Original article Impact of two Williopsis yeast strains on the volatile composition of mango wine Xiao Li, 1 Bin Yu, 2 Philip Curran 2 & Shao-Quan Liu 1 * 1 Food Science and Technology Programme, Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore 2 Firmenich Asia Pte Ltd, Tuas, Singapore 638377, Singapore (Received 2 October 2011; Accepted in revised form 8 November 2011) Summary The aim of the research was to study the volatile composition of mango wine fermented with two Williopsis yeast strains: Williopsis saturnus var. mrakii NCYC500 and W. staurnus var. suaveolens NCYC2586. Thirty terpenoids, twenty-six esters, ten alcohols, nine acids, seven aldehydes and ketones, two ethers, two phenols and one sulphur compound were identified in the mango wine fermented with strain NCYC500, while twenty-seven terpenoids, thirty esters, eleven alcohols, eight acids, eight aldehydes and ketones, three ethers, two phenols, one sulphur compound and one furan were detected in the mango wine fermented with the strain NCYC2586. The kinetic changes, final concentrations and odour activity values of major volatiles were compared between the two Williopsis yeast strains and also with other yeast reported in the literature. The results showed that Williopsis yeast strains NCYC500 and NCYC2586 were high producers of acetic acid and acetate esters, but low producers of medium- to long-chain fatty acids and their corresponding ethyl esters. Unlike mango wine fermented with Saccharomyces cerevisiae, most terpenoids derived from mango juice were retained in the resultant mango wine fermented with the two Williopsis yeast strains, suggesting the mango wine could retain the aromatic hints of fresh mango. Keywords Fermentation, flavour, mango wine, volatiles, Williopsis yeast. Introduction Mango (Mangifera indica L.) is one of the most popular tropical fruits in Southeast Asia with over thirty different varieties of mango grown worldwide and is beneficial for human health because of its nutrition content (Masibo & He, 2008). The fruits are usually consumed fresh or used in food industry for the production of canned fruits, jam and concentrated juice. Mango fruits can also be used in fruit wine production. The mango variety chosen for this study was Mangifera indica L. cv. Chok Anan, which is mostly grown in Malaysia and Thailand. Ripe Chok Anan mango has a high content of sugar (>16°Brix). These characteristics make Chok Anan mango as a valuable raw material for mango wine fermentation. In grape wine fermentation, Saccharomyces cerevisiae yeasts play a fundamental role by producing flavour compounds (so-called fermentation bouquet) from sim- ple nutrients such as carbon and nitrogen sources via de novo biosynthesis and ⁄ or precursors (Janssens et al., 1992). Ethanol, esters, higher alcohols and volatile acids are examples of aroma compounds produced by these yeasts during fermentation. Saccharomyces yeasts also have the ability to hydrolyse conjugated aroma precur- sors in grape juices, improving wine aroma (Zoecklein et al., 1997). However, wines produced with pure Saccharomyces yeasts often lack complexity of flavour, stylistic distinction and vintage variability caused by indigenous yeasts, commonly non-Saccharomyces (Lambrechts & Pretorius, 2000). Besides S. cerevisiae, the role of non-Saccharomyces in wine production has been extensively debated. Non- Saccharomyces yeasts, such as Kloeckera apiculata, Candida pulcherrima, Candida stellata, Torulaspora del- brueckii, Pichia anomala and Kluyveromyces marxianus, can seriously affect the chemical and sensory character- istics of wine (Jolly et al., 2006). Williopsis saturnus (formerly Hansenula saturnus) was chosen for this study because of its capability to produce ester. The ability of Williopsis yeast to utilise sugars for growth and biosynthesis of esters (especially fruity acetate esters) and other flavour compounds with only minimal formation of ethanol suggests a method for the production of low-alcohol wines with pleasant ‘fer- *Correspondent: Fax: +65 6775 7895; e-mail: chmLsq@nus.edu.sg International Journal of Food Science and Technology 2012, 47, 808–815 808 doi:10.1111/j.1365-2621.2011.02912.x Ó 2012 The Authors. International Journal of Food Science and Technology Ó 2012 Institute of Food Science and Technology