Stefan K. Baier

The impact of the molecular weight of dextran on formation of whey protein isolate (WPI)–dextran conjugates in fibers produced by needleless electrospinning after annealing

The conjugation reaction of electrospun fibers of a mixture of whey protein isolate (WPI) and dextran using different molecular weights (40, 70, and 100 kDa) and mixing ratios was studied. This study includes the electrospinnability of a mixture of WPI and dextran, and the conjugation reaction between them via the initial stage of the Maillard reaction. The WPI-dextran fibers were characterized using optical and transmission electron microscopy. The covalent attachment of dextran to WPI was confirmed using sodium-dodecyl-sulfate-polyacrylamide gel-electrophoresis with protein and glycoprotein staining. Both 70 and 100 kDa of dextran and WPI at mixing ratios of 2 : 1 and 3 : 1 in phosphate buffer (30 mM, pH 6.5) were electrospun using needleless electrospinning. The solution concentration of the mixture was 50 wt% (33.3/37.5 wt% for dextran/16.5/12.5 wt% for WPI). The optimal conjugation conditions chosen from the experiments were a mixture of dextran (70 kDa)-WPI at 3 : 1 (75% relative humidity, 60 °C, 48 h).

Formation of Whey Protein Isolate (WPI)–Maltodextrin Conjugates in Fibers Produced by Needleless Electrospinning

Glycation of proteins via the first stage of the Maillard reaction is capable of improving their stability but not economically feasible yet. This work reports the glycation of whey protein isolate (WPI) with maltodextrin at a high yield after heating electrospun fibers made from the reactants. Glycoconjugates were characterized by Fourier transform infrared spectroscopy (FTIR) and SDS-PAGE. The binding ratio between WPI and maltodextrin was assessed via the free amino groups. The molecular weight of the conjugates and the reaction yield were studied by size exclusion chromatography. The impact of different mass ratios between WPI and maltodextrin in the fibers (5:95, 10:90, 20:80, and 25:75 w/w) was investigated. With increasing WPI content, the binding ratio of maltodextrin decreased from ∼2.1 to ∼1.2. Preferably small polysaccharides (2-13 kDa) from the maltodextrin reacted. Protein specific reaction yields of up to 44.52 ± 7.46% w/w were demonstrated in all WPI-maltodextrin fibers after heating.