Modeling and optimization of equipment operation in powder production of apple pulp: drying time and browning index

Producing powder from fruit pulp is a good way to prevent the loss of useful properties in the remaining meat from the skin, juice and core of fruits. The physicochemical properties of the powder play an important role in its storage time, customer friendliness and taste.This process was carried out using a vacuum dryer using the atmosphere control method and was checked in terms of drying time and browning index. The dryer is set on a laboratory scale for five temperature levels of 45, 55, 65, 75 and 85 °C and five vacuum pressure levels of 40, 50, 60, 70 and 80 kPa for a thickness of 6.5 mm.The statistical analysis of the obtained data and the optimization of the vacuum drying process were performed using the response surface method. The results showed that by increasing the temperature of the drying chamber, the drying rate of apple pulp sheets increased and the drying time decreased by 78.3%. The temperature values of the drying chamber were significant to the color indices of apple pulp powder. The lowest amount of browning index under the conditions of the temperature of the dryer chamber of 45 degrees Celsius and the vacuum pressure of 60 kPa for the vacuum dryer using the atmosphere control method was 100.26. The optimum point of the powder produced from the dried apple pulp sheets was proposed by the vacuum system using the atmosphere control method at the temperature of the drying chamber at 74.83 °Cand the vacuum pressure at 55.9 kPa. Under these conditions, the optimal value of the response variables, including drying time and browning time, were obtained in equal order.