Influences of Key Components and Surface Modifications on Beer Lacing

Sammanfattning: Beer is one of the most favorable alcoholic beverages and has a large consumption in the world. However, there are fewer beer consumers who perceive the lacing character after drinking. Four different concentrations (25 mg/L, 50 mg/L, 75 mg/L and 100 mg/L) of iso-α-acid and two levels (0.3% and 0.15%, w/w) of protein content were investigated towards lacing property on modified hydrophilic and hydrophobic glassware. Lacing area, lacing index and connectivity of laced foam were measured and two-way ANOVA was conducted to each result. There was no linear correlations found in each factor for every indication, but the statistical analysis showed that there was significant difference (p<0.05) among iso-α-acid concentrations on hydrophilic surface in terms of lacing area, and it is also the same case on both glass surface properties as for lacing index, in addition protein content influenced the value of lacing index on hydrophobic surface as well. Perimeter Maybe perimeter of lacing fragments was calculated to analyze lacing connectivity. It also showed the significant difference (p<0.05) over iso-α-acid concentrations. The interaction effect of protein and iso-α-acid also affect the results significantly. However, the specific interaction between these two factors needs more investigations. Independence of lacing pattern on hydrophilic and hydrophobic glass surface was demonstrated from student t-test according to perimeters. Moreover, the contact angle of each sample on hydrophilic and hydrophobic glass slides was discussed in detail. This thesis provides some new viewpoints for the evaluation of beer from beer lacing property and interesting results obtained in this work are important for comprehensive understanding the nature of foam and lacing connecting to the composition of beer and the glassware surface property.