Abstract
Volatile ester formation in high-gravity wort is strongly influenced by yeast pitching rate because cell growth, nutrient demand, oxygen use, and stress response affect aroma metabolism. This study evaluates ester formation under controlled yeast pitching rates during high-gravity wort fermentation. Brewing trials were conducted using low, moderate, and high pitching rates while maintaining constant wort gravity, temperature, oxygenation, and yeast strain. Ester concentration, higher alcohol formation, yeast viability, sugar uptake, ethanol yield, attenuation, pH reduction, and sensory aroma intensity were measured. The results show that low pitching rates increased yeast growth demand and promoted stronger ester formation, but also increased fermentation variability. High pitching rates improved fermentation speed but reduced aroma complexity due to lower cell growth activity. Moderate pitching rates produced the best balance between attenuation, ethanol yield, and fruity ester character. The study demonstrates that pitching rate control is essential for aroma consistency in high-gravity brewing.