Effect of kiwifruit variety on the efficiency of ultrafiltration pretreatment during its juice membrane concentration with nanofiltration

Kiwifruit is widely consumed all over the world due to its nutritional compounds. It is recommended to prevent many types of diseases. The thermal concentration requires high temperatures, which destroy heat-sensitive compounds. Membrane processes are a suitable alternative to thermal processes due to the absence of high temperatures, simplicity, and lower cost. In this research, the juice of four varieties of kiwifruit, including Hayward, Abbott, Monty, and Allison, was clarified by ultrafiltration, and the permeate flux was measured at different pressures and flow rate. The results showed that the highest permeate flux was obtained at 2 bar and 20 mL/s. Also, Abbott and Allison had the highest and lowest product yield, respectively. The ultrafiltration permeate was treated by nanofiltration and the concentration value was investigated at different volume concentration factors (VCF). The results showed that by increasing the VCF to 4, the concentration of the target nutrient compounds begins in most varieties. Polyphenolic compounds, flavonoids, and antioxidant properties especially in Abbott and Hayward has increased about seven times. Hayward was seen to have the highest increase in polyphenolic compounds. The Hermia model showed that the cake formation mechanism was the dominant fouling mechanism in most of the processes.