Proximate Composition of Banana and Pineapple Wine Fermented by Meyerozyma guilliermondii and Pichia guilliermondii

Wine is an alcoholic beverage produced from juices of a variety of fruits by the fermentative action of microorganisms. There is a quest for alternative sources of must for wine fermentation, however, the proximate composition should be known to ascertain how nutritious it is. The study was thus aimed at determining the proximate composition of the wines fermented by Meyerozyma guilliermondii and Pichia guilliermondii. Two isolates identified as Meyerozyma guilliermondii strain 1621 and Pichia guilliermondii strain PAX-PAT 18S were used for the fermentation of the substrates obtained from a mixture of pineapple and banana pulp. The fermentation process was for 28 days, followed by a series of racking, clarification, and aging process which was for 2 months. The fermentation process comprised two setups: one was fermented by Meyerozyma guilliermondii strain 1621 and the other by Pichia guilliermondii strain PAX-PAT 18S. The process was monitored and the proximate analysis of the wines was ascertained. The wine produced by Meyerozyma guilliermondii strain 1621 had a moisture content of 82.56 %, ash content of 1.41 %, fat content of 0.08 %, protein content of 1.43%, and carbohydrate content of 9.77%. The wine produced by Pichia guilliermondii strain PAX-PAT 18S had a moisture content of 79.51%, ash content of 1.19%, fat content of 0.15%, protein content of 0.49%, and carbohydrate content of 10.49%. Although this study is not exhaustive, it shows that wines with good nutritional composition can be successfully produced using Meyerozyma guilliermondii strain 1621 and Pichia guilliermondii strain PAX-PAT 18S.

Molecular identification of Pichia guilliermondii, Debaryomyces hansenii and Candida palmioleophila

Traditional phenotypic methods and commercial kits based on carbohydrate assimilation patterns are unable to consistently distinguish among isolates of Pichia guilliermondii, Debaryomyces hansenii and Candida palmioleophila. As result, these species are often misidentified. In this work, we established a reliable method for the identification/differentiation of these species. Our assay was validated by DNA sequencing of the polymorphic region used in a real-time PCR assay driven by species-specific probes targeted to the fungal ITS 1 region. This assay provides a new tool for pathogen identification and for epidemiological, drug resistance and virulence studies of these organisms.

Spoilage yeasts in Patagonian winemaking: molecular and physiological features of Pichia guilliermondii indigenous isolates / Levaduras contaminantes en vinos patagónicos: características moleculares y fisiológicas de los aislamientos indígenas de Picchia guilliermondii

Yeasts belonging to the genus Dekkera/Brettanomyces, especially the species Dekkera bruxellensis, have long been associated with the production of volatile phenols responsible for off-flavour in wines. According to recent reports, the species Pichia guilliermondii could also produce these compounds at the initial stages of fermentation. Based on the abundance of P. guilliermondii in Patagonian winemaking, we decided to study the relevance of indigenous isolates belonging to this species as wine spoilage yeast. Twenty-three indigenous isolates obtained from grape surfaces and red wine musts were analyzed in their capacity to produce volatile phenols on grape must. The relationship between molecular Random Amplified Polymorphic DNA (RAPD) and physiological (killer biotype) patterns detected in indigenous populations of P. guilliermondii and volatile phenol production was also evaluated. Different production levels of 4-ethylphenol, 4-vinylguaiacol and 4-ethylguaiacol were detected among the isolates; however, the values were always lower than those produced by the D. bruxellensis reference strain in the same conditions. High levels of 4-vinylphenol were detected among P. guilliermondii indigenous isolates. The combined use of RAPD and killer biotype allowed us to identify the isolates producing the highest volatile phenol levels.

Las levaduras del género Dekkera/Brettanomyces, sobre todo la especie Dekkera bruxellensis, siempre han sido asociadas con la producción de fenoles volátiles responsables de aromas desagradables en los vinos. Recientemente, se ha demostrado que la especie Pichia guilliermondii también es capaz de producir estos compuestos, particularmente durante las etapas iniciales de la fermentación. Dada la abundancia de P. guilliermondii en las bodegas de la Patagonia, se decidió evaluar la importancia de algunos aislamientos indígenas de esta especie como levaduras alterantes de vinos regionales. Se evaluó la capacidad de producir fenoles volátiles en ensayos sobre mosto de 23 aislamientos de P. guilliermondii provenientes de superficie de uvas y de mostos de fermentación de vinos tintos. Asimismo, se analizó la relación entre los patrones moleculares (RAPD) y fisiológicos (biotipo killer) de estos aislamientos y la producción de fenoles volátiles. Se detectaron diferentes niveles de producción de 4-etilfenol, 4-vinilguayacol y 4-etilguayacol entre los aislamientos de P. guilliermondii analizados; sin embargo, los valores obtenidos fueron en todos los casos inferiores a los producidos por D. bruxellensis cepa de referencia en las mismas condiciones. En general, se detectaron altos niveles de 4-vinilfenol en los mostos fermentados con los aislamientos indígenas de P. guilliermondii. El uso combinado de RAPD-PCR y el biotipo killer permitió identificar los aislamientos que producen los niveles más altos de fenoles volátiles.