Comparative Study on Physio-chemical and Organoleptic Attributes of Apple Wine Fermented from Local and Imported Yeasts

Abstract

With home micro-brewing on the rise, use of local indigenous yeast in the fermentation process is a prevalent practice in the country. The indigenous strain found in locally processed yeast can impart certain desirable flavours and aromas to the fermented wine. Furthermore, the use of antioxidant-rich wild herbs in local yeasts is reported to enhance the nutritional value of the wine. However, local yeasts are home-made under dubious processing conditions and cannot afford the advantage of being in a pure uncontaminated microbial form, unlike the commercial strains. This might affect the fermentative capability and compromise the end quality of the wine. Thus, this study was conducted to compare the organoleptic acceptability and physio-chemical properties (total soluble solid, alcohol by volume, transmittance value, pH and titratable acidity) of apple wine fermented by two local yeasts from Trashi Yangtse and Samtse districts in Bhutan and one commercial yeast manufactured in India. Both the local yeast strains seem to yield a wine with better appearance (clarity) and taste (sweetness) based on the sensory evaluation result. In terms of fermentative capability, the commercial strain had shorter fermentation time, but the local strains were able to yield wine with similar alcohol strength to the commercial strain. For the physio-chemical parameters, only pH and titratable acidity results were significantly different with the wine from local yeast from Samtse having a significantly higher malic acid content, while the wine from commercial yeast had lower pH. However, the results deduced from the sensory evaluation does not compliment the values obtained for Total Soluble Solute and clarity measurement. Besides, the difference in pH did not resonate with the taste perception (i.e., lowest pH wine considered sweeter). Thus, other flavour components might have a role to play in the sweet taste perception. Overall, the local strains showed promising results in terms of fermentation capability (ability to convert sugar to alcohol) and organoleptic attributes of the end wine in comparison to the commercial strain.