Study On The Wine And Liquor Making Technology From Spent Coffee

Spent coffee is the solid residual during the processing of coffee powder with hot water or steam in coffee processing.When 1.0 kg instant coffee is produced,there are 0.9 kg spent coffee left.Spent coffee consists of 45.3%carbohydrate,13.6%protein,14.4%?15.0%lipids,11.05?13.24 mg/g polyphenols and aroma compounds.Few spent coffee are used as animal feed and fuel,most are discarded.In this study spent coffee were used to develop coffee wine and coffee liquor,so as to find out a better way to use spent coffee.First,the fermentation characteristics of yeasts in spent coffee wine brewing were investigated.Second fermentation methods were also tested.Third fermentation conditions of spent coffee wine and spent coffee-molasses wine were optimized.Then conventional indicators of liquors made from spent coffee were detected.Finally,sensory quality of wines and liquors made from spent coffee were studied and compared.The main results were as follows:(1)Fermentation characteristics of yeasts in spent coffee mediumThe fermentation performance and flavor producing ability of four yeast stains namely Saccharomyces bay anus BV818.S.cerevisiae D254.S.bayanus EC1118?S.bayanus DV10 were determined.Results showed that D254 was suitable for spent coffee wine fermentation,exhibiting higher ethanol content and better flavor.Growth and metabolism state of D254 in spent coffee mediums of different nutritional conditions were studied,which showed that it was the lack of nitrogen lead to sluggish fermentation and low ethanol content.(2)Fermentation methods of spent coffee wineTwo methods were tested:fermentation by spent coffee extract and fermentation with residuals.It showed that the latter had higher sensory score and rich in taste,which was chosen as a better method.(3)Study of spent coffee wine making technologyThe effect of NH4Cl,NH4SO4,(NH4)2PO4 on spent coffee wine fermentation were investigated.By adding 0.2%(NH4)2PO4,the biomass increased by 0.52 g/L,the ethanol content increased by 2.3%vol,the residual sugar content decreased by 3.4 times,complete fermentation was achieved.Optimum fermented conditions were:solid-liquid ratio of 1:4,inoculation volume of 6%,sugar content of 24%,pH value of 4.3,temperature of 23 ?.Under this condition,spent coffee wine had coffee aroma and rich taste with sensory score of 86.(4)Study of spent coffee-molasses wine making technologyOwing to coordination of molasses and spent coffee in nutrition and flavor,spent coffee-molasses wine was developed.The adding of nitrogen and molasses was studied.It showed that by adding 0.2%(NH4)2PO4,the ethanol content increased by 1.4%vol,the residual sugar content decreased by 6.47 g/L,the fermentation performance of yeast was best.While addition of molasses increased fermentation performance of yeast.When replacing 50%sugar by molasses,complete fermentation,a more complicated flavor were achieved.The optimum conditions were:pH value of 4.5,temperature of 20 ?.Under this condition,spent coffee-molasses wine had coffee aroma and tasted good.(5)Determination of conventional indicators of liquors made from spent coffeeSpent coffee liquor and spent coffee-molasses liquor were made by distilling spent coffee wine and spent coffee-molasses wine with adjusting ethanol content to 50%vol.The total acid content of spent coffee liquor and spent coffee-molasses liquor were 0.370 g/L and 0.333 g/L,while the total ester content were 426.93 mg/L and 469.53 mg/L.The liquors had classic coffee aroma and tasted mellow.(6)Sensory quality analysis of wines and liquors made from spent coffeeThe spent coffee wine was yellowish brown,clear and transparent.The content of typical coffee aroma compounds such as pyridine,furan,aldehydes was 12.653%,while ester compounds increased significantly due to fermentation,accounting for 42.758%,the spent coffee wine was unique with sweet fruit aroma,and tasted sour,bitter and astringent but harmonic.The spent coffee-molasses wine was dark brown and sticky.The content of typical coffee aroma compounds was 11.502%,while ester compounds increased significantly due to fermentation,accounting for 30.439%,being more complicated than that of spent coffee wine.It tasted sour,bitter and astringent but harmonic.The spent coffee liquor and spent coffee-molasses liquor was light amber,clear and transparent.The content of typical coffee aroma compounds was 21.364%,17.849%,while the ester content was 12.18%?18.56%.The liquors had strong coffee aroma and large quantity of esters providing fermented aroma.The liquors were similar with commercial coffee wines in aroma.The bitterness,astringency,sourness taste decreased after distillation.The liquors tasted elegant and soft,which were premium liquors.