A Review on the Effect of Different Yeasts on the Fermentation of Red Dragon Fruit

Soh, Qian Qian (2022) A Review on the Effect of Different Yeasts on the Fermentation of Red Dragon Fruit. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

In this study, the juice of the red dragon fruit (Hylocereus costericensis) was fermented with different yeast strains to form a new “red wine”. Saccharomyces cerevisiae, Lachancea Thermotolerans and Torulaspora delbrueckii yeast strains completed fermentation with equal rates with red dragon fruit juice in terms of sugar consumption rate, eventual ethanol level (8-9 percent v/v), and pH (4.10). The goal of this study is to determine the effect, impact, physicochemical and oenological parameters of red dragon fruit juice during fermentation by three yeast strains. Determining the scope of the research questions, investigating relevant studies, selecting the study, data extraction, and analysing, summarising, and reporting the findings were all part of the technique utilised in this review. During the exponential stage, however, Saccharomyces cerevisiae had a reduced cell growth rate. Ethanol alters sweetness perceptions, increases bitterness, reduces sourness, and adds to the wine's heat and body. Wines must have a minimum alcohol strength of 8.5 percent v/v, according to the International Organisation of Vine and Wine (OIV), albeit this percentage can be reduced to 7 percent v/v in cool temperature wine regions. The highest glycerol concentration was found in Saccharomyces cerevisiae, 9.60 g/L, then will be followed by Torulaspora delbrueckii, 6.07 g/L, and Lachancea thermotolerans, 8.03 g/L. The TPC and TAC levels are highest in Lachancea thermotolerans, while TAC and BC levels are lowest in Saccharomyces cerevisiae. Aside from that, the CIELab parameters (L *, a *, b *, C *, and h°values) were used to determine the colours of red dragon fruit juice and wines. According to the colour criteria, red-purple betacyanin pigments were better retained in red dragon fruit wines fermented by Lachancea thermotolerans and Torulaspora delbrueckii. Betacyanin pigments and total phenolic components were dramatically reduced during fermentation. Furthermore, Lachancea thermotolerans has a low tolerance for alcohol, and too much ethanol might affect the aroma and flavour of a wine. In conclusion, the highest amount of carbon dioxide evolved rate are done by Saccharomyces. cerevisiae. Besides that, Saccharomyces cerevisiae are more stable and more alcohol tolerance than non- saccharomyces yeast. Two non-Saccharomyces yeasts outperformed Saccharomyces yeasts in terms of betacyanin pigment retention and antioxidant capabilities. From the results, Torulaspora. delbrueckii having the darkest wine colour than other yeast. In addition, wine fermentation by using Lachancea. thermotolerans is more redness (a *), more purity and brightness in colour (C *), more purple red colour (h°). In future, the future research shall focus on non- saccharomyces yeast in the fermentation of fruit wine. This is because non- saccharomyces can be a good fermenter if handling well during the fermentation process.