Effect of steam explosion treatments on the functional properties and structure of camellia (Camellia oleifera Abel.) seed cake protein

The underlying reasons for the efficient extraction of peanut oil by aqueous ethanol combined with roasting conditioning pretreatment

To overcome the disadvantages of severe emulsification and difficulty in obtaining free oil during aqueous extraction of peanut oil, the effect of roasting assisted aqueous ethanol extraction on free oil recovery was investigated. When peanut kernels were roasted at 180 °C for 10 min, free oil recovery increased from 57% to 96%, and the acid and peroxide values of the peanut oil met the requirements of good quality. The degree of hydration swelling of proteins in the extract increased, and soluble solids were easier to aggregate, resulting in reduced emulsification and significantly higher free oil recovery. The roasting conditions selected were found to significantly promote protein hydrophilicity, aggregation and fusion of oil bodies, as well as cell rupture, which facilitated the release of free oil but with a lower degree of protein denaturation. This study may promote the practical application of aqueous extraction technology for peanut oil.

Effect of glycosylation modification on structure and properties of soy protein isolate: A review

Soybean protein isolate (SPI) is a highly functional protein source used in various food applications, such as emulsion, gelatin, and food packaging. However, its commercial application may be limited due to its poor mechanical properties, barrier properties, and high water sensitivity. Studies have shown that modifying SPI through glycosylation can enhance its functional properties and biological activities, resulting in better application performance. This paper reviews the recent studies on glycosylation modification of SPI, including its quantification method, structural improvements, and enhancement of its functional properties, such as solubility, gelation, emulsifying, and foaming. The review also discusses how glycosylation affects the bioactivity of SPI, such as its antioxidant and antibacterial activity. This review aims to provide a reference for further research on glycosylation modification and lay a foundation for applying SPI in various fields.

Steam Explosion Pretreatment of Polysaccharide from Hypsizygus marmoreus: Structure and Antioxidant Activity

This paper investigated the effects of steam explosion (SE) pretreatment on the structural characteristics and antioxidant activity of Hypsizygus marmoreus polysaccharides (HPS). Hypsizygus marmoreus samples were pretreated at different SE temperatures (120-200 °C) and polysaccharides were extracted using the water extraction and alcohol precipitation method. The results showed that SE pretreatment improved the extraction rate of HPS. Under the conditions of SE treatment time of 60 s and temperature of 160 °C, the extraction rate of HPS was the highest (8.78 ± 0.24%). After SE pretreatment, the structural changes of HPS tended to enhance the antioxidant activity, which showed that the content of Gal and Man in the monosaccharide composition increased and the molecular weight decreased. When testing antioxidant activity in vitro, the ability of SE-pretreated HPS to scavenge DPPH radicals, hydroxyl radicals, and superoxide anion radicals was better than that of HPS without SE pretreatment. Our findings shed light on SE pretreatment as an efficient method for extracting active polysaccharides, providing a new way to improve their extraction rate and biological activity.

Extraction and improvement of protein functionality using steam explosion pretreatment: advances, challenges, and perspectives

Protein has become an increasingly valuable food component with high global demand. Consequently, unconventional sources, such as industrial and agroindustrial wastes and by-products, emerge as interesting alternatives to meet this demand, considering the UN Sustainable Development Goals and the transition to a circular economy. In this context, this work presents a review of the use of Steam Explosion (SE), a green technique that can be employed as a pretreatment for various waste materials, including bones, hide/leather, feathers, and wool, aimming the extraction of protein compounds, such as low molecular weight biopeptides, gelatin, and keratin, as well as to enhance the protein functionality of grains and meals. The SE technique and the main factors affecting the process's efficiency were detailed. Promising experimental studies are discussed, along with the mechanisms responsible for protein extraction and functionality improvement, as well as the main reported and suggested applications. In general, steam explosion favored yields in subsequent extraction processes, ranging from 27 to 95%, in addition to enhancing solubility and functional protein properties. Nonetheless, it is crucial to maintain the continuity of research on this topic to drive advancements in ensuring the safety of the extracted compounds for use in consumable products and oral ingestion.

Steam Explosion-Assisted Extraction of Ergosterol and Polysaccharides from Flammulina velutipes (Golden Needle Mushroom) Root Waste

In this work, steam explosion (SE) was applied to prompt the rapid extraction of ergosterol and polysaccharides from Flammulina velutipes root (FVR) waste. Ultrasound-assisted saponification extraction (UASE) followed by water extraction was used to prepare ergosterol and polysaccharides. The results indicated that SE destroyed the complicated structure of FVR and increased its internal porosity and surface roughness. SE caused the thermal degradation of FVR's structural components and increased the polysaccharide content 0.97-fold. As a result, the extraction yield and efficiency of ergosterol and polysaccharides were improved. The theoretical maximum extraction concentration (C∞) and diffusion coefficient (D) were increased by 34.10% and 78.04% (ergosterol) and 27.69% and 48.67% (polysaccharides), respectively. The extraction yields obtained within 20-30 min of extraction time exceeded those of untreated samples extracted after several hours. For polysaccharides, SE led to a significant reduction in the average molecular weight, increased the percentage of uronic acids and decreased the neutral sugar percentage. The monosaccharide composition was changed by SE, with an increase in the molar ratio of glucose of 64.06% and some reductions in those of other monosaccharides. This work provides an effective method for the processing of fungi waste and adds to its economic value, supporting its high-value utilization in healthcare products.

Steam explosion-assisted grinding improves the functional properties and antioxidant activity of Java tea-leaf powders (Clerodendranthus spicatus)

BACKGROUND

Java tea is widely consumed and has multiple health effects. This study established a steam explosion (SE) pretreatment method to prepare Java tea-leaf powders. The physicochemical, functional properties, phenolic extraction, and antioxidant activity of Java tea-leaf powders produced by simple and SE-assisted milling methods were investigated.

RESULTS

In comparison with simple milling, SE pretreatment broke the cell wall effectively and reduced the particle size of Java tea-leaf powders. Steam explosion-treated powders showed higher values for sensory signals, bulk and tap density, and for the water solubility index. After SE treatment, the adsorption capacities to glucose, soybean oil, and cholesterol of leaf powders were increased by up to 55, 95, and 80% respectively. The extracts from SE-treated powders also showed higher total polyphenol content and antioxidant activity.

CONCLUSION

Steam explosion treatment is helpful for the improvement of functional properties and antioxidant activity, which can benefit the development and application of Java tea-leaf powders. © 2024 Society of Chemical Industry.

Improvement of soluble dietary fiber quality in Tremella fuciformis stem by steam explosion technology: An evaluation of structure and function

Edible fungi by-products are rich in dietary fiber (DF). In this study, we used steam explosion (SE) to modify Tremella fuciformis (T. fuciformis) stem DF. The SE conditions were optimized using response surface methodology (RSM), and the soluble dietary fiber (SDF) extraction rate increased 1.42-fold (from 23.33 ± 0.42 % to 33.21 ± 0.28 %) under optimized conditions. SE destroyed the dense structure of SDF, which improved the specific surface area and thermal stability. Furthermore, the structural changes induced by SE resulted in improved functional properties, and SDF had better hydration properties (water holding capacity, oil holding capacity, and swelling capacity increased by 1.23, 1.59, and 1.24 times, respectively) and hypoglycemic capacity (glucose adsorption capacity increased 1.84-fold at 100 mmol/L glucose). Therefore, SE is an excellent modification method for improving quality of edible fungi processing by-products SDF.

Pressure-dominated steam explosion for modifying textured soy proteins: Structure and in vitro digestion kinetics

Textured Soy Proteins (TSPs) have been employed as building blocks in various food processes, but their availability remains limited. In this research, influence of Steam Explosion (SE) with pressure ranges (0, 0.5, 1.0, 1.5 MPa) on the structure and in vitro digestibility of TSPs was investigated. The results showed that 0.5 and 1.0 MPa significantly increased the relative content of β-sheets and decreased the relative content of α-helices and β-turns. Correlation analysis revealed that the structural changes made the TSP brittle, with lower thermal stability and resistance to digestion. Moreover, SE decreased the degree of hydrolysis of TSPs in the gastric stage, with the lowest degree observed for the TSP at 0.5 MPa. However, in the intestinal phase, 1.0 and 1.5 MPa significantly increased the hydrolysis degree. These findings provide a better understanding of the SE pressure-modulated quality characteristics of TSPs and suggest the processing potential of modified TSPs as functional ingredients.

Plant-based proteins from agro-industrial waste and by-products: Towards a more circular economy

There is a pressing need for affordable, abundant, and sustainable sources of proteins to address the rising nutrient demands of a growing global population. The food and agriculture sectors produce significant quantities of waste and by-products during the growing, harvesting, storing, transporting, and processing of raw materials. These waste and by-products can sometimes be converted into valuable protein-rich ingredients with excellent functional and nutritional attributes, thereby contributing to a more circular economy. This review critically assesses the potential for agro-industrial wastes and by-products to contribute to global protein requirements. Initially, we discuss the origins and molecular characteristics of plant proteins derived from agro-industrial waste and by-products. We then discuss the techno-functional attributes, extraction methods, and modification techniques that are applied to these plant proteins. Finally, challenges linked to the safety, allergenicity, anti-nutritional factors, digestibility, and sensory attributes of plant proteins derived from these sources are highlighted. The utilization of agro-industrial by-products and wastes as an economical, abundant, and sustainable protein source could contribute towards achieving the Sustainable Development Agenda's 2030 goal of a "zero hunger world", as well as mitigating fluctuations in food availability and prices, which have detrimental impacts on global food security and nutrition.

Distinctive Processing Effects on Recovered Protein Isolates from Laurel (Bay) and Olive Leaves: A Comparative Study

Although there is a well-known awareness of the nutritional potential of plant proteins, their utilization within food formulations is currently limited due to insufficient investigation of the functional properties or processing conditions. In this study, the protein contents of the remaining pulps of laurel (bay) (LL) and olive leaves (OL) after alcoholic washing (representing phenolic compound extraction), heat treatment (representing the usage of the leaves for tea brewing or as cooking aid), and deoiling process (representing oil extraction) were investigated. Bicinchoninic acid assay (BCA) indicated that the best protein yield was achieved with a direct isolation process after hexane oil removal. Both LL and OL isolates contained around 80% protein, but high temperature and alcohol content broke down the protein structure as well as decreased the final protein content (∼40%). Alcohol treatment appears to remove protein-bound phenols and increase fluorescence intensity in OL protein isolates while potentially causing structural alterations in LL proteins. In addition to a dramatic decrease in fluorescence intensity, the absolute zeta potentials of protein extracts of boiling OL and LL increased by 53 and 24%, respectively. The increased zeta potentials along with the decreased fluorescence intensity indicate the changes in the protein conformation and enhanced hydrophilicity of the protein structure, which can influence the functional properties of proteins. Protein extracts of deoiled LL had the highest ΔH value (180 mJ/mg), which is higher than other laurel and all olive protein samples. Laurel protein isolates became more thermally stable after hexane treatment. Moreover, the protein extracts after hexane treatment showed better emulsion capacity from both laurel (71.57%) and olive (61.87%). Water-binding capacity and thermal stability of the protein extracts from deoiled samples were higher than those of the other pretreatments, but the boiled samples showed higher oil-binding capacity due to protein denaturation. These findings indicate the importance of processing conditions in modulating protein properties for various applications.

The Principle of Steam Explosion Technology and Its Application in Food Processing By-Products

Steam explosion technology is an emerging pretreatment method that has shown great promise for food processing due to its ability to efficiently destroy the natural barrier structure of materials. This narrative review summarizes the principle of steam explosion technology, its similarities and differences with traditional screw extrusion technology, and the factors that affect the technology. In addition, we reviewed the applications in food processing by-products in recent years. The results of the current study indicate that moderate steam explosion treatment can improve the quality and extraction rate of the target products. Finally, we provided an outlook on the development of steam explosion technology with a reference for a wider application of this technology in the food processing field.

In-depth potential mechanism of combined demulsification pretreatments (isopropanol ultrasonic pretreatments and Ca2+ flow additions) during aqueous enzymatic extractions of Camellia oils

Emulsification is the practical limitation of aqueous enzymatic extractions of Camellia oils. This study aimed to investigate the influence and demulsification mechanisms of isopropanol ultrasonic pretreatments and Ca²⁺ additions on aqueous enzymatic extractions of Camellia oils. Combining isopropanol ultrasonic pretreatments with Ca²⁺ flow additions obtained the highest free oil recovery (78.03 %) and lowest emulsion content (1.5 %). Results indicated that the superior demulsification performance originated from the decrease in emulsion stabilities and formations. First, demulsification pretreatments reduced the oil (14.69 %) and solid (13.21 %) fractions in emulsions to decrease the stability of as-formed emulsions. Meanwhile, isopropanol ultrasonic pretreatments extracted tea saponins (0.38 mg/mL) and polysaccharides (0.23 mg/mL), while Ca²⁺ combined with protein isolates (5.82 mg/mL), tea saponins (7.48 mg/mL) and polysaccharides (0.78 mg/mL) to form precipitates and reduce emulsion formation. This work could promote the practical application of aqueous enzymatic extractions of Camellia oils and enlighten the rise of advanced demulsification pretreatments.

Sonochemical Effects on the Preparation, Structure and Function of Gliadin-(-)-Epigallo-Catechin 3-Gallate Conjugates

It is essential to understand the mechanism of action of ultrasound synergistic free radical oxidation to promote covalent reactions between proteins and polyphenols. (-)-epigallo-catechin 3-gallate (EGCG) with rich bioactivity could be used to increase the functional properties of cereal protein-gliadin (GL). This study systematically explored the role of ultrasound treatment (US) on the binding mechanisms of GL and EGCG. Electrophoresis and high-performance liquid chromatography (HPLC) confirmed the greater molecular mass of the covalent complexes in the ultrasound environment. Quantitative analysis by the phenol content revealed that the ultrasound environment increased the EGCG content in the covalent complex by 15.08 mg/g of protein. The changes in the spatial structure of the proteins were indicated by Fourier infrared and ultraviolet spectroscopy. Additionally, scanning electron microscopy (SEM) and atomic force microscopy (AFM) found that US disrupted the aggregation of GL and the clustered structure of the covalent complexes. The results demonstrated that the water solubility of ultrasonic conjugates was significantly increased by 8.8-64.19%, the digestion rate was more efficient, and the radical scavenging capacity was twice that of GL. This research contributes to the theoretical basis for broadening the application of polyphenols in modifying protein.

Structural modification of plum (Prunus domestica L) kernel protein isolate by supercritical carbon-dioxide treatment: Functional properties and in-vitro protein digestibility

The effect of supercritical carbon dioxide (SC-CO₂) treatment at different processing temperatures (30-70 °C) on the physico-functional properties, structural features, and in-vitro digestibility (IVPD) of plum kernel protein isolates (PKPI) was examined. The results revealed remarkable changes in the secondary structures of SC-CO₂-treated PKPIs, including a decrease in α-helix proportion, a concomitant increase in β-sheet content, and a considerable variation in random coils and β-turn structures. The temperature rise increased the negative zeta potential to a maximum of 31.35 mV at 60 °C, exhibiting the colloidal stability of PKPI dispersions. SDS-PAGE analysis showed variations in the intensities of protein bands, indicating denaturation and aggregation at higher temperatures. These structural and molecular changes improved water-binding capacity (1.22-fold) and oil binding capacity (1.11-fold), wettability (1.12-fold), and the highest value in all the properties was recorded at 60 °C. Moreover, the highest IVPD value (21.58 %) and a distinguishable colour difference (∆E) of 8.11 was also obtained at 60 °C of the processing temperature. Therefore, SC-CO₂ treatment-induced modification of PKPI contributed to the enhanced digestibility and techno-functional properties, which offered new prospects to extend its use in food applications.

Covalent binding of ultrasound-treated japonica rice bran protein to catechin: Structural and functional properties of the complex

Due to the existence of many disulfide bonds in japonica rice bran protein (JRBP) molecules, their solubility is poor, which seriously affects other functional properties. To improve the functional characteristics of JRBP molecules, they were processed by ultrasound technology, and JRBP-catechin (CC) covalent complex was prepared. The structural and functional properties of indica and japonica rice bran proteins and their complexes were compared; furthermore, the changes in the structural and functional properties of JRBP-CC under different ultrasound conditions were investigated. The results showed that compared with indica rice bran protein (IRBP), the secondary structure of JRBP-CC was very different, the water holding capacity (WHC) was higher, and the emulsification performance was better. Different ultrasound conditions had different effects on the functional properties of JRBP-CC. When the ultrasound power was 200 W, the λ_max redshift of the JRBP-CC complex was the most significant, the particle size was the smallest, the absolute value of the zeta potential was the largest, and the hydrophobicity and microstructure of the JRBP-CC complex were the best. Concurrently, the maximum WHC and oil holding capacity (OHC) of JRBP-CC under these conditions were 7.54 g/g and 6.87 g/g, respectively. Moreover, the emulsifying activity index (EAI) and emulsifying stability index (ESI) were 210 m²/g and 47.8 min, respectively, and the scavenging activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ABTS⁺ were 71.96 % and 80.07 %, respectively.

Characterization of sonicated gluten protein and subsequent rheological properties of model dough and noodles

BACKGROUND

The present study aimed to investigate the effects of the thermo-mechanical and rheological properties of a wheat gluten-sonicated model dough and noodles, as well as the effects of ultrasonic frequency (20, 28, 40, 68 and 80 kHz) on the functional properties and structural features of gluten.

RESULTS

Water absorption, stability and developmental time, and viscoelastic behavior of gluten-sonicated model dough were all found to be improved. Water absorption, tensile resistance and stretching distance of noodles increased markedly, whereas cooking loss decreased. Ultrasonication at different frequencies also significantly affected gluten structure, including its surface hydrophobicity, micro-network structure, and secondary and tertiary structures. These alterations then caused changes in its functional characteristics. Compared to untreated gluten, sonicated gluten exhibited significantly increased oil and water capacities (8.75-15.26% and 100.65-127.71% higher than the untreated gluten, respectively), foaming and emulsifying properties, and increased solubility (63.46-98.83% higher than control). In addition, these findings indicated that 40 kHz was the likely resonance frequency of the cavitation bubble in the gluten solution. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis electropherograms revealed that such treatments did not affect the molecular weight of gluten, which was also consistent with its unchanged disulfide bond content.

CONCLUSION

The present study clarified the impact of frequency on the properties of gluten and model dough. The best frequency for modification of gluten was 40 kHz. Collectively, these findings suggest that ultrasonic technology has the potential for use in modifying wheat gluten and commercial noodle processing. © 2022 Society of Chemical Industry.

Identification of a Novel ACE Inhibitory Hexapeptide from Camellia Seed Cake and Evaluation of Its Stability

The camellia seed cake proteins (CP) used in this study were individually hydrolyzed with neutral protease, alkaline protease, papain, and trypsin. The results showed that the hydrolysate had the highest ACE inhibitory activity at 67.36 ± 0.80% after four hours of neutral protease hydrolysis. Val-Val-Val-Pro-Gln-Asn (VVVPQN) was then obtained through ultrafiltration, Sephadex G-25 gel chromatography separation, LC-MS/MS analysis, and in silico screening. VVVPQN had ACE inhibitory activity with an IC₅₀ value of 0.13 mg/mL (198.66 μmol/L), and it inhibited ACE in a non-competitive manner. The molecular docking indicated that VVVPQN can combine with ACE to form eight hydrogen bonds. The results of the stability study showed that VVVPQN maintained high ACE-inhibitory activity in weakly acidic and neutral environments and that heat treatment (20-80 °C) and Na⁺, Mg²⁺, as well as Fe³⁺ metal ions had little effect on the activity of VVVPQN. Moreover, it remained relatively stable after in vitro simulated gastrointestinal digestion. These results revealed that VVVPQN identified in camellia seed cake has the potential to be applied in functional food or antihypertensive drugs.

Functional properties of glutelin from Camellia oleifera seed cake: Improvement by alkali-assisted phosphorylation through changes in protein structure

To explore the effect and its mechanism of alkali-assisted phosphorylation on the functional properties of Camellia Oleifera seeds cake glutelin (CSCG), CSCG was treated with different concentration of sodium trimetaphosphate (STMP, 1.0, 2.0, 3.0, 4.0, and 5%, w/v) in different pH environment (3.0, 5.0, 7.0, 9.0, and 11.0). The results showed that alkali assist improved the phosphorylation degree of CSCG, and the optimum pH value is 9.0. FT-IR and XPS confirmed the successful modification of phosphate groups on CSCG through covalent interaction. Alkali-assisted phosphorylation decreased the particle size and increased electronegativity of CSCG, as well as changed in its surface hydrophobicity, crystallinity, and intrinsic fluorescence. All these changes of protein structure triggered by alkali-assisted phosphorylation led to the improvement of water solubility, water/oil absorption capacity, emulsifying ability, foamability, and in vitro digestibility of CSCG. This work could provide a theoretical basis for industrial production of CSCG with excellent functional properties.

Extraction of Pectin from Passion Fruit Peel: Composition, Structural Characterization and Emulsion Stability

Extraction methods directly affect pectin extraction yield and physicochemical and structural characteristics. The effects of acid extraction (AE), ultrasonic-assisted acid extraction (UA), steam explosion pretreatment combined with acid extraction (SEA) and ultrasonic-assisted SEA (USEA) on the yield, structure, and properties of passion fruit pectin were studied. The pectin yield of UA was 6.5%, equivalent to that of AE at 60 min (5.3%), but the emulsion stability of UA pectin was poor. The pectin obtained by USEA improved emulsion stability. Compared with UA, it had higher protein content (0.62%), rhamnogalacturonan I (18.44%) and lower molecular weight (0.72 × 10⁵ Da). In addition, SEA and USEA had high pectin extraction yields (9.9% and 10.7%) and the pectin obtained from them had lower degrees of esterification (59.3% and 68.5%), but poor thermal stability. The results showed that ultrasonic-assisted steam explosion pretreatment combined with acid extraction is a high-efficiency and high-yield method. This method obtains pectin with good emulsifying stability from passion fruit peel.

Effect of Hydrothermal Treatment on the Structure and Functional Properties of Quinoa Protein Isolate

The aim of this study was to investigate the effects of hydrothermal treatment at different temperatures and times on the structure and functional properties of quinoa protein isolate (QPI). The structure of QPI was investigated by analyzing changes in the intrinsic fluorescence spectrum, ultra-violet (UV) spectrum, and Fourier transform infrared spectrum. The solubility, water/oil-holding capacity, emulsifying activity, and emulsion stability of QPI were studied, as were the particle size and the thermogravimetric properties of QPI. The results showed that the average particle size of QPI gradually increased with the increase in hydrothermal treatment time and temperature, and reached a maximum value of 121 °C for 30 min. The surface morphology also became rough and its thermal stability also increased. The endogenous fluorescence and UV spectral intensity at 280 nm decreased gradually with increasing hydrothermal treatment time and temperature, and reduced to the minimum values at 121 °C for 30 min, respectively. After hydrothermal treatment, the secondary structure of QPI tended to be disordered. The functional properties of QPI after treatment were all superior to those of the control. The results of this study might provide a basis for the processing and utilization of QPI.

Structural, Physicochemical and Functional Properties of Protein Extracted from De-Oiled Field Muskmelon (Cucumis melo L. var. agrestis Naud.) Seed Cake

For oil plants, the oil extraction method is a crucial factor in influencing the functional characteristics of the protein. However, reports of protein functionality as affected by the oil extraction process are scarce. In this study, field muskmelon seed (FMS) protein was extracted by Soxhlet extraction method (SE), organic solvent extraction method (OSE), aqueous extraction method (AE), and pressing extraction method (PE), and its structure, amino acid profile, physicochemical properties, and functionality were determined. Molecular weight distribution was similar for all FMS proteins, whereas protein aggregates contents were most excellent for SE and OSE. FMS protein comprised predominantly glutamic acid, leucine, aspartic acid, arginine, and proline. Total amino acids content was highest for SE. Differences in functionality between four FMS proteins for different oil extraction methods were vast. PE had the highest value of solubility, and AE exhibited the lowest. AE had the greatest water and oil holding capacity. PE presented better foaming and emulsion capacities than other samples. This study demonstrated that the extraction oil method could impact the protein’s physicochemical and associated functional characteristics. High-quality plant oil and protein could be simultaneously obtained by modulating the oil extraction method in future research.

Effect of Steam Explosion on Structural Characteristics of β-Conglycinin and Morphology, Chemical Compositions of Soybean Meal

In this study, steam explosion was applied as a means to degrade β-conglycinin. We investigated changes in morphology, the chemical composition of soybean meal, and the structural characteristics of β-conglycinin. The results showed that steam explosion at 0.7 MPa for 8 min could effectively decrease the β-conglycinin content of soybean meal while the histamine content was not increased. The structural characteristics of soybean meal proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), and X-ray diffraction (XRD). Steam explosion caused the degradation of high weight proteins and reduced the band density of α', α, and β subunits in β-conglycinin. The micro-surface of soybean meal seemed to be in the cracked or puffed stage and the color became brown or dark after steam explosion. Steam explosion facilitated the dissolution of water-extractable arabinoxylans, which are 4.81 fold higher than that of native soybean meal. Phytic acid was exposed to the hydrothermal environment of the steam explosion process and consequently degraded by 12.95-24.69%. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of soybean meal extract was gradually increased from 20.70 to 33.71% with the rising of treated pressure from 0.3 to 0.7 MPa, which was 1.11-1.81 fold of native extract. The steam explosion may be a new modification technology that could decrease antigenicity, and steam-exploded soybean meal (0.7 MPa, 8 min) with lower β-conglycinin and phytic acid content that could be widely used in food products.

Physicochemical and structural properties of dietary fiber from Rosa roxburghii pomace by steam explosion

Rosa roxburghii pomace was treated by steam explosion (SE) at 0.87 MPa for 97 s. After SE treatment, the Insoluble dietary fiber (IDF) content of Rosa roxburghii pomace decreased from 45.13 ± 0.23 to 30.01 ± 0.15%, and the soluble dietary fiber (SDF) content increased from 9.31 ± 0.07 to 15.82 ± 0.31%. The structure of IDF and SDF after SE showed that the original compact structures were destroyed, and the specific surface areas increased. Thermal analysis showed that the thermal stability of the modified SDF was improved. However, SE did not change the crystal structure and functional group composition of IDF and SDF. Physicochemical analysis indicated that IDF had better hydration capacity after SE treatment, and the oil-holding capacities of IDF and SDF were also significantly improved. SE is an effective method to improve the utilization of Rosa roxburghii pomace and a feasible method for modification of dietary fiber.

Effects of preheat treatment and polyphenol grafting on the structural, emulsifying and rheological properties of protein isolate from Cinnamomum camphora seed kernel

In this study, protein isolate (PI) and purified polyphenol extract (PPE) were prepared from Cinnamomum camphora seed kernel (CCSK). The effects of preheat treatment (50-90 °C) combined with polyphenol grafting (5 % PPE, w/w) on the structural, emulsifying and rheological properties of PI were investigated. Results demonstrated the preheat treatments at 80 and 90 °C significantly increased the extent of protein aggregation of PI. Fluorescence spectra and thermal behavior analysis revealed that preheat-treated PI exhibited more compact structure and higher thermal stability. Moreover, the emulsifying stability and apparent viscosity of PI were enhanced after preheat treatments at 50, 60 and 70 °C. After modification by PPE, the secondary structural changes of preheat-treated PI were confirmed by FTIR. PPE modification improved the thermal stability and antioxidant activities of preheat-treated PI. These results provide a novel way to combine the advantages of preheat treatment and polyphenol grafting in developing a novel protein ingredient.

Preparation of novel self-assembled albumin nanoparticles from Camellia seed cake waste for lutein delivery

The potential utilization value of Camellia seed cake was explored by extracting albumin (CSCA) to develop nanoparticles for lutein delivery. First, thermal property and amphiphilicity of CSCA were evaluated to guide nanoparticle preparation. Next, CSCA nanoparticles modified with chitosan (CS) were prepared through a thermally induced self-assembly method derived by electrostatic attraction and hydrophobic interaction. The optimized nanoparticles were prepared from CSCA:CS at a mass ratio of 2:1 with pH of 4.5, and an incubation temperature and time of 80 ℃ and 10 min, respectively. The nanoparticles had the highest effective loading capacity for lutein at 5.89 ± 0.78%, and the corresponding encapsulation efficiency was 43.82 ± 5.69%. The storage stability of lutein was improved by nanoparticle loading, and the bioaccessibility of lutein in simulated intestinal digestion increased from 26.8 ± 4.4% to 57.3 ± 9.6% after encapsulation into nanoparticles. These findings may facilitate the development of new and sustainable proteins from plant waste for delivery system applications.

Comparative study of the effects of ultrasonic power on the structure and functional properties of gliadin in wheat and green wheat

The impact of different ultrasonic power on the structure and functional properties of wheat gliadin (WG) and green wheat gliadin (GG) was investigated and compared. Ultrasound had no obvious effect on subunit composition and bands of WG and GG, and there were more small molecular weight bands in GG. The results of Fourier transform-infrared spectroscopy, intrinsic fluorescence spectroscopy, and scanning electron microscopy analyses demonstrated that ultrasonic treatment had a significant effect on the structure of WG and GG, inducing the transformation from order structure to disorder structure. The dispersion and uniformity were better at 400 and 300 W, respectively. Under proper ultrasonic treatment, the particle size of WG and GG was significantly reduced, and the free sulfhydryl groups and surface hydrophobicity were significantly increased (p < 0.05). Furthermore, the functional properties of WG and GG such as solubility, emulsification properties, water holding and oil holding properties, thermal stability, and digestibility were enhanced. The better functional properties of WG and GG were obtained at 400 and 300 W, respectively. These results indicated that ultrasonic treatment with appropriate power was a valuable method for improving functional characteristics of WG and GG. PRACTICAL APPLICATION: Ultrasonic treatment could cause structural changes of wheat gliadin (WG) and green wheat gliadin (GG), and their functional properties are improved under appropriate power. This study compares the effects of ultrasound on WG and GG, and the results will provide theoretical guidance for the development of GG in the food industry.

Modulation of the structural and functional properties of perilla protein isolate from oilseed residues by dynamic high-pressure microfluidization

Dynamic high-pressure microfluidization (DHPM) is an alternative method to physically modify proteins to improve their functional properties. In this study, perilla protein isolate (PPI) was treated by DHPM at different pressures. Results showed that DHPM treatment reduced the particle size and absolute potential of PPI by 75.90% and 22.28%. The increased surface hydrophobicity and free sulfhydryl content were observed in DHPM-treated PPI, which may be caused by the comformation changes of PPI. Furthermore, DHPM treatment would not cause the degradation of the main subunits and the variation of crystalline regions in PPI, but enhancing the thermal stability of PPI at 90 MPa and 120 MPa. Functional properties analysis indicated that DHPM treatment at 120 MPa was more effective in improving the solubility, foaming and emulsifying capacities of PPI. The results suggested that DHPM can be used to enhance the functional properties of PPI and expand its application in food systems.

Hairless canary seeds (Phalaris canariensis L.) as a potential source of antioxidant, antihypertensive, antidiabetic, and antiobesity biopeptides

Rising consumer concerns with synthetic drugs to treat non-communicable diseases (NCDs) have promoted a shift towards using natural biological active constituents that offer similar health benefits. Hairless canary seed (Phalaris canariensis L) is an emerging crop traditionally used in Mexico to treat NCDs. Peptides liberated during simulated digestion of canary seed protein are believed to be responsible for their biological activity; however, no studies have shown the effect of controlled protein hydrolysis using commercial proteases on canary seed protein’s biological activity. Therefore, this study aimed to explore the in vitro antihypertensive, antidiabetic, and anti-obesity activity of canary seed peptides derived from proteolysis with Alcalase®. Protein fractions were primarily composed of prolamins (54.07 ± 1.8%), glutelins (32.19 ± 3.18%), globulins (5.97 ± 0.52%) and albumins (5.97 ± 0.52%). The < 3 kDa and 3–10 kDa peptide fractions showed the highest inhibition capacity (p < 0.05) towards angiotensin-converting enzyme (IC50= 0.028–0.032 mg/mL) lipase (IC50= 2.15–2.27 mg/mL), α-glucosidase (IC50= 0.82–1.15 mg/mL), and dipeptidyl-peptidase-IV (IC50= 1.27–1.60 mg/mL). Additionally, these peptide fractions showed high antioxidant activity against DPPH (134.22–150.66 μmol TE/mg) and ABTS (520.92–813.33 μmol TE/mg). These results provide an insight into the potential development of functional foods using commercial enzymatic hydrolysis of canary seed proteins for treating hypertension, type-2 diabetes, and obesity.

Effects of multi-frequency ultrasound on physicochemical properties, structural characteristics of gluten protein and the quality of noodle

In this study, the influence of multi-frequency ultrasound irradiation on the functional properties and structural characteristics of gluten, as well as the textural and cooking characteristics of the noodles were investigated. Results showed that the textural and cooking characteristics of noodles that contain less gluten pretreated by multi-frequency ultrasonic were ultrasonic frequency dependent. Moreover, the noodles that contain a smaller amount of sonicated gluten could achieve the textural and cooking quality of commercial noodles. There was no significant difference in the cooking and texture characteristics between commercial noodles and noodles with 12%, 11%, and 10% gluten pretreated by single-frequency (40 kHz), dual-frequency (28/40 kHz), and triple-frequency sonication (28/40/80 kHz), respectively. Furthermore, the cavitation efficiency of triple-frequency ultrasound was greater than that of dual-frequency and single-frequency. As the number of ultrasonic frequencies increased, the solubility, water holding capacity and oil holding capacity of gluten increased significantly (p < 0.05), and the particle size was reduced from 197.93 ± 5.28 nm to 110.15 ± 2.61 nm. Furthermore, compared to the control group (untreated), the UV absorption and fluorescence intensity of the gluten treated by multi-frequency ultrasonication increased. The surface hydrophobicity of gluten increased from 8159.1 ± 195.87 (untreated) to 11621.5 ± 379.72 (28/40/80 kHz). Raman spectroscopy showed that the α-helix content of all sonicated gluten protein samples decreased after sonication, while the β-sheet and β-turn content increased, and tryptophan and tyrosine residues were exposed. Through scanning electron microscope (SEM) analysis, the gluten protein network structure after ultrasonic treatment was loose, and the pore size of the gluten protein network increased from about 10 μm (untreated) to about 26 μm (28/40/80 kHz). This work elucidated the effect of ultrasonic frequency on the performance of gluten, indicating that with increasing frequency combination increases, the ultrasound effect became more pronounced and protein unfolding increased, thereby impacting the functional properties and the quality of the final product. This study provided a theoretical basis for the application of multi-frequency ultrasound technology in the modification of gluten protein and noodle processing.