Polysaccharide from Thymelaea hirsuta L. leaves: Structural characterization, functional properties and antioxidant evaluation

In this study, we successfully extracted a new polysaccharide from Thymelaea hirsuta L., which we named THP, with a yield of 13.94 % through aqueous extraction. The polysaccharide comprises 46.83 % neutral sugars and 7.08 % uronic acids. This heteropolysaccharide contains glucose, glucuronic acid, rhamnose, arabinose, and galactose with relative molar ratios of 29.68: 25.73: 21.31: 13.47 and 9.8, respectively. Analysis of glycosylation positions via methylation and structural features using Fourier transform infrared (FT-IR) and solid-state nuclear magnetic resonance (ssNMR) spectroscopy revealed that THP has a repeating unit (1 → 3 and 1 → 4)-linked β-d-glucopyranosyl backbone, with the d-glucopyranosyl residue as the branch point at O-6. The scanning electron microscopy (SEM) examination showed ellipsoidal granules with smooth surface. This polysaccharide also has good foaming capacity and emulsion stability, and a water holding capacity of 1.81 g/g. The THP dispersion at 1 % showed shear thinning behavior, demonstrating that it is a promising natural additive in various food formulations. The polysaccharide also demonstrated significant antioxidant properties, with a total antioxidant capacity of 315 mg α-tocopherol equivalents/g and an IC50 value of 8.01 mg/mL using the β-carotene bleaching method, surpassing those of synthetic antioxidants. Additionally, when added at a concentration of 0.13 % to an oil/water emulsion system, THP effectively delayed lipid oxidation during storage at 37 °C. The kinetic study of THP-stabilized oil/water emulsion is anticipated to provide valuable insights for its future applications in food and pharmaceutical emulsions.

Biodegradable and hemocompatible alginate/okra hydrogel films with promising stability and biological attributes

Currently, combinations of natural polymers and semi-synthetic biomolecules have gained attention for food-packaging, drug delivery, coatings, and biomedical applications. In this work, cross-linking property of two biopolymers was employed for the fabrication of hydrogel films. Sodium alginate (SAlg) and Okra gel (OkG) were used in different ratios (95:05, 75:25 and 85:15) to synthesize hydrogel films by solvent-casting method. Formation of the films was confirmed by FTIR and Raman techniques which specified the interaction between biomolecules of SAlg and OkG. XRD pattern has shown the presence of both amorphous and micro-crystalline phases in the hydrogel films and SEM studies have shown porosity, amorphousness and agglomerated morphology. TGA and DSC analyses revealed degradation of the film at 420 °C and stability studies using PBS buffer indicated stability and hydrophilic nature of hydrogel films. In-vitro degradation test was also performed for 10 weeks through the incubation of hydrogel-films in simulated body fluid and the effect of pH and temperature was also studied. Results have shown worth-some influence of okra gel on the fabricated films. Hemolytic and antioxidant activities of the gels were also determined and being non-toxic, all these ratios were found suitable for biomedical applications; especially 85:15 have shown maximum potential.

Tremella fuciform Polysaccharides: Extraction, Physicochemical, and Emulsion Properties at Different pHs

The chemical composition, macromolecular characteristics, and structure of four types of Tremella fuciform polysaccharides (TPS) were analyzed, including one TPS that was extracted in the laboratory (L-TPS) and three commercial TPS. The effects of pH on the properties of TPS emulsions were investigated by analyzing their zeta potential, particle size, apparent viscosity, and stability. The results showed that L-TPS presented a higher percentage content of protein (2.33%) than commercial TPS (0.73–0.87%), and a lower molecular mass (17.54 × 106 g/mol). Thus, L-TPS exhibited the best emulsifying activity but gave poor emulsion stability. The droplet sizes and apparent viscosity of commercial TPS-stabilized emulsions were larger or higher in acidic environments. At pH 2, the apparent viscosity was the lowest for L-TPS. Commercial TPS emulsions were most stable at pH 6, while the L-TPS-stabilized emulsion was most stable at pH 2. The obtained results revealed that the emulsifying properties of TPS varied and the effects of pH on emulsion characteristics differed, as determined from the molecular mass, macromolecular characteristics, and structure. This research is useful for expanding the application of TPS as a novel food ingredient in emulsions.

Development and Characterization of Biocomposite Films Based on Polysaccharides Derived from Okra Plant Waste for Food Packaging Application

Polysaccharide-based composite films were developed using mucilage polysaccharides (OLP) and carboxymethyl cellulose (CMC) extracted from okra leafstalk wastes. The rheological properties of biocomposite OLP/CMC film-forming solutions were characterized using the Power-law model, and fabricated films were characterized for their potential food packaging applications. OLP/CMC solutions exhibited pseudo-plastic fluid characteristics and differences in rheological behavior (n, 0.478-0.743), and flow consistency (K, 1.731-9.154) with increasing content of OLP (5 to 30 % w/w of CMC) were associated with variations in the physical, mechanical, and barrier properties of films. Surface hydrophobicity (24%) increased and oxygen (39%) and water vapor (32%) permeability reduced in OLP/CMC films containing up to 10% OLP. Moreover, a higher content of OLP enhanced the antioxidant activity and thermal stability of OLP/CMC films. Subsequently, OLP/CMC was applied as a coating to preserve cherry tomatoes for 14 days at 30 °C. Quality deterioration characterized by high weight loss (22%), firmness loss (74.62%), and discoloration (∆E, 21.26) occurred in uncoated tomatoes and were within unusable/unmarketable limits based on their visual quality score. In contrast, OLP/CMC effectively minimized quality losses, and coated tomatoes exceeded the limit of marketability after 14 days of storage. This study successfully applied value-added polysaccharides derived from okra plant residues for edible food packaging.

Enzymatic Hydrolysis Modifies Emulsifying Properties of Okra Pectin

Okra pectins (OKPs) with diverse structures obtained by different extraction protocols have been used to study the relationship between their molecular structure and emulsifying properties. A targeted modification of molecular structure offers a more rigorous method for investigating the emulsifying properties of pectins. In this study, three glycoside hydrolases, polygalacturonase (PG), galactanase (GL), and arabinanase (AR), and their combinations, were used to modify the backbone and side-chains of OKP, and the relationships between the pectin structure and emulsion characteristics were examined by multivariate analysis. Enzymatic treatment significantly changed the molecular structure of OKP, as indicated by monosaccharide composition, molecular weight, and structure analysis. GL- and AR- treatments reduced side-chains, while PG-treatment increased side-chain compositions in pectin structure. We compared the performance of hydrolyzed pectins in stabilizing emulsions containing 50% v/v oil-phase and 0.25% w/v pectin. While the emulsions were stabilized by PG (93.3% stability), the emulsion stability was reduced in GL (62.5%), PG+GL+AR (37.0%), and GL+AR (34.0%) after 15-day storage. Furthermore, microscopic observation of the droplets revealed that emulsion destabilization was caused by flocculation and coalescence. Principal component analysis confirmed that neutral sugar side-chains are key for long-term emulsion stabilization and that their structure explains the emulsifying properties of OKP. Our data provide structure-function information applicable to the tailored extraction of OKP with good emulsification performance, which can be used as a natural emulsifier.