Corn Protein Hydrolysate Research Articles

Improved Antioxidant, Antihypertensive, and Antidiabetic Activities and Tailored Emulsion Stability and Foaming Properties of Mixture of Corn Gluten and Soy Protein Hydrolysates Via Enzymatic Processing and Fractionation

ABSTRACTBioactive peptides and protein hydrolysates have gained considerable attention in the food industry and functional food markets due to their diverse health effects, including antioxidant, antihypertensive, and antidiabetic properties. This study aimed to produce combined soy and corn protein hydrolysates using Alcalase (Al), modification of Al‐hydrolysates through sequential hydrolysis using Flavourzyme (Al‐FL), cross‐linking of Al‐hydrolysates using microbial transglutaminase (MTGase) (Al‐TG), and fractionation of Al‐hydrolysates by ultrafiltration (UF) with molecular weight (MW) cut‐off of 100 (Al‐F4), 30 (Al‐F3), 10 (Al‐F2), and 2 kDa (Al‐F1). Notably, the < 2 kDa fraction (Al‐F1) showcased exceptional biological activities, including antioxidant (81.54% DPPH, 98.02% ABTS), antihypertensive (95.45%), and antidiabetic effects (44.72% α‐glucosidase, 77.52% α‐amylase), linked to its high hydrophobic amino acid content and low molecular weights (111 and 263 Da). Conversely, the higher molecular weight fraction (Al‐TG) excelled in emulsion and foam stability, attributed to its balanced amino acid profile and larger peptides (1385–7057 Da). Our findings reveal that specific protein hydrolysate fractions, particularly Al‐F1 and Al‐TG, are promising for applications in food and pharmaceutical formulations due to their enhanced biological and functional properties.

Exploring novel antioxidant cyclic peptides in corn protein hydrolysate: Preparation, identification and molecular docking analysis

Antioxidant cyclic peptides were successfully identified from a corn protein hydrolysate. Hydrolysate by Alcalase + Flavourzyme showed the highest cyclic peptide purity (48.36 ± 1.81 %) and higher antioxidant activities compared with other hydrolysate. The success of peptide cyclization in hydrolysate was demonstrated by thermogravimetric analysis and thin-layer chromatography (TLC) analysis. Thermogravimetric analysis showed that the thermal stability of hydrolysate after cyclization was significantly increased, which was related to the formation of cyclic peptides. Peptides with molecular weight less than 1000 Da accounted for more than 80 % in hydrolysate after cyclization. After separation using gel silica chromatography and semi-preparative reverse phase high performance liquid chromatography (RP-HPLC), 22 novel antioxidant cyclic peptides were identified by ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS) and orbitrap-tandem mass spectrometry (Orbitrap-MS/MS). Synthetic cyclic peptides with the same sequence were synthesized and characterized for their antioxidant activity. Molecular docking suggested that the free radical molecules could bind with the cyclic backbone and side chain of cyclic peptides through hydrogen bonding, hydrophobic interaction as well as electrostatic interaction. This study has important implications for the high-value utilization of corn protein and new cyclic peptides drugs or functional food development.

Corn protein hydrolysate with glutamine-rich peptides protects intestinal barrier in Caco-2 cells: Insights into structural characteristics of identified glutamine peptides

Intestinal barrier is an important basis for intestinal function, which can strictly control the exchange of substances between the host and the external environment. An intact intestianl barrier is also the guardian of human health. In this study, the protective effect of corn protein hydrolysate with glutamine-rich peptides (APH) on intestinal epithelial cell barrier was evaluated in Caco-2 cell inflammatory damage model induced by lipopolysaccharide (LPS). Then, the sequences of glutamine peptides in APH were identified by Nano LC-MS/MS, and the structural characteristics of the identified glutamine peptides were analyzed. The results showed that the hydrolysate effectively alleviated LPS-induced cell damage and decreased the inflammatory response by down-regulating the levels of pro-inflammatory cytokines (TNF-α, IL-8, and IL-1β) and up-regulating the levels of anti-inflammatory cytokine (IL-10). Moreover, the hydrolysate also up-regulated the gene expression of three tight junction proteins (ZO-1, Occludin, Claudin-1) to maintain the integrity of the intestinal epithelial barrier. More importantly, the hydrolysate protected the intestinal barrier function via down-regulating the key genes expression (TLR4, MyD88, NF-κB) in the NF-κB signaling pathway and inhibiting the overexpression of MLCK gene in the MLCK signaling pathway. Finally, 374 corn glutamine peptides were identified from APH, and their structural characteristics showed that corn glutamine peptides had high affinity with membrane proteins. Taken together, these results indicated that APH has excellent potential to protect intestinal barrier function and can be developed into a functional health food.

Physicochemical stability of corn protein hydrolysate/tannic acid complex-based β-carotene nanoemulsion delivery system.

Moderate non-covalent interaction of protein and polyphenols can improve the emulsifying property of protein itself. The corn protein hydrolysate (CPH) and tannic acid (TA) complex was successfully used to construct nanoemulsion for algal oil delivery. There has been no study on the feasibility of this nanoemulsion delivery system for other food functional components, for example, β-carotene (β-CE). CPH/TA complex-based nanoemulsion system for β-CE delivery was studied, focusing on the effect of β-CE content on the physicochemical stability of the nanoemulsions. The nanoemulsion delivery systems (dia. 150 nm) with low viscosity and good liquidity were easily fabricated by two-step emulsification. The nanoemulsions with high β-CE content (>71.5 μg/mL) significantly increased (p < .05) the emulsion droplet size. However, there was no significant (p > .05) effect of β-CE content on polydispersity index (PDI) and zeta potential of the nanoemulsions. The storage (30 days) experiment results demonstrated that the droplet size of the nanoemulsions with varying β-CE content increased slightly during storage. However, the PDI values showed a slightly decreasing trend. Zeta potentials of the nanoemulsions showed no noticeable change during storage. Moreover, after storage of 30 days, the retention ratios of β-CE were found to be up to 90%, which suggests an excellent protective effect for β-CE by the nanoemulsion systems. The CPH/TA complex stabilized nanoemulsions could aggregate in gastric condition, but the β-CE content did not have obvious effect on the digestive stability of the nanoemulsions. The CPH/TA complex could be employed as an emulsifier to construct a physicochemical stable nanoemulsion delivery system for lipophilic active components.

Identification of Corn Peptides with Alcohol Dehydrogenase Activating Activity Absorbed by Caco-2 Cell Monolayers.

Alcohol dehydrogenase (ADH) plays a pivotal role in constraining alcohol metabolism. Assessing the ADH-activating activity in vitro can provide insight into the capacity to accelerate ethanol metabolism in vivo. In this study, ADH-activating peptides were prepared from corn protein meal (CGM) using enzymatic hydrolysis, and these peptides were subsequently identified following simulated gastrointestinal digestion and their absorption through the Caco-2 cell monolayer membrane. The current investigation revealed that corn protein hydrolysate hydrolyzed using alcalase exhibited the highest ADH activation capability, maintaining an ADH activation rate of 52.93 ± 2.07% following simulated gastrointestinal digestion in vitro. After absorption through the Caco-2 cell monolayer membrane, ADH-activating peptides were identified. Among them, SSNCQPF, TGCPVLQ, and QPQQPW were validated to possess strong ADH activation activity, with EC50 values of 1.35 ± 0.22 mM, 2.26 ± 0.16 mM, and 2.73 ± 0.13 mM, respectively. Molecular Docking revealed that the activation of ADH occurred via the formation of a stable complex between the peptide and the active center of ADH by hydrogen bonds and hydrophobic interactions. The results of this study also suggest that corn protein hydrolysate could be a novel functional dietary element that helps protects the liver from damage caused by alcohol and aids in alcohol metabolism.

Purification and structural characterization of three novel anti-adhesive peptides against Helicobacter pylori from corn gluten meal

More than 50% of the world population is infected with Helicobacter pylori (H. pylori). Potential anti-adhesive peptides from corn protein hydrolysate were developed using in vitro methodologies to prevent Helicobacter pylori infection. To obtain anti-adhesive peptides against Helicobacter pylori, corn gluten meal (CGM) was hydrolyzed by neutrase, and the hydrolysate (CPHN) was purified by using Superdex peptide gel filtration, Q anion exchange and Mono Q anion exchange. Then, sequences of peptides were identified by Nano-LC-MS/MS, and the structural and functional properties of the identified peptides were characterized. Three novel peptides Pro-Tyr-Ala-Glu-Tyr (PYAEY, PY5), Ile-Ile-Pro-Gln-Cys-Ser (IIPQCS, II6) and Thr-Ile-Ile-Pro-Gln (TIIPQ, TI5) were identified, respectively. PY5 exhibited the best anti-adhesive activity among the three novel peptides, and its anti-adhesive activity was 40.75 ± 0.72% at 4 mg/mL. Meanwhile, PY5 also possessed significant 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and excellent 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity, with IC50 values of 1.650 ± 0.184 and 0.007 ± 0.001 mg/mL, respectively, suggesting that PY5 could alleviate stomach damage induced by Helicobacter pylori infection. In addition, molecular docking and dot blot results showed that PY5 could also conjugate with the Helicobacter pylori adhesins, SabA and BabA, through hydrophobic interactions and hydrogen bond inhibiting Helicobacter pylori adhesion. These results indicate that three novel peptides from corn protein hydrolysate have potential anti-adhesive and antioxidant effects and could serve as functional foods or drugs to prevent Helicobacter pylori infection.

Maillard Reaction Process and Characteristic Volatile Compounds Formed During Secondary Thermal Degradation Monitored via the Change of Fluorescent Compounds in the Reaction of Xylose-Corn Protein Hydrolysate.

Until now, no effective method has been found to monitor the Maillard reaction process for complex protein hydrolysates. Dynamic changes in the concentration of α-dicarbonyl compounds, fluorescence intensity, and browning degree were investigated during the Maillard reaction of corn protein hydrolysates. When the fluorescence intensity reached the peak, deoxyosones would continue to be increased by ARP's degradation. However, the reaction node with the highest fluorescence intensity coincided with the turning point of the browning reaction, and the subsequent browning rate remarkably increased. Therefore, the change in fluorescence intensity could be used to monitor the degradation of ARP and the formation of browning melanoidin at different stages of the Maillard reaction of complex systems, thus effectively indicating the process of the Maillard reaction. When Maillard reaction intermediates (MRIs) with maximum fluorescent compounds were heated, the most abundant pyrazines were subsequently achieved. However, furan compounds would be progressively increased during the thermal process of MRIs with continuously enhanced browning.

Preparation of Corn Peptides with Anti-Adhesive Activity and Its Functionality to Alleviate Gastric Injury Induced by Helicobacter pylori Infection In Vivo.

More than 50% of the world population is infected with Helicobacter pylori (H. pylori), which is classified as group I carcinogen by the WHO. H. pylori surface adhesins specifically recognize gastric mucosal epithelial cells' (GES-1 cells) receptor to complete the adhesion. Blocking the adhesion with an anti-adhesion compound is an effective way to prevent H. pylori infection. The present study found that corn protein hydrolysate, hydrolyzed by Neutral, effectively alleviated gastric injury induced by H. pylori infection through anti-adhesive and anti-inflammatory effects in vitro and in vivo. The hydrolysate inhibited H. pylori adhesion to GES-1 cells significantly, and its anti-adhesive activity was 50.44 ± 0.27% at 4 mg/mL, which indicated that the hydrolysate possessed a similar structure to the GES-1 cells' receptor, and exhibited anti-adhesive activity in binding to H. pylori. In vivo, compared with the H. pylori infection model group, the medium and high dose of the hydrolysate (400-600 mg/kg·bw) significantly decreased (p < 0.05) the amount of H. pylori colonization, pro-inflammatory cytokines (IL-6, IL-1β, TNF-α and MPO), chemokines (KC and MCP-1) as well as key metabolites of NF-κB signaling pathway levels (TLR4, MyD88 and NF-κB), and it increased antioxidant enzyme contents (SOD and GSH-Px) and the mitigation of H. pylori-induced pathological changes in the gastric mucosa. Taken together, these results indicated that the hydrolysate intervention can prevent H. pylori-induced gastric injury by anti-adhesive activity and inhibiting the NF-κB signaling pathway's induction of inflammation. Hence, the corn protein hydrolysate might act as a potential anti-adhesive agent to prevent H. pylori infection.

A fast stop-flow two-dimensional liquid chromatography tandem mass spectrometry and its application in food-derived protein hydrolysates

Food-derived bioactive peptides have many outstanding features like high safety, easy absorption, etc. However, explorations of the peptides are suffering from the limited knowledge of sample composition and low efficiency of separation techniques. In this work, a fast stop-flow two-dimensional liquid chromatography tandem mass spectrometry (2DLC-MS) was designed and constructed in-house. For chromatographic system optimization, the effects of column pairs and fraction transfer volumes on separation performance were studied. The pair of Protein BEH SEC and HSS T3 columns was found of high orthogonality. The peak capacity detected by the optimized 2DLC reached 1165 (for corn protein hydrolysates), indicating high resolving power. Moreover, the number of peptides identified from corn, soybean and casein protein hydrolysates reached as high as 8330, 8925 and 7215, respectively, demonstrating the high potential of the system. This would help reveal the peptide composition and facilitate the research on exploring bioactive peptides from food-derived protein hydrolysates.

Production of Corn Protein Hydrolysate with Glutamine-Rich Peptides and Its Antagonistic Function in Ulcerative Colitis In Vivo.

Ulcerative colitis is a typical chronic inflammatory disease of the gastrointestinal tract, which has become a serious hazard to human health. The purpose of the present study was to evaluate the antagonistic effect of corn protein hydrolysate with glutamine-rich peptides on ulcerative colitis. The sequential hydrolysis of corn gluten meal by Alcalase and Protamex was conducted to prepare the hydrolysate, and then the mouse ulcerative colitis model induced by dextran sulfate sodium was applied to evaluate its biological activities. The results indicated that the hydrolysate significantly improved weight loss (p &lt; 0.05), reduced the colonic shortening and the disease activity index, diminished the infiltration of inflammatory cells in the colonic tissue, and reduced the permeability of the colonic mucosa in mice. In addition, the hydrolysate decreased the contents of pro-inflammatory factors IL-1β, IL-6, and TNF-α, increased the anti-inflammatory factor IL-10 and oxidative stress markers GSH-Px and SOD in the animal tests. Moreover, the hydrolysate also regulated the abundance and diversity of the intestinal microbiota, improved the microbiota structure, and increased the content of beneficial bacteria including Lactobacillus and Pediococcus. These results indicated that the hydrolysate might be used as an alternative natural product for the prevention of ulcerative colitis and could be further developed into a functional food.

Tripeptide Leu-Pro-Phe from Corn Protein Hydrolysates Attenuates Hyperglycemia-Induced Neural Tube Defect in Chicken Embryos.

Neural tube defect (NTD) is the most common and severe embryopathy causing embryonic malformation and even death associated with gestational diabetes mellitus (GDM). Leu-Pro-Phe (LPF) is an antioxidative tripeptide isolated from hydrolysates of corn protein. However, the biological activity of LPF in vivo and in vitro remains unclear. This study is aimed at investigating the protective effects of tripeptide LPF against NTD in the high glucose exposure condition and delineate the underlying biological mechanism. We found that LPF alleviated NTD in the high glucose-exposed chicken embryo model. In addition, DF-1 chicken embryo fibroblast was loaded with high glucose for induction of oxidative stress and abnormal O-GlcNAcylation in vitro. LPF significantly decreased accumulation of reactive oxygen species and content of malondialdehyde in DF-1 cells but increased the ratio of reduced glutathione and oxidized glutathione in chick embryo. Oxygen radical absorbance capacity results showed that LPF itself had good free radical scavenging capacity and could enhance antioxidant activity of the cell content. Mechanistic studies suggested that the resistance of LPF to oxidative damage may be related to promotion of NRF2 expression and nuclear translocation. LPF alleviated the overall O-GlcNAcylation level of cellular proteins under high glucose conditions and restored the level of Pax3 protein. Collectively, our findings indicate that LPF peptide could act as a nutritional supplement for the protection of development of embryonic neural tube affected by GDM.

Simulated gastrointestinal digests of corn protein hydrolysate alleviate inflammation in caco-2 cells and a mouse model of colitis.

Inflammatory bowel disease, a typical chronic inflammatory disease of the gastrointestinal tract, make up a growing share of the global disease burden. This study firstly evaluated the anti-inflammatory effects of corn protein hydrolysate (CPH) using a cell model of tumor cell necrosis factor-α (TNF-α)-induced inflammation and a mouse model of colitis induced by dextran sodium sulfate. CPH digests significantly inhibited the expression of cyclooxygenase-2 and inducible nitric oxide synthase, and reduced the secretion of interleukin-8 in TNF-α-induced inflammation in Caco-2 cells. In mice, CPH digests significantly improved the body weight loss, clinical scores, shortening of the colon and histological symptoms, and decreased the myeloperoxidase activity, and down regulated the expression of TNF-α, and interleukin-6 in the colon. The above results indicate that the CPH can potentially be used as a health food/nutraceutical for the treatment/management of intestinal inflammation.

Synergistic effects of plant protein hydrolysates and xanthan gum on the short- and long-term retrogradation of rice starch

Controlling and delaying the retrogradation of gelatinized rice starch (GRS) can improve the quality of GRS-based foods during storage. Here, we evaluated the influence of corn protein hydrolysates (CPHs), rice protein hydrolysates (RPHs), wheat protein hydrolysates (WPHs), and soybean protein hydrolysates (SPHs) on inhibiting the short- and long- term retrogradation of RS-xanthan gum mixtures. Compared with WPHs, RPHs, CPHs, the SPHs cooperating with xanthan gum (SPHs-XT) showed the highest inhibitory effect. The increased loss tangent (tan δ) in the dynamic viscoelastic measurement suggested that SPHs-XT enhanced the liquid-like properties of GRS gel. The decreased storage modulus (G') and the reduced setback value indicated that the short-term retrogradation of GRS was restrained by SPHs-XT. Meanwhile, during a 14-day storage at 4 °C, the hardness of GRS gel was significantly decreased from 1382.5 g to 201.4 g after the addition of SPHs-XT before storage determined by using a texture profile analysis (TPA), and the relative crystallinity of the retrograded GRS was decreased from 18.18% to 8.15% determined by using a X-ray diffraction (XRD) with a corresponding decrease of the retrogradation enthalpy determined by using a differential scanning calorimetry (DSC). These results suggested that SPHs-XT could inhibit the the long-term retrogradation of GRS. Moreover, the water molecules were determined to be locked in GRS gel after the addition of SPHs-XT by using a low-field nuclear magnetic resonance (LF-NMR). In addition, thin membranes and filaments formed by the addition of SPHs-XT in GRS gel were observed by using a scanning electron microscopy (SEM), suggesting a decreased cross-linking of GRS molecules by the addition of SPHs-XT to form ordered structures. These results indicated that the addition of SPHs-XT is a potential to inhibit the short- and long-term retrogradation of GRS and further to improve the nutrition of the GRS based products.

Corn protein hydrolysate as a new structural modifier for soybean protein isolate based O/W emulsions

In the work, a new approach to modify the structure of soybean protein isolate (SPI) stabilized oil in water (O/W) emulsions based on peptides induced protein aggregation was reported.The results indicated that corn protein hydrolysate (CPH) considerably changed the physical characteristics of the SPI stabilized emulsions under the heating conditions, and the emulsions changed from flow state to semi-solid one with the increasing of CPH in CPH/SPI mixture. The results from microstructure investigation showed that more SPI molecules were adsorbed at the O/W interface and the interfacial thickness could increase due to the presence of CPH. Moreover, the study on rheological behavior showed that the apparent viscosity, viscoelasticity and thixotropic properties of the emulsions all could be modified by controlling CPH content. The structural changes of SPI-based emulsions may be attributed to the hydrophobic interactions of CPH and SPI under heating treatment, and CPH may have enhanced SPI molecular connection (at the interface or aqueous phase) through the unfolded hydrophobic locus. These findings suggested that protein hydrolysate could be used as a new structural modifier for native protein stabilized emulsions.

Changes in peptidomes and Fischer ratios of corn-derived oligopeptides depending on enzyme hydrolysis approaches

Enzyme hydrolysis of corn gluten meal (CGM) is a promising process to prepare oligopeptides with high Fischer ratios (HFOPs). However, the relationship between Fischer ratios and enzyme hydrolysis approaches remains poorly understood. In this study, peptidomes of varying corn protein hydrolysates (CPHs) before and after activated carbon adsorption were profiled and analyzed according to sequence composition and chain length. Fischer ratios of HFOPs depended on sequences in CPHs by differing enzyme hydrolysis approaches, especially branched-chain amino acid (BCAA)-aromatic amino acid (AAA)-containing-oligopeptides. Activated carbon adsorption increased BCAA-containing-oligopeptide contents and decreased oligopeptide contents including AAAs, preferring BCAA-AAA-containing-oligopeptides with long chain length. Employing a three-enzyme hydrolysis approach, HFOPs were obtained with a yield of 49%, comprising 90% of dipeptides and tripeptides and possessing additional bioactivities. This work revealed the mechanism of HFOP production depending on the release and selective removal of oligopeptides and confirmed CGM was a promising alternative for value-added HFOP production.

Stability and antioxidant activities of corn protein hydrolysates under simulated gastrointestinal digestion

AbstractBackground and objectivesBioactive peptides are expected to be ingested orally; it is important to study the effect of simulated gastrointestinal (GI) digestion on the stability and antioxidant activity of these peptides.FindingsAfter simulated GI digestion, degree of hydrolysis of corn protein hydrolysates (CPH) significantly increased from 22.7% to 39.4% while 77.5% peptides were still retained. Compared to the undigested CPH, the final CPH digests exhibited excellent antioxidant activity, including 1,1‐diphenyl‐2‐picrylhydrazyl radical 2,2‐diphenyl‐1‐(2,4,6‐trinitrophenyl) hydrazyl radical scavenging activity (12.9% increase), hydroxyl radical scavenging activity (4.1% increase), and reducing power (50.9% increase), but lower inhibition rate of linoleic acid peroxidation (41.5% decrease). The free amino acids including Pro, Asp, and Glu maintained at a low proportion during the entire course of digestion. Two GI‐resistant antioxidant peptides (Tyr‐Pro‐Gln, 406.45 Da; Ala‐Tyr‐Leu, 365.43 Da) were purified with multistep chromatography and identified by UPLC‐ESI‐MS.ConclusionsThe CPH digests exhibited excellent antioxidant activity after simulated GI digestion. The results suggested that CPH obtained by alcalase digestion are potential functional foods or nutraceuticals due to their content of bioactive peptides.Significance and noveltySome peptides containing Pro, Asp, and Glu had a strong ability to resist digestion. Two novel antioxidant peptides have been purified and identified from the CPH digests.

Contribution of specific amino acid and secondary structure to the antioxidant property of corn gluten proteins

The composition, structure, and proper positioning of amino acid in a peptide are closely related to its antioxidant activity. In this study, we purified antioxidant peptides from corn protein hydrolysates (CPH) and identified novel antioxidant peptides from fraction CPH2-III as Ala-Gly-Ile/Leu-Pro-Met (AGI/LPM; 487.62Da) and His-Ala-Ile/Leu-Gly-Ala (HAI/LGA; 467.53Da). AGLPM and HALGA exhibited better oxygen radical absorbance capacities than AGIPM and HAIGA did (P<0.05), as assessed using HepG2 cells with the cellular antioxidant activity assay (CAA) and electron spin resonance (ESR) spectroscopy. Finally, the secondary structure was determined using circular dichroism (CD). ESR showed that the AGLPM and HALGA peptides had the strongest abilities to scavenge hydroxyl radicals, by 79.41±1.41% and 75.16±2.26%, respectively. Thus, corn gluten meal could be used as a potential source of antioxidant peptides for food applications. Additionally, the amino acid Leu compared with Ile may be a critical factor contributing to strong antioxidant activity than the Ile in the peptide sequence (not C-terminus or N-terminus) and CD showed that the lower α-helix and random coil are the main causes.

Purification and identification of corn peptides that facilitate alcohol metabolism by semi-preparative high-performance liquid chromatography and nano liquid chromatography with electrospray ionization tandem mass spectrometry.

In this study, peptides that facilitate alcohol metabolism were purified and identified from corn protein hydrolysates. The ultra-filtered fraction with a molecular weight < 3 kDa (F3) potential activity was separated into six fractions (F3-H1-F3-H6) by semi-preparative high-performance liquid chromatography. Among the resultant six fractions, F3-H4 and F3-H5 exhibited the highest ability to eliminate alcohol in vivo. A total of 16 peptides with strong signal values were identified from F3-H4 and F3-H5 fractions by nano liquid chromatography coupled with electrospray ionization tandem mass spectrometry. Several identified peptides were then selected and synthesized to determine their potential to facilitate alcohol metabolism. We found that Leu-Leu and Pro-Phe were the key structure units in Gln-Leu-Leu-Pro-Phe responsible for this peptide's ability to facilitate alcohol metabolism. However, the role of Leu-Leu and Pro-Phe may be affected by peptide chain length and hydrophobic properties. Our results have thus provided some insight into the study of the structure-activity relationships of corn peptides.

Comparison of the colloidal stability, bioaccessibility and antioxidant activity of corn protein hydrolysate and sodium caseinate stabilized curcumin nanoparticles.

The aims of this work were to construct corn protein hydrolysate (CPH)-based curcumin nanoparticles (Cur NPs) and to compare the colloidal stability, bioaccessibility and antioxidant activity of the Cur NPs stabilized CPH and sodium caseinate (NaCas) respectively. The results indicated that Cur solubility could be considerably improved after the Cur NPs fabrication. The spectroscopy results demonstrated that the solubilization of Cur should be attributed to its complexation with CPH or NaCas. The Cur NPs exhibited good colloidal stability after 1week's storage but showed smaller (40nm) size in CPH than in NaCas (100nm). After lyophilization, the Cur NPs powders showed good rehydration properties and chemical stability, and compared with NaCas, the size of Cur NPs stabilized by CPH was still smaller. Additionally, the Cur NPs exhibited higher chemical stability against the temperature compared with free Cur, and the CPH could protect Cur from degradation more efficiently. Comparing with NaCas, the Cur NPs stabilized by CPH exhibited better bioaccessibility and antioxidant activity. This study demonstrated that CPH may be better than NaCas in Cur NPs fabrication and it opens up the possibility of using hydrophobic protein hydrolysate to construct the NPs delivery system.

Corn protein hydrolysate as a novel nano-vehicle: Enhanced physicochemical stability and in vitro bioaccessibility of vitamin D3

The application of colloidal delivery systems for the encapsulation, protection and increased bioavailability of bioactive ingredients has recently gained increasing interest. The aim of this work was to prepare corn protein hydrolysate-based vitamin D3 (CPH-VD3) nanocomplexes. UV and FT-IR spectra indicated the existence of non-covalent interactions (i.e. hydrogen bonding) between CPH and VD3. The result from X-ray diffraction further suggested the formation of amorphous structure of VD3 after its complexation with CPH. Additionally, dynamic light scattering and transmission electron microscope showed that the CPH-VD3 complexes exhibited a spherical structure with a size scale from 102 to 121 nm. The encapsulation and loading efficiency of VD3 could reach 97% and 9%, respectively. Furthermore, the complexation obviously avoided spontaneous particle aggregation of VD3 against ionic strength ([NaCl] ≤ 200 mmol/L). The remaining ratio of the encapsulated VD3 after exposure to high levels of UV light was as high as 72%. More importantly, in vitro bioaccessibility of VD3 could be up to 95% for the complexes. This study demonstrated that CPH could serve as a novel nano-vehicle for VD3 and it opens up the possibility of using CPH to construct the colloidal delivery system.