The structural characteristics and physicochemical properties of mung bean protein hydrolysate of protamex induced by ultrasound

BACKGROUND

The limited physicochemical properties (such as low foaming and emulsifying capacity) of mung bean protein hydrolysate restrict its application in the food industry. Ultrasound treatment could change the structures of protein hydrolysate to accordingly affect its physicochemical properties. The aim of this study was to investigate the effects of ultrasound treatment on the structural and physicochemical properties of mung bean protein hydrolysate of protamex (MBHP). The structural characteristics of MBHP were evaluated using tricine sodium dodecylsulfate-polyacrylamide gel electrophoresis, laser scattering, fluorescence spectrometry, etc. Solubility, fat absorption capacity and foaming, emulsifying and thermal properties were determined to characterize the physicochemical properties of MBHP.

RESULTS

MBHP and ultrasonicated-MBHPs (UT-MBHPs) all contained five main bands of 25.8, 12.1, 5.6, 4.8 and 3.9 kDa, illustrating that ultrasound did not change the subunits of MBHP. Ultrasound treatment increased the contents of α-helix, β-sheet and random coil and enhanced the intrinsic fluorescence intensity of MBHP, but decreased the content of β-turn, which demonstrated that ultrasound modified the secondary and tertiary structures of MBHP. UT-MBHPs exhibited higher solubility, foaming capacity and emulsifying properties than MBHP, among which MBHP-330 W had the highest solubility (97.32%), foaming capacity (200%), emulsification activity index (306.96 m2  g-1 ) and emulsion stability index (94.80%) at pH 9.0.

CONCLUSION

Ultrasound treatment enhanced the physicochemical properties of MBHP, which could broaden its application as a vital ingredient in the food industry. © 2023 Society of Chemical Industry.

Structural, functional and antioxidant properties of Lentinus edodes protein hydrolysates prepared by five enzymes

The purpose of this study was to investigate structural, functional and antioxidant properties of Lentinus edodes protein hydrolysates (LEPHs) by alcalase, protamex, trypsin, papain and neutrase. Structural and functional properties were determined using gel electrophoresis, Fourier transform infrared spectroscopy, laser scattering, fluorescence spectroscopy, emulsifying properties etc. Antioxidant activities were detected by Fe2+ chelating, hydroxyl and DPPH radical scavenging assays. Enzymatic hydrolysis destroyed secondary and tertiary structures of Lentinus edodes protein, decreased its molecular weight and particle size, particularly hydrolysate prepared by alcalase with the highest hydrolytic degree (32.86 ± 0.98 %), the smallest particle (130.77 ± 1.85 nm) and molecular weight (5.86 kDa). Moreover, alcalase hydrolysate exhibited the highest emulsifying stability, the strongest hydroxyl radical scavenging activity and Fe2+ chelating ability among LEPHs. Whilst trypsin hydrolysate displayed the highest DPPH radical scavenging, foaming and fat absorption capacity. These results provided basis for LEPH as ingredients to be used for food industry.

Galectin isolated from parasite inhibits remission of experimental autoimmune encephalomyelitis by up-regulating autoantibody

Recently, parasite infections or parasite-derived products have been suggested as a therapeutic strategy with suppression of immunopathology, which involves the induction of regulatory T cells or/and T helper type 2 (Th2) responses. In a recent study, researchers reported that constructed recombinant galectin (rTl-gal) isolated from an adult worm of the gastrointestinal nematode parasite Toxascaris leonina attenuated clinical symptoms of inflammatory bowel disease in mice treated with dextran sulphate sodium. Noting the role of rTl-gal in inflammatory disease, we attempted to investigate the effect of the parasite via its rTl-gal on neuronal autoimmune disease using experimental autoimmune encephalomyelitis (EAE), a mouse inflammatory and demyelinating autoimmune disease model of human multiple sclerosis. In this model, rTl-gal-treated experimental autoimmune encephalomyelitis (EAE) mice failed to recover after the peak of the disease, leading to persistent central nervous system (CNS) damage, such as demyelination, gliosis and axonal damage. Further, rTl-gal-treated EAE mice markedly increased the number of CD45R/B220(+) B cells in both infiltrated inflammation and the periphery, along with the increased production of autoantibody [anti-myelin oligodendrocyte glycoprotein (MOG)35-55 ] in serum at chronic stage. Upon antigen restimulation, rTl-gal treatment affected the release of overall cytokines, especially interferon (IFN)-γ and tumour necrosis factor (TNF)-α. Our results suggest that galectin isolated from a gastrointestinal parasite can deliver a harmful effect to EAE contrary to its beneficial effect on inflammatory bowel disease.