RESUMO
The study focused on the production of wine from date palm fruits (Phoenix dactylifera L.) using a strain of yeast isolated from selected Nigerian locally fermented beverages ('pito', 'brukutu' and palm wine). Seven (7) distinct yeasts were isolated and identified using cultural, microscopy and biochemical tests (temperature tolerance, flocculation, ethanol tolerance, H2S production and killer toxin production and the ability to assimilate and ferment sugars. The yeast isolates were screened using refractometric and spectrophotometric methods to select the isolate with the best ability for wine production. This isolate was molecularly characterized, grown in 1 L of potatoes dextrose broth, freeze dried and used for wine production. The population of yeast, bacteria and the physicochemical analysis of the must were monitored during fermentation. Populations of bacteria in the wine were assessed by standard pour plate count. The proximate content and physicochemical properties of the produced wine before and after ageing, as well as the sensorial quality of the produced wine was determined. All the yeast isolates possessed the ability to flocculate, tolerate ethanol concentration of between 5 and 20% and temperature range of 30-45 °C, produced low concentration of H2S and does not produce killer toxins. A palm wine isolate, identified as Saccharomyces cerevisiae X01 was selected as the best isolate with the most ability for wine production. The total yeast count increases as the period of fermentation progressed while the total viable bacterial count reduced as the fermentation period progressed. There was a significant difference (P < 0.05) in the physicochemical properties of the must during fermentation. At the end of the fermentation, the produced wine had 5.22% and 4.86% ethanol content for S. cerevisiae QA23 and S. cerevisiae X01 respectively. There was no significant difference (P > 0.05) between the proximate and physicochemical compositions of the produced wine before and after ageing using Saccharomyces cerevisiae X01 when compared to the control S. cerevisiae QA23. This study revealed that the Nigerian locally sourced S. cerevisiae X01 can be used as an alternative substrate for industrial scale production of wine with a mild alcoholic content.
