Cellulose Nanofiber-Based Aerogels from Wheat Straw: Influence of Surface Load and Lignin Content on Their Properties and Dye Removal Capacity

Water pollution is one of the most serious problems worldwide. Nanocellulose-based aerogels usually show excellent adsorption capacities due to their high aspect ratio, specific surface area and surface charge, making them ideal for water purification. In this work, (ligno)cellulose nanofibers (LCNFs/CNFs) from wheat straw residues were obtained using two types of pre-treatments: mechanical (Mec) and TEMPO-mediated oxidization (TO), to obtain different consistency (0.2, 0.4, 0.6 and 0.8) bioaerogels, and their adsorption capacities as dye removers were further studied. The materials were characterized in terms of density, porosity and mechanical properties. An inversely proportional relationship was observed between the consistencies of the aerogels and their achieved densities. Despite the increase in density, all samples showed porosities above 99%. In terms of mechanical properties, the best results were obtained for the 0.8% consistency LCNF and CNF-Mec aerogels, reaching 67.87 kPa and 64.6 kPa for tensile strength and Young’s modulus, respectively. In contrast, the adsorption capacity of the aerogels was better for TEMPO-oxidized aerogels, reaching removal rates of almost 100% for the CNF-TO5 samples. Furthermore, the residual lignin content in LCNF-Mec aerogels showed a great improvement in the removal capacity, reaching rates higher than 80%, further improving the cost efficiency of the samples due to the reduction in chemical treatments

Image Analysis Assessment of the Shelf Life of Fresh Strawberries

Extending the shelf life of food products like strawberries (Fragaria ananassa) is one of Europe's main goals to improving food safety and reduce food waste. In this study, a model has been developed to estimate and predict the quality of strawberries. Strawberries appearance and colour parameters has been determined by image analysis and traditional methods. Pictures of strawberries stored at 5-35 ºC were taken daily for 15 days. In total, 48 images were recorded and analysed. The colour images (RGB images) were processed in the laboratory using a specific image acquisition and analysis program. A linear model has been developed with high accuracy (R2=0.83) to estimate appearance based only in image analysis. This approach allows the use of this technology in the food chain industry

Exploring the microbiota of tomato and strawberry plants as sources of bio-protective cultures for fruits and vegetables preservation

This review explores the agri-food residues of tomato and strawberry as sources of bacteria with bio-protective potential against different pathogenic and spoilage microorganisms for enhancing product shelf life and improving food safety. A comprehensive review of research highlights that Pseudomonas (e.g., P. fluorescens) and Bacillus (e.g., B. subtilis) are relevant genera in the microbiota of both tomato and strawberry plants, as opposed to lactic acid bacteria which are a minority in both plants. Interestingly, those dominant microbial groups have been reported to exhibit potential bio-protective capabilities. This work also discusses different innovative and sustainable methods, such as the use of protective coating or microencapsulation, and the importance of related factors (produce surface properties, bacterial adhesion, etc.) for applying bio-protective cultures in tomato and strawberry, emphasizing the pros and cons. As a conclusion, we suggest that bio-protective cultures are applied at an earlier stage, at crop, exploiting the antimicrobial abilities in the pre- and post-harvest continuum. This bio-protective approach contributes to a more bio-based strategy to sustainably preserve fruits and vegetables from farm to fork

Orange peel waste biorefinery in multi-component cascade approach: Polyphenolic compounds and nanocellulose for food packaging

Embargado hasta 01/11/2024This study proposed an efficient valorization of orange peel waste (OPW) thorugh a multi-product cascade biorefinery approach. In a first step, polyphenolic-rich bioactive extract was obtained using 100% ethanol after a suitability study of different solvent systems. Its use in ultrasound-assisted extraction at 80 °C also allowed obtaining bioactive extracts with higher characteristics and reducing the extraction time (30 min) compared to conventional extraction (5 h). The extractives free-OPW was then used to obtain nanocellulose with high yield (>70%), solely by subjecting the fiber to a high-pressure homogenization treatment without the need for additional pretreatments, highlighting the efficiency of the process. The different components obtained were used separately and together on poly(vinyl alcohol)-based (PVA) films to study the isolated and synergistic effect they contributed to the properties of the films. The optimum cellulose nanofibers (CNF) content was found to be 5%, at higher contents a tendency to clustering of the nanofibers in the matrix was observed. The addition of polyphenol-rich extracts conferred interesting bioactive properties of special interest for food packaging. The antioxidant properties of the films increased as the extract content in the formulation increased, reaching almost 100% for an extract content of 30%. Also, UV-light blocking capacity was increased reaching values of 100% for extract contents above 20%. The synergistic effect of the joint addition of CNF and polyphenols resulted in bioactive films with high UV-blocking capacity that maintained the structural and mechanical properties of pure PVA films. Regarding the antioxidant capacity, a more controlled release action is observed. These results evidenced that the synergistic effect between bioactive extracts and CNF could be an excellent enhancer of the active packaging