Production and optimization of date fruit and honey wines using Saccharomyces cerevisiae isolated from various palm wine sources

Abstract

Dates and honey are known for their high nutritional values and associated benefits. Wine production with dates and honey will help in value addition to dates and also reduce post-harvest losses. This study aims to produce and evaluate wine produced from dates and honey using yeasts isolated from palm wine. Yeasts were isolated from various samples of palm wine, selected, and identified using molecular techniques. The best-performing yeasts, namely, isolate 065 (Saccharomyces cerevisiae) and isolate 047 (Candida tropicalis), were used to produce date fruit and honey wines combined in the ratios of: date100%, D/H 50%/50%, D/H 40%/60% and D/H 30%/70% for 7 days. The performance results of the yeasts indicated that isolate BFC 065 recorded the highest invertase activity (40.95 μmol min⁻¹), followed by PPE 047 (36.84 μmol min⁻¹), while IPA 151 showed the least invertase activity (4.3 μmol min⁻¹). The alcohol dehydrogenase activity results indicated that PPE 047 had the highest activity (13.67 unit per mL), followed by BFC 065 (11.42 unit per mL), while IPA 151 had the least activity (2.4 unit per mL). The yeast isolate's sugar tolerance properties showed that isolates 065 and 047 had the highest sugar tolerance level at 20% sugar concentration with optical densities (OD) of 1.098 and 0.947, respectively, after 72 h of incubation. In contrast, the isolate BFC 168 showed the least sugar tolerance level (OD = 0.674). The ethanol tolerance potentials of the yeasts showed that the highest ethanol tolerance was observed for BFC 065 (17.5 ± 0.18% v/v), followed by PPE 047 (14.00 ± 0.81% v/v), while IPA 142 showed the least tolerance (4.5 ± 0.47% v/v). The total titratable acidity (TTA) producing potential of the yeasts showed that the highest acid-producing potential was observed for BFC 065 (3.21% ± 0.144%), followed by PPE 047 (2.16% ± 0.35%), while IPA 131 had the least potential (0.27% ± 0.00%). The highest pH tolerance of the yeasts was observed at pH 2. The isolate BFC 168 tolerated the lowest pH (pH 2), while IPA 110 (OD = 0.115) showed the least tolerance. The composite value of the date syrup and honey showed that the energy level of dates was 303.36 kJ, while that of honey was 335.69 kJ; the protein contents were 2.37% and 1.09%, respectively, while the carbohydrate contents were 72.21% and 82.09%, respectively. The essential element composition of dates and honey showed that they contained calcium levels of 468.90 mg and 3.67 mg, respectively, magnesium levels of 117.8 mg and 2.98 mg, respectively, and iron levels of 29.50 mg and 1.34 mg, respectively, while copper and zinc were not detected in honey. There was a gradual decrease in soluble sugar (⁰Brix), pH, and specific gravity of various wines, while TTA increased with the fermentation time. The alcohol contents of the wines fermented with the isolate 047 were higher than those fermented with the isolate 065. The alcohol content ranged from 7.54% (D/H30/70) and 9.65% (D/H30/70) to 9.98% (date100%) and 12.24% (date100%) for the isolates 065 and 047, respectively. The result of the flavor compounds in the top three developed wines identified using GC-MS indicated that hexadecanoic acid, oleic acid, octadecenoic acid, and methyl ester were present in all the wines. In contrast, cis-vaccenic acid was present only in D/H40/60 fermented with the isolate 065. The sensory evaluation of the wines ranked the commercial wine first, wine 2 second and wine 1 sixth. This shows that acceptable wine could be produced from date fruit and honey blends.