Alginate/gelatin crosslinked system through Maillard reaction: preparation, characterization and biological properties

Development of crosslinked gelatin films through Maillard reaction and reinforced with poly(vinyl alcohol) for active food packaging

In order to improve the functionality of natural gelatin films for active food packaging applications, a combined strategy of crosslinking via Maillard reaction and blending enhancement incorporated with poly(vinyl alcohol) (PVA) was explored. In this study, when the mass ratio of gelatin to glucose was 10:1, Maillard reaction of crosslinked gelatin films was the highest, UV absorption and browning index reached the maximum. Infrared analysis showed that PVA could form strong interfacial interactions with gelatin matrix. The presence of PVA could significantly improve the toughness, water absorption, transparency, and oxygen barrier properties of crosslinked gelatin films. When the amount of PVA reached 5 %, elongation at break and oxygen barrier properties of crosslinked gelatin films were improved by 76.7 % and 47.9 % compared with pure crosslinked gelatin film. Even when the amount of PVA reached 10 %, UV absorption (at 315 nm) of crosslinked gelatin films still exceeded 98.7 %. The addition of PVA could accelerate the dissolution and swelling of crosslinked gelatin films, promoting the migration and release of active substances (Maillard reaction products (MRPs)). The two antioxidant activities tests (DPPH and ABTS method) achieved the highest radical scavenging rates of 71.6 % and 91.2 %, respectively, with corresponding PVA addition of 5 % and 7.5 %. After continuing to add PVA, antioxidant activities began to significantly decrease, which was directly related to the decrease in the generation of MRPs. Therefore, crosslinked gelatin films reinforced with appropriate amount of PVA can be considerable potential as active films for renewable food packaging applications.

Ishophloroglucin A-based multifunctional oxidized alginate/gelatin hydrogel for accelerating wound healing

This study investigated the potential applicability of wound dressing hydrogels for tissue engineering, focusing on their ability to deliver pharmacological agents and absorb exudates. Specifically, we explored the use of polyphenols, as they have shown promise as bioactive and cross-linking agents in hydrogel fabrication. Ishophloroglucin A (IPA), a polyphenol not previously utilized in tissue engineering, was incorporated as both a drug and cross-linking agent within the hydrogel. We integrated the extracted IPA, obtained through the utilization of separation and purification techniques such as high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), and nuclear magnetic resonance (NMR) into oxidized alginate (OA) and gelatin (GEL) hydrogels. Our findings revealed that the mechanical properties, thermal stability, swelling, and degradation of the multifunctional hydrogel can be modulated via intermolecular interactions between the natural polymer and IPA. Moreover, the controlled release of IPA endows the hydrogel with antioxidant and antimicrobial characteristics. Overall, the wound healing efficacy, based on intermolecular interactions and drug potency, has been substantiated through accelerated wound closure and collagen deposition in an ICR mouse full-thickness wound model. These results suggest that incorporating IPA into natural polymers as both a drug and cross-linking agent has significant implications for tissue engineering applications.

A Generalized Polymer Precursor Ink Design for 3D Printing of Functional Metal Oxides

Three-dimensional-structured metal oxides have myriad applications for optoelectronic devices. Comparing to conventional lithography-based manufacturing methods which face significant challenges for 3D device architectures, additive manufacturing approaches such as direct ink writing offer convenient, on-demand manufacturing of 3D oxides with high resolutions down to sub-micrometer scales. However, the lack of a universal ink design strategy greatly limits the choices of printable oxides. Here, a universal, facile synthetic strategy is developed for direct ink writable polymer precursor inks based on metal-polymer coordination effect. Specifically, polyethyleneimine functionalized by ethylenediaminetetraacetic acid is employed as the polymer matrix for adsorbing targeted metal ions. Next, glucose is introduced as a crosslinker for endowing the polymer precursor inks with a thermosetting property required for 3D printing via the Maillard reaction. For demonstrations, binary (i.e., ZnO, CuO, In2O3, Ga2O3, TiO2, and Y2O3) and ternary metal oxides (i.e., BaTiO3 and SrTiO3) are printed into 3D architectures with sub-micrometer resolution by extruding the inks through ultrafine nozzles. Upon thermal crosslinking and pyrolysis, the 3D microarchitectures with woodpile geometries exhibit strong light-matter coupling in the mid-infrared region. The design strategy for printable inks opens a new pathway toward 3D-printed optoelectronic devices based on functional oxides.

Elucidating the structure of melanoidins derived from biscuits: A preliminary study

Melanoidins present important physiological activities, but their structure is largely unknown. The objective of the present work was to reveal the physicochemical characteristics of biscuit melanoidins(BM) prepared under high temperature(HT) and low temperature(LT) conditions (150 °C/25 min-100 °C/80 min respectively). BM were characterised and analysed by differential scanning calorimetry, X-ray and FT-IR. Moreover, the antioxidant capacity and the zeta potential were determined. The phenolic content of HT-BM was higher than that of LT-BM (19.5 ± 2.6% vs 7.8 ± 0.3% respectively, p ≤ 0.05) and the antioxidant capacity determined by ABTS/DPPH/FRAP (p ≤ 0.05) was greater. Also, HT-BM presented a 30% increase in crystal structure compared to LT-BM according to X-ray analysis. The magnitude of the negative net charge was significantly higher in HT-BM (-36.8 ± 0.6) than in LT-BM (-16.8 ± 0.1)(p ≤ 0.05). FT-IR analysis confirmed the presence of phenolic and intermediate Maillard reaction compounds bound to the HT-BM structure. In conclusion, the different heating treatments applied to biscuits led to differences in the melanoidin structure.

Evaluation on the physicochemical and digestive properties of melanoidin from black garlic and their antioxidant activities in vitro

As the important compounds in black garlic, the physicochemical properties and bioactivities of melanoidin (MLD) were investigated in this study. The results showed that MLD possessed strong metal-ion chelating capacity and radical scavenging activities which were positively correlative with molecular weight (MW). During the simulated digestion in vitro, the ultraviolet absorption, browning degree and MW distribution of MLD remained the same as initial. It proved that the MLD from black garlic could be indigestible like the dietary fiber with little loss of volatile compounds and polysaccharides. Remarkably, the bioactivities of MLD were reduced significantly under the treatment of α-amylase or hydrochloric acid, while they were stable and retained over 60% after adding pepsin and pancreatin. This study provides fundamental evidences for further research and widely application of MLD and black garlic in the production of functional food or food additives.

Functional and biological properties of Maillard conjugates and their potential application in medical and food: A review

Protein and peptides are usually sensitive to environmental stresses, such as pH changes, high temperature, ionic strength, and digestive enzymes amongst other, which limit their food and medicinal applications. Maillard reaction (also called Maillard conjugation or glycation) occurs naturally without the addition of chemical agents and has been vastly applied to boost protein/peptide/amino acid functionalities and biological properties. Protein/peptide-saccharide conjugates are currently used as emulsifiers, antioxidants, antimicrobials, gelling agents, and anti-browning compounds in food model systems and products. The conjugates also possess the excellent stabilizing ability as a potent delivery system to enhance the stability and bioaccessibility of many bioactive compounds. Carbonyl scavengers such as polyphenols are able to significantly inhibit the formation of advanced glycation end products without a significant effect on early Maillard reaction products (MRPs) and melanoidins, which are currently applied as functional ingredients. This review paper highlights the technological functionality and biological properties of glycoconjugates in food model systems and products. Recent applications of MRPs in medical sciences are also presented.