Production and characterization of alcohol-free beer by membrane process

• Modified osmotic distillation process was used for alcohol-free beer production.
• Gravity, bitterness, polyphenols content were not influenced by the process.
• Foam stability, turbidity, O2 and CO2 content were statistically different.
• A change of aroma profile was observed in alcohol-free beer.
• A reduced water consumption and decreased environmental impact was estimated.

Alcohol-free beer is a secondary product of brewing industry, nevertheless, its production is motivated by the global trend for healthier lifestyle and the awareness about the benefits of moderate beer drinking. A modified osmotic distillation was investigated in order to minimize the loss of volatile compounds, to reduce the water consumption and, hence, decrease the environmental impact of the process. In particular, the osmotic distillation technique here proposed consists of recycling the stripping solutions from a preliminary dealcoholization process of a batch of beer to that of further batches.A cost estimation showed that the proposed modification of the process was able to significantly reduce the cost of stripping water, which negatively influenced the operating costs in conventional osmotic distillation processes.Regarding to the beer quality, properties such as colour and polyphenols content were almost unchanged in the dealcoholized beer with respect to the original one while bitterness, foam stability, turbidity, O2 and CO2 content were statistically different.From the comparison of alcohol-free and original beer, a modification in the content of volatile compounds was observed. The volatile compounds losses were respectively of 77% for higher alcohols, 99% for esters and 93% for aldehydes. However, the loss of volatile compounds obtained in this study was very similar to literature results on beer dealcoholization by dialysis, falling film evaporation, vacuum distillation and reverse osmosis.Post treatments and blending techniques such as carbonation, addition of fresh yeasts following by maturation or by blending with krausen, original or aromatic beer may be used to improve the product quality.