Hydrolysis kinetics and radical-scavenging activity of gelatin under simulated gastrointestinal digestion

Effects of saccharide type and extended heating on the Maillard reaction and physicochemical properties of high-solid gelatin gels

This research delves into the Maillard reaction (MR) in high-solid gelatin-saccharide mixtures consisting of 8% and 72% of allulose, fructose, or fructo-oligosaccharides, which were subjected to varied duration (0-60min) of thermal processing prior to gelation. Physicochemical properties of the gels, including color, chemical composition, protein crosslinking, mechanical strength, in-vitro digestibility and antioxidant activities, were characterized. At pH ∼5.5 and intermediate water activities (0.6-0.7), fast browning was observed through sugar degradation and sugar-amine interactions, which were intensified by prolonged heating. The MR reactivity of saccharides followed: AL > FRU > FOS. Characteristic products (MRPs, e.g., α-dicarbonyls, 5-hydroxymethylfurfural, and advanced glycation end products) were identified, with the spectra of MRPs varying significantly between monosaccharides and oligosaccharides. The MR-induced protein glycation and crosslinking exhibited certain negative impacts on the gel strength and in-vitro protein digestibility. Furthermore, all gelatin-saccharide mixtures exhibited augmented antioxidant properties, with the gelatin-AL mixtures displaying the highest free radical scavenging rates.

Chia gum-gelatin-based encapsulation of chia sprouts phenolic compounds enhanced storage stability, bioavailability, antioxidant, antidiabetic, and antibacterial properties

Chia seeds are currently gaining popularity as functional and healthy foods. The developed chia 7-day sprout phenolic extract (CSP) is an abundant supply of highly concentrated antioxidant phenolic compounds with health-promoting and antibacterial properties. The easy destruction against different environmental changes and low bioavailability of these phenolic compounds are the main limitations of their applications/utilization. This study aims to microencapsulate the phenolic compounds of developed CSP for use as valuable functional food additives. Three microcapsules were prepared using coating materials, chia gum (CG), gelatin (G), and their mixture (CG/G) via the freeze-drying technique. The prepared CG-, CG/G-, and G-microcapsules demonstrated high encapsulation efficiency percentages of 97.0, 98.1, and 94.5%, respectively. They retained most of the CSP-phenolics (91.4-97.2%) and increased total antioxidant activity (108-127.1%). The prepared microcapsules released more CSP-phenolic compounds into the simulated intestinal stage (70-82%) than the gastric stage (15-24%), demonstrating that the coating materials enhance protection during the gastric stage. The produced microcapsules exhibited higher storage stability at 40 °C for 60 days than the non-capsulated CSP, indicating that the encapsulation provided enhanced stability. The prepared microcapsules microstructures showed uniform, smoother surfaces, and hidden micropores compared to their coating material microstructures. In addition, the connection between the functional groups of coating materials and CSP-phenolic compounds was demonstrated by FTIR analysis. The prepared CG-, CG/G-, and G-microcapsules can perfectly inhibit the α-amylase and α-glucosidase activities by 65, 68, 60 and 74, 78, and 70%, respectively, compared to CSP (54, and 66%). The three prepared microcapsules displayed better antibacterial with low MBC values (0.36-0.68 mg ml-1) compared to CSP (0.53-0.74 mg ml-1). The prepared CSP microcapsules can be incorporated into various food products to enhance their antioxidant, antidiabetic, and antibacterial properties.

Enhanced hydrophobic interaction between fish (Cyprinus carpio L.) scale gelatin and curcumin: Mechanism study

To enhance the solubility of hydrophobic nutrients, the hydrophobicity of fish scale gelatin hydrolysate (FSGH) was increased with moderate acid or alkali hydrolysis. Acid-induced FSG hydrolysate (AcFSGH) at 3 h showed a superior curcumin loading efficiency (18.30 ± 0.38 μg/mL) among all FSGHs. Compared with FSG, the proportion of hydrophobic amino acids (from 41.1% to 46.4%) and the hydrophobic interaction (from 12.72 to 20.10 mg/mL) was significantly increased in the AcFSGH. Meanwhile, the transformation of the α-helix (from 12.8% to 4.9%) to the β-sheet (from 29.0% to 42.8%) was also observed in the AcFSGH. Based on the observation in the molecular weight and morphological analysis, AcFSGH acquired the best hydrophobic interaction with curcumin, presumably due to the formation of the flexible structure of the linear hydrolyzates. The above results call for an investigation of the role of FSG hydrolysate in the synthesis of nanoparticles loaded with bioactive lipophilic compounds.

Three-Dimensional Printing Parameter Optimization for Salmon Gelatin Gels Using Artificial Neural Networks and Response Surface Methodology: Influence on Physicochemical and Digestibility Properties

This study aimed to optimize the 3D printing parameters of salmon gelatin gels (SGG) using artificial neural networks with the genetic algorithm (ANN-GA) and response surface methodology (RSM). In addition, the influence of the optimal parameters obtained using the two different methodologies was evaluated for the physicochemical and digestibility properties of the printed SGG (PSGG). The ANN-GA had a better fit (R2 = 99.98%) with the experimental conditions of the 3D printing process than the RSM (R2 = 93.99%). The extrusion speed was the most influential parameter according to both methodologies. The optimal values of the printing parameters for the SGG were 0.70 mm for the nozzle diameter, 0.5 mm for the nozzle height, and 24 mm/s for the extrusion speed. Gel thermal properties showed that the optimal 3D printing conditions affected denaturation temperature and enthalpy, improving digestibility from 46.93% (SGG) to 51.52% (PSGG). The secondary gel structures showed that the β-turn structure was the most resistant to enzymatic hydrolysis, while the intermolecular β-sheet was the most labile. This study validated two optimization methodologies to achieve optimal 3D printing parameters of salmon gelatin gels, with improved physicochemical and digestibility properties for use as transporters to incorporate high value nutrients to the body.

Nanoencapsulation Motivates the High Inhibitive Ability of Fucoxanthin on H2O2-Induced Human Hepatocyte Cell Line (L02) Apoptosis via Regulating Lipid Metabolism Homeostasis

This study reports an encapsulation system for fucoxanthin (FX) through simple affinity binding with gelatin (GE) and then coating with chitosan oligosaccharides (COS). The effects of FX before and after encapsulation on the human hepatocyte cell line (L02) were investigated. FX-GE and FX-GE-COS nanocomplexes exhibited a spherical shape with diameters of 209 ± 6 to 210 ± 8 nm. FX-GE-COS nanocomplexes were found to perform the best with the highest encapsulation efficiency (EE, 83.88 ± 4.39%), improved FX stability, and enhanced cellular uptake on the nanoscale. The cytotoxicity and cell mitochondrial damage of H₂O₂ exposure to L02 cells decreased with the increase of free-FX and FX-GE-COS nanocomplexes. FX-GE-COS nanocomplexes' intervention decreased the intracellular ROS and inhibited the apoptosis of L02 cells that was induced by H₂O₂ exposure in a concentration-dependent manner. Lipidomic analysis revealed that FX-GE-COS nanocomplexes could regulate the lipid metabolism disturbed by H₂O₂ and protected the mitochondrial function of L02 cells. These results suggested that nanoencapsulation enhanced the antioxidant activity of FX to L02 cells, and the constructed FX-GE-COS nanocomplexes have the potential to be an antioxidant nutritional dietary supplement.

Evaluating the Properties of Ginger Protease-Degraded Collagen Hydrolysate and Identifying the Cleavage Site of Ginger Protease by Using an Integrated Strategy and LC-MS Technology

(1) Methods: An integrated strategy, including in vitro study (degree of hydrolysis (DH) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity) and in vivo study (absorption after oral administration in rats), was developed to evaluate the properties of the fish skin gelatin hydrolysates prepared using different proteases (pepsin, alkaline protease, bromelain, and ginger protease). Meanwhile, in order to identify the hydrolysis site of ginger protease, the peptides in the ginger protease-degraded collagen hydrolysate (GDCH) were comprehensively characterized by liquid chromatography/tandem mass spectrometry (LC-MS) method. (2) Results: The GDCH exhibited the highest DH (20.37%) and DPPH radical scavenging activity (77.73%), and in vivo experiments showed that the GDCH was more efficiently absorbed by the gastrointestinal tract. Further oral administration experiments revealed that GDCH was not entirely degraded to free amino acids and can be partially absorbed as dipeptides and tripeptides in intact forms, including Pro-Hyp, Gly-Pro-Hyp, and X-Hyp-Gly tripeptides. LC-MS results determined the unique substrate specificity of ginger protease recognizing Pro and Hyp at the P2 position based on the amino acids at the P2 position from the three types of tripeptides (Gly-Pro-Y, X-Hyp-Gly, and Z-Pro-Gly) and 136 identified peptides (>4 amino acids). Interestingly, it suggested that ginger protease can also recognize Ala in the P2 position. (3) Conclusions: This study comprehensively evaluated the properties of GDCH by combining in vitro and in vivo strategies, and is the first to identify the cleavage site of ginger protease by LC-MS technique. It provides support for the follow-up study on the commercial applications of ginger protease and bioactivities of the hydrolysate produced by ginger protease.

Nutraceutical profiling of surimi gel containing β-glucan stabilized virgin coconut oil with and without antioxidants after simulated gastro-intestinal digestion

Surimi gels containing β-glucan stabilized virgin coconut oil (VCO) were subjected to simulated gastrointestinal digestion and the resulting digest was analyzed for nutraceutical properties. β-glucan stabilized VCO nanoemulsion (βG-V-N) remarkably improved antioxidant activities of the surimi digest. When epigallocatechin gallate (EGCG) was added in nanoemulsion, the surimi digest showed the highest antioxidant activities. Antidiabetic activity of the digest was also improved by the addition of βG-V-N comprising EGCG. Nevertheless, the addition of βG-V-N lowered ACE inhibitory activity of surimi digest. The surimi digest from the gel added with βG-V-N possessed an inhibitory effect on five cancer cell lines including HEK (Human embryonic kidney 293 cells), MCF-7 (breast cancer cell line), U87 (human glioma), HeLa (human cervical cancer), and IMR-32 (human neuroblastoma), regardless of EGCG or α-tocopherol incorporated. This study demonstrated that surimi gel supplemented with βG-V-N in the presence of EGCG exhibited nutraceutical potential and could be used as a functional food.

Effects of Lactobacillus helveticus Fermentation on the Ca2+ Release and Antioxidative Properties of Sheep Bone Hydrolysate

Both the calcium and collagen in bone powder are hard to be absorbed by the body. Although enzymatic hydrolysis by protease increased the bio-availability of bone powder, it was a meaningful try to further increase Ca2+ release, oligopeptide formation and antioxidant activity of the sheep bone hydrolysate (SBH) by lactic acid bacteria (LAB) fermentation. Lactobacillus helveticus was selected as the starter for its highest protease-producing ability among 5 tested LAB strains. The content of liberated Ca2+ was measured as the responsive value in the response surface methodology (RSM) for optimizing the fermenting parameters. When SBH (adjusted to pH 6.1) supplemented with 1.0% glucose was inoculated 3.0% L. helveticus and incubated for 29.4 h at 36℃, Ca2+ content in the fermented SBH significantly increased (p<0.01), and so did the degree of hydrolysis and the obtaining rate of oligopeptide. The viable counts of L. helveticus reached to 1.1×1010 CFU/mL. Results of Pearson correlation analysis demonstrated that LAB viable counts, Ca2+ levels, obtaining rates of oligopeptide and the yield of polypeptide were positively correlated with each other (p<0.01). The abilities of SBH to scavenge the free radicals of DPPH, OH and ABTS were also markedly enhanced after fermentation. In conclusion, L. helveticus fermentation can further boost the release of free Ca2+ and oligopeptide, enhance the antioxidant ability of SBH. The L. helveticus fermented SBH can be developed as a novel functional dietary supplement product.

Fish Skin Gelatin Hydrolysate Production by Ginger Powder Induces Glutathione Synthesis To Prevent Hydrogen Peroxide Induced Intestinal Oxidative Stress via the Pept1-p62-Nrf2 Cascade

Gelatin hydrolysate was reported to contain large amounts of biologically active peptides with excellent antioxidant properties. However, its inducement of antioxidant response within cells and the underlying molecular mechanism are far from clear. Here, gelatin from Nile tilapia skin was hydrolyzed by ginger protease to produce antioxidant hydrolysate, and three fish skin gelatin hydrolysate fractions (FSGHFs) were obtained by ultrafiltration. Fractionation of the hydrolysate increased the free radical scavenging capacity of the FSGHFs, particularly FSGHF3, which showed the lowest molecular weight (below 1000 Da). Furthermore, FSGHF3 treatment prior to H2O2 exposure increased cell viability and membrane integrity in IPEC-J2 cells. H2O2-induced ROS production and epithelial barrier damage were suppressed by FSGHF3 pretreatment. FSGHF3 stimulated the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), along with increases in the mRNA and protein expression of catalytic and modulatory subunits of γ-glutamylcysteine ligase as well as in the level of glutathione. Silencing of Nrf2 or p62 (an upstream regulator of Nrf2) suppressed FSGHF3-induced Nrf2 activation and its protection against H2O2-induced oxidative stress. Moreover, oligopeptides in FSGHF3 may mediate the cytoprotective effect against oxidative stress, which was confirmed by the result that FSGHF3 failed to inhibit the ROS production in H2O2-exposed cells with the knockdown of Pept1 (an oligopeptide transporter). Therefore, FSGHF3 can induce glutathione synthesis and prevent oxidative stress through the Pept1-p62-Nrf2 cascade and thus may be a functional food for gastrointestinal dysfunction.

Improvement of skin condition by oral administration of collagen hydrolysates in chronologically aged mice

BACKGROUND

Collagen hydrolysates (CHs) have been demonstrated to have positive effects on skin photoaging by topical application or oral ingestion. However, there has been little research on their influence on skin chronological aging. In this study, 9-month-old female ICR mice were given normal AIN-93M diets containing CHs (2.5, 5 and 10% w/w) from Nile tilapia scale.

RESULTS

After 6 months, the collagen content and antioxidant enzyme (superoxide dismutase and glutathione peroxidase) activities increased significantly (P < 0.05), while the survival rate, viscera indices and contents of moisture, fat and non-collagenous protein in skin did not change (P > 0.05). The color, luster and quantity of hair were obviously ameliorated. Moreover, the structure of epidermis and dermis, the density and distribution of collagen fibers and the ratio of type I to type III collagen were improved in a dose-dependent manner as shown by histochemical staining.

CONCLUSION

Oral ingestion of CHs increased the collagen content and antioxidant enzyme activities and improved the appearance and structure of skin. These results suggest the potential of CHs as an anti-skin-aging ingredient in nutraceuticals or functional foods. © 2016 Society of Chemical Industry.

Influence of hydrolysis behaviour and microfluidisation on the functionality and structural properties of collagen hydrolysates

The functionality and structural properties of pig skin hydrolysates with different degrees of hydrolysis (DH, 10% and 20%) and microfluidisation (120MPa), prepared by pepsin and Alcalase® have been investigated in this study. Extensive hydrolysis can significantly improve the absolute value of the zeta potential and surface hydrophobicity. The particle distribution of hydrolysates decreased with increasing DH. The numbers of free sulfhydryl (SH) and disulfide bonds (SS) were significantly increased with increasing DH (p<0.05). Hydrolysates with a lower DH showed a better emulsifying property than those with a higher DH. Microfluidisation led to the transformation of structural and interfacial properties of the hydrolysates and increased the value of the zeta potential, S₀, and gel strength. Microfluidisation results in limited breakage of chemical bonds, the number of SS and SH bonds unchanged in the treatment. These results reflect the functionality and structural properties of collagen-rich pig skin hydrolysates.

Antioxidant properties of salmon (Salmo salar L.) protein fraction hydrolysates revealed following their ex vivo digestion and in vitro hydrolysis

BACKGROUND

Salmon (Salmo salar L.) myofibryllar protein (MP) and sarcoplasmic protein (SP) were digested with human gastric and duodenal juices and hydrolysed in vitro with commercial pepsin and Corolase PP.

RESULTS

The digestion after duodenal juice/Corolase PP caused almost complete breakdown of peptide bonds in MP and SP. The DPPH(•) scavenging activity of proteins decreased during both ex vivo digestion and in vitro hydrolysis. The highest value of DPPH(•) scavenging activity was shown for the gastric digest of SP (8.88 ± 0.87%). The ABTS(+•) scavenging activity of MP and SP increased during digestion/hydrolysis. The duodenal digest of SP was characterised by the highest value of ABTS(+•) scavenging activity (72.7 ± 1.2%). In turn, the highest value of ferric-reducing power was determined for the gastric digest of SP (84.8 ± 0.2%). Salmon antioxidant peptides Phe-Ile-Lys-Lys, His-Leu, Ile-Tyr, Pro-His-Leu, Pro-Trp, Val-Pro-Trp were identified in both ex vivo digested and in vitro hydrolysed MP and SP. An antioxidant peptide, Val-Tyr, was additionally detected in the in vitro hydrolysate of SP.

CONCLUSION

The results indicate the salmon myofibrillar and sarcoplasmic protein fractions as potential sources of antioxidant peptides that could be released in the gastrointestinal tract but their amino acid sequence and quantification vary. © 2015 Society of Chemical Industry.

Determination of bioavailability and identification of collagen peptide in blood after oral ingestion of gelatin

BACKGROUND

Gelatin has long been widely used in foods, pharmaceuticals, cosmetics, and other products. However, there are few reports on its bioavailability and bioavailable forms. In this study, the bioavailability of gelatin was indirectly evaluated by the determining the bioavailability of total hydroxyproline in gelatin using a pharmacokinetic method after oral administration to rats.

RESULTS

The relative and absolute bioavailability of gelatin were 74.12% and 85.97%, respectively. The amino acid profile of plasma indicated that 41.91% of the digested gelatin was absorbed from the intestine in the form of peptide, and there was a good linear correlation between the absorbed amount of an amino acid and its content in gelatin (R(2) = 0.9566). Moreover, 17 types of collagen peptide were purified by multi-step chromatography and identified with ultra-performance liquid chromatography-electrospray ionisation-mass spectrometry.

CONCLUSION

Gelatin had high oral bioavailability. Nearly half of digested gelatin was absorbed from the intestine in the form of various collagen peptides.