Nanofiltration for Separation of L‐Citrulline From Watermelon Rind Juice

, respectively). Fouling analysis revealed a transition in the dominant mechanism from cake filtration to complete blocking when ultrafiltration was applied prior to nanofiltration. These findings highlight the effectiveness of integrating ultrafiltration as a pretreatment step to enhance nanofiltration performance for selective L-citrulline recovery from watermelon rind. PRACTICAL APPLICATIONS: This study demonstrated that integrating ultrafiltration with nanofiltration effectively reduced sugars while concentrating L-citrulline in watermelon rind juice, making the resulting permeate suitable for functional beverage and nutraceutical formulations. The proposed membrane-based process offers a scalable, clean-label strategy for valorizing fruit-processing by-products, thereby supporting sustainable manufacturing and the development of health-oriented food products.