TY - JOUR T1 - Monitoring Volatile Aroma Compounds during Fermentation in a Chemically Defined Grape Juice Medium Deficient in Leucine JF - American Journal of Enology and Viticulture JO - Am. J. Enol. Vitic. DO - 10.5344/ajev.2016.15026 SP - ajev.2016.15026 AU - Jade J. Haggerty AU - Dennis K. Taylor AU - Vladimir Jiranek Y1 - 2016/03/01 UR - http://www.ajevonline.org/content/early/2016/02/25/ajev.2016.15026.abstract N2 - Model media are frequently used to study wine fermentation outcomes as they are considered an acceptable and reproducible representation of real juices. Identifying and quantifying the progression of the aroma compounds formed during fermentation is of importance for studies aimed at tailoring winemaking outcomes. Overexpression libraries of the yeast Saccharomyces cerevisiae can have utility in determining the impact of the overexpression of specific genes. Recently, an S. cerevisiae overexpression library has been reported that encompasses a plasmid-borne construct, which utilizes a leucine selectable marker to differentiate between yeast that contain the plasmid and those that do not. As such these experiments with this library require a leucine deficient fermentation medium. Aroma progression studies have been performed in real juice and in an MS300 model media, however to date none have been performed in chemically defined grape juice media (CDGJM) or in media lacking certain amino acids. This study reports on the progression of a library of 34 oenologically relevant aroma compounds formed during fermentation using a leucine-requiring wine strain derivative of S. cerevisiae bearing the overexpression library platform plasmid and grown in a CDGJM-Leu media. The results indicate that the production and accumulation of all 34 aroma compounds followed similar progression trends to that found in previous studies with MS300 and juice exploiting wild type yeast. This is with the exception of the compounds associated with pathways connected to the biosynthesis and metabolism of leucine. The findings confirm the likely utility of this system for evaluating the importance of overexpression of specific genes in aroma compound production. ER -