Valorization of okara by-product for obtaining soluble dietary fibers and their use in biodegradable carboxymethyl cellulose-based film

In the face of mounting environmental concerns and the need for sustainable innovation, the use of agro-industrial wastes as raw materials offers a promising pathway. In this context, this study investigated the okara, a by-product of soy processing, as a novel source of soluble dietary fiber for the enrichment of carboxymethyl cellulose (CMC) biodegradable films based on environmental benefits of waste reduction with the creation of renewable packaging alternatives. Okara soluble dietary fiber (OSDF)-enriched CMC film was compared with films made from traditional and innovative soluble dietary fibers, such as pectin, inulin, and β-glucan. OSDF was obtained through acid hydrolysis at 121 °C, achieving a yield of 5.31 % relative to its initial dry weight. All the produced films exhibited a maximum crystallinity of 5 %, as revealed by X-ray diffraction (XRD), indicative of their largely amorphous structure, while scanning electron microscopy (SEM) ensured their uniformity and flawlessness. The CMC film enriched with okara soluble dietary fiber exhibited key properties, such as thickness, water vapor permeability, and thermal stability, comparable to other soluble fibers studied. These characteristics are essential for effective packaging applications. A notable distinction of the OSDF-enriched film was its capacity to block UV light, offering protection for light-sensitive items. The solubility tests showed that okara and β-glucan contributed to films with a higher solubility percentage. Mechanical testing underscored the influence of fiber on tensile strength, with the film enriched with β-glucan outperforming others at 27.5 MPa. All films showed rapid biodegradation within one week, emphasizing their eco-friendliness and the study alignment with sustainable development objectives in packaging.

pH-Responsive Color Indicator of Saffron (Crocus sativus L.) Anthocyanin-Activated Salep Mucilage Edible Film for Real-Time Monitoring of Fish Fillet Freshness

Researchers have been focusing increasingly on preparing innovative packaging films made from renewable and biodegradable materials in recent years. This research set out to fabricate and analyze pH-sensitive edible films based on salep mucilage combined with anthocyanin from saffron (Crocus sativus L.) (SAAs). A casting technique was developed with varying concentrations of SAAs (0, 2.5, 5, 7.5, and 10%v/v) pH-sensitive edible films. The surface morphology, physicochemical, barrier, and mechanical properties, as well as the pH sensitivity of films, were investigated. The results showed SAAs increased thickness, water solubility, moisture content, and oxygen permeability (O2P) up to 199.03 µm, 63.71%, 14.13%, and 47.73 (cm3 µm m−2 day−1 kPa−1), respectively, of the pH-sensitive salep mucilage edible indicator films. As expected, the SAAs concentration from 0% to 10%v/v decreased tensile strength, transparency, and contact angle to 11.94 MPa, 14.27%, and 54.02°, respectively. Although achieving the highest elongation at the break (108%) and the lowest water vapor permeability (WVP) (1.39 g s−1 m−1 Pa−1 × 10−11), the pH-sensitive edible indicator film containing 5 %v/v of SAAs showed the best results. An investigation of pH sensitivity revealed that the solution’s pH variation altered the SAAs color. When the pH was raised from 3 to 11, the SAAs’ color shifted from pink to brown. The SAAs-halochromic salep mucilage edible indicator film was employed as a label in an experiment to track the degradation of fish fillets stored at 4 °C, revealing that the halochromic indicator changed color from yellow to brown as the fish was stored. Our findings show that SAAs-loaded salep mucilage indicator films help monitor real-time food deterioration.

Characterization of a natural biodegradable edible film obtained from arrowroot starch and iota-carrageenan and application in food packaging

Future food packaging trends are shifting to natural and eco-friendly materials developed from biopolymers such as starch and other hydrocolloids, to reduce pollution from synthetic polymers. Arrowroot starch (AS) (3.5, 3, 2.5, and 2%) and iota-carrageenan (IC) (0.5, 1, 1.5, and 2%) were blended to develop biodegradable edible films (AS/IC-BEF), which were compared against AS-BEF (4%, control). All films were characterized based on their physico-mechanical and barrier properties, functional group properties, crystallinity properties, thermal properties, and soil and seawater biodegradation. AS-BEF exhibited smooth surface, high transparency, and completed composting soil biodegradation in 7 days whereas AS/IC-BEF samples exhibited higher tensile strength, water solubility, swelling properties, and barrier properties, but completed biodegradation after 30 days. XRD analysis indicated IC fractions contributed to increase in degree of crystallinity (28.35°) and FTIR signaled strong hydrogen bond interactions between polymers. AS/IC-BEF samples demonstrated melting temperatures between 158 and 190 °C while glass transition temperatures ranged from 153 to 176 °C, which resulted in maximum weight loss around 50-55% at melting temperatures. Finally, AS/IC-BEF samples successfully inhibited weight loss of cherry tomatoes at room temperature and extended their shelf life to 10 days, which indicated that the AS/IC composite material produced a BEF with potential food and industrial applications.

Application of plant mucilage polysaccharides and their techno-functional properties' modification for fresh produce preservation

The use of edible coating/film to improve fresh produce's quality and shelf life is an old but reliable and popular method of preservation. Recently, plant-derived mucilages have been extensively used to prepare edible packages (MEPs). This review focuses on recent studies that characterize mucilages from different plants, and examine their specific applications as edible packages in preserving fruits and vegetables. Structure-function relations and corresponding influence on film-forming properties are discussed. This review also surveys the additive-modifications of MEPs techno-functional properties. MEPs from a range of plant sources are effective in preventing quality loss and improving the storability of various fruits and vegetables. The preservative mechanisms and essential techno-functional properties of MEPs required for fruit and vegetable packaging were summarized. The key findings summarized in this study will help promote the utilization of mucilages and draw attention to other novel applications of this valuable polymer.

Eco-friendly UV protective bionanocomposite based on Salep-mucilage/flower-like ZnO nanostructures to control photo-oxidation of kilka fish oil

The carbohydrate source has shown great potential for preparing edible film structures, particularly as bionanocomposite edible films. In the present study, highly effective eco-friendly UV protective bionanocomposite based on Salep-mucilage (SaM)/ZnO flower-like (ZnOF) nanostructures were developed and characterized. To investigate microstructure and structure properties of SaM/ZnO_F bionanocomposite, scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques, Fourier transformed infrared (FT-IR) and X-ray diffraction (XRD) were utilized. Our results showed that the increasing ZnO_F content decreased transparency (~80%) of the bionanocomposites. The hunter color values observations confirmed the films' UV-Vis spectrum and their UV-protective properties. Additionally, SaM/ZnO_F bionanocomposite were examined for their efficacy to decrease photo-oxidation in kilka fish oil under fluorescent light during 12 days of storage. The outcomes of our investigation confirm that SaM/ZnO_F bionanocomposite with performance as the adequate light barrier to delay photo-oxidation of kilka fish oil during extended storage.

Preparation and characterization of a new edible film based on Persian gum with glycerol plasticizer

A new type of biodegradable film was formulated and characterized when based on the water-soluble-phase of Persian gum (SPG). The edible film was formulated optimally by using different concentrations of SPG (2.0, 2.5, 3.0, 3.5 and 4%) and glycerol as plasticizer (25, 35, and 35% based on dried SPG). Further examinations involved evaluating the manufactured films in terms of the barrier and physical properties, mechanical qualities, optical indices, microstructural properties and Fourier transform. The results showed that the increase in SPG and plasticizer content caused increases in thickness, moisture uptake, water vapor permeability and density of films (p < 0.05). Water solubility increased in response to higher concentrations of glycerol but decreased by higher amounts of dry matter (p < 0.05). The highest levels of the tensile strength (59.95%) and elongation at break (40.3 MPa) were obtained by SPG (3.5%) + 35% glycerol treatment. The L*, a* and opacity values decreased, while there was an increase in the b* value, as a result of increasing the plasticizer content (p < 0.05). A reduction occurred in the L* value of films, while the a* and b* values increased when using higher amounts of dry matter (p < 0.05). By analyzing the samples with field emission scanning electron microscopy, no cracks were observed on films when the contents of glycerol and dry matter were higher than 30% and 2.5%, respectively. The findings demonstrated that creating edible films from SPG can be an effective approach to the production of edible films.