Investigations on reducing the methanol content in distilled spirits made of Bartlett pears

Methanol is naturally present in distilled fruit spirits. In excessive quan tities methanol is considered a toxic compound. For this reason European li mits of methanol concentration in distilled fruit spirits were established. We here demonstrate that the formation of methanol in fruit mashes is affec ted by the mash pH value. Due to a mash acid treatment the enzymatic methan ol deesterification is delayed. Using short fermentation periods and mash p H values of 2.5 instead of pH 4.0, the mean methanol reduction in Bartlett mashes reaches 50 %. Probably as a result of poor mash liquefaction, the et hanol yields are reduced to a minor extent. A mash pH of 3.0 leads to 30 % lower mean methanol contents without loss of ethanol. Extremely long fermen tation periods result in a total methanol deesterification out of pectin su bstances and thus a maximum increase in methanol concentration. The distillation conditions additionally affect the methanol content of the distilled spirits. Together with ethanol and water, methanol is transferre d during the entire distillation into the distillate. A low reflux ratio re sults in small methanol concentrations of distilled spirits and correspondi ngly high stillage levels after distillation. Distillations of Bartlett mas hes resulted in a 17 % lower mean ethanol regarded methanol content of the product fractions using reflux ratios of v(M) = 1.1 in comparison to v(M) = 2.8. As a consequence of the poor enrichment efficiency with low reflux ra tios, the starting point of tailings is earlier. Therefore the product etha nol yields are reduced to a minor extent. The flavour of the distilled Bart lett spirits is not influenced by different distillation conditions tested here.