Hydrolysis of chlorogenic acid in apple juice using a p‐coumaryl esterase of Rhizoctonia solani

Abstract

BACKGROUND: Apple juice is rich in polyphenolic compounds, especially in chlorogenic acid. A sour and bitter taste has been attributed to the compound. Chlorogenic acid in coffee powder was quickly hydrolysed by a p‐coumaryl esterase of Rhizoctonia solani (RspCAE) at its optimal pH of 6.0. It was unknown, however, if RspCAE would also degrade chlorogenic acid under the strongly acidic conditions (pH 3.3) present in apple juice. RESULTS: Treatment of apple juice with RspCAE led to a chlorogenic acid degradation from 53.38 ± 0.94 mg L−1 to 21.02 ± 1.47 mg L−1. Simultaneously, the caffeic acid content increased from 6.72 ± 0.69 mg L−1 to 19.33 ± 1.86 mg/L−1. The aroma profile of the enzymatically treated sample and a control sample differed in only one volatile. Vitispirane had a higher flavour dilution factor in the treated juice. Sensory analysis showed no significant difference in the taste profile ( p < 0.05). CONCLUSION: These results demonstrated a high stability and substrate specificity of RspCAE. An increase in caffeic acid and a concurrent decrease in chlorogenic acid concentration may exert a beneficial effect on human health.