Evaluation of performance of Torulaspora delbrueckii, Williopsis saturnus and Kluyveromyces lactis in lychee wine fermentation
By Chen, D., Yap, Z. Y and Liu, S. –Q. Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 3, Singapore 117543, Singapore
(Article published in: International Journal of Food Microbiology, 2015, 206, 45-50)
Liu S.Q. reports on research conducted for the National University of Singapore. His research centres on the performance of various yeasts in lychee wine fermentation.
What was the purpose of your research?
In this study we investigated the suitability of three non-Saccharomyces yeasts, namely Torulaspora delbrueckii, Williopsis saturnus and Kluyveromyces lactis in making wine from lychee fruits, a type of popular delicious aromatic tropical and subtropical fruit. Several fermentation parameters were analysed and monitored, including non-volatiles (sugars, organic acids and amino acids) by HPLC, and volatiles by HS-SPME-GC-MS-FID.
What were the key result from your research?
The yeast T. delbrueckii had the fastest rate of growth and high sugar consumption that was comparable to Saccharomyces cerevisiae or Saccharomyces bayanus (the wine maker’s yeasts). T. delbrueckii had a better ability to generate high levels of ethanol and key aroma compounds (isoamyl alcohol, 2-phenylethyl alcohol, ethyl octanoate, and ethyl decanoate, imparting fruity and floral flavour notes) and to retain high odour activity values of lychee aroma-character compounds cis-rose oxide and linalool. Thus, this strain is considered as a suitable non-Saccharomyces yeast for lychee wine fermentation. Williopsis saturnus and Kluyveromyces lactis fermented sugars inadequately and produced low levels of ethanol, although they also retained lychee aroma-impact compounds.
What does this actually mean?
Fruit wines are commonly made by following the grape wine making practices e.g., using Saccharomyces cerevisiae or Saccharomyces bayanus yeasts, which may not be suitable for fruit wines. The resultant fruit wines often lack the distinct original fruit flavour characters, especially tropical fruits that possess more delicate flavours. Our findings suggest that fruit wine making (especially tropical fruits) entail new processes and practices; adoption of novel yeasts would be a good starting point so as to produce fruit wines with original flavour characters.
Fig. 1. Changes in Brix value (a), as well as the concentrations of ethyl hexanote (b), 2-phenylethyl alcohol (c), and linalool (d) throughout fermentation. T. delbrueckii PRELUDE (●); W. saturnus NCYC22 (▼); K. lactis KL71 (■).
Dr Shao Quan LIU is an Associate Professor with the Food Science and Technology Programme, National University of Singapore. Before joining NUS in 2008, he worked in the dairy industry in New Zealand for 13 years. His teaching interests are food fermentation and flavour science. His research interests include food bioscience (probiotics, yeast, and lactic acid bacteria), bioflavour, coffee and tropical fruit wine as well as food waste utilization.