Effects of Purified Yeasts From Natural Oil Palm and Raffia Palm Wine on Quality of Grape Fruit Wine

Abstract

Yeast (Saccharomyces cerevisiae) was purified from oil palm (Elaeis guineensis) and raffia palm (Raphia vinifera) wines and used to ferment grapefruit must (Citrus paradise). The Commercial Bakers' Yeast (CBY) was used as control. They were propagated and pitched at a rate of 4 % (v/v). The results of viability test showed that Oil Palm Wine Yeast (PWY) was 98% viable with an initial cell count of 1.0 x 10⁷,Raffia Palm Wine Yeast (RPWY) was 95 % viable with an initial cell count of 5.0 x 10⁶ and commercial Bakers' yeast (CBY) was 96 % viable with an initial cell count of 7.0 x 10⁶. The must had a pH of 3.59; titratable acidity of 0.69 % (as % tartaric acid) and soluble solids of 16 % and was fermented at 30±2 °C for 14 days followed by racking, fining and ageing (5+2 °C) for 15 days. The wines fermented (PWY, RPWY and CBY) had 10.0, 9.0 and 10.0 (% v/v) alcohol, residual soluble solids of 5.0 %, 6.1 % and 5.2 %; 3.71, 3.74 and 3.69 pH and 0.83 %, 0.79% and 0.81 % tartaric acid, respectively. The results of sensory evaluation showed that except in flavour, there was no significant difference (p>0.05) in taste, colour and overall acceptability of the wine samples when compared with the control.