Higher Emulsifying Activity Index Research Articles

High-pressure homogenization to improve the stability of liquid diabetes formula food for special medical purposes: Structural characteristics of casein–polysaccharide complexes

The stability of diabetes formula food for special medical purposes (D-FSMP) was improved by high-pressure homogenization (HPH) at different homogenization pressures (up to 70 MPa) and number of passes (up to 6 times). The process at 60 MPa/4 times was the best. Casein had the highest surface hydrophobicity in this condition. The casein–polysaccharide complexes were endowed with the smallest size (transmission electron microscopy images). The complex particles exhibited nearly neutral wettability (the three-phase contact angle was 90.89°), lower interfacial tension, and the highest emulsifying activity index (EAI) and emulsifying stability index (ESI). The prepared D-FSMP system exhibited the narrowest particle size distribution range, the strongest interfacial deformation resistance and the best storage stability. Therefore, an appropriate intensity of HPH could enhance the stability of D-FSMP by improving the interfacial and emulsifying properties of casein–polysaccharide complexes. This study provides practical guidance on the productions of stable D-FSMP.

Emulsifying property, antioxidant activity, and bitterness of soybean protein isolate hydrolysate obtained by Corolase PP under high hydrostatic pressure

Enzymatic hydrolysis of proteins can enhance their emulsifying properties and antioxidant activities. However, the problem related to the hydrolysis of proteins was the generation of the bitter taste. Recently, high hydrostatic pressure (HHP) treatment has attracted much interest and has been used in several studies on protein modification. Hence, the study aimed to investigate the effects of enzymatic hydrolysis by Corolase PP under different pressure treatments (0.1, 100, 200, and 300 MPa for 1–5 h at 50 °C) on the emulsifying property, antioxidant activity, and bitterness of soybean protein isolate hydrolysate (SPIH). As observed, the hydrolysate obtained at 200 MPa for 4 h had the highest emulsifying activity index (47.49 m2/g) and emulsifying stability index (92.98 %), and it had higher antioxidant activities (44.77 % DPPH free radical scavenging activity, 31.12 % superoxide anion radical scavenging activity, and 61.50 % copper ion chelating activity). At the same time, the enhancement of emulsion stability was related to the increase of zeta potential and the decrease of mean particle size. In addition, the hydrolysate obtained at 200 MPa for 4 h had a lower bitterness value and showed better palatability. This study has a broad application prospect in developing food ingredients and healthy foods.

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.

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.

Design Optimization of a Tray Bioreactor for Solid-State Fermentation: Study of Process Parameters through Protein Modification of By-Products

This study investigated the design of a tray bioreactor for solid-state fermentation, applying Rhizopus oryzae to oilseed meals as the substrate. Two process variables were continuously monitored in the bioreactor to ensure precise control of the environmental conditions: temperature and relative humidity (RH). The comprehensive analysis covered the effects of different fermentation conditions on the protein content, technological properties, and molecular distribution of the samples. The study revealed that the configuration factors suffered a stratification within the three trays of the bioreactor. Notably, the upper tray registered the largest dispersion, with a range of 1.5 °C. When analyzing the differences between sensors within each tray, the largest difference was found in the lower tray (10.9%). Furthermore, higher EAI (Emulsifying Activity Index) values were observed in the upper tray (T3) for rapeseed. As for ESI (Emulsion Stability Index) values, no differences were observed between the trays or fermentation periods. Using the changes induced by Rhizopus oryzae fungal enzymes, the study quantitatively examined the changes in the by-product valorization. While the bioreactor factors did not affect the protein quantity itself, they had significant impacts on specific changes within the molecular weight protein fraction. The findings of this study offer significant insights into the complex dynamics of solid-state fermentation processes. The outcomes of this study not only advance understanding of solid-state fermentation but also offer practical guidance for the design and operation of fermenters in industrial applications.

Functional, physicochemical, and structural properties of the hydrolysates derived from the abalone (Haliotis discus subsp hannai Ino) foot muscle proteins.

This study was conducted to investigate functional, physicochemical, and structural properties of abalone foot muscle proteins (AFPs) and their hydrolysates (HAFPs) obtained using animal protease (HA), papain (HPP), and Protamex® (HP) at different time points. The HA-hydrolysate obtained after 0.5h of treatment demonstrated the highest solubility at pH 7.0 (84.19%); the HPP-hydrolysate at 4h exhibited the highest degree of hydrolysis (11.4%); the HPP-hydrolysate at 0.5h had the highest oil holding capacity (2.62g/g) and emulsion stability index (39.73min), and the HP-hydrolysate at 4h had the highest emulsifying activity index (93.23m2/g) and foaming stability (91.45%); Regarding the physicochemical properties, the HPP-hydrolysates revealed the largest particle size, higher absolute zeta potential, and superior interfacial activity. Structural characterization demonstrated the enzymolysis-based changes in the composition and the secondary structure of the AFPs. These results provide practical support for the theoretical basis of the use of AFPs as a source of nutritive proteins in the food industry.

Structural and functional properties of self-assembled peanut protein nanoparticles prepared by ultrasonic treatment: Effects of ultrasound intensity and protein concentration

Peanut protein isolate (PPI) nanoparticles were prepared by self-assembly under the combined action of ultrasound (US) and protein concentration. The effects of ultrasound intensity (150–500 W) and protein concentration (1–12 %, w/v) on the structural and functional properties of PPI nanoparticles were investigated. Low-intensity US significantly increased the particle size of PPI, but high-intensity US decreased it. The largest PPI nanoparticles were obtained when 10 % PPI was subjected to low-intensity US treatment (200 W for 5 min). These nanoparticles possessed unique structural characteristics, such as the lowest absolute ζ-potential and the highest contents of exposed free sulfhydryl and disulfide bond, which may be responsible for their excellent heat-set gelling properties. The 12 % PPI treated with low- and high-intensity US had the highest emulsifying activity index and emulsifying stability index, respectively. The self-assembled PPI nanoparticles induced by US treatments at high protein concentrations have great potentials for application in the food industry.

Curcumin-encapsulated hydrophilic gelatin nanoparticle to stabilize fish oil-loaded Pickering emulsion

Herein, pH-cycle method was explored to prepare curcumin-encapsulated hydrophilic bovine bone gelatin (BBG/Cur) nanoparticle and then the obtained nanoparticle was applied to stabilize fish oil-loaded Pickering emulsion. The nanoparticle had a high encapsulation efficiency (93.9 ± 0.5 %) and loading capacity (9.4 ± 0.1 %) for curcumin. The nanoparticle-stabilized emulsion had higher emulsifying activity index (25.1 ± 0.9 m2/g) and lower emulsifying stability index (161.5 ± 18.8 min) than BBG-stabilized emulsion. The pH affected the initial droplet sizes and creaming index values of the Pickering emulsions: pH 11.0 < pH 5.0 ≈ pH 7.0 ≈ pH 9.0 < pH 3.0. Curcumin provided obvious antioxidant effect for the emulsions, which was also dependent on pH. The work suggested pH-cycle method could be used to prepare hydrophobic antioxidant-encapsulated hydrophilic protein nanoparticle. It also provided basic information on the development of protein nanoparticles for Pickering emulsion stabilization.

Hydrophobic surface modification of citrus fiber using octenyl succinic anhydride (OSA): Preparation, characterization and emulsifying properties

We reported herein the modification of fiber acquired from citrus processing residue via the esterification with octenyl succinic anhydride. OSA-CF with degree of substitution (DS) of 0.904–0.103 were obtained. The chemical compositions of fiber were changed in pectin content. The hydration properties of the fiber increased significantly with the esterification reaction, especially the water holding capacity (WHC) increased from 12.42 g/g to 17.23 g/g. OSA-CF has more negative charge than CF since the exposure of hydrophilic group and addition of carboxyl (-COO - ). FT-IR spectrum of the OSA-CF at 1734 cm −1 revealed characteristic absorption peaks of the ester carbonyl groups (C O). Compared to original fiber, OSA-CF showed higher crystallinity and slightly lower thermal stability from the XRD, TG and DTG patterns. It can be seen from the scanning electron microscope (SEM) image that the surface of OSA-CF has more fold and porous structure. Meanwhile, emulsion prepared by OSA-CF showed superior emulsifying abilities such as higher emulsifying activity index (EAI) and emulsifying stability (ES) and smaller particle size. In conclusion, OSA esterification did improve the physicochemical properties and change chemical composition of fiber. The purposed mechanism and characterization for surface modification of citrus fiber using octenyl succinic anhydride (OSA). • The original water holding capacity of citrus fiber was retained. • Octenyl succinate citrus fiber ester (OSA-CF) displayed higher emulsifying capacities. • OSA-CF has more surface negative charge. • The carbonyl group (C O) decreased first and then increased. • OSA-CF has more folds and deeper pore structure.

The Effects of Ultrasound Times and Amplitudes on the Particle Size and Emulsifying Properties of Whey Protein Concentrate

The current study was conducted to investigate the effects of ultrasound times and amplitudes on the particle sizes and emulsifying properties of samples of whey protein concentrate (WPC). The ultrasound (US) application was performed using VC-7500 ultrasonic power equipment at a 20 kHz frequency, at various times (10, 20, and 30 min at a 50% amplitude) and amplitudes (60%, 80%, and 100% for 5 min). The results showed that the US procedure had a significant effect (p&amp;lt;0.05) on both particle sizes and emulsifying properties (p&amp;lt;0.05). The smallest particle size was obtained for the WPC samples exposed to 30 min of US at a 100% amplitude (US310) (498.6 nm). The WPC samples treated at a 100% amplitude showed a smaller particle size compared to the other WPC samples at 60% and 80% amplitudes. While the WPC samples treated for 10 min had the biggest particle size (790.3 nm), those treated for 30 min had the smallest particle size (697.1 nm). On the other hand, among the treatments, US310 whey protein concentrate samples had the highest EAI (emulsifying activity index) (198 m2/g) and ESI (emulsion stability index) (34.0 min), whereas the untreated WPC samples had the lowest EAI (56 m2/g) and ESI (13.0 min). In general, 30-min US treatment at a 100% amplitude showed the lowest particle size (498.6 nm) and the highest emulsifying properties (EAI: 198 m2/g and ESI: 34.0) compared to the other sonication times and amplitudes.

Bioactive Peptide Fractions from Collagen Hydrolysate of Common Carp Fish Byproduct: Antioxidant and Functional Properties.

Collagen isolated from byproducts of common carp was hydrolyzed with alcalase enzyme to obtain peptide fractions. The resulting >30 kDa (PF1), 10–30 kDa (PF2), 3–10 kDa (PF3) and <1 kDa (PF4) fractions were studied for their antioxidant and functional properties. All peptide fractions illustrated antioxidant activity at different concentrations (1, 5, and 10 mg/mL). Although PF4 indicated the highest DPPH radical-scavenging activity (87%) at a concentration of 1 mg/mL, the highest reducing power (0.34) and hydroxyl radical scavenging activity (95.4%) were also observed in PF4 at a concentration of 10 mg/mL. The solubility of the peptide fractions was influenced by pH. The lowest solubility of the peptide fractions was observed at pH 4. The highest emulsifying activity index (EAI) was observed for PF4 (121.1 m2/g), followed by PF3 (99.6 m2/g), PF2 (89.5 m2/g) and PF1 (78.2 m2/g). In contrast to what has been found in the case of EAI, the emulsion stability of the peptide fractions decreased at lower molecular weight, which ranged from 24.4 to 31.6 min. Furthermore, it was revealed that PF1 had the highest foam capacity (87.4%) and foam stability (28.4 min), followed by PF2 and PF3. Overall, the findings suggest that peptide fractions isolated from byproducts of common carp are a promising source of natural antioxidants for application in functional food and pharmaceutical products.

Comparison of oil-in-water emulsions prepared by ultrasound, high-pressure homogenization and high-speed homogenization

This study was designed to compare the properties of myofibrillar protein (MP) stabilized soybean oil-in-water emulsions fabricated by ultrasound-assisted emulsification (UAE), high-pressure homogenization (HPH) and high-speed homogenization (HSH). The emulsion properties, droplet characteristics, interfacial proteins, protein exposure extent, microrheological properties, multiple light scattering results, and 7 d storage stabilities of the three emulsions were specifically investigated. Our results indicate that UAE and HPH were better emulsification methods than HSH to obtain high-quality emulsions with higher emulsifying activity index (UAE 20.73 m2·g−1, HPH 11.76 m2·g−1 and HSH 6.80 m2·g−1), whiteness (UAE 81.05, HPH 80.67 and HSH 74.09), viscosity coefficient (UAE 0.44 Pa·sn, HPH 0.49 Pa·sn and HSH 0.22 Pa·sn), macroscopic viscosity index (UAE 2.31 nm−2·s, HPH 0.38 nm−2·s and HSH 0.34 nm−2·s), and storage stability, especially for the UAE. Furthermore, UAE was a more efficient emulsification method than HPH to prepare the fine MP-soybean oil emulsion. The protein-coated oil droplets were observed in the three emulsions. The emulsion droplet size of the UAE-fabricated emulsion was the lowest (0.15 μm) while the interfacial protein concentration (93.37%) and the protein exposure extent were the highest among the three emulsions. During the 7 d storage, no separation was observed for the UAE-fabricated emulsion, while the emulsions fabricated by HPH and HSH were separated after storage for 5 d and 2 h. Therefore, this work suggests that UAE could be a better method than HPH and HSH to fabricate MP-soybean oil emulsion.

Effect of solvent polarity on the formation of flexible zein nanoparticles and their environmental adaptability

Zein possesses strong self-assembly ability due to its amphiphilicity. To investigate the effect of solvent polarity on both the flexibility of zein and the formation of flexible zein nanoparticles, various ethanol aqueous solutions were chosen. Alkaline modification was applied to improve the flexibility of the zein and a liquid-liquid method was used to produce zein nanoparticles. Solvent polarity plays a positive role in improving the flexibility of zein. Furthermore, native and flexible zein nanoparticles were formed from native zein and flexible zein, respectively. However, nanoparticles could not form from highly flexible zein due to their strong adaptability to changes in solvent. Compared with the emulsifying activity index (EAI) and emulsifying stability index (ESI) of native zein nanoparticles, a higher EAI and ESI of flexible zein nanoparticles were acquired. These results may be attributed to the strong adaptability of flexible zein to the medium changing through changing their secondary structure. Furthermore, the adaptability of flexible zein nanoparticles significantly depended on the initial polarity of the solvent. The deamidation reaction of zein was responsible for the change in zein flexibility. These findings thus provide clear evidence of the relationship between the solvent polarity and structural flexibility of modified zein.

Dark septate endophytes (DSE): potential bioremedial promoters of oil derivatives

Oil spills are a global environmental problem. One of the management tools used to solve this problem is phytoremediation, a process that uses the capacity of plants and microorganisms to metabolize the components of the oil. The aims of the present study were to isolate, identify and characterize the fungi obtained from plants growing in an oil-contaminated area and evaluate their growth response and emulsifying and degrading capacity in two petroleum derivatives (kerosene and lube oil). Four dark septate endophytes (DSE) strains were isolated and identified: Exserohilum pedicellatum, Ophiosphaerella sp., and two Alternaria alternata strains. E. pedicellatum was found in an oil-contaminated environment for the first time. All strains were grown in kerosene, although some showed inhibition, whereas in lube oil, all showed growth induction. Ophiosphaerella sp. showed “drops” in kerosene, but the four strains showed surfactant capacity in lube oil. Ophiosphaerella sp. showed the highest emulsifying activity index but both A. alternata strains presented the highest lube oil degradation, which was directly related to the weight of the fungal biomass. There was not relationship between emulsifying capacity and oil degradation. However, these fungi show technological potential for application in phytoremediation processes.

Physicochemical and functional properties of lactoferrin-hyaluronic acid complexes: Effect of non-covalent and covalent interactions

The molecular characteristics and functional properties of lactoferrin (LF)-hyaluronic acid (HA) non-covalent complexes and conjugates formed by physical mixing and chemical conjugation were compared. LF and HA interactions were characterized using phase behavior, particle size, zeta-potential and isothermal titration calorimetry (ITC) analysis. The physicochemical and functional properties of the LF-HA complexes and conjugates were also measured, including their foaming, emulsifying, and antioxidant capacities. LF and HA formed molecular complexes over a wide range of pH values, resulting in changes in particle size, charge and structure. The net charge and thermal stability of the proteins in the LF-HA complexes and conjugates were higher than that of free proteins. Covalently attaching HA to LF significantly (p < 0.05) improved its emulsifying capacity, with the highest emulsifying activity index (47.7 ± 0.1 m2/g) and emulsion stability index (83.2 ± 0.4 min) being obtained, but it did not improve its foaming properties. The antioxidant capacity of LF in complexes and conjugates was increased by around 9% and 10%, respectively. This study showed that the functional performance of LF could be enhanced by forming complexes or conjugates with HA, which may extend its use in a variety of food applications.

Physicochemical, emulsifying, and interfacial properties of different whey protein aggregates obtained by thermal treatment

To date, few studies are found to compare the interfacial properties of protein aggregates with different structures and characteristics. In this research, different whey protein isolate (WPI) aggregates (native, nanoparticles, and nanofibrils) were fabricated, and characterized, and the emulsifying, and interfacial properties of WPI (native), its nanoparticle, and nanofibril as a function of pH values and salt concentrations were systematically investigated. The Z-average diameters of WPI (native), its nanoparticle, and nanofibril were 10, 355, and 122 nm, respectively. The isoelectric point (IEP) of native WPI was found to be approximately 5.0, whereas IEP of nanoparticles was decreased to 4.7, but increased to 5.5 for nanofibrils. WPI nanofibrils exhibited highest emulsifying activity index (EAI) and emulsifying stability index (ESI) at pH 3.0, whereas WPI nanoparticle had the highest EAI and ESI at pH 7.0. Low salt concentrations can increase the EAI and ESI of proteins. The EAI and ESI were highly correlated with the particle size, zeta-potential, and surface hydrophobicity of protein molecules. A negative correlation between interfacial tension of protein molecules and EAIs was observed regardless of protein types.

Microwave-assisted extraction of arabinan-rich pectic polysaccharides from melon peels: Optimization, purification, bioactivity, and techno-functionality

The effects of water to solids ratio (WSR, 10–30 mL/g), power (180–540 W), and irradiation time (IT, 5–15 min) in microwave-assisted extraction (MAE) were optimized to extract polysaccharides from melon peels (PMP). The maximum extraction yield (32.81 %) was obtained under 20.94 mL/g WSR, 414.4 W power, and 12.75 min IT. The main monosaccharide composition of purified PMP with an average molecular weight of 5.71 × 104 kDa were d-galacturonic acid, arabinose, glucose, and galactose. An ascending dose-dependent antiradical and antioxidant behavior for PMP (0–5.0 mg/mL) was found. The initial foaming capacity (38.6–110.3 %) and foaming stability (5.2–65.2 %) were significantly increased as a function of PMP concentration (1.0–5.0 %), while they reduced by increasing the mixing time (p < 0.05). The highest emulsifying activity index (44.1 m2/g) and emulsifying stability (69.3 %) at 5.0 % PMPs were determined. PMP gels with FTIR-identified functional groups can be formulated in new gluten-free functional products.

Formation and emulsification properties of self‐assembled potato protein microgel particles under different pH conditions

SummaryThis study evaluated the formation of potato protein microgel particles (PPM) formed by heating a protein solution at pH 2–8 in order to improve emulsifying potential of commercial potato protein (PP). The physicochemical properties (particle diameter, ζ‐potential and contact angle), structural characteristics and emulsifying capacity of PPM were investigated. The results indicated that preparation pH of PPM had significantly influenced the emulsification properties. The PPM samples prepared near the isoelectric point of PP (pI ~ 4.5) had low ζ‐potential, high particle size, lower emulsifying activity index (EAI) and emulsifying stability index (ESI). Meanwhile, compared to PP, PPM prepared at pH (pH = 2, pH = 6–8) stay away from isoelectric point had higher EAI and ESI, evidenced by the appropriate ζ‐potential and contact angel. In conclusion, PPM prepared at specific pH (pH = 6) would enhance the emulsifying properties of potato protein, the findings would broaden the application of potato protein in the food industry.

Biological and functional properties of peptide fractions obtained from collagen hydrolysate derived from mixed by-products of different fish species.

Fish by-products are excellent sources of collagen. Acid-soluble collagen (ASC) derived from a mixed by-product of different fish species was hydrolyzed to obtain peptide fractions and evaluate their biological and functional activities. All fractions obtained (F1: ≥30, F2: 10-30, F3: 5-10, F4: 1-5, and F5: ≤1kDa) exhibited antioxidant activity at concentrations of 5, 10, and 15mg/mL. However, F5 registered the highest reducing power (absorbance 0.366) and hydroxyl-radical-scavenging activity (91%) at 15mg/mL; whereas the highest DPPH scavenging activity (81%) was also detected in F5 at 5mg/mL. The solubility of F1, F2, and F3 was≥95% at pH 7. The highest foaming capacity (78%), foaming stability (60%), and emulsion stability index (42min) were registered for F1. However, the highest emulsifying activity index (130m2/g) was for F3. These results place collagen obtained from a mixed by-product of different fish species as a potential biotechnological alternative for the industry.

Improving the functional properties of bovine serum albumin-glucose conjugates in natural deep eutectic solvents

Glycation between target proteins and saccharides is time-consuming or requires high temperatures. Here, a promising reaction medium, natural deep eutectic solvents (NADES), for glucose glycation with bovine serum albumin (BSA) was applied to improve the grafting of glucose-glycated BSA by shifting reaction equilibrium. Two types of glucose-glycated BSA products were prepared using NADES and water systems. SDS-PAGE and MALDI-TOF-MS revealed that BSA and glucose were covalently bonded. Compared with in water system, glycated BSA products in NADES system had more –OH groups, more disordered secondary structures, lower intrinsic fluorescence intensity, and higher ultraviolet–visible absorption. Lower surface hydrophobicity (1100 versus 1356), higher emulsifying activity index (66.17 versus 46.49 m2/g), higher emulsion stability index (79.62 versus 63.61%), and lesser free sulfhydryl (8.07 versus 8.98 μmol/g) groups were obtained with NADES system than with water system. The results suggest that NADES is a suitable alternative reaction medium for promoting the glycation of BSA.