An original method for producing acetaldehyde and diacetyl by yeast fermentation

Abstract

In this study a natural culture medium that mimics the synthetic yeast peptone glucose medium used for yeast fermentations was designed to screen and select yeasts capable of producing high levels of diacetyl and acetaldehyde. The presence of whey powder and sodium citrate in the medium along with manganese and magnesium sulfate enhanced both biomass and aroma development. A total of 52 yeasts strains were cultivated in two different culture media, namely, yeast peptone glucose medium and yeast acetaldehyde-diacetyl medium. The initial screening of the strains was based on the qualitative reaction of the acetaldehyde with Schiff's reagent (violet color) and diacetyl with Brady's reagent (yellow precipitate). The fermented culture media of 10 yeast strains were subsequently analyzed by gas chromatography to quantify the concentration of acetaldehyde and diacetyl synthesized. Total titratable acidity values indicated that a total titratable acidity of 5.5 °SH, implying culture medium at basic pH, was more favorable for the acetaldehyde biosynthesis using strain D15 (Candida lipolytica; 96.05 mg L−1 acetaldehyde) while a total titratable acidity value of 7 °SH facilitated diacetyl flavor synthesis by strain D38 (Candida globosa; 3.58 mg L−1 diacetyl). Importantly, the results presented here suggest that this can be potentially used in the baking industry.

Beer Molecules and Its Sensory and Biological Properties: A Review

“…Diacetyl concentration should not exceed 0.1 ppm, since its threshold from 0.05–0.1 ppm and higher concentrations may develop a stale milk aroma and flavor, and it is often reported as an undesirable volatile compound. A sulfur-containing volatile compound, 3-methylbut-2-ene-1-thiol (MBT), which synthesis pathway has been previously elucidated by researchers, is produced not by yeast metabolism during fermentation, but by the degrading effects of the light on light-sensitive compounds of the beer, and gives off-flavors described as skunk-like odor at concentrations of a few tens of ng·L −1 [68,73,74].…”

Prospecting the Potential of Agroresidues as Substrate for Microbial Flavor Production

“…It is produced by lactic acid bacteria and several other microorganisms in dairy foods (Longo and Sanromán, 2006). Interestingly, a high concentration of diacetyl (1.45 g/L) was produced in metabolically engineered Enterobacter clocae, whereas acetaldehyde and diacetyl were synthesized by the yeast Candida tropicalis strain D15 on a whey-based medium (Rosca et al, 2016).…”

Natural Flavours Obtained by Microbiological Pathway

“…Similarly, aldehydes can also be generated by chemical oxidation of α-ketoacids catalysed by bivalent cations [16]. Manganese and magnesium sulphate enhanced both biomass and aroma development of 52 different yeasts by obtaining 96.05 mg/L acetaldehyde for Candida lipolytica and 3.58 mg/L diacetyl for Candida globosa [4].…”

“…Acetaldehyde represents a secondary metabolite in alcoholic fermentation of yeasts, being a precursor of the ethanol production in beer and wine. It is the most important carbonyl compound produced during alcoholic fermentation in concentrations between 10 and 200 mg/L depending on technological factors, such as culture medium composition, pH, fermentation temperature, aeration and SO 2 concentration and on the yeast strain used [4]. Acetaldehyde is biosynthesized from glucose by the glycolytic pathway enzyme pyruvate decarboxylase.…”

“…Diacetyl is almost exclusively synthesised by LAB and is the key flavour compound naturally produced by the Leuconostoc sp. [4].…”