Production Of Wine From Tomato(Lycopersicon Esculentum Mill.)Using Saccharomyces Bayanus, BV818

The consumption of fruits and vegetables has received much attention in recent times. This is probably because reports have indicated that there is an inverse relationship between their consumption and coronary heart diseases, diabetics, cataracts, different types of cancers, etc. Tomato is one of the most consumed vegetables in the world and a major source of the carotenoid, lycopene known to be the most efficient quencher of singlet oxygen. It is also a good source of p-carotene, vitamin C, vitamin E, flavonoids and phenolics. Fresh tomato contains about95%water and this makes it susceptible to spoilage and can therefore be kept for a few weeks. In order to extend its shelf life tomato has to be processed. In this study tomato was processed into wine using the yeast Saccharomyces bayanus, BV818. The original tomato must pH of4.11was adjusted to two other pH levels3.40and3.20and alcoholic fermentation was carried out at15and20℃, and the wines produced from the three pH levels were designated as Control, Wine A and Wine B. The objectives of the study were to monitor tomato must fermentation, determine the physicochemical properties of the wines, assess the bioactive compound composition of the wines and their antioxidant activity, model the colour of the tomato wines during ageing, compare the quality of wines aged in bottles to those aged with ultrasound of33kHz frequency, and to assess the volatile compound composition and the sensory properties of the tomato wines produced.The fermentation dynamics study indicated that sugar consumption was more efficient in the fermentation conducted at20℃than at15℃, and fermentation lasted for12days in the former but17days in the latter. At both fermentation temperatures, the wine (Wine B) made with tomato must of pH3.20gave the lowest rate of ethanol production, therefore the adjusted pH level4.20was less suitable for yeast activity.Fermentation temperature and tomato must pH significantly influenced most physicochemical properties (P<0.05) of the tomato wines after fermentation. Among the parameters whose concentration in the tomato wines were not influenced significantly by tomato must pH and fermentation temperature were ethanol content and volatile acidity. The ethanol content of the wines ranged from8.15to9.25(%v/v). The volatile acidity was in the range0.036-0.057g/L, and was below the minimum permissible level in wines. After90days bottle ageing, while most physicochemical properties of the tomato wines made at20℃were significantly affected (P<0.05) by the storage temperature, the influence of storage temperature for most physicochemical properties was not significant for those made at15℃. Also at the end of the90days ageing period, multivariate analysis of the physicochemical data indicated that the tomato wine samples were differentiated from one another mainly on the basis of fermentation temperature followed by storage temperature.Generally, significantly higher (P<0.05) bioactive compound concentration was obtained for tomato wines made at20℃than those made at15℃. In addition, the antioxidant activity, reducing power and DPPH scavenging activity was generally significantly higher (P<0.05) for wines made at fermentation temperature20℃than15℃. Even though most bioactive compound concentration of Wine B20was significantly higher than the other wines, Contro120gave significantly higher reducing power and total antioxidant activity than Wine20. Storage temperature exerted statistical significant influence (P<0.05) on the content of most bioactive compounds of the tomato wines after ageing. Wines B15and C20stored at15℃gave the best total antioxidant activity value (P<0.05), Wine A20stored at10℃recorded the best reducing power value (P<0.05), and the best DPPH scavenging activity values (P<0.05) were given by wine C20aged at both10℃and15℃. During tomato wine ageing the quadratic and linear models were fitted to the colour parameters L*, a*, b*, C*, H*and△E*us^ng co-efficient of determination (R2), root mean square error (RMSE), residual sum of squares (RSS), and Chi-square (CS) as the criteria for best model selection. For almost all the colour parameters of the wines the quadratic model gave the highest R2, the lowest RSS, RMSE, and CS, and was therefore considered the best for describing the colour changes of the wines which took place during ageing. The changes in a*was significantly related to the β-carotene and the lycopene contents of the wines (P<0.05). However, changes in b*was much correlated with the β-hydroxycinnamic index. At the end of the ageing process cluster analysis using a dendrogram indicated that the b*value was related to the β-carotene content, a*was related to lycopene and anthocyanin, and L*was related to the pH of the wines. Generally, the wines stored at15℃gave significantly higher L*, a*, b*and C*values (P<0.05) than those stored at10℃.The results on the comparative study of ultrasonic and bottle ageing indicated that the ultrasonic treated wines were of comparable physicochemical properties to the bottle aged ones. However, though most bioactive compounds concentration of ultrasonic treated wines were significantly enhanced (P<0.05) than that of bottle aged samples, the two were of comparable antioxidant properties. The principal component analysis (PCA) results indicated that wines A and B made at both15and20℃and treated with the ultrasound were likely to have much more similar properties as the bottle aged wines. Significantly higher△E*(P<0.05) was obtained for most wines aged in bottles than the ultrasonic treated wines, and the colour of the bottle aged samples could be perceived to be much different from the untreated samples.The solid phase micro extraction (SPME) technique was used for the extraction of volatile compounds from tomato wine and the volatile compounds were identified using Gas chromatography-Mass spectrometry (GC-MS) and the NIST Library. The concentration of the volatile compounds was obtained through the use of1-propanol as an internal standard. In all a total of171volatile compounds were identified in the tomato wines, and this was made up of31higher alcohols,82esters,23fatty acids,19carbonyls,4furans,7sulphur-containing compounds,4terpenes, and1other (eucalyptus). There were a total of32volatile compounds which recorded odour activity values (OAV) greater than1, and while the tomato wines made at15℃had25volatile compounds of OAV greater than1, wines made at20℃gave29volatile compounds. Out of the volatile compounds which had OAV greater than1, ethyl octanoate, ethyl hexanoate and isoamyl acetate with characteristic fruity fragrances were the major contributors to the overall aroma of the tomato wines. After fermentation at15and20℃, the joint relative odour contribution (ROC) of ethyl octanoate, ethyl hexanoate, and isoamyl acetate to the global aroma of the tomato wines produced was96.12-98.44%and91.04-94.81respectively. After ageing the ROC of these three compounds were97.72-98.07and97.68-98.11%for wines made at15℃and stored at10and15℃respectively. However, for those made at20℃and stored at10and15℃, the respective ROC values were94.89-95.66and94.29-96.08%. Fermentation temperature and tomato must pH significantly influenced (P<0.05) the volatile compound composition and concentration of the tomato wines produced. In addition storage temperature also affected the volatile composition and concentration of the tomato wines significantly (P<0.05). Tomato wines of acceptable quality was produced from tomato with rating in the range4.7to5.5on a scale of7. Wine C15recorded the highest overall acceptability among wines made at15℃, but for those made at20℃, Wines A10and B10were rated the best.The futre study should consider the tilization of a different strain of yeast in tomato wine production; optimization of sugar concentration, pH, temperature and inoculums size; and finally the effect of different fermentation conditions on lycopene content of tomato residue and the extraction of lycopene from this residue to be microencapsulated into the tomato wine.