Molecular Weight Distribution Of Proteins Research Articles

Characterisation, antibacterial activity, and prebiotic potential of dried Hermetia illucens L. larvae and of their fractions

Abstract In this study, black soldier fly (BSF) dried larvae were fractionated into their defatted, lipid, protein, and chitin-rich fractions. The samples were then characterised in terms of proximate composition, analysis of amino acids, analysis of the molecular weight distribution of proteins via gel electrophoresis, and fatty acids analysis of the lipid fraction. The antibacterial activity of all fractions was determined against Escherichia coli F4 and Streptococcus suis, two common swine pathogens. Finally, the prebiotic activity of the whole larvae and of their protein isolate and chitin-rich pellet was determined for Limosilactobacillus reuteri, a naturally occurring species in the gastro-intestinal tract of the pig. The results on amino acid profile showed that the protein extraction method used was not fully effective in cleaving chitin-bound proteins, as expected, as the true protein content of the chitin-rich sample was 48.5%. This was in accordance with the SDS-PAGE analysis, where the molecular weight distribution of proteins in the protein isolate sample did not show band at higher molecular weight, which were instead present in the chitin-rich sample. The analysis of fatty acid (FA) profile showed that lauric acid was the most abundant FA, in accordance with the literature. The results on microbiological analyses highlighted how all nitrogen-containing samples showed antibacterial activity against E. coli, the highest being the defatted fraction at 1% with a decrease of −0.77 log CFU/mL, while only the lipid fraction against S. suis (−0.48 log CFU/mL at 1%). All tested samples showed prebiotic activity for L. reuteri, but it was noticed that the increase in chitin concentration resulted in the decrease of the prebiotic effect. By combining the results of both antibacterial and prebiotic tests, it could be inferred that chitin might be considered as an antibacterial compound.

Collagen-rich liver-derived extracellular matrix hydrogels augment survival and function of primary rat liver sinusoidal endothelial cells and hepatocytes

Liver sinusoidal endothelial cells (LSECs) are key targets for addressing metabolic dysfunction-associated steatotic liver disease (MASLD). However, isolating and culturing primary LSECs is challenging due to rapid dedifferentiation, resulting in loss of function. The extracellular matrix (ECM) likely plays a crucial role in maintaining the fate and function of LSECs. In this study, we explored the influence of liver-ECM (L-ECM) on liver cells and developed culture conditions that maintain the differentiated function of liver cells in vitro for prolonged periods. Porcine liver-derived L-ECM, containing 34.9 % protein, 0.045 % glycosaminoglycans, and negligible residual DNA (41.2 ng/mg), was utilized to culture primary rat liver cells in generated hydrogels. Proteomic analyses and molecular weight distribution of proteins of solubilized L-ECM revealed the typical diverse ECM core matrisome, with abundant collagens. L-ECM hydrogels showed suitable stiffness and stress relaxation properties. Furthermore, we demonstrated that collagen-rich L-ECM hydrogels enhanced LSECs' and hepatocytes' viability, and reduced the dedifferentiation rate of LSECs. In addition, hepatocyte function was maintained longer by culture on L-ECM hydrogels compared to traditional culturing. These beneficial effects are likely attributed to the bioactive macromolecules including collagens, and mechanical and microarchitectural properties of the L-ECM hydrogels.

Contribution of yeast freezing to the quality of frozen dough: Rheological properties, protein depolymerization, gluten conformation and water state

The present study has comparatively investigated the variation in yeast leachates in frozen suspension and dough systems and assessed the effects of leachate released from frozen yeast cells on dough rheology, protein molecular weight distribution, gluten conformation, and water state. The results revealed that yeast in the dough was more susceptible to freezing than that in the suspension and released more low-molecular-weight metabolites (e.g., trehalose, glutathione, and amino acids) into the dough matrix. Dynamic rheological measurements showed that frozen yeasted dough had weaker viscoelastic properties than non-yeasted dough. Fourier transform infrared spectroscopy revealed a high fraction of β-turns and random coils at the expense of α-helices and β-sheets, demonstrating a flexible protein secondary structure and increase in weakened hydrogen bonds in the gluten network. The presence of yeast in the frozen dough facilitated dough depolymerization via the cleavage of interchain disulfide bonds of gluten protein and softened the gluten network structure. Yeast leachates released from frozen yeast cells caused water redistribution in the dough and increased water release from the weakened gluten network, increasing freezable water content. This study has revealed the essential role of yeast freezing in gluten depolymerization and the deterioration of dough quality.

Selenium-enriched yeast, a selenium supplement, improves the rheological properties and processability of dough: From the view of yeast metabolism and gluten alteration

This study investigated the effect mechanism of selenium (Se)-enriched yeast on the rheological properties of dough from the perspective of yeast metabolism and gluten alteration. As the yeast Se content increased, the gas production rate of Se-enriched yeast slowed down, and dough viscoelasticity decreased. The maximum creep of Se-enriched dough increased by 29%, while the final creep increased by 54%, resulting in a softer dough. Non-targeted metabolomics analyses showed that Se inhibited yeast energy metabolism and promoted the synthesis of stress-resistance related components. Glutathione, glycerol, and linoleic acid contributed to the rheological property changes of the dough. The fractions and molecular weight distribution of protein demonstrated that the increase in yeast Se content resulted in the depolymerization of gluten. The intermolecular interactions, fluorescence spectrum and disulfide bond analysis showed that the disruption of intermolecular disulfide bond induced by Se-enriched yeast metabolites played an important role in the depolymerization of gluten.

Moderate regulation of wheat B-starch ratio: Improvement of molecular structure, spatial conformation, aggregation behavior of reconstituted fermented doughs and its processing suitability

Aiming to investigate the changes and effects of different particle sizes of wheat A/B starch during dough fermentation, the present study reconstituted A/B starch fractions in ratios of 100:0, 75:25, 50:50, 25:75, and 0:100, further blended with gluten and subjected to slight (20 min), medium (30 min), and high (60 min) fermentation processes by yeasts. Results showed that fermentation gas production promoted gluten network extension, inducing starch granule exposure and dough surface roughness. Also, fermentation fractured protein intermolecular disulfide bonds and decreased α-helix and β-folded structure content, contributing to GMP, LPP, and SPP content decreases. Moreover, moderately increasing the B-starch ratio in the dough can improve gluten network stability, continuity, and air-holding capacity. The 25A-75B steam bread exhibited optimal processing suitability (better morphology, texture, and quality) due to its higher GMP and polymer protein content with lower free sulfhydryl and monomeric protein content. Further, conformational relationships indicated the key indicators influencing dough products' properties were free sulfhydryl content, GMP content, protein molecular weight distribution, and secondary structure. The obtained findings contributed to understanding the effect of wheat starch granule size distribution on dough processing behavior, and future targeted breeding for wheat cultivars with high B-starch content for improved fermentation pasta product qualities.

Analytical Methods and Effects of Bioactive Peptides Derived from Animal Products: A Mini-Review.

Peptides with bioactive effects are being researched for various purposes. However, there is a lack of overall research on pork-derived peptides. In this study, we reviewed the process of obtaining bioactive peptides, available analytical methods, and the study of bioactive peptides derived from pork. Pepsin and trypsin, two representative protein digestive enzymes in the body, are hydrolyzed by other cofactors to produce peptides. Bicinchoninic acid assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, chromatography, and in vitro digestion simulation systems are utilized to analyze bioactive peptides for protein digestibility and molecular weight distribution. Pork-derived peptides mainly exhibit antioxidant and antihypertensive activities. The antioxidant activity of bioactive peptides increases the accessibility of amino acid residues by disrupting the three-dimensional structure of proteins, affecting free radical scavenging, reactive oxygen species inactivation, and metal ion chelating. In addition, the antihypertensive activity decreases angiotensin II production by inhibiting angiotensin converting enzyme and suppresses blood pressure by blocking the AT1 receptor. Pork-derived bioactive peptides, primarily obtained using papain and pepsin, exhibit significant antioxidant and antihypertensive activities, with most having low molecular weights below 1 kDa. This study may aid in the future development of bioactive peptides and serve as a valuable reference for pork-derived peptides.

Brown rice protein–dietary fibre conjugate improves bioaccessibility of minerals via modifying gelling structure of yoghurt

SummaryThe present study aims to provide an overview of the impact of brown rice protein (BRP) conjugated with microcrystalline cellulose via the Maillard reaction on characteristic features of yoghurt and the bioaccessibility of essential minerals in this dairy product. The confirmation of conjugation was conducted using FTIR spectroscopy. Adding BRP or Maillard conjugate (MC) proved beneficial in enhancing the water‐holding capacity and decreasing the syneresis of samples. Additionally, yoghurt (MCY) containing the Maillard conjugate demonstrated superior performance in these properties. A lower number of pores and a stronger gel network (structural integrity) were identified in MCY compared to the other samples (BRPY: yoghurt containing BRP and PY: plain yoghurt). On the other hand, in general, supplementation of BRP and MC led to slight alteration in the concentration of aroma compounds. Similarly, the impact of BRP and MC on changes in the molecular weight distribution of proteins during in vitro gastrointestinal digestion was negligible. Bioaccessibility values of Ca and Mg in PY were 53.72% and 10.72%, respectively. The improvement in these values was observed in BRPY (Ca: 57.33% and Mg: 15.60%). Moreover, adding MC to yoghurt led to a tighter interface structure (indicating rigid gel), which allowed more minerals to bind, increasing mineral bioaccessibility (Ca: 64.40% and Mg: 31.14%). A higher general acceptability in sensory evaluation was scored for PY followed by MCY and BRPY. Ultimately, the positive effect of ingredients (especially MC) on yoghurt quality was obvious.

Acheta domesticus: A Natural Source of Anti-Skin-Aging Ingredients for Cosmetic Applications.

Acheta domesticus is an edible insect, rich in nutritional value and considered a sustainable protein source. This study aimed to investigate the potential application of A. domesticus extracts for anti-skin-aging purposes. The extracts were prepared by maceration at ambient temperature with 95% ethanol or hexane and maceration in gentle heat (45 °C) with 95% v/v ethanol or DI water. The extracts were examined for total protein, phenolic, and flavonoid contents. Protein molecular weight distribution was analyzed. The safety of the extracts was investigated in terms of irritation and cytotoxicity. Biological activities relevant to the inhibition of skin aging were evaluated, including increasing transforming growth factor-beta 1 (TGF-β1) expression and inhibitory activities on collagenase and hyaluronidase. The aqueous extract from maceration in gentle heat had the highest total protein content (63 ± 1% w/w), total phenolic content (0.48 ± 0.03 mg GAE/g extract), TGF-β1 stimulating activities (33 ± 2 pg/mL), and collagenase inhibition (with a half maximal inhibitory concentration of 26 ± 1 µg/mL) among various extracts investigated. It caused no irritation to the hen's egg chorioallantoic membrane and showed no cytotoxicity to human dermal fibroblasts and peripheral blood mononuclear cells. Therefore, aqueous A. domesticus extract is proposed as an innovative natural anti-skin-aging ingredient.

Modified method for obtaining a concentrate with a high total content of phycocyanins from A. platensis

The work proposes a modified method for obtaining phycocyanin concentrate including extraction of biomass of the food cyanobacterium Arthrospira platensis and subsequent stages of membrane processing, involving combined use of double microfiltration and single- stage ultrafiltration. Extraction of A. platensis biomass was carried out at a temperature of +40°C for 3 hours in potassium phosphate buffer, and the purity of the extract was 0.61. Double microfiltration of the extract and ultrafiltration increased the purity of the intermediate product to 2.7. The content of C-phycocyanin and allophycocyanin in the dry concentrate was (63.6±1.0)% and (4.3±0.4)%, respectively. The molecular weight distribution of protein and peptide fractions of intermediate and final products was characterized using high-pressure size exclusion liquid chromatography.

A comprehensive evaluation of milk protein molecular weight distribution based on exclusion chromatography dataset

Molecular weight is one of the main characteristic parameters of proteins, which is the basis for the functional properties of milk protein. This research aims at establishing molecular weight distribution pattern of milk protein based on exclusion chromatography. The method selected Na3PO4-Na2SO4 (0.1 M, pH 6.7) buffer as the mobile phase and detected at 220 nm by HPLC-UV. The protein molecular weight distributions were determined and compared for human milk, bovine milk, and infant formula. The proportion of macromolecular proteins is much higher in infant formula compared to human or bovine milk. The protein molecular weights of human and bovine milk are significantly different around 90, 20, 14, and 2 kDa. The results provide holistic compare of bovine milk, human milk, and infant formula through protein molecular distribution. The new evaluation indicators for protein will drive technological simulation of infant formula.

The molecular mechanisms of extracellular matrix-derived hydrogel therapy in idiopathic pulmonary fibrosis models

Idiopathic Pulmonary Fibrosis (IPF) is a progressively debilitating lung condition characterized by oxidative stress, cell phenotype shifts, and excessive extracellular matrix (ECM) deposition. Recent studies have shown promising results using decellularized ECM-derived hydrogels produced through pepsin digestion in various lung injury models and even a human clinical trial for myocardial infarction. This study aimed to characterize the composition of ECM-derived hydrogels, assess their potential to prevent fibrosis in bleomycin-induced IPF models, and unravel their underlying molecular mechanisms of action. Porcine lungs were decellularized and pepsin-digested for 48 h. The hydrogel production process, including visualization of protein molecular weight distribution and hydrogel gelation, was characterized. Peptidomics analysis of ECM-derived hydrogel contained peptides from 224 proteins. Probable bioactive and cell-penetrating peptides, including collagen IV, laminin beta 2, and actin alpha 1, were identified. ECM-derived hydrogel treatment was administered as an early intervention to prevent fibrosis advancement in rat models of bleomycin-induced pulmonary fibrosis. ECM-derived hydrogel concentrations of 1 mg/mL and 2 mg/mL showed subtle but noticeable effects on reducing lung inflammation, oxidative damage, and protein markers related to fibrosis (e.g., alpha-smooth muscle actin, collagen I). Moreover, distinct changes were observed in macroscopic appearance, alveolar structure, collagen deposition, and protein expression between lungs that received ECM-derived hydrogel and control fibrotic lungs. Proteomic analyses revealed significant protein and gene expression changes related to cellular processes, pathways, and components involved in tissue remodeling, inflammation, and cytoskeleton regulation. RNA sequencing highlighted differentially expressed genes associated with various cellular processes, such as tissue remodeling, hormone secretion, cell chemotaxis, and cytoskeleton engagement. This study suggests that ECM-derived hydrogel treatment influence pathways associated with tissue repair, inflammation regulation, cytoskeleton reorganization, and cellular response to injury, potentially offering therapeutic benefits in preventing or mitigating lung fibrosis.

Protein hydrolysis of Camelina sativa meals: A study of molecular weight distribution and emulsifying properties

Camelina is an ancient oilseed known for its healthy oil composition and high crude protein content. Efforts have recently been made to reintroduced camelina in Europe and North America. This study aimed to propose an innovative strategy for valorising the camelina meal, a by-product obtained after oil extraction. Specifically, the investigation focused on the hydrolysis of protein directly applied to camelina meal studying two enzymes (Alcalase® and Protamex®) across three Camelina varieties (Calena, Vera and Sonny). Protein hydrolysates were successfully produced, with a maximum weight yield of 47%, and achieved values above 49 g/100 g in crude protein content and 58% in protein yield. The study revealed that Alcalase® and Protamex® produced similar protein molecular weight distribution but exhibited distinct technological properties. The emulsifying capacities of the protein hydrolysates were enhanced by Alcalase®, with the maximum emulsifying activity index reaching 36 m2/s. Conversely, Protamex® decreased the emulsifying capabilities of protein hydrolysates. To evaluate the applicability of the protein hydrolysates obtained, an oil-in-water emulsion was selected as a food application. The results suggested that camelina protein hydrolysates have the potential to serve as a new emulsifier ingredient. Furthermore, no significant differences were observed among the three camelina varieties in terms of protein yields or technological properties.

Sea Bass Side Streams Extracts Obtained by Pulsed Electric Fields: Nutritional Characterization and Effect on SH-SY5Y Cells.

Fish side streams are an environmental and economic problem. In this work, pulsed electric fields (PEF) extraction was optimized and used as a new method for their valorization. Sea bass head, skin, viscera, and backbone were used. PEF technology (123-300 kJ/kg, 1-3 kV/cm) improved the extraction of proteins and antioxidant compounds from head and skin, but was not successful for viscera. SDS-PAGE showed that the protein molecular weight distribution was affected by the extraction process, revealing differences between the control and PEF extraction conditions. In addition, the extraction of macro-minerals and micro-minerals were also evaluated. The effect of PEF differed according to the matrix and the mineral studied. Heavy metals were also taken into account, studying the presence of As, Cd, Hg, and Pb in the extracts. PEF pre-treatment reduced the presence of As in skin, viscera, and backbone, ranging from 18.25 to 28.48% according to the matrix evaluated. The analysis of potential antioxidant bioactive peptides showed that the treatment of the sample directly influenced their variety. Additionally, the extracts obtained from the head were found to increase cell viability when tested on SH-SY5Y cells. In conclusion, PEF extraction can be a useful tool for the valorization of fish side streams.

Peptide Mapping with LC-HRMS and In Silico Tools for Evaluation of Potential Allergenicity of Commercially Available Whey Protein Hydrolysates

Hypoallergenic formulas containing hydrolyzed protein are intended for use by infants to prevent cow’s milk protein allergy. The degree of hydrolysis of epitopic areas determines the residual allergenicity of whey protein hydrolysates (WPHs). However, only amino-acid-based infant formulas (IFs) are considered entirely nonallergenic. The aim of this study was to investigate four commercially available WPHs with different degree of hydrolysis (H1–H4) for potential allergenicity, by applying LC-HRMS analysis of peptides, and using in silico tools to search for the immunoglobulin (IgE)-binding allergenic epitopes from the Immune Epitope Database. Additionally, the molecular weight distribution of proteins and peptides in the WPHs was measured by SE-UPLC. Based on the peptide coverage and peptide-length distribution profiles, the WPHs showed different extents of hydrolysis: extensively (H1 and H2), partially (H3), and slightly hydrolyzed (H4). Altogether, numerous peptides related to 46 specific IgE-binding epitopes from β-lactoglobulin and α-lactalbumin were found in all the WPHs, regardless of their extent of hydrolysis. Sequence-based identification of the specific peptide composition, with an application of in silico tools, is a reliable approach for discovering the potential allergenicity of protein hydrolysates for IFs.

Emulsion formation during enzymatic protein hydrolysis and its effect on protein recovery and molecular weight distribution of protein hydrolysates from sardine (Sardina pilchardus) by-products

AbstractRecovery of protein is one of the important variables to optimise enzymatic hydrolysis of fish processing by-products. This study investigated the role played by emulsion formation on protein recovery and the molecular weight distribution of the protein hydrolysates at different solids concentration of fish processing by-products with a high oil content. Solids concentration of fish processing by-products was varied between 26 and 50% at constant pH of 7.8, 60 °C hydrolysis temperature and 4% enzyme dosage using Alcalase 2.4L. The results showed that emulsion formation, more than inhibition of enzyme activity, at high solids concentration contributed to the reduction in yield of dry solids and protein recovery. Emulsion formation also led to the presence of high molecular weight lipo-protein complexes in the protein hydrolysates, which caused an increase in the average molecular weight of the hydrolysates. The findings show the negative relationship between solids concentration, protein recovery and emulsion formation in enzymatic hydrolysis, and the need for methods that eliminate or reduce emulsion formation at high solids concentration without increasing process complexity or reducing protein recovery.

Study of Physicochemical and Gelation Properties of Fish Gelatin from Different Sources

Fish gelatin has been increasingly used as a safe alternative to cattle and pig gelatin due to its similar structure, avoiding the health and socio-cultural issues associated with the use of materials of mammalian origin. Fish gelatin can be produced from processed fish products to achieve a high yield at a low cost. Recent studies show that although fish gelatin comes from a wide range of sources, the protein content and amino acid composition of fish gelatin from different sources are different, and some fish gelatin is soft and unstable transglutaminase (TGase) can catalyze the γ-amide group of glutamine residues and the ε-amino group of lysine residues in proteins to form covalent bonds to form a stable protein network structure, improve the strength of the gel so that it can be applied in a more special environment. In this experiment, after screening the raw materials of cold-water fish gelatin M06 and M08, warm-water fish gelatin M03 and M04, a strong fish gelatin was successfully prepared by catalytic modification of cold-water fish gelatin by transglutaminase (TGase), and the excellent performance of TG enzyme-catalyzed modified gelatin was proved through the application effect of chicken salt soluble protein. In this experiment, the protein content of cold-water fish M08 was the highest, which was up to 99.9%, 1.09 times that of warm-water fish. The gelatin content of cold-water fish M08 was the highest of the four kinds of fish gelatin, with a wide proportion of components and rich amino acid composition. Cold-water fish M08 gelatin-derived gel had the highest strength of 253 ± 1 g/cm at 4 °C. It was found that fish gelatin with protein molecular weight distribution and rich amino acid composition had higher gel strength. M08 gelatin is cross-linked by transglutaminase (TGase), which increases the strength of enzyme gels by approximately 200% compared to self-assembled gels. Fish gelatin catalyzed by the TG enzyme improves the gel strength of raw material and makes it more applicable. M08 gelatin also showed good application performance at low temperatures in compound chicken salt-soluble protein gel, with a water retention rate of 95.84% and gel strength of 198.5 g/cm. This study expanded the application range of fish gelatin by TG enzyme and improved the application potential of fish gelatin.

Characterization of commercial cricket protein powder and impact of cricket protein powder replacement on wheat dough protein composition

Background and Objectives Supplementation of foods with insect flours has been shown to be promising for improving the nutritional profile of food products. The objective of this study was to characterize two commercially available cricket protein powders and investigate their impact on molecular weight distribution when incorporated into wheat dough. Findings Characterization of commercial cricket protein powders, GrioPro® (G) and Entomo Farms (E) was carried out by size exclusion high-performance liquid chromatography (SEC-HPLC), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The functionality of the cricket protein powders was examined by measuring water holding capacity (WHC) and protein solubility across a range of pH. To see the interactions between the cricket proteins in a food-based system wheat dough samples containing 10% or 20% replacement levels of the cricket powders were collected at peak torque development and analyzed to SEC-HPLC to quantify the change in soluble polymeric proteins (SPP) and insoluble polymeric proteins (IPP) and provide information on changes to protein molecular weight distribution. SDS-PAGE analysis showed bands ranging from 40 kDa to 160 kDa for sample E while sample G had no visible bands either due to poor solubility in SDS-PAGE sample buffer and/or the presence of very high molecular proteins that did not enter the gel. Sample E absorbed approximately 2.5 times its weight in water, which was significantly lower than G (~3.0 times its weight) while sample G was significantly lower in solubility than E across all pH levels. Conclusions Both cricket protein powders increased in WHC and solubility as the pH increased. Wheat dough samples containing sample E had lower peak areas of IPP and no significant difference in SPP peak areas compared to the control. On the other hand, doughs containing sample G had a significant increase in IPP peak areas at the 20% replacement level. Significance and Novelty This study shows how the difference in processing changed the functionality of G and E which impacted their interactions when added to a wheat dough-based system.

Improving the surface tackiness of frozen cooked noodles by the addition of glutenin, gliadin, and gluten

The mechanism of gluten components on surface tackiness of frozen cooked noodles (FCNs) during processing is still unclear. The internal relationship between gluten components and the surface tackiness of FCNs during manufacturing process was investigated. Texture characteristics, surface tackiness, gelatinization degree, thermal stability, free sulfhydryl, protein molecular weight distribution, secondary structure, surface and internal microstructure of FCNs were determined. The results showed that the addition of glutenin could strengthen the backbone of gluten network, decrease free sulfhydryl content (1.81 μmol/g) of pre-cooked noodles, increase the gelatinization degree (89.71%), protein aggregation (glutenin macropolymers: 86.55%) and ordered secondary structure of recooked FCNs, and resist the damage of gluten network caused by pre-cooking. The addition of gliadin could promote the formation of membrane gluten network, improve the extensibility (tensile distance: 0.0212 m) of FCNs, resist the damage of gluten network during freezing storage for wrapping starch particles more tightly, and decrease the surface tackiness (3.60 N) of recooked FCNs. Gluten combined the advantages of glutenin and gliadin to strengthen gluten network and reduce the surface tackiness of FCNs. In the future, the synergistic effect of glutenin and gliadin will be further studied to regulate the surface tackiness and edible quality of FCNs.

PH and ultrasound driven structure-function relationships of soy protein hydrolysate

The structural, thermodynamic and functional properties of soy protein hydrolysate (SPH) modified by treatment at different pH values (3, 5, and 9 and pH 7 as control) followed by ultrasound treatment (240 W, 30 min) were investigated. The treatment of SPH at alkaline pH combined with ultrasound treatment resulted in a reduction in the particle size and turbidity, enhancement in the surface negative charge and disulfide bond (SS) content, and exposure of more surface sulfhydryl (SH) groups, resulting in increased surface hydrophobicity and fluorescence intensity compared to those of the samples treated at pH 3–7. In addition, the alkaline-treated samples were more structurally stable than those treated at other pH values, having higher denaturation temperatures and enthalpies; moreover, these samples had higher solubility and emulsifying and foaming capacities. In addition, ultrasound-assisted pH treatment altered the secondary and tertiary structures of SPH by altering the covalent and non-covalent interactions, although there was no effect on the molecular weight distribution of proteins. In conclusion, ultrasound-assisted pH treatment is an effective method to improve physicochemical properties of SPH for applications in the food industry.

Effect of Grafted Insect Protein with Palatinose on Quality Properties of Phosphate-Free Meat Emulsion.

Due to concerns about the negative effects of phosphate on human health, the development of phosphate substitutes is an active area of research. Among the various methods, the structural modification of proteins has previously been established. In this study, we used grafting technology. Extracted insect protein was grafted with palatinose (GI), and 0.1 and 0.15% of GI were added to a phosphate-free meat emulsion mixed with 0.1% of eggshell powder (ES). The pH, myofibrillar protein solubility, and apparent viscosity increased with the addition of GI and ES (p < 0.05). Color values were also affected by GI and ES addition (decreased CIE L* and CIE a* and increased CIE b*; p < 0.05), while cooking loss was only improved by the addition of ES and not GI. Although the total fluid separated more than negative control (p < 0.05), the addition of ES improved emulsion stability and total expressible fluid separation and the fat separation reduced with addition of GI and ES (p < 0.05). Lipid oxidation was inhibited by the addition of GI and ES (p < 0.05). Moreover, the protein molecular weight distribution under 20 kDa was modified by the addition of GI, and the hardness and springiness of treatments decreased. In conclusion, the addition of GI and ES might be used to improve cooking loss, emulsion stability, and antioxidants, while the textural properties should be further researched.