Physicochemical Kinetics and Determination of Methyl and Ethyl Alcohols in Own-Manufactured Craft Beer and Comparison with Commercial Mexican Craft Beers

Beer is a fermented beverage part of socio-cultural traditions, and recently, craft beer (small and industrial manufacturers) has been covering interest in many regions, such as México. The objective of this work was to analyze physicochemical kinetics and determine the ethyl and methyl content in our own-manufactured (OM) craft beer and compare it with commercial craft beer. The experiment was divided into two sections: (1) three types of Ale craft beer (Blonde, American Pale, and Stout) were manufactured, and during the fermentation process, physicochemical kinetics (pH, specific gravity, lactic acid, ethanol, and sugars) were analyzed, and (2) both the OM and six commercial craft beers were studied to analyze the content of methyl and ethyl alcohols via HPLC. Statistical analysis: (1) A completely randomized design with repeated measurements and a Pearson’s correlation test (p < 0.05) were conducted. (2) A complete block randomized design to compare alcohol production in OM and commercial beers was conducted. Results: (1) The pH, specific gravity, and maltose tended to decrease during the first 24–48 h of fermentation; however, no changes were observed during the remaining 120 h. In contrast, lactic acid production started after 48 h in Blond and American Pale beers and after 72 h in Stout. Maltose, glucose, and fructose were consumed immediately during ethanol production. (2) The HPLC analysis showed a retention time of 25.9 min for ethanol, with the lowest levels for Blond (6.2%) and the highest for Pale (7.5%) in OM, while commercial beers ranged from 4.5% to 6.8%. No methanol was detected in any beer analyzed; on the other hand, lactic acid was observed in all beers analyzed. In conclusion, physicochemical changes were observed immediately at the beginning of the fermentation process. Commercial and OM beers comply with the provisions of the Official Mexican Standards.