Effect of natural deep eutectic solvent and chitosan nanoparticles on physicochemical properties of locust bean gum films

Chitosan/Polyvinyl Alcohol-Based Biofilms Using Ternary Deep Eutectic Solvents towards Innovative Color-Stabilizing Systems for Anthocyanins

Anthocyanins are amazing plant-derived colorants with highly valuable properties; however, their chemical and color instability issues limit their wide application in different food industry-related products such as active and intelligent packaging. In a previous study, it was demonstrated that anthocyanins could be stabilized into green plasticizers namely deep eutectic solvents (DESs). In this work, the fabrication of edible films by integrating anthocyanins along with DESs into biocompatible chitosan (CHT)-based formulations enriched with polyvinyl alcohol (PVA) and PVA nanoparticles was investigated. CHT/PVA-DES films' physical properties were characterized by scanning electron microscopy, water vapor permeability, swelling index, moisture sorption isotherm, and thermogravimetry analysis. Innovative red-to-blue formulation films were achieved for CHT/PVA nanoparticles (for 5 min of sonication) at a molar ratio 1:1, and with 10% of ternary DES (TDES)-containing malvidin-3-glucoside (0.1%) where the physical properties of films were enhanced. After immersion in solutions at different pH values, films submitted to pHs 5-8 were revealed to be more color stable and resistant with time than at acidic pH values.

Deep eutectic solvents (DESs) films based on gelatin as active packaging for moisture regulation in fruit preservation

To develop a novel active packaging for fruit preservation, two different deep eutectic solvents (DESs) comprising choline chloride, betaine and glycerol [ChCl:Gly (1:2) and Be:Gly (1:2)] were prepared and the corresponding DESs-based films (DES@Gel) using gelatin as polymer matrix were fabricated. DES@Gel showed smoother morphologies and better optical and mechanical properties as compared with Gel. Moisture sorption isotherm curves, the enhancement of water vapour permeability (WVP) and the excellent moisture absorption-desorption cyclist performance illustrated the moisture regulation hypothesis mechanism of DES@Gel. Furthermore, cherry tomato preservation experiment was carried out and the groups treated with DES@Gel showed better performances. The moisture regulation property of DES@Gel could broaden new avenues for active packaging.

Development and characterization of sustainable active pectin films: The role of choline chloride/glycerol-based natural deep eutectic solvent and lavender extracts

This study aimed to evaluate the potential effects of choline chloride: glycerol-based natural deep eutectic solvent (NADES) as a plasticizer, NADES extract (NADESext) of lavender as both plasticizer and active ingredient, as well as the lyophilized extract (LE) of lavender at different concentrations (0.5 %, 1 %, and 2 %) on the physical, mechanical, optical, thermal, barrier, morphological, and antioxidant properties of pectin films. The properties of the films were compared to those of the neat pectin film and the film plasticized with glycerol. The addition of plasticizers and LE increased thickness, water vapor permeability, and elongation at break values of the films while decreasing tensile strength and young modulus. Pectin films plasticized with glycerol, NADES, and NADESext had a similar color property but a lower opacity. The use of LE decreased lightness and increased opacity compared to the films with plasticizers. The addition of plasticizers revealed a smoother surface than neat pectin film while LE triggered the formation of agglomerates on the films. Changes in the FTIR spectra of the films showed some interactions between pectin and polyphenols in LE. The plasticizers had an insignificant effect on the antioxidant capacity of films whereas LE improved antioxidant capacity depending on the concentration. In conclusion, the results suggested that pectin films with NADES and LE could be beneficially used to improve antioxidant packaging technology along with acceptable mechanical properties.

Enhancement of water barrier and antimicrobial properties of chitosan/gelatin films by hydrophobic deep eutectic solvent

Biodegradable chitosan/gelatin (CS/GEL) films have attracted attention as food packaging, but the poor water sensitivity and functional limitations of these films should be addressed. In this study, the hydrophobic deep eutectic solvent (DES, 0-15 %) consisting of thymol and octanoic acid was used to improve the water resistance and antibacterial performance of the CS/GEL composite films. FTIR and SEM analyses revealed a strong interaction between the CS/GEL matrix and DES. The films blended with DES showed increased water contact angle values and thermal stability. Furthermore, the addition of DES resulted in a significant increase in the elasticity and decrease water vapor transmission rate (WVTR). The CS/GEL films blended with 9% DES showed a 38.5% decrease in WVTR compared to those without DES. Additionally, the DES-containing film displayed good antibacterial activity against Staphylococcus aureus and Escherichia coli. Overall, the CS/GEL-DES composite films are expected to contribute an improvement to food packaging.

Advances in green solvents for production of polysaccharide-based packaging films: Insights of ionic liquids and deep eutectic solvents

The problems with plastic materials and the good film-forming properties of polysaccharides motivated research in the development of polysaccharide-based films. In the last 5 years, there has been an explosion of publications on using green solvents, including ionic liquids (ILs), and deep eutectic solvents (DESs) as candidates to substitute the conventional solvents/plasticizers for preparations of desired polysaccharide-based films. This review summarizes related properties and recovery of ILs and DESs, a series of green preparation strategies (including pretreatment solvents/reaction media, ILs/DESs as components, extraction solvents of bioactive compounds added into films), and inherent properties of polysaccharide-based films with/without ILs and DESs. Major reported advantages of these new solvents are high dissolving capacity of certain ILs/DESs for polysaccharides (i.e., up to 30 wt% for cellulose) and better plasticizing ability than traditional plasticizers. In addition, they frequently display intrinsic antioxidant and antibacterial activities that facilitate ILs/DESs applications in the processing of polysaccharide-based films (especially active food packaging films). ILs/DESs in the film could also be further recycled by water or ethanol/methanol treatment followed by drying/evaporation. One particularly promising approach is to use bioactive cholinium-based ILs and DESs with good safety and plasticizing ability to improve the functional properties of prepared films. Whole extracts by ILs/DESs from various byproducts can also be directly used in films without separation/polishing of compounds from the extracting agents. Scaling-up, including costs and environmental footprint, as well as the safety and applications in real foods of polysaccharide-based film with ILs/DESs (extracts) deserves more studies.

Locust bean gum/carboxycellulose nanocrystal coating incorporating ZnO clusters built by the accretion of micro spindles or sheets for strawberries preservation

Two shapes of ZnO clusters constructed by the growth of spindle-like (I-ZnO) and sheet-like (II-ZnO) microparticles added to Locust bean gum/carboxycellulose nanocrystal (LBG/C-CNC) coating for improving properties as the enhancers and antibacterial agents. Subsequently, active LBG/C-CNC/ZnO (LCZ) coatings were evaluated to combat the fruits rot triggered by microorganisms aiming to extend their shelf life. The results showed that II-ZnO clusters with flower-shape enhanced the properties more obviously due to more interaction sites. The oxygen and water vapor permeability of the coating containing 5 % II-ZnO (LCZII-5) decreased from 2.00 and 5.98 × 10^-11 to 0.6 cm³ mm m^-2 day^-1 atm^-1 and 1.85 × 10^-11 g m^-1 s^-1 Pa^-1, respectively. And the antibacterial rate against E. coli and S. aureus could reach more than 75 %. Meanwhile, the tensile strength (TS) increased by 50.95 %. The inhibition rates on strawberries of weight and Vc loss by LCZII-5 coating were 30.64 % and 53.59 %, respectively. More importantly, the coatings could be easily washed off with water in spite of tightly being connected with the surface of the strawberries. As was expected, this study provides a feasible method for preparing novel fruit coatings with an effective preservation.

Locust Bean Gum, a Vegetable Hydrocolloid with Industrial and Biopharmaceutical Applications

Locust bean gum (LBG), a vegetable galactomannan extracted from carob tree seeds, is extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behavior with other biopolymers (xanthan gum, carrageenan, etc.). In addition, this hydrocolloid is easily modified by derivatization or crosslinking. These LBG-related products, besides their applications in the food industry, can be used as encapsulation and drug delivery devices, packaging materials, batteries, and catalyst supports, among other biopharmaceutical and industrial uses. As the new derivatized or crosslinked polymers based on LBG are mainly biodegradable and non-toxic, the use of this polysaccharide (by itself or combined with other biopolymers) will contribute to generating greener products, considering the origin of raw materials used, the modification procedures selected and the final destination of the products.

Effect of Melissa officinalis L. Essential Oil Nanoemulsions on Structure and Properties of Carboxymethyl Chitosan/Locust Bean Gum Composite Films

This study aimed to develop active films based on carboxymethyl chitosan (CMCS)/locust bean gum (LBG) films containing Melissa officinalis L. essential oil (MOEO) nanoemulsions. The results showed that the active films incorporated with MOEO nanoemulsion resulted in an increase in the elongation of break, water resistance and improved the film hydrophilicity. Elongation of break increased from 18.49% to 27.97% with the addition of 4% MOEO nanoemulsion. Water resistance was decreased from 56.32% to 25.43%, and water contact angle was increased from 75.13 to 83.86 with the addition of 4% MOEO nanoemulsion. However, the water vapor barrier properties and tensile strength decreased with the addition of MOEO nanoemulsions. The scanning electron microscopic images and Fourier transform infrared spectroscopy results showed that the MOEO was very compatible with the film materials and dispersed evenly in the films. At the same time, the addition of MOEO nanoemulsion significantly enhanced antioxidant and antibacterial activities of C/L-MOEO films. The antioxidant and antimicrobial activities of C/L-MOEO films were increased from 7.16% to 33.81% and 3.52% to 54.50%, respectively. In general, C/L-MOEO film has great application prospects.