Microwave-assisted foam mat drying of red beet pulp: influence of milk protein concentrate (MPC) and maltodextrin as a foaming agent, optimization and quality attribute

The objective of this study is to produce red beet root powder by using foam mat drying by microwave-assisted method and evaluate the effect of process parameters (Maltodextrin and milk protein concentrate (MPC) as the foaming agent concentration (0–10% w/w) and the power of microwave (400–800 W) on the foam and powder properties (foam density and foam expansion, unit density and bulk density, flowability and porosity, color and betalain content of powder, water soluble index and water absorption index. The optimal process condition was determined using response surface methodology. The optimum conditions for the foam mat process were 9.92% of maltodextrin, 10% of MPC concentration, and a microwave power of 400W. In optimal conditions, higher amounts of betalain (119.678 mg/100 g) and solubility (41.12%) were seen compared to the control sample (powder produced with a hot air dryer at 70 °C). Also, the color of the optimal sample had a higher level of Lightness compared to the control sample, and the high browning index belongs to the control sample (98.52). The Scanning electron microscopy images show that the optimal sample has finer particles and smooth, softer, flaky surfaces. The Fourier transform infrared spectra of the optimal and control showed remarkable similarities. Intensifying and shifting some absorption peaks of the FTIR spectra pattern confirmed the interaction of functional groups of amide and carbonyl groups in the control sample so that the decrease in the number of amide groups in the control sample was more significant. Graphical abstract