Stability and digestibility of encapsulated lycopene in different emulsion systems stabilized by acid-modified soybean lipophilic protein.

BACKGROUND: Owing to the harsh acidic environment of the stomach, acid-resistant emulsion products have wide-ranging applications in the food industry. Herein, natural soybean lipophilic protein (LP) was used to establish coarse emulsions, nanoemulsions, emulsion gels, and high internal phase Pickering emulsions (HIPPE) under acidic conditions. Furthermore, the carrying characteristics of the acid-resistant emulsion system with lycopene were explored. RESULTS: Comparisons of particle sizes, potentials, microstructures, and rheology of the four carrier systems revealed that HIPPE has a single particle-size distribution, the largest zeta potential, and an elastic gel-like network structure. Comparison of encapsulation rates indicated that HIPPE had the best effect on encapsulating lycopene, reaching approximately 90%. The pH stability, storage stability, and simulated in vitro digestion experiments showed that the four emulsions that were stable under acidic conditions had good acid resistance. Among them, the acid-induced LP-stabilized HIPPE had the best storage stability and superior compatibility with the harsh acidic environment of the stomach, which not only achieved the purpose of delaying the release of lipids but also conferred better protection to lycopene in the gastric tract; moreover, it achieved the best bioavailability. CONCLUSION: LP-stabilized HIPPE has the best stability and can yield better absorption and utilization of lycopene by the body. The results of this study are helpful for the development of acid-resistant functional emulsion foods that are conducive to the absorption of lycopene. © 2022 Society of Chemical Industry.

Relationship between flexibility and interfacial functional properties of soy protein isolate: succinylation modification.

BACKGROUND: In this paper, the effects of different succinic anhydride (SA) additions on the flexibility of soy protein isolate (SPI) were investigated, and changes in protein conformation and interfacial functional properties were measured. The structure-effect relationship between conformation, flexibility, and interfacial functional properties was established. RESULTS: SPI was bound to SA through disulfide bonds, and the zeta potential was reduced. The ß-sheet content decreased, the disordered structure increased, and there were changes in tertiary structure and microstructure. The surface hydrophobicity, disulfide bond content, and solution turbidity were reduced to 5063, 1.0967 µmol g-1 , and 0.0036 µmol g-1 respectively. The best flexibility of SPI (0.3977) and interfacial functional properties were obtained when the mass ratio of SA/SPI was 15%. Correlation analysis showed a highly significant positive correlation (P < 0.01) between flexibility and emulsification and foaming properties, with correlation coefficients of 0.960 and 0.942 for flexibility with emulsifying activity and emulsion stability respectively, and 0.972 and 0.929 for flexibility with foaming capacity and foaming stability respectively. CONCLUSION: The results suggest that succinylation-induced conformational changes of SPI improved its interfacial functional properties by changing its flexibility. These results provide theoretical guidelines for the development and application of highly emulsifiable and stable soy protein products utilizing succinylation. © 2022 Society of Chemical Industry.

NaCl induces flocculation and lipid oxidation of soybean oil body emulsions recovered by neutral aqueous extraction.

BACKGROUND: Soybean oil bodies (SOB) are naturally pre-emulsified lipid droplets recovered directly from soybean seeds. Almost all food emulsions contain salts. However, it was not clear how the incorporation of salts affected the physicochemical stability of SOB. RESULTS: This study investigated the effect of NaCl (0-1.2%) on the physical and oxidative stability of SOB emulsions under neutral (pH 7) and acidic (pH 3) conditions. In the presence of NaCl, the SOB emulsion (pH 7) showed strong flocculation during storage due to electrostatic screening. The NaCl-induced flocculation of SOB was attenuated at pH 3, which may be due to the difference in conformation or interaction of the protein interfaces covering SOB at different pH values. The increase in ionic strength or acid conditioning treatment resulted in a remarkable increase in the stability of SOB emulsions against coalescence. The confocal laser scanning microscopy images also confirmed the NaCl-induced changes in the flocculation/coalescence properties of SOB. The oxidative behavior tests indicated that SOB emulsions containing NaCl were more susceptible to lipid oxidation but protein oxidation was inhibited due to electrostatic screening, which reduced pro-oxidant accessibility of unadsorbed proteins in the emulsion. This oxidative behavior was attenuated at pH 3. CONCLUSION: The incorporation of NaCl significantly reduced the physical and oxidative stability of the SOB emulsion, and acidic pH mitigated NaCl-induced flocculation and lipid oxidation of SOB. © 2021 Society of Chemical Industry.

Oil-in-water Pickering emulsion stabilization with oppositely charged polysaccharide particles: chitin nanocrystals/fucoidan complexes.

BACKGROUND: Chitin nanocrystals (ChN) are insoluble particles that can be used as stabilizers for Pickering emulsions. Their unique cationic properties and antibacterial activity have generated considerable interest among researchers. However, ChN have remained largely underexplored. Furthermore, the droplets of the emulsions stabilized by ChN are as large as 10-100 µm, and their physical stability requires further improvement. Some studies have shown that the spontaneous reaction of oppositely charged particles can effectively stabilize the emulsions. Positively charged ChN and negatively charged fucoidan (F) were therefore compounded to stabilize Pickering emulsions, and the stability of these emulsions was analyzed qualitatively. RESULTS: The results showed that the composite particles comprising two polysaccharides in a mass ratio of 1:1 and at a pH of 2 (ChN1 -F1 -pH 2) possessed the lowest sulfate content (20.1%) and almost zero potential (-3 mV), indicating a high degree of neutralization of the positively charged amino group in ChN and the negatively charged sulfate group in F. Meanwhile, ChN1 -F1 -pH 2 displayed a dense network structure that improved the dispersibility and wettability (contact angle = 9.3°). Fourier transform infrared spectroscopy results confirmed that ChN and F were effectively combined through electrostatic interaction or neutralization to produce a polyelectrolyte complex. Furthermore, the particle size of the Pickering emulsion stabilized by ChN-F was significantly reduced, and the maximum size did not exceed 10 µm; the physical and storage stability also improved. The ChN1 -F1 -pH 2 emulsion presented excellent storage stability; in particular, the emulsions stabilized by ChN1 -F1 -pH 5 and ChN1 -F1 -pH 6 exhibited excellent flocculation stabilities. CONCLUSION: The size of the emulsion droplets stabilized by the oppositely charged polysaccharide particles (ChN-F complexes) reduced significantly. Furthermore, by changing the mass ratio and pH, the microstructure and binding degree of the complexes can be adjusted, thereby promoting their adsorption on the oil-water interface and improving the stability of the Pickering emulsion. © 2020 Society of Chemical Industry.

Soy/whey protein isolates: interfacial properties and effects on the stability of oil-in-water emulsions.

BACKGROUND: The adsorption of proteins at oil/water interfaces can reduce interfacial tension and increase emulsion stability. However, emulsions stabilized by soy protein isolate (SPI) are not sufficiently stable. Using SPI as a control, a theoretical basis for the adsorption behavior of mixed SPI and whey protein isolate (WPI) at the oil/water interface was established and the effects of the protein ratio and content on the emulsion stability were studied. RESULTS: Compared to SPI solution, SPI-WPI mixed solutions were found to reduce the size distribution of emulsion droplets and significantly improve the emulsion stability. Among the studied protein contents and ratios, the protein content of 0.2 g kg-1 and SPI/WPI mass ratio of 1:9 offered the lowest creaming stability index (15%), the smallest droplet size (278 nm), and the largest absolute value ζ-potential (35 mV), i.e. the emulsion stability was excellent. The largest dilatational modulus (10.08 mN m-1 ), dilatational elasticity (10.01 mN m-1 ), and dilatational viscosity (1.18 mN m-1 ), were observed with a protein content of 0.15 g kg-1 (SPI/WPI ratio of 1:9), along with a high interfacial protein adsorption capacity (47.33%). SPI-WPI complexes form a thick adsorption layer around oil droplets, resulting in an increase of the expansion modulus of the interfacial layer. CONCLUSION: SPI-WPI complexes can form a thick adsorption layer around oil droplets, resulting in increased expansion modulus of the interfacial layer, which improves emulsion stability. © 2020 Society of Chemical Industry.

Lipase catalysis of α-linolenic acid-rich medium- and long-chain triacylglycerols from perilla oil and medium-chain triacylglycerols with reduced by-products.

BACKGROUND: Medium- and long- chain triacylglycerols (MLCTs) are functional structural lipids that can provide the human body with essential fatty acids and a faster energy supply. This study aimed to prepare MLCTs rich in α-linolenic by enzymatic interesterification of perilla oil and medium-chain triacylglycerols (MCTs), catalyzed by Lipozyme RM IM, Lipozyme TL IM, Lipozyme 435, and Novozyme 435 respectively. RESULTS: The effects of lipase loading, concentration of MCTs, reaction temperature, and reaction time on the yield of MLCTs were investigated. It was found that the reaction achieved more than a 70% yield of MLCTs in triacylglycerols under the conditions of 400 g kg-1 MCTs and 60 g kg-1 lipase loading after equilibrium. A novel two-stage deodorization was also applied to purify the interesterification products. The triacylglycerols reach over 97% purity in the products with significant removal (P < 0.05) of the free fatty acids, and the trans fatty acids were strictly controlled at below 1%. There was more than 40% α-linolenic in the purified products, with long-chain fatty acids mostly occupying the desired sn-2 position in acylglycerols, which are more active in hydrolysis. CONCLUSION: A series of novel α-linolenic acid-rich medium- and long-chain triacylglycerols was prepared. Under appropriate reaction conditions, the yield of MLCTs in triacylglycerols was above 70%. A novel two-stage deodorization can be used to promote the elimination of free fatty acids and limit the generation of trans fatty acids. © 2020 Society of Chemical Industry.

Effect of pH on physicochemical properties of oil bodies from different oil crops.

The objective of this study was to determine the effects of pH on the physicochemical properties of soybean oil bodies (SBOBs), peanut oil bodies (PNOBs) and sunflower oil bodies (SFOBs). The mean particle diameter[4,3] (D[4,3]) of oil bodies (OBs) changed to a stationary trend with increased pH. The surface hydrophobicity (H0) of SBOBs, PNOBs and SFOBs significantly decreased with increasing pH 2-12. The emulsifying activity index of SBOBs, PNOBs and SFOBs decreased with increased pH from 2 to 10. The viscosity modulus (G″) value of SBOBs at pH 4 was significantly higher than at pH 7 and pH 9. The initial elastic modulus (G') and G″ values of PNOBs at pH 9 were significantly higher than at pH 4 and pH 7. The G″ values of SFOBs at pH 4 and pH 9 were significantly lower than at pH 7. The steroleosin protein bands of SBOBs significantly decreased at pH 12. The protein bands of PNOBs were reduced at pH 2-4 and pH 10-12, and protein bands decreased most obviously at pH 2. The enthalpy of denaturation (ΔH) values of the oil body (OB) protein at pH 9 were significantly higher than at pH 4 and pH 7. The results showed that the ζ-potential, D[4,3], emulsifying property and H0 of SBOBs, PNOBs and SFOBs were similar to the change of pH value. The three types of OBs have better stability away from the isoelectric point.

Preparation of the Pt/CNTs Catalyst and Its Application to the Fabrication of Hydrogenated Soybean Oil Containing a Low Content of Trans Fatty Acids Using the Solid Polymer Electrolyte Reactor.

Pt/CNTs were synthesized with an ethylene glycol reduction method, and the effects of carboxyl functionalization, ultrasonic power and the concentration of chloroplatinic acid on the catalytic activity of Pt/CNTs were investigated. The optimal performance of the Pt/CNTs catalyst was obtained when the ultrasonic power was 300 W and the concentration of chloroplatinic acid was 40 mg/mL. The durability and stability of the Pt/CNTs catalyst were considerably better compared to Pt/C, as shown by cyclic voltammetry measurement results. The trans fatty acids content of the obtained hydrogenated soybean oil (IV: 108.4 gl2/100 g oil) using Pt/CNTs as the cathode catalyst in a solid polymer electrolyte reactor was only 1.49%. The IV of hydrogenated soybean oil obtained using CNTs as carrier with Pt loading 0.1 mg/cm2 (IV: 108.4 gl2/100 g oil) was lower than carbon with a Pt loading of 0.8 mg/cm2 (IV: 109.9 gl2/100 g oil). Thus, to achive the same IV, the usage of Pt was much less when carbon nanotubes were selected as catalyst carrier compared to traditional carbon carrier. The changes of fatty acid components and the hydrogenated selectivity of octadecenoic acid were also discussed.

Identification of an ACE-Inhibitory Peptide from Walnut Protein and Its Evaluation of the Inhibitory Mechanism.

In the present study, a novel angiotensin I-converting enzyme inhibitory (ACE inhibitory) peptide, EPNGLLLPQY, derived from walnut seed storage protein, fragment residues 80-89, was identified by ultra-high performance liquid chromatography electrospray ionization quadrupole time of flight mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) from walnut protein hydrolysate. The IC50 value of the peptide was 233.178 µM, which was determined by the high performance liquid chromatography method by measuring the amount of hippuric acid (HA) generated from the ACE decomposition substrate (hippuryl-l-histidyl-l-leucine (HHL) to assess the ACE activity. Enzyme inhibitory kinetics of the peptide against ACE were also conducted, by which the inhibitory mechanism of ACE-inhibitory peptide was confirmed. Moreover, molecular docking was simulated by Discovery Studio 2017 R2 software to provide the potential mechanisms underlying the ACE-inhibitory activity of EPNGLLLPQY.

Effects of ultrasound treatment on physico-chemical, functional properties and antioxidant activity of whey protein isolate in the presence of calcium lactate.

BACKGROUND: The aim of this study was to investigate the effects of ultrasound applied at various powers (0, 200, 400, 600 or 800 W) and for different times (20 or 40 min) on the physico-chemical, functional properties and antioxidant activities of whey protein isolate (WPI) dispersions in the presence of 1.20 mmol L-1 calcium lactate. RESULTS: Surface hydrophobicity and free sulfhydryl group of the WPI dispersions containing 1.2 mmol L-1 calcium lactate were significantly enhanced after sonication. Furthermore, particle size of WPI dispersions containing 1.20 mmol L-1 calcium lactate was minimised after sonication. Scanning electron microscopy of sonicated WPI suspensions containing 1.20 mmol L-1 calcium lactate showed that WPI microstructure had significantly changed. After WPI dispersions were treated by sonication assisted with calcium lactate, its gel strength enhanced and solubility decreased. Gel strength of sonicated WPI dispersions (600 W, 40 min) was the maximum among all the WPI treatments. Emulsification activity of sonicated WPI dispersions reduced while its emulsion stability increased. The DPPH radical scavenging activity and ferrous reducing power of sonicated WPI dispersions mostly increased. CONCLUSION: Ultrasound treatments induced structural changes in WPI molecules, leading to different microstructure and improved gel strength of WPI in the presence of calcium lactate. © 2017 Society of Chemical Industry.

Effect of ultrasound treatment on the wet heating Maillard reaction between mung bean [Vigna radiate (L.)] protein isolates and glucose and on structural and physico-chemical properties of conjugates.

BACKGROUND: The objective of this study was to determine the effect of ultrasound treatment on the wet heating Maillard reaction between mung bean protein isolates (MBPIs) and glucose, and on structural and physico-chemical properties of the conjugates. RESULTS: The degree of glycosylation of MBPI-glucose conjugates treated by ultrasound treatment and wet heating (MBPI-GUH) was higher than that of MBPI-glucose conjugates only treated by wet heating (MBPI-GH). Solubility, emulsification activity, emulsification stability and surface hydrophobicity of MBPI-GUH were higher than that of MBPI-GH. Grafted MBPIs had a lower content of α-helix and unordered coil, but a higher content of ß-sheet and ß-turn structure than MBPIs. No significant structural changes were observed in ß-turn and random coil structure of MBPI-GUH, while α-helix content increased with ultrasonic time, and decreased at 300 W ultrasonic power with the increase of ß-sheet. MBPI-GUH had a less compact tertiary structure compared to MBPI-GH and MBPI. Grafting MBPIs with glucose formed conjugates of higher molecular weight, while no significant changes were observed in electrophoresis profiles of MBPI-GUH. CONCLUSION: Ultrasound-assisted wet heating Maillard reaction between MBPIs and glucose could be a promising way to improve functional properties of MBPIs.

Raman Spectroscopy Study Structural Changes in Black Bean Protein Isolate upon Ultrasonic-Treatment.

This article focused on the assessment of the potential of Raman spectroscopy for the determination of structural changes in black-bean protein isolate (BBPI) dispersions with low-frequency (20 kHz) ultrasonication applied at various powers (150, 300 or 450 W) and for different durations (12 or 24 min). It also reported on differential scanning calorimetry analyses. A decrease in TD at low- and medium-power ultrasonication confirmed these ultrasonication treatment disrupted internal hydrophobic interactions of protein molecules and broke up unstable aggregates to smaller soluble protein aggregates, while an increase in TD at high-power was attributed to repolymerization of aggregates. Raman spectroscopy analysis revealed a decrease in the α-helix proportion and an increase in ß-sheets after ultrasonic treatment except Sample E (300 W, 24 min). Transformation of aggregation results in a reconstruction in secondary structure of BBPI, especially in ß-sheet structure. Ultrasonic-treatment induced a decrease in the normalized intensity of the Raman band near 760 cm-1 which indicated that Tryptophan residues tended to expose and also indicated protein partially unfolding. No significant difference was found in Tyr doublet ratios between unheated and ultrasound-treated BBPI indicated that ultrasound did not change the microenvironment around tyrosyl residues. While the intensity of 1 450 cm-1 band increased with increasing ultrasonic intensity and treatment time, and then decreased with further increase in power and treatment time. In general, the formation of aggregation transferred g-g-t conformation to t-g-t conformation. Though some mechanism of aggregation-repolymerization of BBPI remains to be clearly defined, Raman spectroscopy provide a feasible tool to study the structural changes of BBPI prepared under different ultrasonic conditions, give a new perspective to elucidation of protein structure.

Lipase-catalyzed transesterification of soybean oil and phytosterol in supercritical CO2.

The transesterification of phytosterol and soybean oil was performed using Novozym 435 in supercritical carbon dioxide (SC-CO2). The transesterification reaction was conducted in soybean oil containing 5-25% phytosterol at 55-95 °C and free-water solvent. The effects of temperature, reaction time, phytosterol concentration, lipase dosage and reaction pressure on the conversion rate of transesterification were investigated. The optimal reaction conditions were the reaction temperature (85 °C), reaction time (1 h), phytosterol concentration (5%), reaction pressure (8 Mpa) and lipase dosage (1%). The highest conversion rate of 92% could be achieved under the optimum conditions. Compared with the method of lipase-catalyzed transesterification of phytosterol and soybean oil at normal pressure, the transesterification in SC-CO2 reduced significantly the reaction temperature and reaction time.

Effect of extruding full-fat soy flakes on trans fat content.

To evaluate the effects of extrusion process on the trans fatty acids (TFAs) formation in soybean crude oils, three different extrusion parameters, namely, extrusion temperature (80-160 °C), feed moisture (10-26%), and screw speed (100-500 rpm), were carried out. It was found that only five different types of TFAs were detected out using gas chromatography-mass spectrometry. Before the extrusion started, the initial amount of total TFAs was 3.04 g/100 g. However, after extruding under every level of any variable, the total amounts of TFAs were significantly higher than those in the control sample (P < 0.05). For example, taking the effect of extrusion temperature into account, we can find that the highest amount of total of trans fatty acid (TTFA) was 1.62 times the amount of that in the control sample, whereas the lowest amount of TTFA was 1.54 times the amount of that in the control sample. Importantly, it was observed that the amounts of every type of trans fatty acid were not continuously increasing with the increase of the level of any extrusion variable. This phenomenon demonstrated that the formation and diversification were intricate during extruding process and need to be further studied.

[Characteristic wavelength variable optimization of near-infrared spectroscopy based on Kalman filtering].

Combining classical Kalman filter with NIR analysis technology, a new method of characteristic wavelength variable selection, namely Kalman filtering method, is presented. The principle of Kalman filter for selecting optimal wavelength variable was analyzed. The wavelength selection algorithm was designed and applied to NIR detection of soybean oil acid value. First, the PLS (partial leastsquares) models were established by using different absorption bands of oil. The 4 472-5 000 cm(-1) characteristic band of oil acid value, including 132 wavelengths, was selected preliminarily. Then the Kalman filter was used to select characteristic wavelengths further. The PLS calibration model was established using selected 22 characteristic wavelength variables, the determination coefficient R2 of prediction set and RMSEP (root mean squared error of prediction) are 0.970 8 and 0.125 4 respectively, equivalent to that of 132 wavelengths, however, the number of wavelength variables was reduced to 16.67%. This algorithm is deterministic iteration, without complex parameters setting and randomicity of variable selection, and its physical significance was well defined. The modeling using a few selected characteristic wavelength variables which affected modeling effect heavily, instead of total spectrum, can make the complexity of model decreased, meanwhile the robustness of model improved. The research offered important reference for developing special oil near infrared spectroscopy analysis instruments on next step.

High-Moisture Extrusion of Plant Proteins: Fundamentals of Texturization and Applications.

The growing demand for sustainable and healthy food alternatives has led to a significant increase in interest in plant-based protein products. Among the various techniques used in creating meat analogs, high-moisture extrusion (HME) stands out as a promising technology for developing plant-based protein products that possess desirable texture and mouthfeel. During the extrusion process, plant proteins undergo a state transition, causing their rheological properties to change, thereby influencing the quality of the final extrudates. This review aims to delve into the fundamental aspects of texturizing plant proteins using HME, with a specific focus on the rheological behavior exhibited by these proteins throughout the process. Additionally, the review explores the future of HME from the perspective of novel raw materials and technologies. In summary, the objective of this review is to provide a comprehensive understanding of the potential of HME technology in the development of sustainable and nutritious plant-based protein products.

Sacrificial hydrogen bonds enhance the performance of covalently crosslinked composite films derived from soy protein isolate and dialdehyde starch.

Soy protein films have the advantage of being eco-friendly and renewable, but their practical applications are hindered by the mechanical properties. The exceptional tensile strength and fracture toughness of natural silk stem from sacrificial hydrogen bonds it contains that effectively dissipates energy. In this study, we draw inspiration from silk's structural principles to create biodegradable films based on soy protein isolate (SPI). Notably, composite films containing sodium lignosulfonate (LS) demonstrate exceptional strain at break (up to 153%) due to the augmentation of reversible hydrogen bonding, contrasted to films with the addition of solely dialdehyde starch (DAS). The enhancement of tensile strength is realized through a combination of Schiff base cross-linking and sacrificial hydrogen bonding. Furthermore, the incorporation of LS markedly improves the films' ultraviolet (UV) blocking capabilities and hydrophobicity. This innovative design strategy holds great promise for advancing the production of eco-friendly SPI-based films that combine strength and toughness.

Recovery of soy whey protein from soy whey wastewater at various cavitation jet pretreatment time and their structural and emulsifying properties.

Protein-polysaccharide composite is of great significance for the development of soluble protein recovery process. This study investigated the effects of cavitation jet (CJ) pretreatment at different time (0, 60, 120, 180, 240, 300 s) intervals on the recovery of soy whey protein (SWP) from soy whey wastewater using chitosan (CH). In addition, the structure and properties of the SWP/CH complexes were examined. The results showed that the recovery yield of SWP reached 84.44 % when the CJ pretreatment time was 180 s, and the EAI and ESI values of the SWP/CH complex increased from 32.39 m2/g and 21 min to 48.47 m2/g and 32 min, respectively. In the CJ pretreatment process, SWP promotes the recombination with chitosan through electrostatic interaction and hydrogen bond, while hydrophobic interaction is also involved. This study has guiding significance for CJ technology in the recovery and utilization of protein in industrial wastewater.

Analytical approaches for assessing protein structure in protein-rich food: A comprehensive review.

This review focuses on changes in nutrition and functional properties of protein-rich foods, primarily attributed to alterations in protein structures. We provide a comprehensive overview and comparison of commonly used laboratory methods for protein structure identification, aiming to offer readers a convenient understanding of these techniques. The review covers a range of detection technologies employed in food protein analysis and conducts an extensive comparison to identify the most suitable method for various proteins. While these techniques offer distinct advantages for protein structure determination, the inherent complexity of food matrices presents ongoing challenges. Further research is necessary to develop and enhance more robust detection methods to improve accuracy in protein conformation and structure analysis.