Effect of non-Saccharomycesyeasts on the volatile chemical profile of Shiraz wine

Abstract

Background and Aims This study evaluated the impact that the non‐Saccharomyces yeasts, Torulaspora delbrueckii (TD), Lachancea thermotolerans (LT), Pichia kluyveri (PK), Metschnikowia pulcherrima (MP), Candida zemplinina (CZ) and Kazachstania aerobia (KA), in sequential inoculation with Saccharomyces cerevisiae (SC), had on the volatile chemical profile of Shiraz wine. Methods and Results Shiraz grape must was inoculated with monocultures of the non‐Saccharomyces yeasts, which were allowed to ferment until 2% v/v ethanol concentration was reached at which point, SC was added to complete the alcoholic fermentation. The control was SC in monoculture. The final wines were subjected to solid phase microextraction‐GC × GC‐time of flight‐MS to evaluate the untargeted volatile metabolite profile of each treatment. Each fermentation produced a unique chemical profile. The LT–SC sequential fermentation was the most significantly different from the control primarily in the ester, alcohol and terpene profile. The KA–SC sequential fermentation had the highest amount of volatile acidity, and the PK–SC sequential fermentation had a relatively high amount of acetaldehyde and a few esters. The MP–SC sequential fermentation also revealed a higher concentration of several esters. The TD–SC sequential fermentation was notable for its lack of a distinct pattern in comparison with that of the other fermentations. Conclusions Given these characteristics, the LT–SC sequential fermentation showed the most potential for increased chemical complexity of the Shiraz volatile profile. Significance of the Study The results demonstrate that there is no clear, singular trend for how different, non‐Saccharomyces species of yeast – once thought to be wholly unfavourable in wine fermentations – will impact wine chemistry, flavour or quality. Each species presents unique metabolic characteristics, many of which could be beneficial, and their potential application in the wine industry should be considered.

Microbial Resources and Enological Significance: Opportunities and Benefits

“…Metschnikowia pulcherrima is commonly associated with grapes and wine (Whitener, 2016). It is a high producer of β-glucosidase and its presence in mixed cultures can decrease the volatile acidity and increase the production of medium-chain fatty acids, higher alcohol, esters, terpenols and glycerol (González-Royo et al, 2015).…”

“…The genus Candida is large and extremely diverse with over 50 different identified species several of which have been associated with winemaking (Whitener, 2016). Among the non- Saccharomyces wine yeasts involved in grape juice fermentation, C. stellata has been frequently isolated during the course of must fermentations in different countries (fermentation of botrytized wines and other wines produced by overripe grapes, in cooked musts, and in traditional balsamic vinegars) (Tofalo et al, 2012).…”

“…Zygosaccharomyces bailii and Zygosaccharomyces rouxii are often the source of spoilage in acidic and shelf-stable foods as well as sweet wines due to their ability to tolerate high acid, salt and sugar conditions (Whitener, 2016). However, selected strains of Zygosaccharomyces spp.…”

“…Kazachstania aerobia was first identified in 2004 from corn silage while Kazachstania gamospora was discovered as a species in 2007. Being relatively new yeasts and closely related to S. cerevisiae , the genus is worthy of investigation (Whitener, 2016). …”

Chemical and sensory profiling of Shiraz wines co-fermented with commercial non-Saccharomycesinocula

“…Shiraz is one of the most widely planted red grape cultivars globally (Anderson and Aryal 2013), and a choice of yeast strain to conduct the fermentation markedly affects its vinification outcome , Whitener et al 2017). An impact of Saccharomyces inocula on a range of Shiraz compositional parameters, including tannins, other phenolic substances and fermentation (by)products, is well recorded .…”