Abstract
Foam stability is an important quality attribute in specialty beers because it affects visual appeal, mouthfeel, aroma release, and consumer perception. This study evaluates foam stability responses to protein–polyphenol interactions in specialty beer formulations. Model beer samples were prepared with varied malt protein fractions, hop-derived polyphenol levels, alcohol content, and maturation conditions. Foam height, foam half-life, bubble size distribution, turbidity, surface tension, haze tendency, and colloidal stability were measured. The results show that moderate protein–polyphenol interaction improved foam persistence by strengthening interfacial films around gas bubbles. Excessive polyphenol concentration increased colloidal aggregation, haze formation, and foam collapse during storage. Samples with balanced protein composition and controlled hop polyphenol contribution produced the most stable foam structure. The study demonstrates that specialty beer foam quality depends on managing colloidal balance rather than increasing malt protein or hop material independently. This supports better formulation and maturation control.