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Traditional smoke flavours bear the risk of containing a multitude of contaminating carcinogenic side-products. Enzymatic decarboxylation of ferulic acid released from agro-industrial side-streams by ferulic acid esterases (FAE) enables the sustainable generation of pure, food grade 4-vinylguaiacol (4-VG), the impact compound of smoke flavour. The first basidiomycetous ferulic acid decarboxylase (FAD) was isolated from Schizophyllum commune (ScoFAD) and heterologously produced by Komagataella phaffii. It showed a molecular mass of 21 kDa, catalytic optima at pH 5.5 and 35°C, and a sequence identity of 63.6% to its next relative, a FAD from the ascomycete Cordyceps farinosa. The ScoFAD exhibited a high affinity to its only known substrate ferulic acid (FA) of 0.16 mmol L-1 and a turnover number of 750 s-1. The resulting catalytic efficiency kcat KM-1 of 4,779 L s-1 mmol-1 exceeded the next best known enzyme by more than a factor of 50. Immobilised on AminoLink Plus Agarose, ScoFAD maintained its activity for several days. The combination with FAEs and agro-industrial side-streams paves the way for a new generation of sustainable, clean, and safe smoke flavours. [ABSTRACT FROM AUTHOR]

The naturally occurring 2,6-dimethoxybenzoquinone (DMBQ) has anti-bacterial, anti-fungal and anti-cancer activities. As it is probably formed in plants via oxidative degradation of the anthocyanin malvidin and its glycosides, a targeted analysis of the DMBQ concentration of different wines and grape juices was performed. Whereas no DMBQ was detected in white wines, concentrations between 28 and 137 μg/l were measured in red wines. In vivo formation kinetics in crushed anthocyanin-rich fruits were monitored, and up to 2.84 mg/kg DMBQ were found showing that its formation was triggered by cell disruption and catalysed by intrinsic oxidases. Ethanolic extraction of grape pomace, a cheap and sustainable source of malvidin-3- O -glucoside, yielded around 1.3 g/l corresponding to 272 mg/100 g dry matter. Solid phase purification of malvidin on XAD7HP resulted in the separation of 229 mg malvidin/100 g dry matter. A basidiomycetous laccase converted the purified malvidin to DMBQ with a yield of 94% followed by adsorption on XAD16N separating 65 mg DMBQ/100 g dry grape pomace under full food-grade conditions. DMBQ may contribute to the shelf life of malvidin-rich foods and is a promising candidate as a natural alternative to other food preservatives. • 2,6-Dimethoxybenzoquinone is a natural substance found in various plants. • Its concentration correlated to malvidin-3- O -glucoside in grape wines. • Cell disruption triggered its formation in anthocyanin-rich fruits. • A fungal laccase produced 65 mg of the quinone from 100 g dry grape pomace. • With its antibacterial properties, the quinone may be used in future food applications. [ABSTRACT FROM AUTHOR]