P-20 - Study on Filtration-inhibitory Substances in Wheat Beer Using Originally Developed Microscale Filtration System

Generally, beer is filtered before packaging to remove yeast and turbidity. Filtration of wheat malt-brewed beer (wheat beer) is often challenging, resulting in a long filtration time and considerable beer processing loss and environmental impact. In this study, we developed a microscale filtration system to determine the factors influencing beer filterability. We aimed to study the factors improving the filtration of wheat beer using the microscale filtration system, and to investigate filtration-inhibitory substances in the wheat beers. First, we brewed test beer on a 2.5-L laboratory scale and subjected it to the microscale filtration (experiment 1) to evaluate its filterability. Next, we brewed the test beer on a 100-L pilot-scale and conducted the microscale filtration test and nanoparticle tracking and magnetophoretic analyses (experiment 2) to determine the filtration-inhibiting components of wheat beer. In experiment 1, five wheat beers (beers 1-1, 1-2, 1-3, 1-4, and 1-5) were brewed. Beer 1-1 was brewed using 100% barley malt, whereas beers 1-2 to 1-5 were wheat beers prepared with a step change in the amount of wheat malt used (beer 1-2: 20%, 1-3: 40%, 1-4: 60%, and 1-5: 80%). Filterability of all beers was evaluated using the microscale filtration system. In experiment 2, three wheat beers (beers 2-1, 2-2, and 2-3) were brewed. Notably, ingredients and brewing conditions for beers 2-1 and 2-2 were the same as those for beers 1-1 and 1-4. As lowering the pH improves the beer filterability, beer 2-3 was prepared at a lower pH than that used for beer 2-2 by adding lactic acid. In experiment 1, filterability of beers 1-2 to 1-5 gradually decreased with increasing wheat dosage compared to that of beer 1-1. Our microscale filter successfully evaluated beer filterability based on the wheat dosage. Moreover, our results indicated that the presence of wheat significantly affected the beer filterability. In experiment 2, filterability of beer 2-2 was approximately half of that of beer 2-1. Notably, filterability of beer 2-3 was similar to that of beer 2-1, suggesting that lowering the pH increases the beer filterability. Nanoparticle tracking analysis showed different particle distributions in all samples. Magnetophoretic analysis revealed the presence of wheat-derived components easily adsorbed onto diatomaceous earth, suggesting that some wheat-derived components and their surface charges affect the beer filtration efficiency. Overall, our study assessed the filterability of wheat beers with different wheat ratios and revealed variable particle distribution at different pH levels, even in wheat beers with the same wheat malt dosage ratio. Collectively, our findings suggest that the surface charges of wheat beer components significantly impact its filterability.