Aggregation kinetics and ζ-potential of soy protein during fractionation

Immobilization of human tyrosine hydroxylase onto magnetic nanoparticles - A novel formulation of a therapeutic enzyme

Human tyrosine hydroxylase (hTH) has key role in the production of catecholamine neurotransmitters. The structure, function and regulation of hTH has been extensively researched area and the possibility of enzyme replacement therapy (ERT) involving hTH through nanocarriers has been raised as well. However, our understanding on how hTH may interact with nanocarriers is still lacking. In this work, we attempted to investigate the immobilization of hTH on magnetic nanoparticles (MNPs) with various surface linkers in quantitative and mechanistic detail. Our results showed that the activity of hTH was retained after immobilization via secondary and covalent interactions as well. The colloidal stability of hTH could be also enhanced proved by Dynamic light scattering and Zeta potential analysis and a homogenous enzyme layer could be achieved, which was investigated by Raman mapping. The covalent attachment of hTH on MNPs via aldehyde or epoxy linkers provide irreversible immobilization and 38.1 % and 16.5 % recovery (ER). The hTH-MNPs catalyst had 25 % ER in average in simulated nasal electrolyte solution (SNES). This outcome highlights the relevance of immobilization applying MNPs as a potential formulation tool of sensitive therapeutic enzymes offering new opportunities for ERT related to neurodegenerative disorders.

Impact of Incorporating Free Calcium and Magnesium on the Heat Stability of a Dairy- and Soy-Protein-Containing Model Emulsion

This study investigated the impact of calcium chloride (CaCl2) and magnesium chloride (MgCl2) at varying concentrations on a model milk formulation's physical and chemical properties after thermal treatment. The model milk was subjected to two-stage homogenization and pasteurization before being supplemented with different concentrations of CaCl2 or MgCl2. The findings revealed that elevating the concentration of either calcium or magnesium resulted in the milk emulsion having a higher viscosity and median particle size following heating. CaCl2 had a slightly stronger impact than MgCl2, particularly at higher concentrations. The milk samples also exhibited a reduction in the zeta potential as the ionic strength of the salt solution increased, with the CaCl2-fortified milk displaying a slightly lower negative surface charge than the MgCl2-fortified milk at the same dose. The model milk's viscosity was evaluated after adding various salt concentrations and a temperature ramp from 20 to 80 °C. Notably, the viscosity and particle size changes demonstrated a non-linear relationship with increasing mineral levels, where a significant increase was observed at or above 5.0 mM. An emulsion stability analysis also revealed that the de-stabilization pattern of the high salt concentration sample differed significantly from its low salt concentration counterparts. These findings could serve as a basis for the future development of fortified UHT milk with nutritionally beneficial calcium and magnesium in industrial applications.

The Potential Use of Cold-Pressed Coconut Oil By-Product as an Alternative Source in the Production of Plant-Based Drink and Plant-Based Low-Fat Ice Cream: The Rheological, Thermal, and Sensory Properties of Plant-Based Ice Cream

This study aimed to investigate the potential use of cold-pressed coconut oil by-products (COB) as a low-cost alternative source for plant-based drink and ice cream production. Firstly, a plant-based drink was produced from cold-pressed coconut oil by-products (COB drink) and compared with a commercial coconut drink. The fat, protein, and zeta potential values of coconut drink obtained from COB were higher than those of the commercial samples. In addition, the particle size value of the drink obtained from COB was found to be lower than that of the commercial drink. In the second stage, full-fat and low-fat plant-based ice cream samples using COB drink were produced and compared to control ice cream samples (produced by the commercial coconut drink) in terms of rheological, sensorial, and thermal properties. Rheological analysis showed that all plant-based ice cream samples indicated pseudoplastic, solid-like, and recoverable characteristics. Low-fat commercial control ice cream samples (C1) indicated the lowest K value (9.05 Pasⁿ), whereas the low-fat plant-based ice cream sample produced by the COB drink (COB-3) exhibited the highest K value (17.69 Pasⁿ). ΔH_f values of the plant-based ice cream samples varied from 144.70 J/g to 172.70 J/g. The low-fat COB ice cream stabilized with 3% COB and full-fat COB ice cream samples showed lower ΔH_f values than control ice cream samples, indicating that the COB ice cream showed desired thermal properties. The COB drink may be utilized in plant-based ice cream without altering sensory qualities, and low-fat ice cream could be manufactured in the same manner to attain full-fat ice cream quality characteristics. The results of this study demonstrated that COB can be successfully used as an inexpensive raw material source in the production of full-fat and reduced-fat vegetable-based ice cream.

Ionic Strength and pH Responsive Permeability of Soy Glycinin Microcapsules

Recently, hollow protein microcapsules have been made simply by heating the microphase separated soy glycinin microdomains. However, the properties (e.g., mechanical properties and permeability) that relate to the application of these microcapsules are unknown. In this study, the permeability of the soy glycinin microcapsules was investigated by confocal laser scanning microscopy (CLSM), as influenced by ionic strength and pH using fluorescein isothiocyanate-dextran (FITC-dextran). The glycinin microcapsules kept the integrity between pH 1 and 11.5, swelled when pH was below 3 or above pH 11, dissociated at pH above 11.5 and deswelled slightly at pH 1. When the pH increased above 11, the permeability of the microcapsule significantly increased. Remarkably, when the pH was below the isoelectric point of glycinin (≈pH 5), FITC-dextran spontaneously accumulated inside the microcapsule with a significantly higher concentration than that in bulk solution, as evidenced by the strong intensity increase of fluorescence. This unique feature significantly increased the loading amount of FITC-dextran. The permeability of microcapsules was also increased by adding salt but less significant than by adjusting pH. The surface of the microcapsules became coarser when the permeability increased, which was revealed by scanning electron microscopy. These results show that soy glycinin has a great potential to be used as a wall material to fabricate hollow microcapsules that could find applications in biomedicine and food industry.

Removal of copper(II) using deacetylated konjac glucomannan conjugated soy protein isolate

In this study, an environmentally friendly biosorbent deacetylated konjac glucomannan conjugated soy protein isolate (abbreviated as DKGM-C-SPI) was prepared for Cu(2+) ions removal from aqueous solution. Scanning electron microscopy, Fourier transform infrared spectroscopy and zeta potential analysis revealed successful conjugation of soy protein isolate (SPI) onto deacetylated konjac glucomannan (DKGM) matrix. A comparative adsorption performance of DKGM-C-SPI and DKGM was tested to remove Cu(2+) ions from aqueous solution. DKGM-C-SPI showed the desired adsorption performance for Cu(2+) ions. The adsorption equilibrium of DKGM-C-SPI was achieved within 30 min. The adsorption behavior of DKGM-C-SPI followed a pseudo-second-order reaction model. The maximum Cu(2+) ion adsorption capacities obtained from the Langmuir isotherms fit were shown to be 62.50 mg g(-1) for DKGM-C-SPI and 12.23 mg g(-1) for DKGM. This impressive increase about 5 times in Cu(2+) ion adsorption capacity is attributed to the strong Cu(2+) ion chelating ability of the soy protein isolate (SPI) on the DKGM matrix. These results confirm that the DKGM-C-SPI biosorbent has a potential for Cu(2+) ion extraction from wastewater.

Formulation and characterisation of antibody-conjugated soy protein nanoparticles--implications for neutralisation of snake venom with improved efficiency

The present study reports the formulation of soy protein nanoparticles and its conjugation to antivenom. The conditions for nanoparticle formation were optimised by considering particle size, count rate, stability and zeta potential. The smallest particle size of 70.9 ± 0.9 nm with a zeta potential of -28.0 ± 1.4 mV was obtained at pH 6.2, with NaOH 5.4 % and 28 μg/mg glutaraldehyde. The nanoparticle was conjugated with antisnake venom immunoglobulins (F(ab')2 fragments) using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide. TEM analysis indicated the increased size of particle to 600 nm after conjugation to antivenom. Further, in vitro studies indicated that conjugated antibodies inhibited the activity of protease, phospholipase and hyaluronidase enzymes of Bungarus caeruleus venom more efficiently than the free antivenom. This is the first report on the use of protein nanoparticles for conjugating snake venom antibodies and their implications for neutralising snake venom enzymes with increased efficiency.

Effect of cattle breeds on milk composition and technological characteristics in china

Cattle breeds have a striking effect on milk, including milk composition and technological characteristics. This study aims to compare milk composition, acidification activity, viscosity, milk dispersion system stability and casein molecular weight among three buffalo breeds in China. The technological characteristics of milk produced by three cattle breeds of river buffalo (Murrah), crossbreed 1st generation (F1), crossbreed multiple generation (FH, H≥3) buffaloes were investigated. Cattle breeds showed evident effect on milk protein, fat and total solids content, but little effect on most of buffalo casein molecular weight. Milk fat, protein content and the viscosity of buffalo milk from river buffalo were lower than those of F1 and FH, so was the buffer capacity. The viscosity was negatively correlated to temperature and concentration. Results of stability coefficient showed that milk dispersion system had the best dynamic stability characteristics under pH 6.6 and 6 times dilution, while zeta potential of Murrah milk was slightly higher than that of hybrid offspring (F1, FH). SDS-PAGE results showed that buffalo αs-casein had a slightly faster mobility than standard αs-casein; while buffalo β-casein showed a slightly slower mobility than standard β-casein. There is no clear differences in molecular weight of αs-, β-, and κ-casein among Murrah, F1 and FH.

Postfertilization changes in nutritional composition and protein conformation of hen egg

Fertilized hen egg is traditionally considered as a dietary supplement in many Asian countries. This work aimed to obtain information on the effect of fertilization on total nutritional composition of egg contents and protein conformation. Chemical analysis showed that the lipid level in fertilized egg began to decrease after day 9. Fertilized egg before day 9 was higher in essential free amino acids (EFAA) and monounsaturated fatty acids (MUFA) contents but lower in cholesterol and polyunsaturated fatty acids (PUFA) than unfertilized counterparts. Fertilized egg proteins were characterized by an increase in hydrophobicity and a decrease in electrostatic interaction. Circular dichroism analysis showed that β-sheet decreased with increasing incubation time, whereas unordered structure increased. The findings observed in this work provide a crucial basis for understanding nutritional composition and protein conformation of fertilized egg, with the potential of being utilized as an EFAA/MUFA-rich, low-cholesterol dietary supplement.

Structure modification of montmorillonite nanoclay by surface coating with soy protein

To achieve exfoliated and/or intercalated structures, montmorillonite (MMT) was surface-coated by soy protein at 60 °C, at MMT/soy protein powder mass ratios of 49:1, 9:1, 4:1, and 2:1 and pH 2.0-10.0. The protein-coated MMT was triple-washed and lyophilized for characterization. Protein coating was observed at all pH conditions, based on data from X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential, and quantification of protein remaining in the continuous phase and present in the triple-washed MMT. At a mass ratio of 4:1, >90% protein bound with MMT, with the largest d-spacing at pH 9.0. When the mass ratio was increased to 2:1, protein-coated MMT at pH 9.0 demonstrated the highest degree of intercalation/exfoliation, corresponding to disappearance of the diffraction peak characteristic of pristine MMT. This study thus demonstrated that intercalation/exfoliation of MMT can be easily achieved by coating with low-cost soy protein for manufacturing nanocomposite materials.