewed with Tai 22 sugarcane contained the largest species and the most abundant content of esters,followed by Gui 00122 and Daheixiong Rum.(2)The four kinds of clarification methods including filtrations by quartz sand,pectinase,lime and pectinase-lime were used to clarify Tai 22 sugarcane juice to explore the clarification of these types of clarification effect and feasibility based on the total sugar content,total nitrogen content,solid content,appearance,aroma ingredients,as well as the fermentation and distilled rum aroma ingredients.The results showed that the pectinase-lime method was the best and able to clarify the sugarcane juice,leading to the relatively low loss of the nutrient composition and aroma material.In addition,after processing with this method,the aroma composition of fermented rum is also loss less.Thus,the use of enzyme-lime method may be most appropriate in the optimization of rum process.(3)Fermentation ability of six kinds of strains of yeast(R2,F5,F33,X16,QA23 and EC1118)was studied by evaluating the utilization rate of sucrose and free amino acid,the production of oleanol and ester producing substances.Moreover,the content of fusel oil in rums was determined.The results showed that the most active stage of yeast,the production of fusel oil was most.The addition of leucine can reduce the production of fusel oil such as isoamyl alcohol,isobutanol and n-propanol in rum.(4)The dynamic analysis of the changes in the rum fermentation process was monitored.The results showed that the content of each amino acid was fluctuating in the process of rum fermentation,and it was consumed and regenerated in the rum fermentation process.After fermentation,the content of most amino acids has dropped significantly,but there are some amino acids,such as arginine and lysine has increased.During the fermentation process,twenty-two volatile aroma compounds were monitored including eight kinds of higher alcohol compounds,ten kinds of ester compounds and four fatty acid compounds.Most of them were produced in the fermentation stage,and began to change drastically from two to five days,but some aromatic substances are metabolized in the fermentation process,and the content is reduced.In addition,in the distillation process,the aroma substances of rum in different distillation were ever-changed.Among them,the relative content of esters increased first and then decreased.Alcohol substances generally show a decreasing trend,but the fifth paragraph has risen.The proportion of aldehydes and ketones is gradually increased.(5)Ethyl carbamate is one of the harmful byproducts which occurs in alcohol drinks,such as wine,rum,whisky,Saki and other fruit wines as a result of a spontaneous reaction between ethanol and urea in the fermentation process.In this work,the relationship between arginase car1 gene in Saccharomyces cerevisiae EC1118 and Ethyl carbamate generation in sugarcane juice fermentation was investigated.Results indicate that the content of Ethyl carbamate can be controlled by regulating the expression of arginase car1 encoding gene.Urea and arginase improved expression of arginase car1 gene,which resulted in an increase of Ethyl carbamate content.Besides arginine and urea,the expression of arginase car1 gene was also significantly influenced by the content of ethanol,salt and culture temperature.Low fermentation temperature,(below 25 ?)and lower ethanol and salt content showed some benefits in terms of controlling the EC content by decreasing the expression of arginase.