Brewing with prolyl endopeptidase from Aspergillus niger : The impact of enzymatic treatment on gluten levels, quality attributes and sensory profile

Beer is considered unsafe for those affected by coeliac disease because it is traditionally made by gluten-containing raw materials. During the stabilisation phase, the addition of processing aids leads to a gluten reduction, because the haze-forming activity of a protein in beer depends greatly on proline-rich barley hordeins. Prolyl endopeptidase (PE) is commonly used as a stabiliser in the brewing industry. This study was conducted to evaluate the impact of treatment with PE on gluten level, quality attributes and sensory profile of three different styles of barley/wheat malt beer. The addition of PE lowered the content of gluten below the ELISA kit LOQ (<10 mg kg-1). The foam stability was decreased by addition of PE, reaching values greater than 220 s. Some volatile compounds changed significantly, but panellists found no significant differences between treated and untreated beer in both description analysis and triangle test performed. Furthermore, treatment with PE reduces turbidity by hydrolysing the haze precursors, thereby improving beer stability.