Physicochemical properties and antioxidant activities of tree peony (Paeonia suffruticosa Andr.) seed protein hydrolysates obtained with different proteases

Physicochemical Antioxidative and Emulsifying Properties of Soybean Protein Hydrolysates Obtained with Dissimilar Hybrid Nanoflowers

This study investigated the changes in the structure and properties of soybean protein after hydrolysis using two types of hybrid nanoflowers (alcalase@Cu3(PO4)2•3H2O (ACHNs) and dispase@Cu3(PO4)2•3H2O (DCHNs)) and examined the basic properties and oxidative stability of hydrolyzed soybean protein emulsions. The formations of the two hybrid nanoflowers were first determined using a scanning electron microscope, transmission electron microscope, and Fourier infrared spectroscopy. The structure and functional properties of soybean protein treated with hybrid nanoflowers were then characterized. The results indicated that the degree of hydrolysis (DH) of the ACHNs hydrolysates was higher than that of the DCHNs for an identical reaction time. Soybean protein hydrolysates treated with two hybrid nanoflowers showed different fluorescence and circular dichroism spectra. The solubility of the hydrolysates was significantly higher (p < 0.05) than that of the soybean protein (SPI) at all pH values tested (2.0−10.0)*: at the same pH value, the maximum solubility of ACHNs hydrolysates and DCHNs hydrolysates was increased by 46.2% and 42.2%, respectively. In addition, the ACHNs hydrolysates showed the highest antioxidant activity (DPPH IC50 = 0.553 ± 0.009 mg/mL, ABTS IC50 = 0.219 ± 0.019 mg/mL, and Fe2+ chelating activity IC50 = 40.947 ± 3.685 μg/mL). The emulsifying activity index of ACHNs and DCHNs hydrolysates reached its maximum after hydrolysis for 120 min at 61.38 ± 0.025 m2/g and 54.73 ± 0.75 m2/g, respectively. It was concluded that the two hydrolysates have better solubility and antioxidant properties, which provides a theoretical basis for SPI product development. More importantly, the basic properties and oxidative stability of the soybean-protein-hydrolysates oil-in-water emulsions were improved. These results show the importance of proteins hydrolyzed by hybrid nanoflowers as emulsifiers and antioxidants in the food and pharmaceutical industry.

The self-assembled zein hydrolysate-curcumin nanocomplex: improvement on the stability and sustainable release of curcumin

BACKGROUND

The bioavailability of curcumin (Cur) is generally limited by its poor stability. However, it is beneficial to improve the stability of Cur by using self-assembled zein hydrolysate (ZH) as delivery carrier. This paper aimed to explore the formation mechanism of zein hydrolysate-curcumin nanocomplexes as a function of critical micelle concentration (CMC).

RESULTS

In this work, The CMC of ZH (0.535 mg mL^-1 ) was obtained by the pyrene fluorescent probe method. ZH-Cur nanocomplexes undergo hydrogen bonding and hydrophobic interactions, and the fluorescence quenching effect was concentration dependent with the process of static quenching. Moreover, the differences of colloidal properties on ZH and ZH-Cur nanocomplexes were systematically compared by dynamic light scattering and scanning electron microscopy near CMC. ZH presented irregular spherical shapes and would aggregate to form micelles at the CMC and above. The tight micellar structure promoted more uniform size distribution (double peaks reduced) and higher potentials (over -30 mV) within 10 days. In addition, the nanocomplexes demonstrated an obvious core-shell structure. Within 10 days of storage, the particle size distributions were uniform and the potentials increased significantly, indicating that the micellar nanostructure made the Cur stably embedded in the hydrophobic core of ZH. Finally, ZH-Cur nanocomplexes effectively improved the water solubility and encapsulation rate (over 70%) of Cur. Moreover, over 90% of Cur was released steadily within 91 h.

CONCLUSION

This work provided a theoretical basis for the application of amphiphilic peptide micellar nanostructure as novel food-grade nanocarriers to transport hydrophobic bioactive substances. © 2022 Society of Chemical Industry.

Antioxidant Activity, Functional Properties, and Cytoprotective Effects on HepG2 Cells of Tree Peony (Paeonia suffruticosa Andr.) Seed Protein Hydrolysate as Influenced by Molecular Weights Fractionation

In recent years, plant protein hydrolysates have gained increased attention due to their superior antioxidant activity and potential to prevent several chronic diseases associated with oxidative stress. This study aimed to investigate the antioxidant activity, functional properties, and cytoprotective effects of the tree peony seed protein hydrolysate (TPSPH) with different molecular weights (MWs). The antioxidant activities were evaluated by DPPH, hydroxyl radicals scavenging, Fe2+ chelating, and inhibition of the β-carotene oxidation abilities. The protective effects and mechanism against oxidative stress were determined using H2O2-stressed HepG2 cells. MW > 30 kDa of TPSPH showed the highest radical scavenging (DPPH IC50 = 0.04, hydroxyl IC50 = 0.89 mg/mL) and inhibition of β-carotene oxidation (80.07% at 2.0 mg/mL) activity. Moreover, MW > 30 kDa possessed high hydrophobicity, emulsifying capacity, and abundant antioxidant amino acids (28.22% of hydrophobic amino acids and 8.3% of aromatic amino acids). MW 5−10 kDa exhibited more effective protection against H2O2-induced HepG2 cells, by reducing reactive oxygen species (ROS), malonaldehyde (MDA), lactate dehydrogenase (LDH), and activating antioxidant enzymes (superoxide dismutase and catalase). These results indicated the potential application of TPSPH as an antioxidant in food and functional foods.

Characterization of Pleurotus citrinopileatus hydrolysates obtained from Actinomucor elegans proteases compared with that by commercial proteases

Pleurotus citrinopileatus, a nutritious and palatable edible mushroom, can be used as an appropriate material to prepare high-grade flavoring agents. Based on this, the current study aimed to investigate the feasibility of a productive protease system from Actinomucor elegans to prepare P. citrinopileatus hydrolysate (PCH). The Actinomucor elegans crude protease (AECP) was prepared from the solid-state fermentation product of P. citrinopileatus by A. elegans. AECP and four commercial proteases (alcalase, neutrase, papain, and protamex) were applied to acquire five kinds of PCHs. The physical-chemical properties of PCHs as well as its concentration and composition of nonvolatile compounds were comparatively analyzed. Sensory evaluation and electronic tongue analysis were utilized to evaluate sensory characteristics. AECP was found to be the most effective protease, with the highest hydrolysis degree (35.91%) and protein recovery (81.46%). The result of molecular weight distribution indicated that peptides below 500 Da were the main fraction of AECP hydrolysates, while AECP hydrolysates showed the highest content of monosodium glutamate-like (20.23 ± 0.16 mg/g) and flavor 5'-nucleotide (4.30 ± 0.07 mg/g) peptides. In summary, the AECP hydrolysate had superior sensory profiles compared with other hydrolysates. In addition, AECP hydrolysates exhibited favorable kokumi taste in which peptides below 500 Da showed the highest correlation with kokumi by the results of partial least-squares regression. These results indicated the feasibility of applying PCHs as flavor additives or seasoning in the food industry. AECP might be used as an alternative enzyme choice because of its low cost and high hydrolysis efficiency. PRACTICAL APPLICATION: Pleurotus citrinopileatus served as a potential raw material for natural seasonings because of its high protein content and appropriate ratio of umami amino acids to total amino acids. Enzymatic hydrolysis was an efficient approach to improve the flavor of P. citrinopileatus, where the choice of enzyme was one of the most critical factors. The research indicated that P. citrinopileatus hydrolysate prepared by A. elegans crude protease (AECP) exhibited an acceptable flavor, which provided theoretical support for the high-value utilization of P. citrinopileatus as food seasoning. AECP might be applied as an alternative enzyme resource because of its low cost and high hydrolysis efficiency.

Effect of radio frequency, ultrasound, microwave-assisted papain, and alcalase hydrolysis on the structure, antioxidant activity, and peptidomic profile of Rosa roxburghii Tratt. seed protein

Traditional enzymatic hydrolysis methods have defects such as low efficiency and poor bioactivity in the production of active peptides. In this study, radio frequency (RF) technology was innovatively used to assist the hydrolysis of Rosa roxburghii Tratt. seed protein (RTSP) by papain and alcalase. RF-assisted hydrolysis was compared with ultrasound-(US) and microwave (MW)-assisted techniques in terms of the degree of hydrolysis, structure, antioxidant properties, and changes in the peptidome of the hydrolysates to clarify the mechanism of functional change of physically-assisted hydrolysate. All three methods improved hydrolysis efficiency. The degree of hydrolysis (DH) of papain group increased from 6.38% to 7.97%, 9.97% and 8.37% after US-, MW- and RF-assisted hydrolysis, respectively, while the DH of alcalase-treated group increased from 21.13% to 25.66%, 26.03%, and 23.01%, respectively. The in vitro antioxidant capacity and intracellular antioxidant capacity of RTSP and its hydrolysates were measured and evaluated by fuzzy statistical evaluation, and MW-assisted alcalase hydrolysis had the highest in vitro and intracellular antioxidant activity scores of 0.713 and 0.820, respectively. Fourier transform infrared and amino acid composition analysis explained the enhanced antioxidant properties of the hydrolysates. Further peptide profiling showed the physical assistance led to an increase in the species and contents of small molecule antioxidant peptides compared to enzyme treatment alone. Pearson's linear correlation analysis showed that AY, LY, IY, PHW, SVL, LHL, YYV, VYY, and NHAV were significantly correlated with the antioxidant properties of hydrolysates. Our data suggested that physical assistance such as US, MW, and RF were effective to improve the efficiency of enzymatic hydrolysis and produce novel antioxidant peptides. PRACTICAL APPLICATION: In this study, it was found that electromagnetic wave-assisted enzymatic hydrolysis could improve the efficiency of hydrolysis and enhance the antioxidant activity of hydrolysates compared to unassisted means. Compared with MW treatment, RF has the comparable hydrolysis effect, but has the advantages of high penetration ability, good uniformity, and low energy consumption and has greater potential for the production of bioactive peptides.

Protective effects of tree peony seed protein hydrolysate on Cd-induced oxidative damage, inflammation and apoptosis in zebrafish embryos

The objective of this study was to investigate protective effects of tree peony seed protein hydrolysate by Alcalase (AL-TPSPH) on oxidative damage, inflammation and apoptosis using Cd-induced zebrafish embryos. Zebrafish embryos were treated with either Cd (2 μg/L) or AL-TPSPH (25, 50 and 75 μg/mL) alone or in combination of both from 4 to 144 h post fertilization (hpf). The effects of these treatments on developments, antioxidant parameters and mRNA expression of genes related to oxidative damage, inflammation and apoptosis were examined. The results showed that co-treatment with Cd and AL-TPSPH significantly increased hatching and survival rates and decreased malformation rates of zebrafish embryos compared with Cd treatment alone group (P < 0.05). Cd-induced increase of MDA content, decreases of T-AOC content, GSH/GSSG ratio and activities of SOD, CAT and GPx in zebrafish embryos were modified upon treatment with AL-TPSPH. AL-TPSPH treatment significantly suppressed Cd-induced down-regulations of the antioxidant gene expressions (Mn-sod, Cat and GPx1a) in zebrafish embryos (P < 0.05). AL-TPSPH also prevented Cd-induced up-regulations of pro-inflammatory cytokine (TNF-α, IL-1β and IFN-γ) expressions. Moreover, AL-TPSPH inhibited Cd-induced up-regulations of pro-apoptotic genes (C-jun, Caspase-3 and Caspase-9) in zebrafish embryos. Collectively, these results indicated that AL-TPSPH could reduce Cd-induced oxidative damage, inflammation and apoptosis in zebrafish embryos, suggesting its future applications as functional food or pharmaceutical ingredient.

Physico-chemical properties, antioxidant activity, and ACE inhibitory activity of protein hydrolysates from wild jujube seed

Wild jujube seed protein (WJSP) as one kind of functional food material has attracted much attention due to its highly nutritive and medicinal value in anti-inflammatory and improving immunomodulatory ability. However, owing to its large molecular weight and complex structure, biological activities of WJSP were greatly limited and cannot be fully utilized by the human body. Therefore, how to improve the bioavailability of WJSP and develop promising WJSP nutritious materials is a great challenge. In this work, wild jujube seed protein hydrolysates (WJSPHs) were prepared from WJSP via enzymatic hydrolysis method, and their physico-chemical properties, antioxidant activity, and angiotensin converting enzyme (ACE) inhibitory activity in vitro have been investigated for the first time. SDS-PAGE electrophoresis and size-exclusion chromatographic results indicate that WJSPHs have lower molecular weight distribution (< 5,000 Da) than WJSP. Circular dichroism (CD) spectroscopy and Fourier transform infrared spectroscopy (FTIR) results illustrated that random coil is the main secondary structure of WJSPHs. Antioxidant experiments indicate that WJSPHs exhibit high radicals-scavenging ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals (94.60%), 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS⁺ ) radicals (90.84%), superoxide radicals (44.77%), and hydroxyl radicals (47.77%). In vitro, WJSPHs can significantly decrease the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), and increase the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in HepG2 cells. Moreover, ACE activity was found that can be significantly inhibited by WJSPHs (73.02%). Therefore, all previously mentioned results suggest that WJSPHs may be a promising antioxidant food to prevent oxidative-related diseases in future. PRACTICAL APPLICATION: This study shows that WJSPHs exhibit high antioxidant activity and ACE inhibitory activity in vitro, which provide potential application value as antioxidant peptides to prevent oxidative-related diseases.

Influence of ultrasound treatment on the physicochemical and antioxidant properties of mung bean protein hydrolysate

This study aimed to investigate influence of ultrasonic treatment on physicochemical and antioxidant properties of mung bean protein hydrolysate (MPH). Physicochemical properties of MPH were evaluated by Tricine-SDS-PAGE, particle size distribution, fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy, among others. Radicals scavenging activities of ABTS, hydroxyl, superoxide anion, Fe²⁺ chelating ability and reducing power characterized antioxidant activities of MPH. MPH contained four bands of 25.6, 12.8, 10.6 and 4.9 kDa, in which 4.9 kDa was the most abundant. Ultrasonic treatment increased the contents of aromatic and hydrophobic amino acids in MPH. Ultrasonic treatment decreased the content of α-helix of MPH and increased β-sheet and β-turn compared to MPH. MPH-546 W (ultrasonic treatment 546 W, 20 min) had the lowest average particle size (290.13 nm), zeta potential (-36.37 mV) and surface hydrophobicity (367.95 A.U.). Antioxidant activities of ultrasonicated-MPH increased with the ultrasonic power, achieving the lowest IC₅₀ (mg/mL) of 0.1087 (ABTS), 1.796 (hydroxyl), 1.003 (superoxide anion) and 0.185 (Fe²⁺ chelating ability) in 546 W power. These results indicated ultrasonic treatment would be a promising method to improve the antioxidant properties of MPH, which would broaden the application scope of MPH as bioactive components in the food industry.

Lipid oxidation induced egg white protein foaming properties enhancement: The mechanism study revealed by high resolution mass spectrometry

Lipid oxidation often occurs during egg white protein (EWP) storage and processing periods. Here, 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) was performed to simulate lipid oxidation to probe the oxidation effects on foaming and structural properties of EWP. Results indicated that EWP structure became unfolding and flexible after oxidation, resulting in more hydrophobic groups and negative charge exposed and soluble aggregates formed, which revealed by the results of DLS and AFM. Additionally, high resolution mass spectrometry results evidenced that ovotransferrin and lysozyme trended to be new oxidation targets with the AAPH concentration increasing, and the oxidation sites inside lysozyme proved that EWP unfolding and exposure of internal hydrophobic amino acids, which were related to the enhancement of EWP foaming properties. Overall, our study provided a further analysis of the lipid induced oxidation of EWP, which may contribute to provide a more accurate strategy for enhancing protein foaming properties in food industry.

Modulation of Gut Microbiota Composition and Short-Chain Fatty Acid Synthesis by Mogroside V in an In Vitro Incubation System

Mogroside V (MV), a sweetener, is one of the major components inSiraitia grosvenorii. In our research, after in vitro incubation with MV for 24 h, the human gut microbiota diversity changed, with an enrichment of the genera Bacteroides, Lactobacillus, Prevotella, Megasphaera, and Olsenella and the inhibition of Clostridium XlVa, Dorea, and Desulfovibrio. Moreover, the synthesis of short-chain fatty acids, such as acetate, propionate, and butyrate, was increased by gut microbiota. According to ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) analysis, MV was decomposed into secondary mogrosides, such as mogroside II/I and mogrol, by gut microbiota. Enhanced antioxidant abilities of the metabolites were found in the broth. The results suggested that MV, as a potential prebiotic, could benefit human health through its interaction with gut microbiota.