WINETECH Technical Yearbook 2020

combinationwith S. cerevisiae to conduct the alcoholic fermentation and a commercial L. plantarum culture to induce MLF. SUMMARY This study investigated the interactions between different yeasts, LAB species and MLF strategies, as well as how these interactions affected Shiraz wine composition and flavour. Standard oenological parameters, volatile chemical composition and sensory attributes were investigated. Wines inoculated with O. oeni completed MLF in a shorter period than those inoculated with L. plantarum. Yeast selection, LAB combination and MLF strategy had a significant impact on the volatile composition and sensory profiles of wines. Wines that underwent MLF, as a sequential inoculation, scored higher for spicy aroma than simultaneous MLF and non-MLF wines. Wines inoculated with L. plantarum scored higher for body/ mouthfeel than those inoculated with O. oeni. Winemakers can manipulate the flavour profile and body of wines by applying different yeast and LAB combinations. ACKNOWLEDGEMENTS The authors thank the ARC, Winetech

and the National Research Foundation of South Africa (THRIP programme; Grant numbers UID 71526 and 90103) for funding. Mses P. Adonis, C. du Plessis, D. Blaauw, R. Louw and L. Isaacs, as well as Messrs H. Jumat, M. Mewa Ngongang and J. Boonzaier, are thanked for technical assistance. The opinions, findings and conclusions expressed in this publication are those of the authors. The National Research Foundation accepts no liability in this regard. REFERENCES Du Plessis, H., Du Toit, M., Nieuwoudt, H., Van der Rijst, M., Hoff, J. & Jolly, N., 2019. Modulation of wine flavor using Hanseniaspora uvarum in combination with different Saccharomyces cerevisiae , lactic acid bacteria strains and malolactic fermentation strategies. Fermentation 5(3), 64. Doi: 10.3390/fermentation5030064. Jolly, N.P., Varela, C. & Pretorius, I.S., 2014. Not your ordinary yeast: Non- Saccharomyces yeasts in wine production uncovered. FEMS Yeast Research 14, 215- 237. Capozzi, V., Garofalo, C., Chiriatti, M.A., Grieco, F. & Spano, G., 2015. Microbial

produced with L. plantarum scored higher for body/mouthfeel than those inoculated with O. oeni. It is noteworthy that the relative scores for body varied according to the yeast combination used. Winemakers can manipulate the body/mouthfeel of wines by applying different yeast and LAB combinations. To increase the body of a wine, H. uvarum in combination with S. cerevisiae could be used and MLF should be induced using L. plantarum. CONCLUSIONS Wines produced with the selected yeasts, LAB strains and MLF strategies differed in terms of fermentation kinetics, chemical composition and sensory properties. H. uvarum had a positive effect on the growth of inoculated and naturally occurring LAB, which resulted in shorter MLF periods for wines. The flavour profile of Shiraz wines can be enhanced by using different yeasts, LAB strains and MLF strategies. H. uvarum in combination with MLF, as a sequential inoculation, can be used to increase the vegetative character of Shiraz wines. The spicy aroma of a Shiraz wine can be increased by inducing MLF, as a sequential inoculation, and a fuller body or mouthfeel can be achieved by using H. uvarum in

terroir and food innovation: The case of yeast biodiversity in wine. Microbiological Research 181, 75-83. Tristezza, M., Tufariello, M., Capozzi, V., Spano, G., Mita, G. & Grieco, F., 2016. The oenological potential of Hanseniaspora uvarum in simultaneous and sequential co-fermentation with Saccharomyces cerevisiae for industrial wine production. Frontiers in Microbiology 7, 1-14. Bartowsky, E.J., Costello, P.J. & Chambers, P.J. , 2015. Emerging trends in the application of malolactic fermentation. Australian Journal of Grape and Wine Research 21, 663-669. Alexandre, H., Costello, P.J., Remize, F., Guzzo, J. & Guilloux-Benatier, M., 2004. Saccharomyces cerevisiae-Oenococcus oeni interact ions in wine: Current knowledge and perspectives. International Journal of Food Microbiology 93, 141- 154.

For more information, contact Heinrich du Plessis at dplessishe@arc.agric.za.

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