Changes

Esters and alcohols were also measured in all three bottles by the scientists. Ethyl acetate, which is a byproduct of yeast fermentation (especially ''[[Brettanomyces]]'' fermentation) and has an odor threshold of 30 mg/L in beer, was considerably high in all three beers: Liefmans had around 100 mg/L, Rodenbach Grand Cru had around 132 mg/L, and Rodenbach Vintage had 237 mg/L. By comparison, clean ales have around 8-48 mg/L, pasteurized gueuzes have around 33-67 mg/L, and unpasteurized gueuzes have around 61-167 mg/L. Noticeably, the Rodenbach Vintage had considerably high ethyl acetate, even when compared to gueuze. As expected, isoamyl acetate was below odor threshold (1.2 mg/L) in the Rodenbach beers, but above odor threshold in the Liefmans (1.73 mg/L). Isoamyl alcohol was above odor threshold in all three beers. The ester 2-phenylethyl acetate was also below threshold in the Rodenbach beers but not the Liefmans, while its alcohol precursor was high in the Rodenbach. Both esters, isoamyl acetate and 2-phenylethyl acetate, are known to be degraded into ethyl acetate by ''Brettanomyces''. Ethyl hexanoate, ethyl octanoate, and ethyl decanoate esters had levels similar to typical ''Saccharomyces'' fermentations. The Liefmans bottle reached the odor threshold level for oct-1-en-3-ol, which has an earthy/mushroom/musty odor and is considered an off flavor in beer <ref name="Dusart_2022" />.

==Style Guidelines==