Chitosan glucose complex – A novel food preservative

Use of natural peptide TP4 as a food preservative prevents contamination by fungal pathogens

Molecules of natural origin often possess useful biological activities. For instance, the natural peptide Tilapia Piscidin 4 (TP4) exhibits potent antimicrobial activity against a broad spectrum of pathogens. In this study, we explored the potential application of TP4 as a food preservative, asking whether it can prevent spoilage due to microbial contamination. A preliminary in silico analysis indicated that TP4 should interact strongly with fungal cell membrane components. Hence, we tested the activity of TP4 toward Candida albicans within fruit juice and found that the addition of TP4 could abolish fungal growth. We further determined that the peptide acts via a membranolytic mechanism and displays concentration-dependent killing efficiency. In addition, we showed that TP4 inhibited growth of Rhizopus oryzae in whole fruit (tomato) samples. Based on these findings, we conclude that TP4 should be further evaluated as a potentially safe and green solution to prevent food spoilage.

Effects of Maillard reaction products on myoglobin-mediated lipid oxidation during refrigerated storage of carp

Lipid oxidation is the major cause of quality deterioration in freshwater fish, especially mediated by myoglobin (Mb). This study aimed to investigate the antioxidant mechanism of Maillard reaction products (MRPs) in Mb-mediated lipid oxidation in common carp (Cyprinus carpio). MRPs exhibited promising antioxidant and antimicrobial capacities based on the reduced content of peroxide and thiobarbituric acid-reactive substances and inhibited microbial growth. MRPs inhibited the oxidation of Mb by lowering the transfer from oxymyoglobin to metmyoglobin and improving the stability of heme iron. The correlation analysis showed that MRPs regulated the formation of free radicals by maintaining the reduced structure of Mb and the integrity of heme iron, and also directly inhibited the formation of oxidation products in a chain radical reaction. The texture and electronic nose analysis indicated that MRPs could delay the structural disruption and flavor deterioration of surimi. Therefore, MRPs could effectively inhibit Mb-induced lipid oxidation and further control the resulting changes in the flavor and texture of surimi.

Antimicrobial films fabricated with myricetin nanoparticles and chitosan derivation microgels for killing pathogenic bacteria in drinking water

Pathogenic bacteria in drinking water threaten human health and life. In the work, antimicrobial films composed of myricetin@tannic acid (My@TA) nanoparticles (NPs) and chitosan derivation microgels were developed to kill pathogenic bacteria in drinking water. Hydrophobic My was first made into water soluble My@TA NPs using a solvent exchange method with TA as stabilizer. Polymeric microgels of carboxymethyl chitosan (CMCS)/hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were then fabricated with a blending method. CMCS&HACC/My@TA multilayer films were further deposited on the internal surface of PET bottles by using a layer-by-layer (LbL) assembly technique. The PET bottles coated with the films could effectively kill pathogenic bacteria in water such as S. aureus, E. coli, Staphylococcus epidermidis, Pseudomonas fluorescens, Listeria monocytogenes and methicillin resistant Staphylococcus aureus (MRSA). In addition, CMCS&HACC/My@TA films displayed good antioxidant activity, water resistance, and in vivo biocompatibility with heart, liver, spleen, lung and kidney organs. We believe that the container coated with CMCS&HACC/My@TA films can be applied to prevent microbial contamination of drinking water.

Antibacterial Activity against Escherichia coli and Cytotoxicity of Maillard Reaction Product of Chitosan and Glucosamine Prepared by Gamma Co-60 Ray Irradiation

In this study, the gamma ray-induced Maillard reaction method was carried out for chitosan (CTS) and glucosamine (GA) to improve the water solubility and antibacterial activity. The mixture solution of CTS and GA was exposed to gamma rays at a dose of 25 kGy and freeze-dried to obtain a Maillard reaction product (MRP) powder. The physicochemical and biological properties of the CTS-GA MRP powder were investigated. The CTS-GA MRP powder expressed good solubility at a concentration of 0.05 g/mL. In addition, the result of the antibacterial activity test against Escherichia coli revealed that the CTS-GA MRP powder exhibited highly antibacterial activity at pH 7; in particular, bacterial density was reduced by over 4 logs. Furthermore, the cytotoxicity test of the CTS-GA MRP powder on mouse fibroblast cells (L929) showed non-cytotoxicity with high cell viability (>90%) at concentrations of 0.1-1 mg/mL. Owing to the high antibacterial activity and low cytotoxicity, the water-soluble CTS-GA MRP powder can be used as a favorable natural preservative for food and cosmetics.

Effect of deacetylation of chitosan on the physicochemical, antioxidant and antibacterial properties activities of chitosan-mannose derivatives

BACKGROUND

The present study investigates the physical, chemical, and antibacterial properties of water-soluble chitosan derivatives. Preparation of the water-soluble chitosan derivatives was performed by the Maillard reaction (MR) between chitosan [with the degree of deacetylation (DD) being 50%, 70%, and 90%] and mannose. No organic reagent was used in the process. Systematic evaluations of the effects of chitosan DD on the reaction extent, the structure, the composition, as well as the physicochemical properties, antioxidant properties, and bacterial inhibitory properties of the finished chitosan-mannose MR products (Mc-mrps), were carried out.

RESULTS

Based on the experimental data obtained from Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, Pyrolysis-gas chromatography-mass spectrometry analysis, and 1 H-NMR, the Mc-mrps formed from chitosan with different DDs had different structures and components. An increase in the DD of chitosan led to a significant increase in the degree of reaction, color difference (△E), and solubility (P < 0.05). The zeta potential and particle size of the Mc-mrps were also influenced by the DD of chitosan. Additionally, the antimicrobial action against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative bacteria (Escherichia coli and Salmonella typhimurium), as well as antioxidant activity, were enhanced by the incorporation of mannose. This was also achieved by the increase of the DD of chitosan.

CONCLUSION

The results of the present study suggest that chitosan was derived with mannose to yield a novel, water-soluble polysaccharide with better antioxidant and antimicrobial activities. The DD of chitosan had a significant effect on the properties of the Mc-mrp, which can serve as a reference point for the subsequent preparation and application of such derivatives. © 2023 Society of Chemical Industry.

Current and emerging applications of saccharide-modified chitosan: a critical review

Chitin, as the main component of the exoskeleton of Arthropoda, is a highly available natural polymer that can be processed into various value-added products. Its most important derivative, i.e., chitosan, comprising β-1,4-linked 2-amino-2-deoxy-β-d-glucose (deacetylated d-glucosamine) and N-acetyl-d-glucosamine units, can be prepared via alkaline deacetylation process. Chitosan has been used as a biodegradable, biocompatible, non-antigenic, and nontoxic polymer in some in-vitro applications, but the recently found potentials of chitosan for in-vivo applications based on its biological activities, especially antimicrobial, antioxidant, and anticancer activities, have upgraded the chitosan roles in biomaterials. Chitosan approval, generally recognized as a safe compound by the United States Food and Drug Administration, has attracted much attention toward its possible applications in diverse fields, especially biomedicine and agriculture. Even with some favorable characteristics, the chitosan's structure should be customized for advanced applications, especially due to its drawbacks, such as low drug-load capacity, low solubility, high viscosity, lack of elastic properties, and pH sensitivity. In this context, derivatization with relatively inexpensive and highly available mono- and di-saccharides to soluble branched chitosan has been considered a "game changer". This review critically reviews the emerging technologies based on the synthesis and application of lactose- and galactose-modified chitosan as two important chitosan derivatives. Some characteristics of chitosan derivatives and biological activities have been detailed first to understand the value of these natural polymers. Second, the saccharide modification of chitosan has been discussed briefly. Finally, the applications of lactose- and galactose-modified chitosan have been scrutinized and compared to native chitosan to provide an insight into the current state-of-the research for stimulating new ideas with the potential of filling research gaps.

Effects of Sodium Alginate, Pectin and Chitosan Addition on the Physicochemical Properties, Acrylamide Formation and Hydroxymethylfurfural Generation of Air Fried Biscuits

This study evaluated the effects of sodium alginate, pectin and chitosan addition (0.5–1.5%) on the physicochemical properties including pH, water activity, moisture content, color values, hardness, diameter, thickness, spread ratio, antioxidant activities and sensory scores of biscuits in air frying processing. In addition, the formation of acrylamide and hydroxymethylfurfural (HMF) were discussed. Physicochemical properties of biscuits including water content, water activity, hardness, appearance, shape, color, flavor, texture, overall acceptability, and DPPH radical scavenging activity of biscuits were not influenced significantly by the addition (0.5–1.0%) of three food hydrocolloids. The data showed that the biscuits with hydrocolloids addition had lower acrylamide contents than that of the control biscuit without hydrocolloids addition, and the reducing power of biscuits increased after adding the hydrocolloids. The highest mitigation of acrylamide formation was obtained by the chitosan addition formulation. The formation of acrylamide showed a negative correlation with the content of sodium alginate and chitosan addition, and they were effective ingredients in terms of mitigating the formation of acrylamide in biscuit formulation.

Maillard reaction products-based encapsulant system formed between chitosan and corn syrup solids: Influence of solution pH on formation kinetic and antioxidant activity

Maillard reaction products (MRPs) between chitosan and various sugars with enhanced antioxidant activity were previously produced. However, few reports address the chitosan and corn syrup solids system that has been successfully used to encapsulate nutraceutical oils. Maillard reaction is pH-responsive, the influence of solution pH on the formation kinetic and antioxidant activity of MRPs was therefore evaluated in this work. FT-IR and zeta-potential results confirmed the formation of MRPs between chitosan and corn syrup solids. Possible Amadori compounds signals were observed clearly in the ¹H NMR spectrum. Brown color development depended on initial solution pH, following a zero-order kinetic regression. Antioxidant activity of reaction products was higher than the native system and increased with an increase in the initial pH of the solution. Developed MRPs with a dual function as antioxidant and encapsulant can possibly be used to protect emulsified oil from oxidation.

Chitosan-Based Materials: An Overview of Potential Applications in Food Packaging

Chitosan is a multifunctional biopolymer that is widely used in the food and medical fields because of its good antibacterial, antioxidant, and enzyme inhibiting activity and its degradability. The biological activity of chitosan as a new food preservation material has gradually become a hot research topic. This paper reviews recent research on the bioactive mechanism of chitosan and introduces strategies for modifying and applying chitosan for food preservation and different preservation techniques to explore the potential application value of active chitosan-based food packaging. Finally, issues and perspectives on the role of chitosan in enhancing the freshness of food products are presented to provide a theoretical basis and scientific reference for subsequent research.

Effect of Chitosan Incorporation on the Development of Acrylamide during Maillard Reaction in Fructose-Asparagine Model Solution and the Functional Characteristics of the Resultants

The objectives of this study were to evaluate the effect of 0.5% chitosan incorporation on acrylamide development in a food model solution containing 0.5% fructose and asparagine after heating for 30 min at 180 °C. All the solutions were investigated for the following characteristics: acrylamide, asparagine, reducing sugar content, color, kinematic viscosity, Maillard reaction products (MRPs), and pH every 10 min. After heating for 10 min, the viscosity of chitosan-containing solutions reduced significantly. The investigational data confirmed that chitosan may have decomposed into lower molecular structures, as demonstrated by the reduced viscosity of the solution at pH < 6 and a decrease in the acrylamide content during 30 min of heating in a fructose−asparagine system. This study also confirms that the formation of ultraviolet-absorbing intermediates and browning intensity of MRPs containing acrylamide prepared by fructose−asparagine was more than those of MRPs prepared by glucose−asparagine solution system. MRPs containing acrylamide resulted from the reaction of asparagine with fructose (ketose) rather than glucose (aldose). Acrylamide formation could be significantly mitigated in the fructose−asparagine−chitosan model system as compared to the fructose−asparagine model system for possible beverage and food application.

Chitosan-Based Functional Films Integrated with Magnolol: Characterization, Antioxidant and Antimicrobial Activity and Pork Preservation

The aims of this study were to develop the magnolol-chitosan films and study the positive effect of the combination of magnolol and chitosan. The addition of magnolol made the magnolol-chitosan films exhibit higher density (1.06-1.87 g/cm³), but the relatively lower water vapor permeability (12.06-7.36 × 10^-11·g·m^-1·s^-1·Pa^-1) and water content (16.10-10.64%). The dense and smooth surface and cross-section of magnolol-chitosan films were observed by environmental scanning electron microscopy (ESEM) images. The interaction of magnolol and chitosan was observed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). After the addition of magnolol, the antioxidant capacity of magnolol-chitosan films was increased from 18.99 to 82.00%, the growth of P. aeruginosa was inhibited and the inhibition percentage of biofilm formation was increased from 30.89 to 86.04%. We further verified that the application of magnolol-chitosan films on chilled pork significantly reduced the increases in pH value, inhibited the growth of microorganisms and extended the shelf life. Results suggest that magnolol had a positive effect on magnolol-chitosan films and could be effectively applied to pork preservation.

Preparation and Characterization of Functional Films Based on Chitosan and Corn Starch Incorporated Tea Polyphenols

The functional films based on chitosan and corn starch incorporated tea polyphenols were developed through mixing the chitosan and starch solution and the powder of tea polyphenols by the casting method. The objective of this research was to investigate the effect of different concentrations of tea polyphenols on the functional properties of the films. Attenuated total reflectance Fourier transform infrared spectrometry and X-ray diffraction were used to investigate the potential interactions among chitosan, corn starch and tea polyphenols in the blend films. Physical properties of the blend films, including density, moisture content, opacity, color, water solubility and water swelling, as well as morphological characteristics, were measured. The results demonstrated that the incorporation of tea polyphenols caused the blend films to lead to a darker appearance. The water solubility of the blend film increased with the increase of tea polyphenol concentrations, while moisture content and swelling degree decreased. The hydrogen bonding between chitosan, starch and tea polyphenols restricted the movement of molecular chains and was helpful to the stability of the blend films. The results suggested that these biodegradable blend films could potentially be used as packaging films for the food and drug industries to extend the shelf life to maintain their quality and safety.

Effect of Hydroxymethylfurfural and Low-Molecular-Weight Chitosan on Formation of Acrylamide and Hydroxymethylfurfural during Maillard Reaction in Glucose and Asparagine Model Systems

The aim of this research was to investigate the effects of the addition of 0.5% hydroxymethylfurfural (HMF) and low molecular chitosan on acrylamide and HMF formation in a food model system, which contains 0.5% glucose, asparagine, and HMF within 30 min of heating at 180 °C. At an interval of 10 min, all solutions were evaluated in the following aspects: reducing sugar, asparagine, acrylamide, HMF content, pH, Maillard reaction products, kinematic viscosity, and color. After heating for 10 min, the kinematic viscosity of solutions containing chitosan reduced significantly. The values of the acrylamide, HMF, and absorbance increased at OD₂₉₄ and OD₄₂₀ (optical density measured at 294 nm and 420 nm) of solutions. Experimental results showed that low-molecular-weight chitosan might be hydrolyzed into much lower molecular weight, followed by the decrease in kinematic viscosity of the solution at pH lower than 6 and the increase in the formation of acrylamide after heating for 30 min.

Functionalities of chitosan conjugated with lauric acid and l-carnitine and application of the modified chitosan in an oil-in-water emulsion

The aim of this research was to conjugate chitosan (CT) with lauric acid (LA) and l-carnitine (CNT) to yield a product that is water-soluble at neutral pH and has surface, antimicrobial, and antioxidant activities. The resulting CT-LA-CNT is water-soluble at neutral pH, in contrast with CT and CT-LA, which require the aid of acid to become soluble. Concerning antimicrobial activity, for S. aureus, the minimum bactericidal concentration of CT was lower than those of CT-LA or CT-LA-CNT, while the three compounds exhibited similar bactericidal activity against E. coli. CT-LA-CNT was also used to study the oxidative stability of soybean oil in an oil-in-water (O/W) emulsion; sodium dodecyl sulfate (SDS) and Tween 80 and Span 80 (TS), an emulsifier mixture, were used as controls for comparison. The results showed that CT-LA-CNT was better than SDS and TS at protecting the lipid from oxidation.

Antioxidant and Antibacterial Activity of Caprylic Acid Vanillyl Ester Produced by Lipase-Mediated Transesterification

Vanillyl alcohol (VA), which is abundant in Vanilla bean, has strong antioxidant activity. However, the use of VA in the food and cosmetics industries is limited, due to its low solubility in emulsion or organic solvents. Meanwhile, medium chain fatty acids and medium chain monoglycerides have antibacterial activity. We synthesized butyric acid vanillyl ester (BAVE) or caprylic acid vanillyl ester (CAVE) from VA with tributyrin or tricaprylin through transesterification reaction using immobilized lipases. BAVE and CAVE scavenged 2,2-diphenyl-1-picrylhydrazyl radicals in organic solvents. In addition, BAVE and CAVE decreased the production rate of conjugated diene and triene in the menhaden oil-in-water emulsion system. While BAVE showed no antibacterial activity, CAVE showed antibacterial activity against food spoilage bacteria, including Bacillus coagulans. In this study, the antibacterial activity of vanillyl ester with medium chain fatty acid was first revealed. Zeta potential measurements confirmed that BAVE and CAVE were inserted into B. coagulans membrane. In addition, the propidium iodide uptake assay and fluorescent microscopy showed that CAVE increased B. coagulans membrane permeability. Therefore, CAVE is expected to play an important role in the food and cosmetics industries as a bi-functional material with both antioxidant and antibacterial activities.

Functional properties of chitosan derivatives obtained through Maillard reaction: A novel promising food preservative

This review provides an insight about the functional properties of chitosan obtained through Maillard reaction to enhance the shelf life and food quality. Maillard reaction is a promising and safe method to obtain commercial water-soluble chitosan's through Schiff base linkage and Amadori or Heyns rearrangement. Likewise, chitosan derivatives exert an enhanced antimicrobial, antioxidant, and emulsifying properties due to the development of Maillard reaction products (MRPs) like reductones and melanoidins. Additionally, the application of chitosan-MRPs effectively inhibited the microbial spoilage, reduced lipid oxidative, and extended the shelf life and the quality of fresh food products. Therefore, understand the potential of chitosan-MRPs derivatives as a functional biomaterial to improve the postharvest quality and extending the shelf life of food products will scale up its application as a food preservative.

Preparation, Bioactivities and Applications in Food Industry of Chitosan-Based Maillard Products: A Review

Chitosan, a biopolymer possessing numerous interesting bioactivities and excellent technological properties, has received great attention from scientists in different fields including the food industry, pharmacy, medicine, and environmental fields. A series of recent studies have reported exciting results about improvement of the properties of chitosan using the Maillard reaction. However, there is a lack of a systemic review about the preparation, bioactivities and applications in food industry of chitosan-based Maillard reaction products (CMRPs). The presence of free amino groups in chitosan allows it to acquire some stronger or new functional properties via the Maillard reaction. The present review aims to focus on the current research status of synthesis, optimization and structural identification of CMRPs. The applications of CMRPs in the food industry are also discussed according to their biological and technological properties such as antioxidant, antimicrobial activities and inducing conformational changes of allergens in food. Some promising directions for future research are proposed in this review, aiming to provide theoretical guidance for the further development of chitosan and its derivatives.

In vitro assessment of the antimicrobial efficacy of chitosan nanoparticles against major fish pathogens and their cytotoxicity to fish cell lines

Nanotechnology is an emerging avenue employed in disease prevention and treatment. This study evaluated the antimicrobial efficacy of chitosan nanoparticles (CSNPs) against major bacterial and oomycete fish pathogens in comparison with chitosan suspension. Initially, the minimum inhibitory concentrations (MIC, MIC₉₀ ) were determined and the per cent inhibition of bacterial growth was calculated. Subsequently, the minimum bactericidal concentrations (MBCs) were determined. The time-dependent disruptions of CSNP-treated pathogens were observed via transmission electron microscopy (TEM), and the effect of CSNPs on the viability of two fish cell lines was assessed. No antimicrobial effect was observed with chitosan, while CSNPs (105 nm) exhibited a dose-dependent and species-specific antimicrobial properties. They were bactericidal against seven bacterial isolates recording MBC values from 1 to 7 mg/ml, bacteriostatic against four further isolates recording MIC values from 0.125 to 5 mg/ml and fungistatic against oomycetes recording MIC₉₀ values of 3 and 4 mg/ml. TEM micrographs showed the attachment of CSNPs to the pathogenic cell membranes disrupting their integrity. No significant cytotoxicity was observed using 1 mg/ml CSNPs, while low dose-dependent cytotoxicity was elicited by the higher doses. Therefore, it is anticipated that CSNPs are able to compete and reduce using antibiotics in aquaculture.

Facile synthesis and characterizations of antibacterial and antioxidant of chitosan monoterpene nanoparticles and their applications in preserving minced meat

Chitosan nanoparticles loaded monoterpenes (ChMNPs) were prepared for preservation of minced meat from oxidative changes and growth of microorganisms. Four monoterpenes (limonene, linalool, menthol and thymol) were used to synthesis of four different types of ChMNPs. The physicochemical characteristics of nanoparticles were analyzed using Scanning electron microscopy (SEM) and Zeta potential. SEM showed that the nanoparticles were nearly uniformly shape and size and the zeta potential values ranged between 0.0346 and -0.1690 mV. In vitro antimicrobial activity of Ch, monoterpenes (M) and ChMNPs against Gram (-) bacteria Escherichia coli (ATCC 8739) and Salmonella typhimurium (ATCC 1402) was analyzed using serial dilution test. E. coli was more susceptible than S. typhimurium to these products. ChMNPs exhibited good in vivo antimicrobial and antioxidant property for the minced meat samples during refrigerated storage. Verification of testing hypothesis was performed by assessing a DPPH radical scavenging activity, peroxide value and E. coli reduction of experimental nanoparticles. Significant effects of ChMNPs were observed at 1000 and 2500 mg/kg on the total number of E. coli in meat samples during storage time. The results indicate that ChMNPs can be used to preserve food as antimicrobial agents and to extend shelf life.

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.

Chitin/chitosan derivatives and their interactions with microorganisms: a comprehensive review and future perspectives

Chitosan, obtained as a result of the deacetylation of chitin, one of the most important naturally occurring polymers, has antimicrobial properties against fungi, and bacteria. It is also useful in other fields, including: food, biomedicine, biotechnology, agriculture, and the pharmaceutical industries. A literature survey shows that its antimicrobial activity depends upon several factors such as: the pH, temperature, molecular weight, ability to chelate metals, degree of deacetylation, source of chitosan, and the type of microorganism involved. This review will focus on the in vitro and in vivo antimicrobial properties of chitosan and its derivatives, along with a discussion on its mechanism of action during the treatment of infectious animal diseases, as well as its importance in food safety. We conclude with a summary of the challenges associated with the uses of chitosan and its derivatives.

Antioxidant Activity Improvement of Apples Juice Supplemented with Chitosan-Galactose Maillard Reaction Products

Chitosan-galactose Maillard reaction (CG) were prepared by heating at 100 °C for 3 hrs in a model system containing chitosan (CH) and 1%, 1.5% and 2% (w/v) of galactose. The results showed that the absorbance at 294 and 420 nm, the fluorescence intensity and the color differences of CG Maillard reaction products (MRPs) increased significantly with the increase of galactose concentration, which indicated the development of MRPs. In addition, FT-IR analysis showed that the degree of deacetylation of CG-MRPs was reduced with the increasing galactose ratio by the schiff base (-C=N) formation, indicating that the galactose has been attached to the amino group of chitosan. Likewise, the antioxidant activities (DPPH, chelating ability and reducing power) of CG-MRPs were investigated. Notably, the effect of galactose concentration in CG-MRPs was found to enhance the antioxidant activity, indicating that CG-2% exhibited the highest antioxidant activity in the range of 0.25-2.0 mg/mL. Furthermore, the apple juice supplemented with CG-MRPs could significantly improve the antioxidant activities, and CG-2% in apple juice showed the better antioxidant capacity at the concentration of 1.0 mg/mL. Thus, we conclude that CG-MRPs addition may greatly improve the antioxidant quality of apple juice.

Effect of Chitosan–Tomato Plant Extract Edible Coating on the Quality, Shelf Life, and Antioxidant Capacity of Pork during Refrigerated Storage

The aim of this study was to evaluate the effectiveness of chitosan–tomato plant extract (C-TPE) edible coating (EC) on the physicochemical, microbiological, sensory, and antioxidant capacity changes of pork during storage. Edible coatings prepared with chitosan 1%, acetic acid 1%, glycerol, and TPE (0.1% and 0.3%) were tested. Slices of pork were submerged in different treatments (T1: C 1%; T2: C 1% + TPE 0.1%; T3: C 1% + TPE 0.3%; T4: control) and stored at 4 °C. The different treatments showed the best results in physicochemical and microbiological analyses, with reduced microbial population relative to the control. The highest antioxidant capacity and total phenolic content were shown in T3, and the overall acceptance was better in T2. The results show that the application of C with the addition of natural extracts, such as the tomato plant with antioxidant and antimicrobial properties, can be an alternative method for preserving pork.

Enhancing the antioxidative effects of foods containing rutin and α-amino acids via the Maillard reaction: A model study focusing on rutin-lysine system

Rutin is a bioflavonoid found in many plants and derived foods, accordingly, rutin likely interacts with α-amino acids such as Lys, Ile, His or Glu to give Maillard reaction products (MRPs). The heated rutin-Lys system exhibited highest brown intensity and in vitro antioxidant activities. The 30-50 kDa rutin-Lys fraction had higher in vitro antioxidant activities than the other fractions, and at a dose of 0.4 mg/ml preserved over 90% cell viability for HepG2 cells exposed to H₂ O₂ . The dose-dependent protective effects against H₂ O₂ -induced oxidative stress of the rutin-Lys MRPs may involve the inhibition of reactive oxygen species generation, enhancement of the superoxide dismutase and catalase activities, along with the activation of the Nrf2-dependent pathway and upregulation of phase II antioxidant genes (including NQO1, HO-1, GCLG, and GCLM). PRACTICAL APPLICATIONS: Rutin is widely distributed in vegetables and grains. The Maillard reaction is a common reaction occurring during food processing, and produces Maillard reaction products (MRPs) with distinct processing and biological properties. This study shows that a 30-min thermal treatment at 120°C generates antioxidative MRPs in the rutin-Lys, rutin-His, rutin-Ile and rutin-Glu model systems, which can directly inhibit reactive oxygen species generation and enhance SOD and CAT activities while activating the Nrf2-dependent pathway and upregulating the expression of phase II detoxifying antioxidant genes. Therefore, for food systems containing phenolic antioxidants and proteins (such as rutin and Lys), one may enhance the antioxidant properties of these food systems through a 30-min thermal treatment at 120°C. Also, the resultant rutin-Lys MRPs may be isolated and used as commercial preparations of natural antioxidants.

Anti-Oxidant and Anti-Diabetes Potential of Water-Soluble Chitosan-Glucose Derivatives Produced by Maillard Reaction

Chitosan-sugar derivatives demonstrate some useful biology activities (for example anti-oxidant and anti-microbial activities). In this study, water-soluble chitosan–glucose derivatives (WSCGDs) were produced from a water-soluble chitosan hydrochloride (WSC) with 12.5 kDa of molecular weight and 24.05% of degree of acetylation (DA) via Maillard reaction with the heating temperatures of 100 °C and 121 °C. The Maillard reaction between WSC and glucose was investigated by measuring the absorbances at 420 nm and 294 nm, indicating that the reaction took place more effectively at 121 °C. All WSCGDs exhibited higher anti-oxidant activity than WSC, in which WSCGDs obtained at the treatment 121 °C for 2 h, 3 h, and 4 h expressed the highest ability (IC50 range from 1.90–1.05 mg/mL). Increased anti-α-amylase and anti-α-glucosidase activities were also observed in WSCGDs from the treatment at 121 °C. In detail, the highest IC50 values of anti-α-amylase activity were 18.02 mg/mL (121 °C, 3 h) and 18.37 mg/mL (121 °C, 4 h), whereas the highest IC50 values of anti-α-glucosidase activity were in range of 7.09–5.72 mg/mL (121 °C, for 1–4 h). According to the results, WSCGD obtained from 121 °C for 3 h was selected for further characterizing by high performance liquid chromatography size exclusion chromatography (HPLC SEC), colloid titration, FTIR, as well as 1H-NMR, indicating that the derivative of WSC and glucose was successfully synthesized with a molecular weight of 15.1 kDa and degree of substitution (DS) of 34.62 ± 2.78%. By expressing the excellent anti-oxidant and anti-diabetes activities, WSCGDs may have potential use in health food or medicine applications.

Effects of chitosan oligosaccharide-nisin conjugates formed by Maillard reaction on the intestinal microbiota of high-fat diet-induced obesity mice model

Objectives

The goal of this study was to evaluate the modulatory effect of chitosan oligosaccharide-nisin conjugate (CON-C) on intestinal microbiota of human flora-associated (HFA) mice and also reveal its effect towards the high-fat diet (HFD)-induced obesity. Both Chitosan oligosaccharides and nisin showed great potential in modulating the intestinal microbiota, so it is worth to explore whether the modulation effect of chitosan oligosaccharide could be improved by covalently binding with nisin.

Materials and Methods

CON-C was prepared by heating the mixed solution of chitosan oligosaccharide and nisin at 80°C and pH 2.0 for 24h. The structure of CON-C were analyzed by Fourier transform-infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The CON-C’s anti-obesity effect and modulatory effect toward intestinal microbiota were analyzed using human flora-associated (HFA) mice model.

Results

CON-C could alleviated HFD-induced gut dysbiosis, by significantly decreasing the numbers of Bifidobacterium and Lactobacillus/Enterococcus spp., and increasing the numbers of Bacteroides–Prevotella and Clostridium groups. CON-C could also enriched the most differentially expressed genes through KEGG pathways of biosynthesis of amino acids, two-component system, and ATP binding cassette (ABC) transporters.

Conclusions

The improved therapeutic effect of CON-C against HFD-induced obesity has been approved, and hence, CON-C has a great potential to be utilized as a functional food ingredient in reducing body weight.

Chitosan-glucose Maillard reaction products and their preservative effects on fresh grass carp (Ctenopharyngodon idellus) fillets during cold storage

BACKGROUND

A decreasing freshness occurrs in Ctenopharyngodon (C.) idellus during post-mortem storage. In the present study, chitosan-glucose Maillard reaction products (CG-MRPs) were prepared by heating chitosan and glucose at different reaction temperatures and then used for preserving the freshness and quality of C. idellus fillets during cold storage (4 °C).

RESULTS

High temperature enhanced the chitosan-glucose Maillard reaction and promoted the accumulation of melanoidins and intermediate compounds. The reducing power of CG-MRPs increased with an increasing reaction temperature. CG-MRPs inhibited the microbial growth rate and retarded the oxidation of proteins, lipids and nucleotides in C. idellus fillets by suppressing total bacterial count, total volatile basic nitrogen, thiobarbituric acid reactive substances and K values during cold storage. Furthermore, CG-MRPs prolonged shelf-life. The fillets treated with the CG-MRPs prepared at 120 °C showed an especially longer shelf-life (7 days). The preservative effect of CG-MRPs on fillets was the result of antibacterial components (melanoidins, reductone and furfural) in CG-MRPs and a reducing power against the oxidative degradation of proteins, nucleotides and lipids in C. idellus fillets.

CONCLUSION

The present study demonstrates that, for C. idellus fillets, treatment with CG-MRPs prepared at 120 °C for 40 min could be a feasible approach for maintaining the freshness of C. idellus fillets and prolonging shelf-life during cold storage. © 2018 Society of Chemical Industry.

Antimicrobial and antioxidant capacity of glucosamine-zinc(II) complex via non-enzymatic browning reaction

Coordination compounds play an important role in the life process, and have been widely used in food, cosmetics and pharmaceutical industry. Herein, we have developed a novel kind of glucosamine-zinc(II) complex (GlcN-ZC) for food additive using non-enzymatic browning reaction. The GlcN-ZC was characterized by FTIR and XRD. Moreover, UV absorbance changes, browning intensity, fluorescence changes, antioxidant activity and antimicrobial assessment of GlcN-ZC were also evaluated. Results showed the GlcN-ZC intermediate compounds were accumulated in non-enzymatic browning while prolonging heating time and melanoidins were produced in the final stage. The fluorescence changes confirmed that fluorophores were formed during the non-enzymatic reaction and fluorescence intensity reached a maximun at 60 min. The highest radical scavenging activity of GlcN-ZC formed after 180 min of heating was 79.2%. Furthermore, GlcN-ZC exhibited excellent antibacterial activity against E. coli and S. aureus. Therefore, GlcN-ZC can be used as a novel promising additive in the food industry.

Antibacterial activities and preservative effect of chitosan oligosaccharide Maillard reaction products on Penaeus vannamei

The purpose of this study was to understand the influence of Maillard reaction (MR) on bioactivity of chitosan oligosaccharide (COS). The antibacterial activity against Pseudomonas aeruginosa and Vibrio parahaemolyticus and preservative effect of two kinds of COS MR products (MRPs) on Penaeus vannamei were evaluated. The structures of CG (MRPs of COS and glucose) and CM (MRPs of COS and maltose) were characterized by FT-IR and their molecular weights were measured by gel permeation chromatography (GPC). The results showed that CG has enhanced antibacterial activity and preservative effect compared to COS by evaluating total volatile base-nitrogen (TVB-N), trimethylamine (TMA), pH, total bacterial count (TBC) and sensory evaluation. Meanwhile, CM showed decreased antibacterial activity and preservative effect compared to COS by evaluating TMA, pH and TBC. The results indicated that antibacterial activity and preservative effect of COS increased or decreased after MR. In other words, the type of reducing sugar involved in MR had a great impact on the functional properties of COS-saccharide MRPs and their application to be used as a food preservative.

About the Sterilization of Chitosan Hydrogel Nanoparticles

In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP) associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility) with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS) hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation), a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP) hydrogel nanoparticles (CS-HNP), with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol). Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

Physicochemical and Antibacterial Properties of Chitosan Extracted from Waste Shrimp Shells

This research aims to study the production of chitosan from shrimp shell (Litopenaeus vannamei) of waste origin using two chemical methodologies involving demineralization, deproteinization, and the degree of deacetylation. The evaluation of the quality of chitosan from waste shrimp shells includes parameters for the yield, physical chemistry characteristics by infrared spectroscopy (FT-IR), the degree of deacetylation, and antibacterial activity. The results showed (by Method 1) extraction yields for chitin of 33% and for chitosan of 49% and a 76% degree of deacetylation. Chitosan obtained by Method 2 was more efficient: chitin (36%) and chitosan (63%), with a high degree of deacetylation (81.7%). The antibacterial activity was tested against Gram-negative bacteria (Stenotrophomonas maltophilia and Enterobacter cloacae) and Gram-positive Bacillus subtilis and the Minimum Inhibitory Concentrations (MIC) and the Minimum Bactericidal Concentration (MBC) were determined. Method 2 showed that extracted chitosan has good antimicrobial potential against Gram-positive and Gram-negative bacteria and that the process is viable.

Antioxidative, Antibacterial, and Food Functional Properties of the Half-Fin Anchovy Hydrolysates-Glucose Conjugates Formed via Maillard Reaction

The antioxidative, antibacterial, and food functional properties of the half-fin anchovy hydrolysates (HAHp)-glucose conjugates formed by Maillard reaction (MR) were investigated, respectively. Results of sugar and amino acid contents loss rates, browning index, and molecular weight distribution indicated that the initial pH of HAHp played an important role in the process of MR between HAHp and glucose. HAHp-glucose Maillard reaction products (HAHp-G MRPs) demonstrated enhanced antioxidative activities of reducing power and scavenging DPPH radicals compared to control groups. HAHp-G MRPs produced from the condition of pH 9.6 displayed the strongest reducing power. The excellent scavenging activity on DPPH radicals was found for HAHp(5.6)-G MRPs which was produced at pH 5.6. Additionally, HAHp(5.6)-G MRPs showed variable antibacterial activities against Escherichia coli, Pseudomonas fluorescens, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, and Sarcina lutea, with the MIC values ranging from 8.3 to 16.7 μg/mL. Result of scanning electron microscopy (SEM) on E. coli suggested that HAHp(5.6)-G MRPs exhibited antibacterial activity by destroying the cell integrity through membrane permeabilization. Moreover, HAHp(5.6)-G MRPs had excellent foaming ability and stability at alkaline conditions of pH 8.0, and showed emulsion properties at acidic pH 4.0. These results suggested that specific HAHp-G MRPs should be promising functional ingredients used in foods.