Volatile compound production in Agave duranguensis juice fermentations using four native yeasts and NH4Cl supplementation

Abstract

Nitrogen has a significant effect on the fermentation rate and the chemical composition of alcoholic beverages. Nitrogen deficiency during fermentation of Agave juice for mescal production can lead to slow fermentations and end-products with low aromatic compound variety. In this study, the effects of NH 4 Cl supplementation on volatile compound formation in Agave duranguensis juice fermented at 28°C with the native yeast strains Saccharomyces cerevisiae ITD00185, Hanseniaspora uvarum ITD00108, Torulaspora delbrueckii ITD00110 and Kluyveromyces marxianus ITD00211 were analysed. Nitrogen content in the Agave juice unsupplemented with NH 4 Cl was low. In the control treatments, the four yeasts consumed nitrogen at approximately the same rate, almost completely finishing by 24 h. Nitrogen supplementation increased biomass production with S. cerevisie, H. uvarum and T. delbrueckii but not with K. marxianus. K. marxianus consumed the total assimilable nitrogen more slowly than the other strains in the supplemented fermentations. In addition, the volatile compound profile differed between the studied yeasts. Volatile compound production by S. cerevisiae, H. uvarum and K. marxianus was higher in the supplemented fermentations, compared to the unsupplemented ones. In T. delbrueckii, the initial volatile compound concentrations remained unchanged, or decreased for some compounds, with nitrogen supplementation. The initial acetic acid and vanillin concentrations decreased with all strains tested and nitrogen supplementation. Furthermore, the concentration of higher alcohols increased with S. cerevisiae and H. uvarum in the NH 4 Cl-supplemented fermentations, but they decreased with T. delbrueckii and K. marxianus. In conclusion, the addition of an inorganic nitrogen source promotes microorganism metabolism, increases biomass formation and benefits the fermentation process.

Microbial Succession and Interactions During the Manufacture of Fu Brick Tea

“…For each sample, 10 g was homogenized with sterile distilled water using a blender at 12,000 rpm using three 30 s pulses. The homogenate was serially diluted in sterile distilled water and spread onto each of four types of media: MEA (2% malt extract, 0.1% peptone, 2% glucose, 1.8% agar; containing 100 mg/L chloramphenicol and 100 mg/L streptomycin), LA medium (BD Co.), YDP (1% yeast extract, 1% peptone, 2% glucose, 1.8% agar; containing 100 mg/L chloramphenicol), and Gauze No.1 (AOBOX BIOTECHNOLOGY; 25 mg/L nalidixic acid and 50 mg/L cycloheximide) (Liu et al, 1996 ; Rutiaga-Quiñones et al, 2012 ). Plates were prepared for each sample and medium in triplicate.…”

Volatile Compound Profiles in Mezcal Spirits as Influenced by Agave Species and Production Processes

“…Most compounds were alcohols, esters and acids. The differences in the volatile compounds, such as benzyl alcohol, hexanoic acid ethyl ester, and dodecanoic acid ethyl ester concentrations, could be attributable to the microorganisms and conditions found during the fermentation process [8,9,22]. In previous studies, Kirchmayr et al [10] identified 21 different yeast species, such as Saccharomyces cerevisiae, Kluyveromyces marxianus, Zygosaccharomyces rouxii, Z. bisporus, Torulaspora delbrueckii, and Pichia membranifaciens, and 27 different bacterial species during fermentation in artisan mezcal production.…”

“…Among the factors that have an influence on the artisanal process of making mezcal are Agave species and origin [2,4,7], initial sugar concentration, environmental conditions, native yeast strain, and, in certain cases, the addition of ammonium sulfate or ammonium chloride to the fermentation must [4,6,[8][9][10]. Another important parameter that ultimately defines the quality of agave beverages is the distillation system used [11,12].…”

“…Fructans could form Maillard compounds, such as furans, pyrans, and ketones, as a result of higher temperatures and a lower pH in the agave cooking process [16]. On the other hand, the fermentation process generates ethanol, higher alcohols, esters, organic acid and others [4,6,[8][9][10]. Some of these volatile compound are of greater importance than others due to their concentrations or aromatic characteristics [12,17], and some could be specific to the Agave species.…”

Potential production of 2-phenylethanol and 2-phenylethylacetate by non-Saccharomyces yeasts from Agave durangensis

“…Previously published research on fermentations of agaves suggests that non-Saccharomyces yeasts have an important role in the initial fermentation process and influence the production of the volatile compounds (Lappe-Oliveras et al 2008;Narváez-Zapata et al 2010;Martell Nevárez et al 2011). The potential use of these yeasts as inoculants has been described (Rodríguez-Sifuentes et al 2014;Nuñez-Guerrero et al 2016), as well as their participation in generating the volatile compounds in mescal, mainly esters (Martell Nevárez et al 2011;Rutiaga-Quiñones et al 2012;Hernández-Carbajal et al 2013). Despite the increasing use of non-Saccharomyces yeasts in biotechnology, there are still many opportunities to improve native yeast exploration.…”