The molecular biology of fruity and floral aromas in beer and other alcoholic beverages

Abstract

Aroma compounds provide attractiveness and variety to alcoholic beverages. We discuss the molecular biology of a major subset of beer aroma volatiles, fruity and floral compounds, originating from raw materials (malt and hops), or formed by yeast during fermentation. We introduce aroma perception, describe the most aroma-active, fruity and floral compounds in fruits and their presence and origin in beer. They are classified into categories based on their functional groups and biosynthesis pathways: (1) higher alcohols and esters, (2) polyfunctional thiols, (3) lactones and furanones, and (4) terpenoids. Yeast and hops are the main sources of fruity and flowery aroma compounds in beer. For yeast, the focus is on higher alcohols and esters, and particularly the complex regulation of the alcohol acetyl transferase ATF1 gene. We discuss the release of polyfunctional thiols and monoterpenoids from cysteine- and glutathione-S-conjugated compounds and glucosides, respectively, the primary biological functions of the yeast enzymes involved, their mode of action and mechanisms of regulation that control aroma compound production. Furthermore, we discuss biochemistry and genetics of terpenoid production and formation of non-volatile precursors in Humulus lupulus (hops). Insight in these pathways provides a toolbox for creating innovative products with a diversity of pleasant aromas.

Screening and Application of Cyberlindnera Yeasts to Produce a Fruity, Non-Alcoholic Beer

“…The concentrations of 1.0-1.6 mg/L are within the reported flavor threshold in beer of 0.5-2.0 mg/L [43]. Additionally, it is well known that synergistic effects between esters occur that can push the concentration of perception below their individual flavor thresholds [42,44,45]. Isoamyl acetate could therefore have been a cause of the fruity aroma in the samples fermented with C6.1, CBS 1707 and CBS 5763.…”

“…Interestingly, ethyl acetate concentrations in the remaining samples, characterized by a pleasant, fruity aroma, were low, at only 2.6-3.8 mg/L. However, C6.1, CBS 1707 and CBS 5763 exhibited higher amounts of isoamyl acetate, a desired ester in beer (particularly ales) [42], when compared to the samples with unpleasant aroma. The concentrations of 1.0-1.6 mg/L are within the reported flavor threshold in beer of 0.5-2.0 mg/L [43].…”

Low Lactic Acid-Producing Strain of Lachancea thermotolerans as a New Starter for Beer Production

“…Generally, such methods are recognized as the concept of bioflavoring [52]. The main compounds that influence the aroma of alcoholic beverages are esters, higher alcohols, terpenes, acids and so on [55]. In addition, ethanol is also an important factor in the organoleptic perception of beer.…”

Investigating aroma diversity combining purge‐and‐trap, comprehensive two‐dimensional gas chromatography, and mass spectrometry

“…The aroma composition of the fruit beers is mainly characterized by the presence of esters, aldehydes, ketones, alcohols, and terpenoids . Thus, the selection of the sorbent type for the extraction was driven by the selectivity of the trapping material, with the goal to retain as much as information as possible for the untargeted analysis, therefore, maintaining the widest analyte coverage with acceptable sensitivity and good repeatability.…”

“…In terms of composition, fatty acid esters are the largest class of flavor compounds, and thanks to the lower odor threshold, they are key‐components for the aroma of the alcoholic beverages. Beside the esters, also terpenoids, aldehydes, and ketones with characteristic odors have been detected and reported to contribute to the complex interplay of beer flavors . From the manufacturing point of view, the presence of esters in alcoholic beverages is affected by the different processes involved in their production, for example, the fruit addition, fermentation, or maturation .…”