Morphology of complexes formed between β -lactoglobulin nanofibrils and pectins is influenced by the pH and structural characteristics of the pectins

Unraveling the role of polysaccharide-goethite associations on glyphosate' adsorption-desorption dynamics and binding mechanisms

HYPOTHESIS

Glyphosate retention at environmental interfaces is strongly governed by adsorption and desorption processes. In particular, glyphosate can react with organo-mineral associations (OMAs) in soils, sediments, and aquatic environments. We hypothesize mineral-adsorbed biomacromolecules modulate the extent and rate of glyphosate adsorption and desorption where electrostatic and noncovalent interactions with organo-mineral surfaces are favored.

EXPERIMENTS

Here we use in-situ attenuated total reflectance Fourier-transform infrared, X-ray photoelectron spectroscopy, and batch experiments to characterize glyphosate' adsorption and desorption mechanisms and kinetics at an organo-mineral interface. Model polysaccharide-goethite OMAs are prepared with a range of organic (polysaccharide, PS) surface loadings. Sequential adsorption-desorption studies are conducted by introducing glyphosate and background electrolyte solutions, respectively, to PS-goethite OMAs.

FINDINGS

We find the extent of glyphosate adsorption at PS-goethite interfaces was reduced compared to that at the goethite interface. However, increased polysaccharide surface loading resulted in lower relative glyphosate desorption. At the same time, increased PS surface loading yielded slower glyphosate adsorption and desorption kinetics compared to corresponding processes at the goethite interface. We highlight that adsorbed PS promotes the formation of weak noncovalent interactions between glyphosate and PS-goethite OMAs, including the evolution of hydrogen bonds between (i) the amino group of glyphosate and PS and (ii) the phosphonate group of glyphosate and goethite. It is also observed that glyphosate' phosphonate group preferentially forms inner-sphere monodentate complexes with goethite in PS-goethite whereas bidentate configurations are favored on goethite.

Synthesis of Nano-Scale Biopolymer Particles from Legume Protein Isolates and Carrageenan

Research background

Food proteins and polysaccharides can be used for the synthesis of nano-scale biopolymer particles with potential applications in the fields of food and pharmaceuticals. This study focuses on utilizing legume proteins for the production of biopolymer particles via regulation of their electrostatic interactions with carrageenan.

Experimental approach

Protein isolates were obtained from mung bean (Vigna radiata), cowpea (Vigna unguiculata) and black gram (Vigna mungo) and their protein profiles were determined. Next, these isolates were allowed to interact with carrageenan at pH=5.0-7.0 to determine optimum conditions for obtaining nano-scale biopolymer particles. Selected biopolymer mixtures were then subjected to a heat treatment (85 °C for 20 min) to enhance the interactions among biopolymers.

Results and conclusion

Nano-scale biopolymer complexes were obtained at pH=6.5. They were roughly spherical in shape with a majority having a diameter in the range of approx. 100-150 nm. Heating of the biopolymer mixtures increased the diameter of the biopolymer particles by approx. 2.5-fold. In addition, their negative surface charge was increased, stabilizing them against aggregation over a broader pH range (4.0-7.0), enhancing their potential to be utilized in food matrices.

Novelty and scientific contribution

This study reports the applicability of mung bean, cowpea and black gram proteins for the synthesis of stable biopolymer particles. These biopolymer particles can be potentially used for the encapsulation and delivery of bioactive components.