Improved enzymatic accessibility of peanut protein isolate pre-treated using thermosonication

Interaction of the extracellular protease from Staphylococcus xylosus with meat proteins elucidated via spectroscopic and molecular docking

This study aimed to assess the effect of an external protease secreted by Staphylococcus (S.) xylosus on the hydrolysis and flavor properties of meat protein. The results indicated that the protease significantly increased the solubility of myofibrillar proteins (MPs) and sarcoplasmic proteins (SPs) in water (P < 0.05), and altered their surface hydrophobicity and secondary structure. The results of micromorphological and free amino acids analyses suggested that the protease degraded the large and insoluble meat protein aggregates into small molecular proteins with uniform distribution and amino acids, especially glycine, glutamic acid, leucine, and cysteine. Moreover, the protease-catalyzed hydrolysis promoted the formation of some volatile compounds in the MPs and SPs. Additionally, molecular docking analysis suggested that hydrogen bond and hydrophobic interaction promoted the formation of a S. xylosus protease/meat protein complex. These results provided a basis for the future application of S. xylosus protease in meat products.

Artificial oil bodies: A review on composition, properties, biotechnological applications, and improvement methods

In order to simulate the structure of natural oil body, artificial oil bodies (AOBs) are fabricated by the integration of oleosins, triacylglycerols (TAGs) and phospholipids (PLs) in vitro. Recently, AOBs have gained great research interest both in the food and biological fields due to its ability to act as a novel delivery system for bioactive compounds and as a carrier for target proteins. This review aims to summarize the composition and the preparation methods of AOBs, examine the factors influencing their stability. Moreover, this contribution focusses on exploring the application of AOBs to encapsulate functional ingredients that are prone to oxidation as well as improve efficiency involved in protein purification, renaturation and immobilization by reducing the complex steps. In addition, the improvement measures to further enhance the stability and efficacy of AOBs are also discussed. The application of AOBs is expected to be a big step towards replacing existing bioreactors and delivery systems.

Comparison between hydrodynamic and ultrasound cavitation on the inactivation of lipoxygenase and physicochemical properties of soy milk

The effects of hydrodynamic cavitation (HC) and ultrasound cavitation (UC) on the lipoxygenase activity and physicochemical properties of soy milk were evaluated. The results revealed that both ultrasound cavitation and hydrodynamic cavitation significantly inactivated the lipoxygenase activity. After the exposure to ultrasound cavitation at 522.5 W/L and 70 °C for 12 min, the lipoxygenase activity was inactivated by 96.47 %. Meanwhile, HC treatment with the cavitation number of 0.0133 for 240 min led to the loss of 79.31 % of lipoxygenase activity. An artificial neural network was used to model and visualize the effects of different parameters after ultrasound cavitation treatment on the inactivation efficiency of soy milk. Turbiscan test results showed that hydrodynamic and ultrasound cavitation decreased the instability index and particle size of soy milk. Moreover, the total free amino acid content was significantly increased after hydrodynamic and ultrasound cavitation treatment. Gas chromatography-mass spectrometry showed that the total content of beany flavor compounds decreased after acoustic cavitation and HC treatment. Acoustic cavitation and HC affected the tertiary and secondary structure of soy milk, which was related to the inactivation of lipoxygenase. We aim to explore a potential and effective way of the application in soy milk processing by comparing the ultrasound equipped with heat treatment and hydrodymic cavitation.

Effects of Heat Treatment on the Structural and Functional Properties of Phaseolus vulgaris L. Protein

The paper presents the effect of heat treatment at 80 °C at different times (3, 5, 7, and 9 min) on the structural and functional properties of Phaseolus vulgaris L. protein (PVP, bean protein powder). Surface and structure properties of PVP after heat treatment were analyzed using a Fourier transform infrared spectrometer (FTIR), a fluorescence spectrophotometer, a visible light spectrophotometer, a laser particle size analyzer, and other equipment. The secondary structure and surface hydrophobicity (H0) of PVP changed significantly after heat treatment: the β-sheet content decreased from 25.32 ± 0.09% to 24.66 ± 0.09%, the random coil content increased from 23.91 ± 0.11% to 25.68 ± 0.08%, and the H0 rose by 28.96-64.99%. In addition, the functional properties of PVP after heat treatment were analyzed. After heat treatment, the emulsifying activity index (EAI) of PVP increased from 78.52 ± 2.01 m2/g to 98.21 ± 1.33 m2/g, the foaming ability (FA) improved from 87.31 ± 2.56% to 95.82 ± 2.96%, and the foam stability (FS) rose from 53.23 ± 1.72% to 58.71 ± 2.18%. Finally, the degree of hydrolysis (DH) of PVP after gastrointestinal simulated digestion in vitro was detected by the Ortho-Phthal (OPA) method. Heat treatment enhanced the DH of PVP from 62.34 ± 0.31% to 73.64 ± 0.53%. It was confirmed that heat treatment changed the structural properties of PVP and improved its foamability, emulsification, and digestibility. It provides ideas for improving PVP's potential and producing new foods with rich nutrition, multiple functions, and easy absorption.

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.

Effects of ultrasonic treatment on the structural and functional properties of cactus (Opuntia ficus-indica) seed protein

With the steady increase in the consumption of ultra-processed foods, there is growing interest in sustainable diets that include more plant protein. However, little information is available regarding the structural and functional properties of cactus (Opuntia ficus-indica) seed protein (CSP), a by-product of the cactus seed food-processing chain. This study aimed to explore the composition and nutritional value of CSP and reveal the effects of ultrasound treatment on protein quality. Protein chemical structure analysis showed that an appropriate intensity of ultrasound treatment (450 W) could significantly increase protein solubility (96.46 ± 2.07%) and surface hydrophobicity (13.76 ± 0.85 μg), decrease the content of T-SH (50.25 ± 0.79 μmol/g) and free-SH (8.60 ± 0.30 μmol/g), and enhance emulsification characteristics. Circular dichroism analysis further confirmed that the ultrasonic treatment increased the α-helix and random coil content. Amino acid analysis also suggested that ultrasound treatment (450 W) increased the hydrophobic amino acid content. To evaluate the impact of changes in the chemical structure, its digestion behavior was studied. The results showed that ultrasound treatment increased the release rate of free amino acids. Furthermore, nutritional analysis showed that the digestive products of CSP by ultrasound treatment can significantly enhance the intestinal permeability, increase the expression of ZO-1, Occludin and Claudin-1, thus repairing LPS induced intestinal barrier disfunction. Hence, CSP is a functional protein with high value, and ultrasound treatment is recommended. These findings provide new insights into the comprehensive utilization of cactus fruits.

Effects of homogeneous and ultrasonic treatment on casein/phosphatidylcholine complex-emulsions: Stability and bioactivity insights

Casein (CAS), a typical protein emulsifier, has functional properties limited by its chemical structure in practical production applications. This study aimed to combine phosphatidylcholine (PC) and casein to form a stable complex (CAS/PC) and improve its functional properties through physical modification (homogeneous and ultrasonic treatment). To date, few studies have explored the effects of physical modification on the stability and biological activity of CAS/PC. Interface behavior analysis showed that compared to homogeneous treatment, PC addition and ultrasonic treatment could decrease the mean particle size (130.20 ± 3.96 nm) and increase the zeta potential (-40.13 ± 1.12 mV), indicating the emulsion is more stable. The chemical structural analysis of CAS showed that PC addition and ultrasonic treatment promoted changes in its sulfhydryl content and surface hydrophobicity, exposing more free sulfhydryl groups and hydrophobic binding sites, thereby enhancing its solubility and improving the stability of the emulsion. Additionally, storage stability analysis revealed that the incorporation of PC with ultrasonic treatment could improve the root mean square deviation value and radius of gyration value of CAS. These modifications resulted in an increase the binding free energy between CAS and PC (-238.786 kJ/mol) at 50 °C, leading to an improvement in the thermal stability of the system. Furthermore, digestive behavior analysis indicated that PC addition and ultrasonic treatment could increase the total FFA release from 667.44 ± 22.33 μmol to 1250.33 ± 21.56 μmol. In conclusion, the study underscores the effectiveness of PC addition and ultrasonic treatment in enhancing the stability and bioactivity of CAS, offering novel ideas for designing stable and healthy emulsifiers.

Time-specific ultrasonic treatment of litchi thaumatin-like protein inhibits inflammatory response in RAW264.7 macrophages via NF-κB and MAPK transduction pathways

The pro-inflammation activity of litchi thaumatin-like protein (LcTLP) led to be responsible for the occurrence of adverse reactions after excessive consumption of litchi. This study aimed to characterize the changes in the structure and inflammatory activity of LcTLP induced by ultrasound treatment. Significant molecular structure of LcTLP changes occured at 15 min ultrasound treatment, and then tended to recover with subsequent treatment. Secondary structure (α-helices decreased from 17.3% to 6.3%), tertiary structure (the maximum endogenous fluorescence intensity decreased), and microstructure (mean hydrodynamic diameter reduced from 4 μm to 50 nm) of the LcTLP treated for 15 min (LT15) were significantly affected, which led to the inflammatory epitope of LcTLP (domain II and V-cleft) unfolded. In vitro, LT15 had a significant anti-inflammatory response, which inhibited NO production and had the best effect at 50 ng/mL in RAW264.7 macrophages (73.24%). Moreover, proinflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) secretion and mRNA expression levels were also significantly lower compared with untreated LcTLP (p < 0.05). Western blot further confirmed that the expressions of IκB-α, p65, p38, ERK and JNK reduced markedly (p < 0.05), which indicated LT15 inhibited the inflammatory response through NF-κB and MAPK transduction pathways. Overall, it can be hypothesized that LT15 exposed to low frequency ultrasonic fields have a direct effect on the protein surface structure and thus on the entry of LT15 into cells, making 15-minute ultrasound treatment potentially useful in reducing the pro-inflammatory properties of litchi or related liquid products.

Functional Proteins from Biovalorization of Peanut Meal: Advances in Process Technology and Applications

Environmental costs associated with meat production have necessitated researchers and food manufacturers to explore alternative sources of high-quality protein, especially from plant origin. Proteins from peanuts and peanut-by products are high-quality, matching industrial standards and nutritional requirements. This review contributes to recent developments in the production of proteins from peanut and peanut meal. Conventional processing techniques such as hot-pressing kernels, use of solvents in oil removal, and employing harsh acids and alkalis denature the protein and damage its functional properties, limiting its use in food formulations. Controlled hydrolysis (degree of hydrolysis between 1 and 10%) using neutral and alkaline proteases can extract proteins and improve peanut proteins' functional properties, including solubility, emulsification, and foaming activity. Peanut proteins can potentially be incorporated into meat analogues, bread, soups, confectionery, frozen desserts, and cakes. Recently, pretreatment techniques (microwave, ultrasound, high pressure, and atmospheric cold plasma) have been explored to enhance protein extraction and improve protein functionalities. However, most of the literature on physicochemical pretreatment techniques has been limited to the lab scale and has not been analysed at the pilot scale. Peanut-derived peptides also exhibit antioxidant, anti-hypertensive, and anti-thrombotic properties. There exists a potential to incorporate these peptides into high-fat foods to retard oxidation. These peptides can also be consumed as dietary supplements for regulating blood pressure. Further research is required to analyse the sensory attributes and shelf lives of these novel products. In addition, animal models or clinical trials need to be conducted to validate these results on a larger scale.

Interaction between protease from Staphylococcus epidermidis and pork myofibrillar protein: Flavor and molecular simulation

This study investigated the influence of a protease from Staphylococcus (S.) epidermidis on the hydrolysis and flavor development in pork myofibrillar protein (MP). The surface hydrophobicity, fluorescence, Fourier transform infrared spectra, and atomic force microscopy analysis indicated that hydrolysis significantly changed surface hydrophobicity and secondary structure of MP (p < 0.05), and improved the stability of MP in water. The contents of free amino acid from MP, especially glutamic and alanine, significantly increased (p < 0.05), and the production of volatile compound such as aldehydes, alcohols and acid were promoted under the action of protease. MP treated with S. epidermidis protease is non-cytotoxic to the HEK-293 cells. Molecular docking analysis suggested that the interaction between the protease and actin was spontaneous and mainly involved hydrogen bonding forces. In summary, this study provides a theoretical basis for the future application of S. epidermidis protease in fermented meat products.

Effects of ultrasound on the structural and emulsifying properties and interfacial properties of oxidized soybean protein aggregates

Oxidative attack leads to the oxidative aggregation and structural and functional feature weakening of soybean protein. We aimed to investigate the impact of ultrasonic treatment (UT) with different intensities on the structure, emulsifying features and interfacial features of oxidized soybean protein aggregates (OSPI). The results showed that oxidative treatment could disrupt the native soy protein (SPI) structure by promoting the formation of oxidized aggregates with β1-sheet structures through hydrophobic interactions. These changes led to a decrease in the solubility, emulsification ability and interfacial activity of soybean protein. After low-power ultrasound (100 W, 200 W) treatment, the relative contents of β1-sheets, β2-sheets, random coils, and disulfide bonds of the OSPI increased while the surface hydrophobicity, absolute ζ-potential value and free sulfhydryl content decreased. Moreover, protein aggregates with larger particle sizes and poor solubility were formed. The emulsions prepared using the OSPI showed bridging flocculation and decreased protein adsorption and interfacial tension. After applying medium-power ultrasound (300 W, 400 W, and 500 W) treatments, the OSPI solubility increased and particle size decreased. The α-helix and β-turn contents, surface hydrophobicity and absolute ζ-potential value increased, the structure unfolded, and the disulfide bond content decreased. These changes improved the emulsification activity and emulsion state of the OSPI and increased the protein adsorption capacity and interfacial tension of the emulsion. However, after a high-power ultrasound (600 W) treatment, the OSPI showed a tendency to reaggregate, which had a certain negative effect on the emulsification activity and interfacial activity. The results showed that UT at an appropriate power could depolymerize OSPI and improve the emulsification and interfacial activity of soybean protein.

Modifying the plant proteins techno-functionalities by novel physical processing technologies: a review

Plant proteins have recently gained market demand and momentum due to their environmentally friendly origins and health advantages over their animal-derived counterparts. However, their lower techno-functionalities, digestibility, bioactivities, and anti-nutritional compounds have limited their application in foods. Increased demand for physically modified proteins with better techno-functionalities resulted in the application of different thermal and non-thermal treatments to modify plant proteins. Novel physical processing technologies (NPPT) considered 'emerging high-potential treatments for tomorrow' are required to alter protein functionality, enhance bioactive peptide formations, reduce anti-nutritional, reduce loss of nutrients, prevention of damage to heat liable proteins and clean label. NPPT can be promising substitutes for the lower energy-efficient and aggressive thermal treatments in plant protein modification. These facts captivated the interest of the scientific community in designing novel functional food systems. However, these improvements are not verifiable for all the plant proteins and depend immensely on the protein type and concentration, other environmental parameters (pH, ionic strength, temperature, and co-solutes), and NPPT conditions. This review addresses the most promising approaches of NPPT for the modification of techno-functionalities of plant proteins. New insights elaborating the effect of NPPTs on proteins' structural and functional behavior in relation to other food components are discussed. The combined application of NPPTs in the field of plant-based bioactive functionalities is also explored.

Effect of Different Temperature-Controlled Ultrasound on the Physical and Functional Properties of Micellar Casein Concentrate

Micellar casein concentrate (MCC) is a novel dairy ingredient with high protein content. However, its poor functional properties impair its potential for further application, highlighting the importance of using innovative processing methods to produce modified MCC, such as ultrasound (US). This work investigated the impact of US on the physical and functional properties of MCC under temperature-controlled and -uncontrolled conditions for different time intervals. Under temperature-controlled ultrasound (TC-US) treatment, a reduction was found in the supernatant particle size of casein micelles. Soluble calcium content and hydrophobicity increased following ultrasound treatment at 20 °C, resulting in a remarkable improvement in emulsification. However, long-time ultrasonication led to an unstable state, causing the MCC solutions to show shear thinning behavior (pseudoplastic fluid). Compared with 50 °C temperature-controlled ultrasonication, ultrasonication at 20 °C had a greater influence on particle size, viscosity and hydrophobicity. These findings indicate that 20 °C TC-US could be a promising technology for the modification of MCC.

Comparison of Different Protein Emulsifiers on Physicochemical Properties of β-Carotene-Loaded Nanoemulsion: Effect on Formation, Stability, and In Vitro Digestion

In this study, β-carotene-loaded nanoemulsions are emulsified using four biomacromolecular proteins-peanut protein isolate (PPI), soy protein isolate (SPI), rice bran protein isolate (RBPI), and whey protein isolate (WPI)-in order to explore their emulsion stability and in vitro digestion characteristics. All four nanoemulsions attained high encapsulation levels (over 90%). During the three-stage in vitro digestion model (including oral, gastric, and small intestine digestion phases), the PPI-emulsified nanoemulsion showed the highest lipolysis rates (117.39%) and bioaccessibility (37.39%) among the four nanoemulsions. Moreover, the PPI-emulsified nanoemulsion (with the smallest droplet size) also demonstrated the highest stability during storage and centrifugation, while those for the RBPI-emulsified nanoemulsion (with the largest droplet size) were the lowest. In addition, all four nanoemulsions showed superior oxidation stability when compared with the blank control of corn oil. The oxidation rates of the PPI- and WPI-stabilized groups were slower than the other two groups.

Effect of thermosonication pre-treatment on mung bean (Vigna radiata) and white kidney bean (Phaseolus vulgaris) proteins: Enzymatic hydrolysis, cholesterol lowering activity and structural characterization

Protein hydrolysates have attained great attention due to a good nutritive food ingredient and higher biological activities. In this study, thermosonication, ultrasound and heat were used as a pre-treatment to obtain (<3KDa) hydrolysate from mung bean and white kidney bean to understand the mechanism of cholesterol absorption into micelle and inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA) activity. Size exclusion high performance liquid chromatography (SE-HPLC) results of mung bean showed that the concentration of peptides (0.5KDa-1KDa and 1-3KDa) in the hydrolysate were significantly (p < 0.05) increased after thermosonication while, the peptides concentration (1-3KDa) in white kidney bean was significantly (p < 0.05) decreased. Thermosonication of mung bean hydrolysate exhibited higher inhibition of cholesterol solubilization, hydrophobicity and antioxidant activities. In addition, there was no difference observed in HMG-CoA activity and hydrophobicity between ultrasound alone and ultrasound combined with heat i.e. thermosonication treated hydrolysate of white kidney bean. Changes in secondary and tertiary structures were also analyzed under different processing conditions with maximum change due to thermosonication. Results indicated that mung bean hydrolysate had a great potential for inhibition of cholesterol synthesis and its solubility in the micelle, antioxidant activity and also convinced for its application in food and nutraceutical industries.

Effect of pH-shifting treatment on structural and heat induced gel properties of peanut protein isolate

Modifying proteins with new methods to improve their functional properties is essential to extend their application in food related field. In this study, the effect of pH-shifting treatment on structural and heat induced gel properties of peanut protein isolate (PPI) were investigated. PPI was subject to different pH conditions (pH 2, pH 4, pH 10, and pH 12) for 1 h, then adjusted back to pH 7 and they were marked as PPI2, PPI4, PPI10, and PPI12, respectively. It was found that the breaking force (BF) and water holding capacity (WHC) of PPI10 gel were significantly improved due to the decreased particle size, increased solubility, free sulfhydryl group content and surface hydrophobicity of PPI10. While PPI2 or PPI12 lost their gel ability due to the formation of large protein aggregates. These results indicated that pH-shifting treatment might be a convenient and economical method to prepare PPI with different gel and structural properties.

Thermosonication-induced structural changes and solution properties of mung bean protein

Mung bean protein is considered a highly nutritive food ingredient, but its solution properties are not well defined. In this study, suspensions of mung bean protein isolate (MPI, 10%, w/v) were subjected to high intensity ultrasound (20 kHz, 30% amplitude) at varied durations (5, 10, 20, and 30 min) with controlled temperatures (30, 50, and 70 °C) to determine the effects of thermosonication treatment on physical properties of the protein solution. Results showed that thermosonication treatment significantly reduced the particle size and free sulfhydryl content of MPI in a time-dependent manner. Ultrasound increased surface hydrophobicity, and the exposure of nonpolar groups led to the formation of soluble aggregates. Changes in secondary structure of MPI were minimal at 30 and 50 °C but were significant at 70 °C. The dissociation of native components followed by reaggregation into soluble particles following ultrasound treatment at 70 °C resulted in remarkable improvements of protein solubility (>2 fold), clarity, and stability of the MPI suspensions. The findings indicated that thermosonication could be a promising technology for the processing of mung bean protein beverage.

Study on condition of ultrasound-assisted thermo-alkali-modified peanut protein embedding curcumin for nanoparticles

This study investigated the effects of ultrasound-assisted thermo-alkali modification on the molecular structure of peanut protein. Further, the preparation conditions involved in embedding curcumin by the modified pea protein were also studied. It was found that within the pH range of 7 < pH < 11, with an increase in pH, the content of free sulfhydryl group in peanut protein isolate gradually increased from 10.35 ± 0.63 μmol/g (pH = 7) to 18.26 ± 0.93 μmol/g (pH = 10); and the content of disulfide bonds decreased from 44.62 ± 0.48 μmol/g (pH = 7) to 34.26 ± 2.03 μmol/g (pH = 11). In the ultrasonic power range (P < 300 W), with an increase in power, the content of free mercapto group in peanut protein isolate gradually increased from 12.44 ± 0.73 μmol/g to 19.46 ± 0.24 μmol/g (P = 250 W); and the content of disulfide bonds decreased from 42.29 ± 1.24 μmol/g to 33.28 ± 0.64 μmol/g (P = 300 W). Within the temperature range of 70 °C < T < 90 °C, with an increase in temperature, the content of free sulfhydryl group in peanut protein isolate gradually increased from 10.35 ± 0.94 μmol/g (T = 70 °C) to 19.67 ± 0.68 μmol/g (T = 90 °C), and the content of disulfide bonds decreased from 45.02 ± 2.84 μmol/g (T = 70 °C) to 34.26 ± 2.03 μmol/g (T = 90 °C). Response surface test was used to optimize the preparation conditions of nanoparticles from curcumin. The results showed that the optimum parameters of ultrasonic-assisted modification of peanut protein embedding curcumin were pH = 9.8, heating temperature T = 90 °C, ultrasonic power Q = 225 W, and heating time S = 21 min. Under these conditions, the embedding rate of curcumin reached 83.27 + 1.06%, the ABTS⁺ scavenging activity generally decreases with time over the 2 days period measured in PPI solution and PPI nanoparticles (PPN), the ABTS⁺ scavenging activity decreased from 40.8%, 52.2% and 67.3% to 27.1%, 39.0% and 60.5%, respectively. Compared with pure curcumin, the antioxidant activity was increased at presence of PPI.