P-22 - Browning Rate of High Molecular Weight Peptide-bound Maillard Reaction Products Formed by Thermal Load and Their Impact on Taste

Heating processes, including mashing and boiling in the brewhouse and kilning during malting, are essential in beer brewing. In these processes, the Maillard reaction occurs, which contributes to the taste, aroma, and color of beer. At World Brewing Congress 2024, we analyzed the relationship between the richness (koku) of beer and the molecular weight fractionated peptide-bound Maillard reaction products (B-MRPs), and found that not only low molecular weight B-MRPs, but also high molecular weight (HMW) B-MRPs can be an indicator of richness. The HMW substances produced by the Maillard reaction include brown substances, which have been reported to be involved in the taste of various foods. However, because of their various molecular weights and structures, it is difficult to identify and quantify each substance. In the present study, we conducted test brewing by changing the wort boiling time while maintaining the other aspects of the beer recipe, such as the ingredients, mashing recipe, fermentation yeast, and temperature. We purified the peptides produced during the heating process by combining methods such as size exclusion chromatography, ammonium sulfate precipitation fractionation, and dialysis, and fractionated them into different molecular weights. We then measured the absorbance at 430 nm and investigated the degree of browning per amount of peptide (browning rate of HMW B-MRPs) in each molecular weight fraction. Furthermore, we spiked beer with fractions of different molecular weights and browning rates and investigated the effect of the browning rate of HMW B-MRPs on taste. The results suggested that the browning rate affects taste, but this may differ depending on the molecular weight.