A Novel Approach for Microbial Synthesis of Enantiomerically Pure Whisky Lactones Based on Solid-State Fermentation.

Teresa Olejniczak,Filip Boratyński,Aleksandra Grudniewska,Ewa Szczepańska,Bartłomiej Skalny

doi:10.3390/molecules23030659

Teresa Olejniczak, Filip Boratyński + Show 3 more

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https://doi.org/10.3390/molecules23030659

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Abstract

In this study, solid-state fermentation (SSF) was proposed as an alternative approach to obtain optically pure forms of one of the most common aroma compounds, whisky lactone. Filamentous fungi were used for enantioselective hydrolysis of a racemate of trans and cis whisky lactones, utilizing rapeseed cake as a growth medium. Among the tested fungi, Fusarium oxysporum AM13 and Papularia rosea AM17 were chosen for further studies. Various process parameters, including temperature, moisture content of solid media, and substrate concentration were optimized to maximize the efficiency of the kinetic resolution process. After optimization of the culture conditions (33 °C temperature, 60% moisture content, and substrate concentration of 3 mg/g oilseed cake), F. oxysporum AM13 resolved a mixture of trans-(+)-(4S,5R) and cis-(+)-(4R,5R) whisky lactones with enantiomeric excess (ee), ee > 99% and ee = 98%, respectively. This study presents an inexpensive and environmentally friendly method for the production of enantiomerically pure aroma lactones via the solid-state fermentation of oilseed cake. The results revealed that SSF is an effective method for acquiring highly valued and industrially demanded compounds with negligible economic cost.

Highlights

IntroductionOne of the commonly known and industrially used fragrances is whisky lactone
Lactones are highly valued aroma compounds used in the preparation of various foodstuffs.One of the commonly known and industrially used fragrances is whisky lactone
Each of the four stereoisomers of whisky lactone provides a different fragrance: cis isomers are described as having an earthy and woody fragrance, while trans isomers are reminiscent of celery [3]

Summary

Introduction

One of the commonly known and industrially used fragrances is whisky lactone. This compound, which uses oak wood, is known as oak or quercus lactone. It is found in aged alcoholic beverages, such as whisky, cognac, brandy, and wine [1,2]. Each of the four stereoisomers of whisky lactone provides a different fragrance: cis isomers are described as having an earthy and woody fragrance, while trans isomers are reminiscent of celery [3]. Commercially available whisky lactone, which is used as an additive in the food industry, contains a racemate of trans and cis isomers. The development of profitable biotechnological methods to resolve individual stereoisomers of whisky lactone is necessary

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