Chemical Composition of Alcoholic and Non-Alcoholic Beer

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Presenter(s)

Paola Arrieta-Molinar, Oscar Rodriguez Perez

Abstract or Description

This research focuses on the chemical composition of beers produced by two different yeast strains, Saccharomycodes ludwigii and Saccharomyces pastorianus, with the main difference being the presence or absence of ethanol. The results show that the alcoholic beer sample produced by S. pastorianus had an ethanol concentration of 2.06% by volume and contained 39.3 International Bitterness Units (IBUs), while the non-alcoholic beer sample produced by S. ludwigii had 5.0 IBUs and 0.21% ethanol by volume. The research explored two techniques for measuring ethanol concentration and found limitations in both, highlighting the need for a more accessible and precise ethanol assay. In addition to the techniques used for measuring ethanol concentration, Gas Chromatography/Mass Spectrometry (GC/MS) was also utilized to further analyze the chemical composition of the beers. The chromatogram obtained from the GC/MS showed that maltose was present in both samples after fermentation, with a higher overall concentration in the non-alcoholic sample. The presence of other volatile compounds in both samples, such as esters and aldehydes, were also identified. By comparing the retention index (RI) of an unknown compound to the RI of a standard compound, it is possible to make an identification based on the similarity of their retention times. This allowed for confident identification of the volatile compounds present in the beers analyzed through GC/MS. Overall, the project provides insights into the chemical differences between alcoholic and non-alcoholic beer and the impact of yeast strains on their composition.

Mentor

Dr. Paul Laybourn