Determination of Methanol, Aldehydes, and Ethanol Concentrations in Local Alcoholic Beverages (Gongo, Mnazi, Ulanzi, Mbege, Komoni, Pingu, and Wanzuki) from the Coastal Regions of Tanzania

Traditional alcoholic beverages produced by local distilleries in Tanzania may contain hazardous levels of methanol and aldehydes, posing significant health risks to consumers. This study quantified methanol, aldehydes, and ethanol concentrations in seven locally produced beverages ( Gongo , Mnazi , Ulanzi , Mbege , Komoni , Pingu , and Wanzuki ) from coastal Tanzania using Gas Chromatography-Flame Ionization Detector (GC-FID) for methanol/ethanol analysis and High-Performance Liquid Chromatography (HPLC) for aldehyde detection. Validated methods confirmed reliable detection limits (LOD), quantification limits (LOQ), and recoveries. Results revealed methanol concentrations ranging from 95 to 2115 (mg/L), with Gongo consistently exceeding the Tanzania Bureau of Standards (TBS) safety limit (≤ 1000 mg/L or 0.1%) by 56–112%. Statistical analysis (ANOVA, p < 0.001) confirmed Gongo ’s methanol levels were significantly higher than other beverages. While aldehydes were undetectable, the elevated methanol levels, particularly in Gongo , highlight acute risks of toxicity, including blindness and neurological damage. These findings underscore the urgent need for stricter quality control, regulatory enforcement, and public awareness campaigns to mitigate health hazards associated with traditional alcoholic beverages.