Effects of acetylation and succinylation on the functional properties of the canola 12S globulin

Separation and purification of antioxidant peptides from purple speckled kidney bean by macroporous adsorption resin and analysis of amino acid composition

The protein hydrolysate of purple speckled kidney bean (PSKB) was used as the raw material in this study, and the antioxidant peptide of the PSKB protein hydrolysate was purified using macroporous resin. The XAD-7HP macroporous resin was selected as the best purification material, and the static adsorption-desorption of the purified PSKB antioxidant peptide was optimized. The optimum static adsorption and desorption conditions were as follows: the adsorption capacity reached 11.93 ± 0.11 mg/ml at pH 7 for 24 h, and the desorption capacity was 5.24 ± 0.04 mg/ml with 60% ethanol for 30 min. Under this condition, the amount of antioxidant peptide obtained by adsorption-desorption was the highest. The optimum process conditions were as follows: the appropriate flow rate was 1 ml/min, and the optimal injection volume was 40 ml. The adsorption amount at this time can reach 12.19 ± 0.15 mg/ml. The components with an elution time of 10-30 min were separated using the reversed-phase high-performance liquid chromatography (RP-HPLC) technique to obtain three main components, namely, RP₁, RP₂, and RP₃. The DPPH free radical scavenging ability reached 56.26 ± 0.56, 66.42 ± 0.56, and 78.57 ± 0.56%, respectively, which were 36.65, 46.34 ± 0.56, and 54.39 ± 0.56% higher than those before purification. The amino acid sequences of the three components were identified as Phe-Leu-Val-Asp-Arg-Ile, Phe-Leu-Val-Ala-Pro-Asp-Asp, and Lys-Asp-Arg-Val-Ile-Ser-Glu-Leu.

Pulse protein ingredient modification

Increasing population and depletion of resources have paved the way to find sustainable and nutritious alternative protein sources. Pulses have been identified as a nutritious and inexpensive alternative source of protein that can meet this market demand. Pulses can be converted into protein concentrates and isolates through dry and wet separation techniques. Wet extraction results in relatively pure protein isolates but less sustainable due to higher energy requirements and high waste generation. Dry separation focuses on ingredient functionality rather than molecular level purity. These extracted pulse protein ingredients can be incorporated into different food systems to increase the nutritional value and to achieve the desired functionality. But many plant-based alternative proteins including pulses, face several formulation challenges especially in nutritional, sensory, and functional aspects. Native pulse protein ingredients can contain antinutrients, beany flavor, and undesirable functionality. Modification by biological (enzymatic, fermentation), chemical (acylation, deamidation, glycosylation, phosphorylation), and physical (cold plasma, extrusion, heat, high pressure, ultrasound) methods or a combination of these can improve pulse protein ingredients at the macro and micro level for their desired use. These modification processes will thermodynamically change the structural and conformational characteristics of proteins and expect to improve the quality. © 2021 Society of Chemical Industry.

Partial Removal of Phenolics Coupled with Alkaline pH Shift Improves Canola Protein Interfacial Properties and Emulsion in In Vitro Digestibility

The effect of polyphenol removal (“dephenol”) combined with an alkaline pH shift treatment on the O/W interfacial and emulsifying properties of canola seed protein isolate (CPI) was investigated. Canola seed flour was subjected to solvent extraction to remove phenolic compounds, from which prepared CPI was exposed to a pH₁₂ shift to modify the protein structure. Dephenoled CPI had a light color when compared with an intense dark color for the control CPI. Up to 53% of phenolics were removed from the CPI after the extraction with 70% ethanol. Dephenoled CPI showed a partially unfolded structure and increased surface hydrophobicity and solubility. The particle size increased slightly, indicating that soluble protein aggregates formed after the phenol removal. The pH₁₂ shift induced further unfolding and decreased protein particle size. Dephenoled CPI had a reduced β subunit content but an enrichment of disulfide-linked oligopeptides. Dephenol improved the interfacial rheology and emulsifying properties of CPI. Although phenol removal did not promote peptic digestion and lipolysis, it facilitated tryptic disruption of the emulsion particles due to enhanced proteolysis. In summary, dephenol accentuated the effect of the pH shift to improve the overall emulsifying properties of CPI and emulsion in in vitro digestion.

Stability and bioaccessibility of curcumin emulsions stabilized by casein hydrolysates after maleic anhydride acylation and pullulan glycation

The effects of maleic anhydride (MA) acylation and pullulan glycation on casein hydrolysates (CH) and the physicochemical stability of modified or unmodified CH-stabilized emulsions were explored. Compared with casein, the solubility of CH was improved, and CH₁ (hydrolysis degree 4%) exhibited the optimal emulsifying properties. After the acylation of MA, degrees of acylation (DA) increased with increasing addition of MA. Fourier-transform infrared spectroscopy revealed that a covalent bond was formed between MA and CH₁. The results of pullulan glycation indicated that the degree of glycation decreased with increasing DA. Acylation combined with glycation effectively reduced the surface hydrophobicity of CH. Results of analysis of physicochemical stability and gastrointestinal fate of curcumin in emulsions revealed that CH modified by MA acylation and pullulan glycation played a positive role in enhancing the stability and bioaccessibility of curcumin loaded in emulsions.

Rapeseed Protein Nanogels As Novel Pickering Stabilizers for Oil-in-Water Emulsions

Recently plant protein Pickering particles have received tremendous interests because of their environmentally friendly, biodegradable, and safe characteristics. However, developing plant protein particles as stabilizers of Pickering emulsion still face many challenges. In current study, a novel nanogel system produced from acylated rapeseed protein isolates (ARPI) was used to stabilize Pickering emulsions. Results showed that self-assembled nanogel after native RPI modified by acylation adjusted the three-phase contact angle of ARPI nanogels system to 86.7° closing to a neutral wettability. At constant oil phase fraction (0.3, v/v), increasing the ARPI nanogels concentrations produced smaller droplet sizes of Pickering emulsions, whereas all freshly prepared Pickering emulsions were stable except 0.1% (w/v) ARPI nanogel-stabilized Pickering emulsion occurred with creaming. The rise of the oil phase fraction showed little influences on the droplets size and visual appearances of Pickering emulsions at a fixed ARPI nanogels concentration (0.75%, w/v). Moreover, the prepared ARPI nanogels stabilized Pickering emulsions were stable against aggregations of droplets at a range of pH conditions ranging from 5.5 to 8.5 and salt concentration as high as 0.2 M. Additionally, the ARPI nanogels concentration above 0.5% favored the formation of Pickering emulsion with long-term storage stability (up to 30 days) against creaming. Microscopic images evidenced that ARPI nanogels could absorb and anchor at the droplets surface forming an interfacial layer. Above findings may deliver a potential strategy for fabricating stable Pickering emulsion based on plant protein particles and are of important significance for the utilization of rapeseed protein in the food industry.

Fabrication of Stable and Self-Assembling Rapeseed Protein Nanogel for Hydrophobic Curcumin Delivery

Food-dervied biopolymer nanogels have recently received considerable attention as favorable carrier systems for nutraceuticals and drugs. In the present study, new biocompatible and self-assembled acylated rapeseed protein isolate (ARPI)-based nanogels were fabricated for potential hydrophobic drug delivery by chemical acylation and heat-induced protein denaturation. The effects of the ARPI concentration, pH, heat temperature, and heat time on the physiochemical properties of self-assembled ARPI nanogels were investigated. The optimized ARPI nanogels were characterized by a hydrodiameter of 170 nm in size, spherical morphology, and light core-dark shell structure. In comparison to native rapeseed protein isolates and ARPI without the heat treatment, ARPI nanogels as a result of dual acylation and heat processes exhibited significantly altered spatial secondary and tertiary structures, increased surface hydrophobicity, and decreased free sulfhydryl contents of the protein. Such properties endow amphilic ARPI with the self-aggregating ability, resulting in the hydrophobic core with formations of covalent disulfide bonds and the hydrophilic shell with succinyl moieties exposed to the water side. Such a cross-linked structure allowed for ARPI nanogels to be resistant against a broad array of pH and ionic strength as well as lyophilization and dilution. ARPI nanogels demonstrated 95% encapsulation efficiency of hydrophobic compound curcumin and significantly increased its anticancer activity against multiple cancer cell lines.

Spray-Dried Succinylated Soy Protein Microparticles for Oral Ibuprofen Delivery

The potential value of succinylated soy protein (SPS) as a wall material for the encapsulation of ibuprofen (IBU), a model hydrophobic drug, by spray-drying was investigated. A succinylation rate of 93% was obtained for soy protein isolate, with a molar ratio of 1/1.5 (NH₂/succinic anhydride). The solubility profile at 37°C showed that this chemical modification decreased the solubility of the protein below its isoelectric point, whereas solubility increased in alkaline conditions. Various SPS/IBU ratios (90/10, 80/20, and 60/40) were studied and compared with the same ratio of soy protein isolate (SPI/IBU). High encapsulation efficiency was achieved (91-95%). Microparticles were spherical and between 4 and 8 μm in diameter. The spray-drying of protein/IBU solutions appeared to be beneficial, as it resulted in an amorphous solid dispersion of IBU within the microparticles, coupled with an increase in the thermal stability of IBU. In vitro release was evaluated in acidic (pH 1.2 in the presence of pepsin) and neutral (pH 6.8) conditions similar to those in the gastrointestinal (GI) tract. IBU was released significantly more slowly at pH 1.2, for both proteins. However, this slowing was particularly marked for SPS, for which rapid (within 2 h) and complete release was observed at pH 6.8. These results validate the hypothesis that SPS is suitable for use as a coating material for hydrophobic active pharmaceutical ingredients (APIs) due to its pH sensitivity, which should delay IBU release in the gastrointestinal tract.

Effects of acylation and glycation treatments on physicochemical and gelation properties of rapeseed protein isolate

The aim of this study was to improve the gelation property of rapeseed protein isolates (RPI) by means of acylation and glycation. The results showed that acylation and glycation within RPI occurred at Lys, and Lys, Met, Ile, Leu and Pro, respectively. Acylation and glycation both increased the surface hydrophobicity (So) and molecular weight of RPI, and decreased the free sulfhydryl (SH) content of RPI, while acylation resulted in a lower change of So and SH. The conformational structure of modified RPIs was changed, and acylated RPI (acylation degree, 38 ± 0.2%) possessed the highest ordered structure content among the modified RPIs. The thermal stability of the protein was improved after either acylation or glycation treatments. Furthermore, native RPI with moderate modification (low degree of acylation, 38 ± 0.2%) showed an overall improvement in the gelation and gel properties as evidenced by the reduced least gelation concentration and surface roughness, increased water-holding capacity, and better textural properties.

Soy Protein Microparticles for Enhanced Oral Ibuprofen Delivery: Preparation, Characterization, and In Vitro Release Evaluation

The objective of this work was to evaluate soy protein isolate (SPI) and acylated soy protein (SPA) as spray-drying encapsulation carriers for oral pharmaceutical applications. SPI acylation was performed by the Schotten-Baumann reaction. SPA, with an acylation rate of 41%, displayed a decrease in solubility in acidic conditions, whereas its solubility was unaffected by basic conditions. The drug encapsulation capacities of both SPI and SPA were tested with ibuprofen (IBU) as a model poorly soluble drug. IBU-SPI and IBU-SPA particles were obtained by spray-drying under eco-friendly conditions. Yields of 70 to 87% and microencapsulation efficiencies exceeding 80% were attained for an IBU content of 20 to 40% w/w, confirming the excellent microencapsulation properties of SPI and the suitability of the chemical modification. The in vitro release kinetics of IBU were studied in simulated gastrointestinal conditions (pH 1.2 and pH 6.8, 37°C). pH-sensitive release patterns were observed, with an optimized low rate of release in simulated gastric fluid for SPA formulations, and a rapid and complete release in simulated intestinal fluid for both formulations, due to the optimal pattern of pH-dependent solubility for SPA and the molecular dispersion of IBU in soy protein. These results demonstrate that SPI and SPA are relevant for the development of pH-sensitive drug delivery systems for the oral route.

A pursuit of the functional nutritional and bioactive properties of canola proteins and peptides

This review focuses on updated information about canola proteins and peptides, their functional, nutritional, and bioactive properties, safety aspects, and potential application in foods. Attention is paid to gelation, emulsion, thermal, and water holding capacities of crude and pure proteins and peptides isolated from canola meal. Various factors affecting these properties are discussed. This paper provides an overview of use of canola meal as a protein source in animal diets and their digestibility in vivo. Their effects on a range of health outcomes including ACE inhibition, hypocholesterolemic effects, cancer prevention, anti-viral and anti-diabetic properties are reviewed on the basis of the available in vitro and in vivo animal and human data. The review also focuses on the safety aspects and selected food applications of canola proteins and peptides.

Functionality of succinylated Brazil nut (Bertholletia excelsa HBK) kernel globulin

One of the possible ways to improve the utilisation of defatted Brazil nut kernel flour, a by-product of oil extraction industries, is to improve its functional properties by chemical modification as it possesses very modest functional characteristics. Succinylated Brazil nut kernel globulin at 55.8%, 62.4% and 72.0% level showed a positive effect on functionality. The solubility of acylated globulin was improved above pH 4.0 but was reduced in the pH range of 3.0-4.0. Water absorption (1.96-4.00, 4.12, and 4.21 ml/g protein), oil absorption capacity (1.44-2.72, 2.80 and 2.94 ml/g protein) and apparent viscosity of the succinylated globulin increased with increase in the level of succinylation. The extent of modification also influenced emulsifying capacity, which showed a decrease at pH 3.0, but was increased at pH 5.0,7.0 and 9.0. Highest emulsion activity (approximately 63.0%) was observed at pH 3.0, followed by pH 9.0 and pH 7.0 and, least (about 11.8%) at pH 5.0. Emulsion stability also followed similar behaviour as that of emulsion activity. The improved functional properties of succinylated Brazil nut kernel globulin could be explored in a variety of food formulations such as high protein drinks, soups, bakery and meat products as well as in salad dressings and mayonnaise as an emulsifier.