MSc

The study entitled “Standardization of quality wine production from selected underexploited fruits” was conducted at Department of Post Harvest Technology, College of Agriculture, Vellayani, Thiruvananthapuram, during the year 2017-2019 with the objective to standardize quality wine production technology from selected underexploited fruits of Kerala.
Fruit wines were prepared from four different underexploited fruits viz., carambola, papaya, jamun and rose apple independently by varying three process parameters viz., fruit: water ratio, yeast concentration and clarification methods. Fruit: water ratio was tried at 1:0.75, 1:1 and 1:2; yeast concentration at 0.5, 0.75 and 1% and clarification by pectinase enzyme and by settling, thus formed 18 different wines in each fruit. The experiment was conducted as four continuous steps viz., production of fruit wines, quality evaluation, selection of the best wine and studying the storage potential of wines.
Among the four underexploited fruits, carambola, papaya and rose apple produced wines of acceptable quality. No significant difference was noticed in the TSS content of different wines. All the prepared wines were “dry” due to absence of residual sugar content.
Carambola wines were golden yellow, brilliant to cloudy with a predominant astringent taste and 7.2 to 12.3% alcohol content. Papaya wines were light yellowish with a characteristic papaya odour and their alcohol content ranged from 6.15 to 17.28%, whereas rose apple wines were light pinkish, brilliant with 5.27% to 12.01% alcohol.
The wine with high antioxidant potential and high overall acceptability was selected from each fruit for conducting storage trials. The highest mean overall acceptability score (6.1) was obtained for the carambola wine prepared using 1:2 fruit: water ratio, 0.75% yeast and clarified by pectinase. This wine was brilliant, had 4.60 TSS, 0.5% acidity, 8.9% alcohol, 183.63 mgg-1 polyphenol and the highest antioxidant activity (64.9 %).
Papaya wine prepared using 1:2 fruit: water ratio, 1% yeast and clarified by pectinase had the highest antioxidant activity and high polyphenol content with an overall acceptability score of 4.6. This brilliant wine had 30 TSS, 0.46% acidity, 6.15% alcohol, 201.57 mgg-1 polyphenol and 79.46 % antioxidant activity.
The highest mean overall acceptability score (5.4) was obtained for the rose apple wine prepared using 1:2 fruit: water ratio, 0.75% yeast and clarified by settling. It was brilliant, with 5.60 B, 0.44% acidity, 9.08% alcohol, 97.79 mgg-1 polyphenol and the highest antioxidant activity (91.56 %).
The processing variables tried in the present experiment resulted in a dark purple attractive but unacceptable beverage from jamun with high alcohol (6.44 to 24 %) and acidity (0.69 to 5.42%), pungent smell and vinegary taste; hence could not be subjected to sensory analysis and further storage studies.
In general, wines prepared from 1: 2 fruit: water ratio had superior quality, acceptability and highest antioxidant activity. Addition of 0.5% yeast was not sufficient for producing quality wines. When yeast concentration was increased to 0.75%, the brilliancy and acceptability of the wines increased and at 1%, cloudiness enhanced resulting in reduced acceptability. Use of pectinase enzyme was essential for clarifying papaya and carambola wines where as clarification by settling could give a brilliant quality wine from rose apple.
The best wine selected from each fruit was stored under ambient condition for a period of three months in plain and amber coloured glass bottles for analysing their storage stability. The polyphenol content of the wines decreased during storage in both the containers and the percentage reduction was less in amber containers indicating better retention of quality parameters. The alcohol content increased during storage and the percentage increase was more in amber containers. There was no significant difference in the microbial load of wines stored in different bottles or different storage periods.
The present study highlighted the fermentation capabilities of three underutilized fruits of Kerala and standardized quality wine production from them. It was proved that the wine processing parameters should be formulated for different raw materials based on their initial characteristics for production of acceptable quality wines.