Maillard reaction products between whey powder and water-soluble tempeh protein extract: membrane-based fractionation

Abstract

Whey powder, an industrial by-product, has the potential to be transformed into functional ingredients using the Maillard reaction. In this study, this chemical reaction occurred between whey powder and tempeh protein extract, resulting in increased antioxidant activity. This study aimed to isolate the Maillard reaction products (MRP) with the best antioxidant capacity using an ultrafiltration (UF) membrane by considering the fouling phenomenon that occurred on the membrane surface and critical flux for the filtration. MRP exhibited an antioxidant capacity of 0.09 mg ascorbic acid equivalent antioxidant capacity/mL, and the fractionation using a 5 kDa MWCO PES membrane showed the highest antioxidant capacity in terms of free radical reduction and metal chelating mechanisms. During MRP filtration, fouling on the membrane surface was observed, which could be attributed to the cake filtration model. The critical flux value was determined to be 4.23 LMH with a corresponding pressure of 0.75 bar. A long-term filtration below the critical flux showed stable performance, but filtration above the critical flux resulted in significant fouling. The permeate antioxidant IC₅₀ value was 4.25 mg/mL. Based on the LC-MS analysis, 1,4-dihydroxy-2-methyl-anthraquinone and ilexin II were found as the potential contributors to the antioxidant activity of MRP. In summary, our study demonstrates that fractionating MRP using UF membrane-based filtration is an effective method for isolating MRP with high antioxidant capacity. Our findings also shed light on the critical flux value and fouling phenomenon during MRP filtration, which are important considerations for scaling up the production process.