Characterization of yeast isolates from Ziziphus mauritiana (Indian Jujube) fruits with potential application in oenology · Electronic Theses and Dissertations

Author

Swale, Ethel J.

Title

Characterization of yeast isolates from Ziziphus mauritiana (Indian Jujube) fruits with potential application in oenology

Abstract

Ziziphus mauritiana (Indian Jujube) fruits are highly nutritious and abundant, with a potential source of vitamin C and other valuable components. The utelisation of the fruit in the production of various food items, including wine has been explored. Fermentation using only S. cerevisiae limits the flavour diversity of the wine, hence the need for exploring wild yeast species with potential application in oenology. . One kilogram of the fruits was sampled from Mashonaland Central fruit and vegetable market and the Bindura University Hub. Yeasts were isolated on Potato Dextrose Agar (PDA) at 30℃ for 72 hours. Morphological and biochemical characterization was done. Fermentative yeasts that fermented glucose, sucrose and fructose were selected for further tests. The twelve isolates purified were further screened down using D-glucose and ethanol tolerance, production of hydrogen sulphide and urease activity. The four isolates selected after screening were used as starter culture for production of masau wine. Total Titratable Acidity (TTA) and Total Soluble Sugars (TSS) were analysed on wine at day ten using titration and Brixometer, respectively. Based on the morphological and biochemical characterization, the study identified the genus Saccharomyces, Saccharomycopis, Hanseniaspora, and Issatchenkia as potential starter cultures for wine production . The statistical analysis using One-way ANOVA yielded p-values 8.56E-08 ≤ 0.05 and 2.59E-12 ≤ 0.05 for TSS and TTA, respectively at p< 0.05. The p-values signify a significance difference between the tested groups. Further analysis using Tukey’s post-hoc analysis revealed a significant difference between the positive control commercial S. cerevisiae and the isolates, except for isolate 11 on both parameters. The results obtained after approaching this research reveal the presence of wild yeasts with potential to be applied as fermentation starter cultures. The study also reveals the weak performance of some isolates hence need to be used in combination with powerful fermentative yeasts e.g. S. cerevisiae.

Date

June 2025

Publisher

BUSE

Keywords

Ziziphus mauritiana (Indian Jujube)

Fermentation

Supervisor

Mr. C. Siamayuwa