Emulsifying Activity Index Research Articles

Structural, emulsifying and curcumin-embedded properties of arachin nanoparticles induced by ultrasound and heat

Different types of arachin (one of the major globulins in peanut proteins) nanoparticles were prepared by ultrasound (US) and heat treatments, respectively. The results showed that short-term US treatment induced large nanoparticles (named US200 and US500, ∼267 nm) that maintained a compact globular structure; long-term US treatment induced small nanoparticles (named US500L, ∼197 nm) with a moderately unfolded structure; heat treatment induced medium-sized nanoparticles with an unfolded structure. The large nanoparticles had significantly lower surface hydrophobicity, β-sheet content, and λmax but higher enthalpy of denaturation (ΔH) than other nanoparticles. US500L and US500 exhibited the highest emulsifying activity and stability indices, respectively. As for curcumin-embedded properties, both US and heat treatments enhanced the curcumin encapsulation efficiency (from 88.53 to 94.08–97.88%) and load amount (from 1.77 to 1.88–1.96 μg/mg) of arachin. However, only curcumin in large nanoparticles was effectively protected from damage by heat and light. In simulated digestion tests, curcumin in US500L and heat-induced nanoparticles showed higher stability and bioavailability, which was mainly attributed to the slower digestion of these nanocomplexes. We have established a simple method for the preparation of arachin nanoparticles by US and the nanoparticles have potential applications in the food industry due to their favorable bifunctional properties.

Impact of the Pre-Dehydration and Drying Methods on the Mass Transfer and Quality Attributes of Yak Milk Casein.

Drying is an important preservation method of casein. Traditional natural draining and drying processes have low efficiency, long processing time, and poor product quality, which urgently need to be improved. This study investigated the effects of pre-dehydration intensities (30 N 30 min (PreD1) and 50 N 30 min (PreD2)) and drying methods (including pulsed vacuum drying (PVD), infrared drying (IRD), and hot air drying (HAD)) on the drying kinetics, drying modeling, and quality of yak milk casein. These findings reveal that PreD2 and PVD both had a positive impact on shortening the drying time. Compared to other combined treatments, PreD2-PVD had the shortest drying time of 6 h. The Midilli-Kucuk mathematical model effectively predicted the drying of casein. The yak milk casein powder treated with PreD2-PVD possessed a higher content of gross compositions, superior color, lower levels of fat oxidation and 5-hydroxymethylfurfural (5-HMF), and higher emulsifying activity index (EAI) and emulsion stability index (ESI) values. Overall, combining pre-dehydration with PVD proved effective in improving the drying rate and maintaining a good quality of yak milk casein, showing promising potential for industrial applications.

Soy protein isolate-catechin complexes conjugated by pre-heating treatment for enhancing emulsifying properties: Molecular structures and binding mechanisms

This study aimed to investigate the impact of different pre-heating temperatures (ranging from 40 °C to 80 °C) on the interactions between soy protein isolate (SPI) and catechin to effectively control catechin encapsulation efficiency and optimize the emulsifying properties of soy protein isolate. Results showed that optimal heat treatment at 70 °C improved catechin encapsulation efficiency up to 93.71 ± 0.14 %, along with the highest solubility, enhanced emulsification activity index and improved thermal stability of the protein. Multiple spectroscopic techniques revealed that increasing pretreatment temperature (from 40 °C to 70 °C) altered the secondary structures of SPI, resulting in a more stable unfolded structure for the composite system with a significant increase in α-helical structures and a decrease in random coil and β-sheet structures. Moreover, optimal heat treatment also leads to an augmentation of free sulfhydryl groups within complex as well as exposure of more internal chromophore amino acids on molecular surface. Size-exclusion high-performance liquid chromatography and SDS-PAGE analysis indicated that the band intensity of newly formed high-molecular-weight soluble macromolecules (>180 kDa) increased as the pre-heating temperature rose. Furthermore, fluorescence spectroscopy and molecular docking analysis suggest that hydrophobic and covalent interactions were involved in complex formation, which intensified with increasing temperature.

Combining different ionic polysaccharides and pH treatment improved functional properties of soybean protein amyloid fibrils through structural modifications

This paper reported the effects of different ionic polysaccharides (a cationic polysaccharide (chitosan, CTS), an anionic polysaccharide (high methoxyl pectin, HMP), and a neutral polysaccharide (dextran, DEX)) and pHs (2.0, 4.5, 7.0, and 9.0) on the structural and functional properties of soybean protein amyloid fibrils (SAF) under non-covalent interactions. The fluorescence spectroscopy, ζ-potential, surface hydrophobicity (H0), and turbidity analyses revealed that, at any pH, HMP had a greater effect on the structure of SAF than CTS or DEX. Electrostatic and hydrophobic interactions predominated between SAF and HMP. The addition of negatively charged HMP prevented the exposure of hydrophobic groups, the H0 and ζ-potential decreased. Moreover, compared to SAF, the rheological properties of SAF-HMP complexes were enhanced. In particular, at pH 2.0, HMP was crosslinked with SAF and changed the fibrils conformation, the foaming stability of SAF-HMP increased to 100%. Furthermore, at pHs 2.0 and 4.5, strong electrostatic repulsion occurred between CTS and SAF. Therefore, SAF-CTS exhibited the highest emulsifying activity index and emulsifying stability index, which are 58.21 m2/g and 41.76 min, respectively, followed by SAF-HMP. By contrast, DEX had the least influence on the fibrils. These results will give a hand for industrial production of soybean protein amyloid fibrils.

Utilization of peanut protein isolate amyloid-like fibers as stabilizers for high internal phase Pickering emulsions

This paper focuses on modifying peanut protein isolate (PPI) through fibrillation to enhance its emulsification properties and investigates the potential application of the fibers in stabilizing high internal phase Pickering emulsions (HIPPEs). Th T result indicates that the optimal conditions for peanut protein isolate amyloid-like fibers (PAFs) preparation are pH=2, 90 °C, and 20 h. Electrophoresis and Transmission electron microscope demonstrate that PPI undergoes peptide hydrolysis and self-assembly during the reaction process, leading to the formation of an elongated linear structure with a diameter approximately 14 nm. Furthermore, infrared spectroscopy, X-ray diffraction, and contact angle results further demonstrate an increase in β-sheet content, crystallinity, and surface hydrophilicity compared to PPI. Notably, the emulsification activity index (EAI) of PAFs (78.62 ± 1.68 m2/g) was found to be increased up to threefold compared to that of PPI (27.89 ± 1.98 m2/g). According to visual observation and microstructural analysis, the addition of 1% PAFs has been found to effectively stabilize HIPPEs (φdisp = 0.75) due to the presence of dense protective layers formed by PAFs. Additionally, the particle size results (D[3,2] = 17.02 ± 2.02 μm) also indicate that the oil droplets are tightly enveloped by the dense protective layers formed by PAFs. Moreover, rheological data indicates that HIPPEs stabilized using PAFs exhibit excellent solid-like viscoelastic behavior. Overall, these findings suggest that the utilization of PAFs has significant potential in enhancing the stability of HIPPEs.

Alcalase-hydrolyzed insoluble soybean meal hydrolysate aggregates: Structure, bioactivity, function properties, and influences on the stability of oil-in-water emulsions

We studied the influences of hydrolysis time on the structure, functional properties, and emulsion stability of insoluble soybean meal hydrolysate aggregates (ISMHAs). We assume that the ISMHAs produced by soybean meal can be used as emulsifiers to prepare stable emulsions. The molecular weights of these ISMHAs were below 53 kDa. After hydrolysis, a decrease in α-helices and an increase in random coils indicated that the soybean meal proteins were unfolding. Moreover, the fluorescence intensity, UV absorption, and surface hydrophobicity of ISMHAs increased. These results would contribute to their antioxidant activity and functional properties. Additionally, the 90-min ISMHA sample exhibited the highest ABTS+• scavenging activity (80.02 ± 4.55 %), foaming stability (52.92 ± 8.06 %), and emulsifying properties (emulsifying activity index of 97.09 m2/g; emulsifying stability index of 371.47 min). The 90-min ISMHA emulsion exhibited the smallest particle size and excellent storage stability. Soybean meal peptide by-product emulsifier has potential for sustainable application.

The effects of high‐intensity ultrasonic treatment on emulsification, rheological properties, and flow behavior of liquid egg yolk

AbstractHigh‐intensity ultrasonic (HIU) treatment has been used to improve and modify the functional properties of food. HIU potentially inactivates microorganisms in food and modifies the physicochemical properties via the cavitation effect. This study evaluated the combination of different HIU power intensities, temperatures, and times for their effects on diluted liquid egg yolks’ physicochemical properties and rheological and flow behavior. The results showed that Salmonella enteritidis and Escherichia coli in the diluted liquid egg yolks were significantly destroyed as HIU power was increased, and complete destroyed conditions were achieved at 210 W, 60°C for 6 or 9 min. Moreover, the emulsifying activity index of the diluted liquid egg yolks increased significantly at 45 and 60°C under the 75 W HIU treatment, whereas the maximum emulsifying stability index was obtained at 30°C, 210 W for 9 min. Yolk viscosity was positively correlated with HIU power intensity and temperature; the same trend was observed for flow behavior and shear stress. The fluid dynamics of the storage modulus (G′) for the 150 and 210 W HIU treatments increased significantly following the increase in temperature to 45 and 60°C, and G′ > loss modulus (G″). However, free hydrogen sulfide group content also increased significantly after the HIU treatment. Thus, this study revealed that the HIU treatment effectively destroyed the bacteria population in the diluted liquid egg yolk while maintaining or improving the emulsification properties. Moreover, the diluted liquid egg yolk flow parameters apply to egg yolk product manufacturing processes.

Development of Coconut Protein Concentrate-Xanthan Gum Conjugate by Wet-Dry Heating Method for Red Palm Oil Emulsification

Protein-polysaccharide conjugation is commonly achieved by wet and dry heating methods. Therefore, this study aimed to produce red palm oil (RPO) emulsifiers by conjugating coconut protein concentrate (CPC) and xanthan gum (XG) through a combination of wet and dry heating method using a cabinet dryer. Several factors, including reaction time (3, 4, 5, 6, and 7 hours), pH (3, 5, 7, 9, and 11), and protein-polysaccharide ratio (1:3, 1:2, 1:1, 2:1, and 3:1) were evaluated for their effect on the Emulsion Activity Index (EAI) and Emulsion Stability Index (ESI). The ability of the obtaining conjugate to emulsify RPO was evaluated, and the results showed that CPC contained 67.40% protein. Reaction time, pH, and protein-XG ratio had a significant effect on EAI and ESI. Meanwhile, optimal conditions for the formation of the CPC-XG conjugate, based on EAI and ESI, were a reaction time of 5 hours, pH 9, and protein-polysaccharide ratio of 2:1. Fourier Transform Infrared (FTIR) analysis showed that the CPC-XG conjugate had a change in absorption at a wavelength number of around 1640 cm -1 , indicating the presence of a Maillard reaction product. Furthermore, the CPC-XG conjugate used in RPO emulsion has a characteristic EAI value of 23.74 m 2 /g, ESI of 271.32 minutes, a droplet size of 790 nm, and a zeta potential of -36.9 mV. These results suggest that the CPC-XG conjugate produced by the wet-dry heating method has the potential for producing stable RPO emulsions.

Co-delivery mechanism of curcumin/catechin complex by modified soy protein isolate: Emphasizing structure, functionality, and intermolecular interaction

Modifying proteins to enhance their affinity for polyphenols is essential for developing a practical and efficient delivery system that promotes the synergistic effects of bioactive substances. The study investigated the nanoparticle complexation in both pure soy protein isolate (SPI) or SPI modified by ultrasonic combined heat treatment (UHSPI) with varying concentrations of curcumin/catechin (CU/CA) complex, and its effects on the functionality, structure and conformational changes of protein-polyphenol nanocomplexes. Additionally, the intermolecular interaction and co-delivery mechanisms of nanocomplexes were analyzed. Results showed that the physical modification process (28/40 kHz, 90 °C, 15 min) and a rational concentration of CU/CA (0.6 mg/mL) improve the encapsulation efficiency of polyphenols by SPI (up to 77% for curcumin, and 93% for catechin), resulting in a higher DPPH and ABTS scavenging capacity, along with the highest emulsification activity index, as well as enhanced storage stability and thermal stability. The interaction between UHSPI and CU/CA disrupted the protein's secondary structure and exposed more hydrophobic residues to a hydrophilic environment, and exhibited stronger fluorescence quenching. Molecular docking analysis revealed that protein-polyphenol interactions primarily relied on hydrogen bonds and hydrophobic interactions, and 11S subunits exhibited higher affinity with CU/CA. FTIR, fluorescence spectra, and XRD further confirmed the enhanced interaction ability between UHSPI and CU/CA, resulting in the formation of a more stable nanocomplex. Overall, the modified SPI effectively facilitates the co-delivery of an appropriate concentration of curcumin/catechin complex.

Effect of Steam Flash Explosion on Physicochemical and Emulsifying Properties of High-Temperature Rice Bran Meal Protein

High-temperature rice bran meal (HTRBM) is a valuable plant protein resource derived from heat-stabilized rice bran after oil extraction. Steam flash explosion (SFE) is a promising method for protein modification and has been shown to be effective in improving the properties of a variety of proteins. However, the effects of SFE on the Maillard reaction and emulsification of HTRBM remain poorly understood. This research evaluated how different SFE conditions affect the browning degree, physicochemical properties, solubility, emulsifying properties, thermal stability, zeta potential, and particle size of rice bran protein. Samples were labeled as follows: Sample 0 (SFE-untreated HTRBM), Sample 1 (0.8 MPa/140 s), Sample 2 (0.8 MPa/180 s), Sample 3 (1.25 MPa/90 s), Sample 4 (1.25 MPa/180 s), Sample 5 (1.7 MPa/90 s), and Sample 6 (1.7 MPa/180 s). Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, differential scanning calorimetry (DSC), and other methods were employed to measure the aforementioned properties. The results revealed a substantial elevation in the browning degree of rice bran protein after SFE treatment, with A294 increasing by 82.3% and A420 increasing by 46.3% in Sample 4. The solubility and emulsifying properties exhibited notable enhancements, with an increase of 122.48% in solubility (Sample 5), and 26.51% and 26.58% increment in emulsifying activity index (EAI) and emulsifying stability index (ESI), respectively (Sample 3). FTIR and fluorescence spectra revealed the introduction of sugar groups into rice bran protein molecules, resulting in the Maillard reaction. The observed reduction in particle size and rise in zeta potential of rice bran protein emulsions, along with the reduction in denaturation temperature after SFE treatments, further confirmed the significant enhancements in physicochemical and emulsifying properties of HTRBM, thereby enhancing the utilization value of rice bran protein. This study provides a theoretical basis for the development and utilization of HTRBM and its protein.

Effect of epigallocatechin-3-gallate modification on the structure and emulsion stability of rice bran protein in the presence of soybean protein isolate

For improving the emulsion stability of rice bran protein (RBP), RBP was modified by different concentrations of epigallocatechin-3-gallate (EGCG) in the presence of soybean protein isolate (SPI), and RBP-EGCG-SPI conjugate was prepared by alkaline pH-shifting. The results showed that the addition of EGCG led to an increase in the bound phenol content and the flexibility of the secondary structure, a decrease in the free sulfhydryl and disulfide bond content of the RBP-EGCG-SPI conjugate. EGCG covalently bound to RBP and SPI through non-disulfide bonds. When the concentration of EGCG was 10 % (w/v), the emulsifying activity index and emulsion stability index of conjugate reached the maximum value (36.61 m2/g and 255.61 min, respectively), and the conjugate had the best emulsion stability. However, an EGCG concentration above 10 % (w/v) negatively affected the emulsion stability, with increasing particle size due to protein aggregation. Summarily, the modification of EGCG improved the emulsion stability of conjugate by regulating the spatial structure of RBP-EGCG-SPI conjugate. The work provided an important guide to further improve the emulsion stability of RBP.

Improvement of antioxidant, emulsification properties and thermal stability of egg white protein by covalent binding to gallic acid/tannic acid and xanthan gum

This study aimed to improve the functional properties of egg white protein (EWP) by covalent modification of EWP with xanthan gum (XG) and gallic acid (GA)/tannic acid (TA) to form covalent complexes. The structure and functional properties of EWP before and after modification were explored. The results showed that the grafting degree of EWP-GA-XG and EWP-TA-XG reached 37.23% and 44.01% respectively measured by the OPA method. The secondary structure of EWP became loose after reaction with GA/TA and XG, with a decrease in the content of α-helix and an increase in the β-sheet content, thus contributing to the improvement of its functional properties. The DPPH and ABTS radical scavenging rate and iron reduction ability of EWP-GA-XG (44.94%, 56.38%, 18.29 mg VC/μmol) and EWP-TA-XG (85.45%, 88.39%, 39.26 mg VC/μmol) complexes were significantly improved compared with EWP (7.90%, 12.94%, 0.12 mg VC/μmol). The emulsion activity index and emulsion stability index of EWP-GA-XG (10.05 m2/g, 96.43%) and EWP-TA-XG (11.04 m2/g, 96.53%) complexes were also improved as compared to those of EWP (5.94 m2/g, 51.45%). Moreover, the peak transition temperatures of EWP-GA-XG (138.09 °C) and EWP-TA-XG (143.96 °C) complexes were higher than that of EWP (125.00 °C). This study may provide the theoretical basis for improving the functional properties of EWP and expanding its application in the field of food.

Tracking protein aggregation behaviour and emulsifying properties induced by structural alterations in common carp (Cyprinus carpio) myofibrillar protein during long-term frozen storage

The effect of ultrasound-assisted immersion freezing (UIF), air freezing (AF), and immersion freezing (IF) on the protein structure, aggregation, and emulsifying properties of common carp (Cyprinus carpio) myofibrillar protein during frozen storage were evaluated in the present study. The result showed that, compared with AF and IF samples, UIF sample had higher reactive/total sulfhydryl, protein solubility, and lower protein turbidity (P < 0.05), indicating that UIF was beneficial to inhibit protein oxidation and aggregation induced by frozen storage. UIF inhibited the alteration of secondary structure and tertiary structure during frozen storage. Meanwhile, UIF sample had higher emulsifying activity index, and smaller emulsion droplet diameter than AF and IF samples (P < 0.05), suggesting that UIF was beneficial for maintaining the emulsifying properties of protein during storage. In general, UIF is a potential and effective method to suppress the decrease in protein emulsifying properties during long-term frozen storage.

Nanocomplex of (−)-epigallocatechin-3-gallate and glycated ovalbumin based on natural deep eutectic solvents: Binding analysis and functional improvement

Natural deep eutectic solvents (NADES) are considered an efficient reaction medium for the production of glycated proteins. By optimizing the Maillard reaction conditions through response surface analysis, a glycation product (GOVA) of ovalbumin (OVA) with high grafting degree (92.2%) was prepared in choline chloride/glucose NADES. The binding information of (−)-epigallocatechin-3-gallate (EGCG) to OVA/GOVA was acquired by fluorescence spectroscopy and molecular docking. The interaction strength of GOVA + EGCG was higher than that of OVA + EGCG. Hydrogen bonding and van der Waals forces were the major driving forces in the binding process. Glycation and EGCG binding reduced the surface hydrophobicity, α-helix content and digestibility of OVA. Compared with OVA, the particle sizes of GOVA and GOVA + EGCG were increased by 54.8% and 87.7%, respectively. In addition, glycation increased the emulsifying activity index and foaming capacity of OVA by 32.6% and 20.0%, respectively, which was further increased in the presence of EGCG. The encapsulation of OVA, especially GOVA, improved the antioxidant activity, stability and bioaccessibility of EGCG. The results suggest that the glycated proteins based on NADES may provide an effective alternative for the protection and transport of bioactive ingredients in the food industries.

Stability and bioactivities evaluation of analytical grade C-phycocyanin during the storage of Spirulina platensis powder.

C-phycocyanin (C-PC) is a natural high-value blue phycobiliprotein from Spirulina platensis, which has wide biological applications in food, pharmaceutical, and cosmetics. However, the freshness of S. platensis powder (SPP) materials and C-PC purification play critical roles in evaluating the stability and bioactivities of C-PC, which severely affect its commercial application. This study investigated the effect of spray-dried SPP freshness on the biofunctional activities of analytical grade C-PC (AGC-PC). The yield of AGC-PC extracted from spray-dried SPP could reach 101.88mg/g (75% recovery ratio) after purification by reversed phase high-performance liquid chromatography (RP-HPLC) system. The half-life period (t1/2 ) of AGC-PC stability at 60°C and 8000 lux light could remain 171.70min and 176.11h within 6 months storage of spray-dried SPP. The emulsifying activity index (EAI)and foaming capacity (FC) of AGC-PC from fresh-dried SPP showed maximum values of 68.64 m2 /g and 252.9%, respectively. The EC50 of AGC-PC from fresh spray-dried SPP on 2,2-diphenyl-1-picrylhydrazyl (DPPH)and 2,2'-azinobis(3-ethylbenzothiazoline -6-sulfonic acid (ABTS+·) scavenging activity could reach 63.76 and 92.93mg/L, respectively. The EC50 of AGC-PC from fresh spray-dried SPP on proteinase inhibition and anti-lipoxygenase activity were 302.96 and 178.8mg/L, respectively. The stability and biofunctional activities of AGC-PC remained stable within 6 months storage of SPP, and then rapidly decreased after 9 months storage due to the disintegration of the trimeric (αβ)3 and hexameric (αβ)6 forms of C-PC. It is concluded that the optimal storage period of SPP for preparation of AGC-PC in commercial use should be less than 6 months. PRACTICAL APPLICATION: The C-phycocyanin (C-PC) from dried Spirulina platensis powder (SPP) has been widely applied in food nutritional, florescent markers, pharmaceuticals, cosmetics, etc, due to its blue color, fluorescence, and antioxidant properties. However, the effect of dried SPP freshness on the stability and functional activity of C-PC has been rarely reported. This study found that the thermostability, photostability, emulsifying, antioxidant, and anti-inflammatory activities of analytical grade C-PC (AGC-PC) significantly decreased after 6 months storage of SPP. Based on investigations, we have proposed that the suitable storage time of dried SPP for preparation of AGC-PC in commercial application should be within 6 months.

The structural characteristics and physicochemical properties of mung bean protein hydrolysate of protamex induced by ultrasound.

The limited physicochemical properties (such as low foaming and emulsifying capacity) of mung bean protein hydrolysate restrict its application in the food industry. Ultrasound treatment could change the structures of protein hydrolysate to accordingly affect its physicochemical properties. The aim of this study was to investigate the effects of ultrasound treatment on the structural and physicochemical properties of mung bean protein hydrolysate of protamex (MBHP). The structural characteristics of MBHP were evaluated using tricine sodium dodecylsulfate-polyacrylamide gel electrophoresis, laser scattering, fluorescence spectrometry, etc. Solubility, fat absorption capacity and foaming, emulsifying and thermal properties were determined to characterize the physicochemical properties of MBHP. MBHP and ultrasonicated-MBHPs (UT-MBHPs) all contained five main bands of 25.8, 12.1, 5.6, 4.8 and 3.9 kDa, illustrating that ultrasound did not change the subunits of MBHP. Ultrasound treatment increased the contents of α-helix, β-sheet and random coil and enhanced the intrinsic fluorescence intensity of MBHP, but decreased the content of β-turn, which demonstrated that ultrasound modified the secondary and tertiary structures of MBHP. UT-MBHPs exhibited higher solubility, foaming capacity and emulsifying properties than MBHP, among which MBHP-330 W had the highest solubility (97.32%), foaming capacity (200%), emulsification activity index (306.96 m2 g-1 ) and emulsion stability index (94.80%) at pH 9.0. Ultrasound treatment enhanced the physicochemical properties of MBHP, which could broaden its application as a vital ingredient in the food industry. © 2023 Society of Chemical Industry.

Evaluation of the Emulsifying Property and Oxidative Stability of Myofibrillar Protein-Diacylglycerol Emulsions Containing Catechin Subjected to Different pH Values.

Myofibrillar protein-diacylglycerol emulsions containing catechin (MP-DAG-C) possess outstanding emulsifying property and oxidative stability. However, the effect of pH on MP-DAG-C emulsions should be revealed to provide possibilities for their application in practical meat products. Therefore, MP-DAG-C emulsions at different pH values were used in this study, in which lard, unpurified glycerolytic lard (UGL), and purified glycerolytic lard (PGL) were used as the oil phases. The results indicated that the emulsifying property of the UGL- and PGL-based emulsions increased compared to those of the lard-based emulsions (p < 0.05). The emulsifying activity and stability indices, absolute value of ζ-potential, and rheological characteristics increased with the increase in pH values (p < 0.05), with the droplets were smallest and distributed most uniformly at a pH of 6.5 compared to the other acidic environment (p < 0.05). The thiobarbituric acid substance and carbonyl content increased (p < 0.05), while the total sulfydryl content decreased (p < 0.05) during storage. However, there was no statistical difference between the oxidative stability of the MP-DAG-C emulsions with different pH values (p > 0.05). The results implied that the emulsifying property of MP-DAG-C emulsions increased with an increase in pH values. The oxidative stability of the MP-DAG-C emulsions at high pH values was improved by catechin.

Impact of cod skin peptide-ι-carrageenan conjugates prepared via the Maillard reaction on the physical and oxidative stability of Antarctic krill oil emulsions

This research aimed to construct an emulsifier by the Maillard reaction at various times using cod fish skin collagen peptide (CSCP) and ι-carrageenan (ι-car) to stabilize an Antarctic krill oil (AKO) emulsion. This emulsion was then investigated for physicochemical stability, oxidative stability, and gastrointestinal digestibility. The emulsion stability index and emulsifying activity index of Maillard reaction products (MRPs) were increased by 36.32 % and 66.30 %, respectively, at the appropriate graft degree (25.58 %) compared with the mixture of ι-car and CSCP. In vitro digestibility suggested the higher release of free fatty acids (FFAs) of 10d-MRPs-AKO-emulsion, and the highest bioavailability of AST in 10d-MRPs-AKO was found to be 28.48 %. The findings of this study showed the potential of MRPs to improve peptide function, serve as delivery vehicles for bioactive chemicals, and possibly serve as a valuable emulsifier to be used in the food industry.

Effect of Microwave Intermittent Drying on the Structural and Functional Properties of Zein in Corn Kernels.

Microwave intermittent drying was carried out on newly harvested corn kernels to study the effects of different microwave intermittent powers (900 W, 1800 W, 2700 W, and 3600 W) on the structural and functional properties of zein in corn kernels. The results showed that microwave drying could increase the thermal stability of zein in corn kernels. The solubility, emulsification activity index, and surface hydrophobicity increased under 1800 W drying power, which was due to the unfolding of the molecular structure caused by the increase in the content of irregular structure and the decrease in the value of particle size. At a drying power of 2700 W, there was a significant increase in grain size values and β-sheet structure. This proves that at this time, the corn proteins in the kernels were subjected to the thermal effect generated by the higher microwave power, which simultaneously caused cross-linking and aggregation within the proteins to form molecular aggregates. The solubility, surface hydrophobicity, and other functional properties were reduced, while the emulsification stability was enhanced by the aggregates. The results of the study can provide a reference for the in-depth study of intermittent corn microwave drying on a wide range of applications of zein in corn kernels.

Revealing the interaction mechanism and emulsion properties of carboxymethyl cellulose on soy protein isolate at different pH

In this study, carboxymethyl cellulose (CMC) was introduced to reduce the instability and poor functional properties of soy protein isolate (SPI) in low pH environment. The SPI–CMC systems containing 0–0.5% CMC were prepared at pH 4.0 and 5.0. By exploring the interaction mechanism between them, the optimal formation conditions of the composite systems were revealed. The results showed that CMC was continuously adsorbed on the surface of SPI at pH 4.0, in which electrostatic behavior and hydrogen bonds played an important role. The emulsion properties were the best at 0.4% CMC, and the emulsion activity index (EAI) and emulsion stability index (ESI) were increased by 48.91 m2/g and 91.41 min compared with SPI emulsion. The optical microscope images showed that the emulsion interfacial proteins were formed and the droplets were evenly distributed at 0.4% CMC. At pH 5.0, the stability of the SPI–CMC systems was highly dependent on the steric hindrance and high viscosity of CMC. The EAI and ESI of the emulsion at 0.5% CMC were the highest, which increased by 49.08 m2/g and 83.79 min compared with SPI emulsion. The optical microscope images confirmed that the addition of 0.5% CMC significantly inhibited the leakage of oil droplets. In conclusion, this study provides an effective strategy for stabilizing SPI emulsion in low pH environments, which has important practical application value.