| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 91 === Longan is abundant in Taiwan. Dried longan is the major longan product. Researches on longan wine are few. The purpose of this experiment was to investigate the influence of yeast, additives, and temperature on the yield and quality of dessert wine produced from longan puree baked at 90 °C for 18 hours, and to establish the best process based on sensory evaluation. In addition, we identified the aroma compounds extracted from baked longan puree and the longan dessert wine by GC -mass spectrometer.
The results showed that the addition of yeast nutrient accelerated the fermentation. The fermentation rate was faster, the titratable acidity was lower and the redness was higher at a fermentation temperature of 25°C than at 18°C. The yeast population reached 108 cfu/mL on the fourth day but decreased to 104 cfu/mL at the end of fermentation in fermenting at 25°C. The sensory evaluation on the young wine showed better acceptability when fermented with Lalvin V1116 without adding yeast nutrient but added equal volume of baked longan puree after racking. During aging, temperature influenced the color of the wine. The lightness and yellowness readings of the wine aged at 50°C were lower but the redness was higher. Filteration increased the lightness and decreased the redness. Sensory evaluation showed the acceptability of longan dessert wine was better when it was fermented at 18°C for 14 days and aged at 16°C for 3 months. The major aroma compound of the young wine was phenethyl alcohol which has a rose-like flavor. After aging, some esters were formed, like ethyl lactate, which made the wine rich in fruity flavor.
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