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The interaction between the main protein components of rapeseed, also called canola, was investigated in water as a function of the pH and in the presence of NaCl. Firstly, the solubility of purified cruciferin and napin was determined and the soluble fraction was characterized using light scattering techniques. Napin was found to be soluble over the whole pH range investigated (pH 4–10), whereas cruciferin was only partially soluble at pH ≤ 7. Subsequently, mixtures of the two components were studied as a function of the pH showing that large complexes between the positively charged napin and the negatively charged cruciferin were formed at pH ≥ 7 in water that could be removed by filtration through 0.2 μm pore size filters. It was found that the extent of complexation strongly depended on the fraction of napin in the mixture. Interestingly, in the presence of 0.1 M NaCl much smaller complexes were formed in this pH range that remained in solution. [Display omitted] • The cruciferin has low solubility at pH 4–7, whereas napin remains soluble at pH 4-10. • Large complexes are formed in mixtures of cruciferin and napin at pH ≥ 7. • More napin is needed to form large complexes when the pH is increased from 7 to 9. • Addition of NaCl inhibits complex formation. [ABSTRACT FROM AUTHOR]

Edible protein-based oleogels have garnered extensive attention in food formulation, driven by the desire for enhanced nutritional profiles and improved texture perception. This is facilitated by the nutritional value of the starting ingredient proteins, coupled with high consumer acceptance. However, there exists limited knowledge regarding the connection between the microstructural properties of gels and their macroscopic rheological properties, especially concerning their potential as fat replacers in food products. The present study reveals a simple means of modulating the microstructural properties and macroscopic mechanical features of capillary whey protein oleogels, as well as their aesthetic properties. This is achieved by using whey protein variants with diverse morphologies, such as fibers, particles, and fractal clusters, or by varying the water fraction (s) and the protein concentration (φ) in the formula. Rheological scaling properties and confocal laser scanning microscopy (CLSM) were employed to investigate the structural contribution of protein particles within the gel network. Furthermore, the study explores the practical applications of the derived oleogels, particularly in terms of spreadability or shortening as a potential alternative to margarine, within real food matrices. The spreadability of capillary oleogels with a protein concentration (φ) at 0.16 and 0.18 was comparable to that of commercial margarine. Meanwhile, the capillary oleogel-cake exhibited similarity to the margarine cake in textural parameters and sensory acceptability. This suggests that these capillary whey protein oleogels hold promise for applications in bakery products as margarine alternatives with low levels of saturated/ trans -fat content. [Display omitted] • Capillary oleogels can be formed by using whey protein variants with diverse morphologies. • Capillary oleogels fabricated with different particle shape have diverse mechanical features and aesthetic properties. • The microstructural of capillary oleogels can be tuned by adjusting the water fraction or the protein concentration. • Capillary whey protein oleogels hold promise for applications as margarine alternatives. [ABSTRACT FROM AUTHOR]

The effects of electrostatic repulsion (pH6.5) and attraction (pH4.6) between biopolymers on the physicochemical and foam properties of ovalbumin (OVA)/carboxymethylcellulose (CMC) mixtures subjected to mild heat treatment (60–75 °C) were comparatively investigated. It was found that electrostatic binding between OVA and CMC at pH 4.6 resulted in an increase in the peak temperature of thermal denaturation (T d) of OVA from 71.3 °C to 74.4 °C, while no significant effect was observed at pH 6.5. Thus, 60 and 65 °C below T d were chosen to further investigate the effects of heating on the degree of thermal aggregation, protein conformation and foam properties of OVA/CMC mixtures. Confocal laser scanning microscopy observations and rheological results indicated that electrostatic binding between OVA and CMC at pH 4.6 significantly reduced the degree of protein thermal aggregation, while on the contrary, electrostatic repulsion between proteins and polysaccharides at pH 6.5 promoted OVA thermal aggregation. Raman spectroscopic characterisation indicated that mild heat treatment mainly led to a change in the microenvironment polarity of OVA tyrosine and tryptophan residues, as well as an increase in the content of random coil in the amide III band irrespective of pH. Moreover, after heating at 65 °C for 20 min, The foaming ability of the OVA/CMC mixtures at pH 6.5 and 4.6 increased by approximately 32% and 36% respectively compared to pure OVA. These findings have a positive value for enhancing the heat sterilisation strength of egg white proteins. [Display omitted] • Electrostatic binding enhanced the thermal denaturation temperature of ovalbumin. • Electrostatic binding inhibited thermal aggregation of ovalbumin. • Electrostatic repulsion promoted thermal aggregation of ovalbumin. • Both electrostatic attraction and repulsion enhance the foamability of heated ovalbumin. [ABSTRACT FROM AUTHOR]

Ormosia, as one of the consumer's favorite grains, is rich in protein, but its application is limited by the naturally low solubility of its protein. In order to improve its application capability, the Ormosia protein (OSP) is modified by high-intensity ultrasounds (HIUS), and the effect of ultrasound on the secondary and tertiary structure, as well as the improvement of its foaming property due to the alteration in protein structure, were systematically explored. It has been observed that HIUS greatly reduced the particle size of the OSP, and significantly affected the secondary and tertiary structure. These fundamental changes improved the ability of the OSP to stabilize foam at the water-air interface, and thus the HIUS-treated OSP possessed an excellent foaming property. The results of this study are expected to provide a theoretical basis for expanding the application of the OSP in the food industry. [Display omitted] • HIUS affected the secondary and tertiary structures of OSP. • HIUS enhanced the foam-capacity ability of OSP. • HIUS enhanced the foam-stability ability of OSP. [ABSTRACT FROM AUTHOR]

This research compared effects of heating on the digestion of goat milk proteins in skimmed goat milk model systems with different casein-to-whey protein ratios. The digestion was evaluated both the supernatant and gastric clot part of the digesta. Whey protein concentrates were added in skimmed goat milk (80% casein, C80 sample) to make a 40% casein sample (C40 sample). Heating at 65 °C showed limited influence on digestibility of proteins in supernatant and clot of both model systems. In the supernatant, the C80 sample had a higher soluble protein concentration after 85 °C heating, compared to the C40 sample. After heating at 85 °C for 30 min, the digestibility of proteins in the supernatant of C40 and C80 samples was increased. This heating also increased the casein digestibility of the gastric clot of C80 sample, but resulted in more undigested whey protein aggregates in C40 sample. For the difference between C80 and C40 sample, the proteins in the supernatant of C80 samples showed a higher digestibility than those in the supernatant of C40 samples, both in non-heated and in 85 °C heated samples. The clots of C40 sample showed a relatively higher digestion rate than C80 sample clots, which may be due to their higher water content and looser microstructure. Overall, this study showed that heating induced different digestion kinetics of goat milk model systems with different casein-to-whey ratios. [Display omitted] • Gastric digestion of soluble and coagulated milk proteins were studied. • CaseIn:whey ratio influence reaction of proteins to heating and digestibility. • 85 °C heating increased casein digestion in the clots but induced more whey aggregates. • Whey protein aggregates induced low digestibility in whey-protein rich samples. [ABSTRACT FROM AUTHOR]

Despite the potential benefits of using cellulose ethers and their combination with other polysaccharides and proteins in the creation of reduced-fat water-in-oil (W/O) emulsions, research in this specific area is currently limited. Further studies are needed to explore the optimal combinations and concentrations of these materials to achieve emulsions with desired texture and higher rheological properties. To address this research gap, seven W/O emulsions with a 40 wt% water phase at pH 3.5 are prepared. The water phase consisted of 2 wt% methylcellulose (MC) or hydroxypropyl methylcellulose (HPMC) combined with 10 wt% whey protein isolate (WPI) and/or kappa-carrageenan (kC). The oil phase, comprising 60 wt%, contained 8 wt% polyglycerol polyricinoleate (PGPR) in soybean oil. The emulsions were initially prepared at room temperature and subsequently subjected to a heating process at an elevated temperature of 90 °C for a duration of 30 min. Following this heating step, the emulsions were then cooled back to room temperature. This sequential temperature treatment was employed with the intention of inducing aggregation and gelation within the emulsions. The temperature oscillation measurements (G* versus temperature) provide further evidence for the role of covalent and noncovalent bonding in the rheology and gelation of WPI-based emulsions. The viscosity and moduli of unheated and heated emulsions containing combinations of HPMC were found to be higher compared to those containing MC combinations. This behavior can be attributed to the stronger intermolecular interaction between HPMC, WPI, and/or kC, as well as their attachment with PGPR. These interactions lead to the formation of a more viscous and firmer W–O interface in emulsions. [Display omitted] • W/O emulsions prepared using cellulose ethers, WPI, and/or kappa carrageenan aggregation in the aqueous phase. • They exhibit high viscosity and elasticity and form compact microstructures when undergoing heat treatment. • HPMC combinations showed higher rheological properties compared to the equivalent MC emulsions. [ABSTRACT FROM AUTHOR]

The performance of 3D food printing for hydrogels largely depends on the gel spatial structure and water state. However, the mechanism of microstructure and water state that affects the 3D printing performance of hydrogels remains unclear. Our previous studies found that the hydrogel made from honey bee pupae, a rich source of high-quality protein, has good fluidity but poor structural stability, limiting its use in 3D printing. Based on it, honey bee pupa protein (HBPP) added with soybean dietary fiber (SDF) was selected as a case study in this work. The results revealed that HBPP gel had good fluidity but weak mechanical strength, which was guided by the firm immobilization of water molecules and the lack of a rigid three-dimensional network structure. However, upon adding SDF, the rigid network structure of HBPP gel was enhanced and the degree of water immobilization was reduced. HBPP-SDF gel had better structural stability than HBPP gel and lower water migration ability than SDF gel. Additionally, SDF and HBPP complemented each other, thereby improving the 3D printing performance of the gel. Based on the findings, a possible microstructure evolution mechanism of different types of gels during 3D printing was proposed. Out of all the HBPP-SDF gels evaluated, the HBPP-SDF gel with an optimum SDF concentration of 30% demonstrated the best printing performance. [Display omitted] • Addition of SDF enhanced the network structure and mechanical strength of mixed gel. • Immobilized water in network of SDF gel was easily detached under external force. • SDF filling into HBPP matrix enhanced 3D printing adaptability of individual gel. • 30% SDF level yielded best 3D print adaptability compared to other formulations. • Microstructure evolution mechanism of hydrogels during 3D printing was proposed. [ABSTRACT FROM AUTHOR]

The effect and mechanism of four common proteins (egg white powder (EWP), soy protein isolate (SPI), whey protein isolate (WPI) and wheat gluten (WG)) on the short-term retrogradation of wheat starch (WS) gels were investigated in terms of apparent characteristics, structural properties and crystallization (short-range orderliness and long-range orderliness). The recrystallization style of all gel samples were mainly B-type crystal. Compared to the control group, WS gels with EWP, SPI, and WG delayed formation and aggregation of the double helix structure. This delay was accompanied by a reduction in hydrogen bonding, short-range and long-range orderliness, thereby reducing the enthalpy of retrogradation. EWP and SPI reduced the increase rate of hardness during retrogradation. EWP also had the potential to alter the nucleation mode of recrystallization. Thus, EWP, SPI, and WG had the potential to inhibit the retrogradation of WS gels. Conversely, WPI could reduce the short-range orderliness during retrogradation, and WS gels with WPI exhibited higher hardness, long-range orderliness, and enthalpy of retrogradation during storage. [Display omitted] • Effects of four common proteins on wheat starch retrogradation were compared. • EWP, SPI and WG were effective in inhibiting the short-term retrogradation of WS gels. • Formation of hydrogen bonds, short-term and long-term orderliness were reduced by EWP, SPI and WG. • The changes in nanostructures of starch aggregation pattern were characterised. [ABSTRACT FROM AUTHOR]