Acrylamide formation in apple juice concentrates during storage

This study investigated the acrylamide formation in model systems, laboratory-scale produced apple juice concentrates obtained from different stages of process, and commercial apple juice concentrates at different Brix levels during the storage. Changes in the concentrations of reducing sugars, asparagine, 5-hydroxymethylfurfural, 3-deoxyglucosone, and acrylamide were monitored. In addition, Schiff bases of 3-deoxyglucosone and 5-hydroxymethylfurfural with asparagine were confirmed using high-resolution mass spectrometry in order to understand the contribution of intermediates to acrylamide formation. The results revealed that acrylamide formed in both acidic-aqueous model systems and laboratory-scale apple juice concentrates during production. The concentrations of 3-deoxyglucosone, 5-hydroxymethylfurfural, and acrylamide increased significantly (p < 0.05) with the increase in Brix levels whereas asparagine levels decreased in commercial apple juice concentrates during storage. The concentration of acrylamide reached at the maximum level of 0.30 ± 0.02 µmol/kg dry matter in 70°Bx of the concentrates. The findings showed that long-term storage of apple juice concentrates at high Brix levels contributes the acrylamide formation even in unsuitable systems such as acidic and high moisture medium. The confirmation of Schiff base of 3-deoxyglucosone and 5-hydroxymethylfurfural with asparagine demonstrated that the acrylamide formation was attributed to the accumulation of intermediates leading to the conversion of asparagine to acrylamide.