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Summary: In this work, soy protein isolates (SPIs) were subjected to microparticulation, turning soy protein ingredients into microparticles with improved thermal stability which could be used in high‐protein foods. The pH is a critical determinant in microparticulation. Our work is mainly to investigate the effect of pH on the formation and properties of protein microparticles. To clarify the effects of pH conditions on the properties of the resulting particles, microparticulation was performed at different pH conditions (7.0, 6.0 and 5.0). Aggregation behaviours described by the parameters calculated from the protein dispersion viscosity combined with the observation of the morphology change were used to analyse the particle formation process. For the microparticles prepared at pH 5.0, soy proteins were more inclined to aggregate into clusters on a micro‐scale which had a flexible conformation. After spray drying, This powder could be easily dispersed in water, creating a dispersion with a protein concentration of 10 wt%. At this concentration, the thermal gelation capacity of the proteins was observed to decrease. Conversely, the tendency of protein aggregation was largely restricted when soy protein microparticulation was carried out at pH 7.0. As these soy protein particles in nano‐scale were dispersed in water, a decrease rather than an increase was recorded in the viscosity of this dispersion after it was heated, suggesting that these particles had improved thermal stability. This work has demonstrated that implementing appropriate pH conditions during microparticulation can prepare soy protein particles with different sizes and rheological properties, which might meet the demands of various food processing. [ABSTRACT FROM AUTHOR]

Summary: In this study, we aimed to evaluate the potential of the γ‐zein hydrolysate (γ‐ZH) as a new delivery system for hydrophobic bioactive molecules such as curcumin (Cur). γ‐ZH‐Cur complexes (γ‐ZH‐Cur) with a particle size of 50–60 nm were successfully formed via the hydrogen bonding and hydrophobic interactions. Compared to α‐ZH, the complexation of Cur in γ‐ZH showed a better improvement in the water solubility and physicochemical stability of Cur and showed sustained release and greater potential for absorption of Cur. The differences in the loading capability, the physicochemical storage and the bioaccessibility of Cur between γ‐ZH and α‐ZH may be associated with the differences in the amino acid composition and typical sequence of peptides. These results indicate that γ‐ZH has a better ability to serve as a novel delivery for the hydrophobic bioactive molecules compared to α‐ZH. [ABSTRACT FROM AUTHOR]

In this article, we report the microstructure and rheological property of Pickering emulsions stabilised with zein nanoparticles prepared through phase separation from acetic acid solution. The fresh emulsions showed liquid-like behaviour and reasonable small droplet size. Interestingly, after 3 days of storage at 25° C, the emulsions changed into solid-like state. The viscosity remarkably increased, and the storage modulus was much larger than the loss modulus. These results indicate the formation of the gel-like network in emulsions. The droplet size also showed an obvious increase, while the big droplets could be disrupted into small ones in the presence of sodium dodecyl sulphate. The particle network in the continuous phase was seen in the confocal laser scanning microscopy. Therefore, it is suggested that the gel-like network is formed by the flocculation of oil droplets and particle network in continuous, mainly through the hydrophobic interactions between the particles. [ABSTRACT FROM AUTHOR]

The present work was aimed to evaluate the potential of the gel-like Pickering emulsions (50%, v/v, oil) stabilised by zein/tannic acid (TA) complex colloidal particles (ZTPE) as a new encapsulation system of lipophilic ingredients. Compared with sodium caseinate-stabilised emulsions (SCE) and bulk oil, the better protective effects of ZTPE on the chemical stability of curcumin were observed when they suffered from UV light, and the lipid oxidation rate remarkably reduced in ZTPE. Also, the zein particle layers loaded with TA around the oil droplets can provide protection against harsh gastric environment, facilitating to slow down the release of free fatty acids (FFA) and curcumin during in vitro simulated digestion. These findings show that ZTPE have a good potential to act as an efficient encapsulating agent to protect functional ingredients from degradation and control their release during digestion, which can further improve the bioavailability of bioactive ingredients. [ABSTRACT FROM AUTHOR]

A fermented soya milk (FSM) enriched with isoflavone aglycone ( FSM- SPIA) was prepared from heated soya protein isolate ( SPI)-isoflavone complex. After 48 h of fermentation, FSM- SPIA contained higher contents of living bacteria, free amino acids and aglycone compared with the FSM of SPI ( FSM- SPI) and the FSM of SPI-isoflavone complex ( FSM-Mix). In the in-vitro digestion experiment, FSM- SPIA showed higher antioxidant capacity and isoflavones ( ISO) bioavailability than FSM- SPI and FSM-Mix. This was likely due to the soya milk containing a higher level of amino acid, peptides and the presence of soya bean isoflavone. The improved protein digestibility, the interaction and binding ability between proteins and ISO may affect the properties of the protein and the fermented products. The FSM enriched with isoflavone aglycone can be used as a functional fermented drink, as well as an auxiliary food for menopausal women during a specific pathological period. [ABSTRACT FROM AUTHOR]

This work focused on the effect of glycosylation on the gelation ability of β-conglycinin induced by microbial transglutaminase ( MTGase). Rheological results indicated that the gels of β-conglycinin-dextran conjugate products exhibited higher G′ value (172.2 ± 8.6 Pa) compared with those of dry-heated β-conglycinin (75.2 ± 5.1 Pa), β-conglycinin (53.3 ± 4.0 Pa) and β-conglycinin-dextran mixture (38.6 ± 2.6 Pa) after 4 h incubation with MTGase. The gels prepared from β-conglycinin-dextran conjugate products had higher hardness, fracturability, springiness and cohesiveness values determined by textural profile analysis. The turbidity of β-conglycinin-dextran conjugate products solution incubated with MTGase increased faster than those of the other three protein samples. The conjugated dextran in β-conglycinin-dextran conjugate products could inhibit extensive protein-protein interactions which might result in the formation of more ordered and stronger gel network structures during MTGase cross-linking process. A compact and homogeneous gel networks in β-conglycinin-dextran conjugate products gels were also observed by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Summary Poor solubility caused by thermal aggregation usually limits the utilisation of soy proteins in food industry. In this study, the anionic surfactant, sodium dodecyl sulphate (SDS), was found to be effective in suppressing thermal aggregation of glycinin which was the main composition of the insoluble aggregates of soy proteins. Turbidity, dynamic light scattering, surface tension, circular dichroism and fluorescence spectra analysis were used to reveal the mechanism for the inhibitory of thermal aggregation by SDS. Bound to SDS, the exposed hydrophobic groups on the protein molecules were covered by the ionic head groups of SDS. The approaching of the particles was unavailable in the presence of the strong electrostatic repulsive force. Therefore, the particles remained stable and disperse. Thermal aggregation was not effectively suppressed until the binding sites which interacted with SDS on the glycinin molecules were saturated. The strategy for improving the solubility of food protein was also discussed. [ABSTRACT FROM AUTHOR]