Supplementation of amino acids in apple must for the standardization of volatile compounds in ciders

The aim of this study was to identify the main amino acids responsible for the production of esters in ciders. The experiments were carried out in apple must and synthetic must. The amino acids were analysed by high-performance liquid chromatography and the volatile compounds by gas chromatography. Aspartate, asparagine and glutamate positively influenced the production of esters in the cider models and were used in the experiments with mixtures. The response surface generated by the proposed model yielded two regions that maximized the production of esters. In addition, the combination of aspartate and glutamate predicted a higher production. The optimal suggested concentrations were 43.4% of aspartate and 56.6% of glutamate for 120 mg/L of total nitrogen. The apple must supplemented with these two amino acids resulted in four times more esters than in the same cider without supplementation, demonstrating the effectiveness of the proposed model.