Significance of the reducing power in pale beers

The first part presents the different reasons which led to the development of new rapid methods for the study of the reducing substances of beers. The peculiarities of the retained operating conditions are described in detail s: RK-DPFe3, peroxidase browning, alkaline browning, and DCI-reduction. The second part is devoted to the discussion of the results obtained over a ten-year period. Nearly 2000 beer samples from the most varied origins und erwent very different analyses. Originally they were limited to the determi nation of tannoids with PVP and of the reducing power with the DPFe3-reagen t. They showed close relationships between reducing power, colloidal stabil ity, and flavour stability. These quite general results promoted the develo pment of rapid methods aiming to get more information on the nature and fun ction of the reducing components. The study of peroxidase browning, the DCI-reduction by innovative methods a nd the reversible browning in alkaline medium confirms the important role p layed by the phenolic compounds. The third part summarizes in several tables numerical information about bee rs from various breweries presented by their respective geographic origin. They may have a practical industrial interest. The increase in the size of the manufacturing units which favours the production of increasingly pale b eers during increasingly quicker processes has reduced the polyphenol conte nt in the course of the recent years and accordingly, the reducing power of beer all over the world. It appears that the importance of the reducing po wer, which chiefly depends on the polyphenolic content and is essential for the flavour stability, has been understated.