Physicochemical and rheological characterizations of a novel exopolysaccharide EPSKar1 and its iron complex EPSKar1-Fe: Towards potential iron-fortification applications

Iron is a micronutrient essential for human health and physiology. Iron-deficiency anemia, the most common form of anemia, may occur from an iron homeostasis imbalance. Iron fortification is a promising and most sustainable and affordable solution to tackle the global prevalence of this anemia. Herein, we investigate physicochemical, rheological and stability characteristics of a novel exopolysaccharide 'EPSKar1' (derived from Lacticaseibacillus rhamnosus strain Kar1) and its iron complex 'EPSKar1-Fe (II)'. Our findings demonstrate that EPSKar1 is a high molecular-weight (7.8 x 105 Da) branched-chain heteropolysaccharide composed of galactose, N-acetylglucosamine, and mannose in a molar ratio of 8:4:1, respectively, and exhibits strong emulsifying and water-holding capacities. We find that EPSKar1 forms strong complexes with Fe, wherein the interactions be-tween EPSKar1-Fe (II) complexes are mediated by sulfate, carboxyl, and hydroxyl groups. The rheological an-alyses reveal that the EPSKar1 and EPSKar1-Fe (II) complexes exhibited shear thickening and thinning properties in skim milk and water, respectively; however, the suspension of EPSKar1 in skim milk is viscoelastic with predominantly elastic response (G'>G and tan delta < 1). In comparison, EPSKar1-Fe (II) complex exhibits remarkable stability under various processing conditions, highlighting its usefulness for the development of fortified dairy products. Together, these findings underpin considerable prospects of EPSKar1-Fe (II) complex as a novel iron-fortifier possessing multifarious rheological benefits for food applications.

Automated summary

Iron is essential for human health, and iron fortification is a promising solution for combating iron-deficiency anemia. This study investigates the physical and chemical properties of a new exopolysaccharide called EPSKar1 and its iron complex EPSKar1-Fe (II). The findings demonstrate that EPSKar1 is a high molecular-weight heteropolysaccharide with strong emulsifying and water-holding capacities. EPSKar1 forms stable complexes with iron and exhibits beneficial rheological properties for food applications. Overall, EPSKar1-Fe (II) complex shows great potential as a novel iron fortifier.