Efficacy of Dimethyl Dicarbonate Against Yeasts Associated with Washington State Grapes and Wines

Abstract

Efficacies of dimethyl dicarbonate (DMDC) against yeasts associated with grapes and wines were evaluated. Addition of the legal limit of DMDC (200 mg/L) to grape musts initially inoculated with 10 2 cfu/mL (low population) or 10 5 cfu/ mL (high population) of Candida californica, C. oleophila, Metschnikowia pulcherrima, Meyerozyma caribbica, Mey. guilliermondii, Saccharomyces cerevisiae or Wickerhamomyces anomalus resulted in declines of several logs. However, populations in excess of 10 6 cfu/mL were observed within days regardless of the initial inoculum. In contrast, culturability of Zygosaccharomyces bailii inoculated into grape must (low populations) or wine (low or high populations) did not recover after treatment with DMDC. In wines, low populations of Brettanomyces bruxellensis I1a or E1 declined after DMDC addition while culturability returned for F3 no matter the initial inoculum. Treatment of wines using commercial dosing equipment resulted in a gradual loss of culturability of Brettanomyces when inoculated at 10 4 cfu/mL while the concentrations of volatile phenols remained unchanged after >3 years of storage. PRACTICAL APPLICATIONSUpon exposure to dimethyl dicarbonate (DMDC), initial loss of culturability was noted for several yeasts, most dramatically for Zygosaccharomyces bailii present in wine. Conversely, species of Candida, Metschnikowia, Meyerozyma, Saccharomyces and Wickerhamomyces examined achieved high populations in grape must within a few days after application. DMDC was generally effective against Brettanomyces under laboratory and commercial scale conditions but differences between responses were noted between strains. Although the additive initially reduced culturable populations, DMDC did not completely eradicate yeasts present in grape musts or wines and therefore may not provide long-term microbiological stability.

Production and Characterization of a New Sweet Sorghum Distilled Beverage

“…Compared to the volatile profiles found for sugar cane spirits (Duarte et al 2013;Amorim et al 2016) the sweet sorghum spirit produced with mixed inoculum resulted in higher concentrations of esters, alcohols and terpenes, in addition to decreasing the production of undesirable compounds, such as volatile acids and aldehydes. These results reinforce the fact that the use of M. caribbica in a mixed inoculum contributes to the production of desirable aromatic volatile compounds, even when using different substrates such as sweet sorghum, sugarcane (Duarte et al 2013;Amorim et al 2016) and grapes (Zuehlke et al 2015). Among the 24 identified esters, 11 were ethyl esters, which are the main volatile compounds to provide floral and fruity aroma to distilled beverages.…”

The microbiomes of a XVIII century mummy from the castle of Krásna Hôrka (Slovakia) and its surrounding environment

“…found only in these skin crystals. One reason for their exclusive presence could be the presence of sulfur compounds, which can inhibit growth of fungi and bacteria, but are less inhibiting to the colonization of some yeasts (Zuehlke et al ., ). Yeasts are involved in several biogeochemical processes (Gadd, ), but we found no information regarding the mineralization of arcanite.…”

Effectiveness of chitosan preparations against <em>Brettanomyces bruxellensis</em> grown in culture media and red wines

“…Limiting or eliminating the spoilage yeast, Brettanomyces (Dekkera) bruxellensis, from red wines is not an easy task for winemakers. While researchers have studied the use of dimethyl dicarbonate (Costa et al, 2008;Zuehlke et al, 2015), maintaining low temperatures (Barata et al, 2008b), membrane filtration (Umiker et al, 2013), thermal inactivation (Couto et al, 2005), and other approaches, SO 2 continues to be the primary method of control in a winery (Barata et al, 2008a ;Agnolucci et al, 2010). However, du Toit et al (2005) and Zuehlke and Edwards (2013) suggested that B. bruxellensis might enter a viablebut-non-culturable (VBNC) state in the presence of SO 2 , making detection by conventional microbiological methods (e.g., plating) difficult.…”