Optimization and physicochemical & antioxidant properties of leek (Allium porrum L.) dried by foam-mat drying

The foam drying method has evolved as a novel food drying technique. In the present study, the foam-mat drying technique is used to produce powder from leek (Allium porrum L.). The proportions of foaming agents were systematically optimized using the response surface methodology (RSM) and central composite design model. The optimized formulation was identified as 1.50% carboxymethyl cellulose, 14.37% maltodextrin, and 8.93% egg white. The optimal composition was adjusted for achieving high foam stability, high volume, and low density. This improved formula was then freeze-dried and dried using hot air at 50 °C and 70 °C, and its physical and chemical properties, antioxidant abilities, and overall quality were analyzed afterward. Based on the data obtained, the Midilli model was identified as the most suitable drying model. The TPC values for the samples dried at 50 °C, 70 °C, and freeze-dried were 1340.31, 1368.87, and 1349.83 mg/kg, while the TFC values were 208.78, 225.61, and 225.61 mg/kg. The antioxidant activities measured using the ABTS, DPPH, and FRAP tests were 8.58, 16.18, and 13.83 mmol/g for ABTS; 3.43, 4.56, and 1.91 mmol/g for DPPH; and 1.04, 1.32, and 1.27 mmol/g for FRAP, respectively. Considering the types of volatile compounds and the qualities of the powder, the samples dried at 50 °C using the convective method showed the best outcomes.