The Non-Saccharomyces Microflora Inhabiting Sri Lankan Grapes for Wine Fermentation: An Unveiled Physiochemical Characteristic and Fermentation Dynamics

Abstract

Wine microbial consortium (WMC) plays a significant role in wine fermentation and the final sensorial properties of wine. Modern wines are produced by inoculated fermentation, resulting in predictable sensory properties and consistency in quality. To avoid this, controlled mixtures of unconventional yeast inhabiting the grape microbiota are used in wine fermentation. However, still there is no indigenous Sri Lankan wine starter culture to be used in local production. Therefore, this attempt is to isolate efficient yeast wild types from Sri Lankan grape varieties and to correlate their microbial fingerprints to the sensorial characteristics of wine. Grape samples (Israel blue) were collected from vineyards in the Northern Province and microbes were isolated from grape skin and different fermenting stages of must. Three different strains of yeast were isolated and they were identified as Hanseniaspora guilliermondii, Starmerella bacillaris, and Hanseniaspora uvarum by sequencing of ITS region. The identified yeast monocultures were inoculated into surface sterilized grapes must as starter cultures and kept for 14 days for fermentation. Then physicochemical characteristics of wine samples were analyzed by High-Performance Liquid Chromatography (HPLC). Comparably, H. guilliermondii doesn’t have the ability to survive at a high alcoholic level. It is the lowest alcohol producer (6.73%) while H. uvarum and S. bacillaris were able to survive in high alcoholic conditions as they are significantly (p<0.05) the highest alcohol producers. H. guilliermondii showed a high level of acetic acid (23.4 ± 0.01 g/L) compared to others while S. bacillaris showed a low level of acetic acid, 4.8 ± 0.03 g/L. Furthermore, H. guilliermondii expressed a shorter half-life time (2.29) and the highest growth rate, while H. uvarum expressed a longer half-life time (3.34), and the lowest growth rate. Overall, H. uvarum indicated a competitive advantage in wine production compared to other isolates.