Hot air‐assisted instant controlled pressure drop drying impact on the Maillard reaction‐related physicochemical properties of apple slices

This research investigated the instant controlled pressure drop-assisted hot air drying (DIC) impact on Maillard reaction-related components of apple slices, with freeze drying (FD) and hot air drying (AD) as control. DIC apple slices were significantly (*p < .05) differentiated from FD and AD apple slices by marked browning, high levels of 5-hydroxymethylfurfural (5-HMF), and fluorescence intermediary compounds (FIC). DIC processing reduced fructose by 18.95%–45.68% and glucose by approximately 50%, while, the free amino acid reduction was 80.7%–95.1% and the reduction of hydrolysable amino acid was 15.1%–65.9% in DIC drying. In multivariate analysis, the DIC apple slices were significantly (*p < .05) differentiated from fresh, FD, and AD apple slices by three principal components that explained 46.7%, 12.9%, and 10.5% variances, respectively. Also, DIC apple slices were characterized by the FIC, 5-HMF, total free amino acid, and CIE a*, b* values. This research compared the Maillard reaction-related components of DIC apple slices with that of FD and AD apple slices. The results revealed that DIC apple slices were significantly (*p < .05) differentiated from FD and AD apple slices by marked browning and high levels of 5-HMF and FICs. This research would provide information on the Maillard reaction-related properties of DIC drying apple products, and offer the reference on apple varieties selection for DIC apple slices production. Novelty impact statement This research compared the Maillard reaction-related components of drop-assisted hot air drying (DIC) apple slices with that of freeze drying (FD) and AD apple slices. The results revealed that DIC apple slices were significantly (*p < .05) differentiated from FD and AD apple slices by marked browning and high levels of 5-hydroxymethylfurfural and fluorescence intermediary compounds. This research would provide information on the Maillard reaction-related properties of DIC drying apple products, and offer the reference on apple varieties selection for DIC apple slices production.