Phytochemicals-based edible coating for photodynamic preservation of fresh-cut apples

Clinically Approved Ferric Maltol: A Potent Nanozyme with Added Effect for High-Efficient Catalytic Disinfection

Nanozyme has been proven to be an attractive and promising candidate to alleviate the current pressing medical problems. However, the unknown clinical safety and limited function beyond the catalysis of the most reported nanozymes cannot promise an ideal therapeutic outcome in further clinical application. Herein, we find that ferric maltol (FM), a clinically approved iron supplement synthesized through a facile scalable method, exhibits excellent peroxidase-like activity than natural horseradish peroxidase-like (HRP) and commonly reported Fe-based nanozymes, and also shows high antibacterial performance for methicillin-resistant Staphylococcus aureus (MRSA) elimination (100%) and wound disinfection. In addition, with added effects inherited from contained maltol, FM can accelerate skin barrier recovery. Therefore, the exploration of FM as a safe and desired nanozyme provides a timely alternative to current antibiotic therapy against drug-resistant bacteria.

Thermal-Driven Curcumin Release Film with Dual-Mode Synergistic Antibacterial Behavior for Efficient Tangerine Preservation

Antimicrobial packing showed great potential in extending the shelf life of food. However, developing a new biocomposite film with an intelligent and efficient antimicrobial performance is still desirable. Herein, a Fe-MoOx encapsulated with curcumin (Cur) filled chitosan-based composite film (CCF films) was prepared by solvent casting method. The total color differences of the CCF films were less than 30%, and satisfactory surface color, transparency, hydrophobicity, and thermal stability were also obtained. Besides, the UV-light/water/oxygen barrier capability and mechanical properties were enhanced with the incorporation of Cur@Fe-MoOx. Moreover, CCF films showed photothermal performance and thermal-controlled curcumin release ability, which endowed the CCF0.15 film with excellent antibacterial capability toward E. coli (≥99.95%) and S. aureus (≥99.96%) due to the synergistic antibacterial effect. Fe-MoOx exhibited high cell viability and less than 5% hemolysis even under the concentration of 500 μg mL-1. Based on those unique characteristics, the CCF0.15 film was chosen for tangerine preservation. The CCF0.15 film could prolong the shelf life of tangerine by at least 9 days compared with the unpacking group, and the tangerines could maintain the freshness characteristics over a 24 day storage period. Such thermal-mediated antibacterial film proposed by our work showed promising potential in food packaging.

Effects of High-Pressure Homogenization Treatment on the Development of Antioxidant Zanthoxylum bungeanum Leaf Powder Films for Preservation of Fresh-Cut Apple

This study determined that Zanthoxylum bungeanum leaves (ZBLs) are rich in functional components such as cellulose, protein, flavone, and polyphenols. Therefore, they were used as the main raw material, with sodium alginate as a thickener and glycerol as a plasticizer, to investigate the preparation of active films from ZBL powder through high-pressure homogenization (HPH). The physical, optical, mechanical, and antioxidant properties of the films were evaluated, and their application in preserving fresh-cut apples was examined. The results showed that the optimal concentration of ZBL powder was 1.5% under a 30 MPa HPH treatment. The resulting HPH-treated films exhibited a denser microstructure and improved water vapor barrier properties and mechanical strength. Compared to the films without HPH treatment, the tensile strength increased from 4.61 MPa to 12.13 MPa, the elongation at break increased from 21.25% to 42.86%, the water vapor permeability decreased from 9.9 × 10-9 g/m·s·Pa to 8.0 × 10-9 g/m·s·Pa, and the transparency increased from 25.36% to 38.5%. Compared to the control group, the fresh-cut apples packaged with the HPH-treated ZBL active films exhibited effective preservation of apple quality during a five-day period at 4 °C and 70% humidity, showing better preservation effects than the other groups. In conclusion, the use of HPH treatment in developing novel biopolymer active films from ZBL powders with enhanced properties holds potential for various applications.

Effect of Aloe vera and carboxymethyl cellulose-derived binary blend edible coating on the shelf life of fresh-cut apple

In recent years, the demand and market for minimally processed fruits are increasing worldwide. Fresh-cut apples are extremely sensitive to environmental factors including oxygen, temperature, and microorganisms in resulting the browning of apples. Therefore, in this study, different concentration of blended edible-coating solution was prepared using Aloe vera and carboxymethyl cellulose (1:1, 1:2, 2:1, 3:3, 3:2, 4:2, 2:4, 3:4, and 4:3, respectively). Lease particle size (101.74 ± 0.67 nm) of the coating solution was observed with 3% A. vera and 2% carboxymethyl cellulose (CMC). Afterward, the shelf life of the apples was evaluated for 10 days at refrigeration condition. Results showed that a significant difference was found in weight loss of coated (6.42%-10.26%) and uncoated apples (8.12%-15.32%) for 2-10 days. Moreover, the titrable acidity of the cut apples increased during the storage time. Rheological data emerged that the viscosity of the coating solution decreases with the increasing temperature from 0 to 50°C. Fourier transform infrared spectroscopy data confirmed the presence of hydroxyl group (-OH), C=O, C-O, and N-H banding in the A. vera, CMC, and blend-coating solution. The blend solution indicated excellent antimicrobial efficiency. Total phenolic content of coated and uncoated apples at 0 day was 737.55 mg GAE kg-1 for uncoated and 717.88 mg GAE kg-1, respectively. Whereas, aerobic and psychrotrophic bacteria counts for edible coated apples significantly lower than control apples. For coated apples, aerobic and psychrotrophic bacteria counts were 1.59 ± 0.84 and 1.25 ± 0.49 log CFU g-1 were 4.26 ± 0.67 and 2.68 ± 0.22 log CFU g-1 at 10th day, respectively. Overall, it can be inferred that blend of A. vera and carboxymethyl cellulose could be used as a nontoxic potential anti-browning and antimicrobial component for the enhancement of the shelf life and additional nutritional value of fresh-cut apples.

Dual-Mechanism Tuned Engineered Polyphenols with Cascade Photocatalytic Self-Fenton Reaction for Sustainable Biocidal Coatings

Traditional disposable personal protective equipment (PPE) only blocks pathogenic bacteria by mechanical filtration, with the risk of recontamination and transmission remaining. Herein, inspired by phenolic-enabled nanotechnology (PEN), we proposed engineered polyphenol coatings by plant-derived aromatic aldehydes and metal involvement, denoted as FQM, to obtain the desired photocatalysis-self-Fenton antibacterial performance. Experiments and theoretical analysis proved the dual mechanism of Fe-induced enhancement: (1) tuning of molecular structure realized improved optical properties; (2) Fe(III)/Fe(II) triggered photocatalytic cascade self-Fenton reaction. Mechanism study reveals FQM killing bacteria by direct-contact ROS attack and gene regulation. Further, the FQM was developed as the ideal antibacterial coating on different fabrics (cloth cotton, polyester, and N95 mask), killing more than 93% of bacteria after 5 cycles of use. Such photocatalysis-self-Fenton coatings based on engineered polyphenols endowed with desirable safety, sustainability, and efficient antibacterial features are promising solutions to meet the challenges of the currently available PPE.

Impact of Novel Active Layer-by-Layer Edible Coating on the Qualitative and Biochemical Traits of Minimally Processed 'Annurca Rossa del Sud' Apple Fruit

The color changes brought on by the enzymatic interactions of phenolic compounds with released endogenous polyphenol oxidase and the penetration of oxygen into the tissue has a significant impact on the commercialization of fresh-cut fruit, such as apples. This process causes a loss of quality in fresh-cut apples, resulting in browning of the fruit surface. By acting as a semipermeable barrier to gases and water vapor and thus lowering respiration, enzymatic browning, and water loss, edible coatings can provide a chance to increase the shelf life of fresh-cut produce. In this study, the effect of edible coatings composed of carboxymethylcellulose (CMC, 1%), sodium alginate (SA, 1%), citric acid (CA, 1%), and oxalic acid (OA, 0.5%) on fresh-cut 'Annurca Rossa del Sud' apple was studied. Four formulations of edible coatings, A. SA+CMC, B. SA+CMC+CA, C. SA+CMC+OA, and D. SA+CMC+CA+OA, were tested. Fresh-cut apples were dipped into different solutions and then stored at 4 °C, and physicochemical and biochemical analyses were performed at 0, 4, 8, and 12 days of storage. Results demonstrated that all four combinations improved the shelf-life of fresh-cut apple by slowing down the qualitative postharvest decay, total soluble solid, and titratable acidity. The browning index was highest in the control samples (82%), followed by CMC+SA (53%), CMC+SA+CA (32%), CMC+SA+OA (22%), and finally CMC+SA+CA+OA (7%) after 12 days of cold storage. Furthermore, coating application increased the bioactive compound content and antioxidant enzyme activities. Furthermore, the synergistic activity of SA+CMC+CA+OA reduces enzymatic browning, prolonging the postharvest life of minimally processed 'Annurca Rossa del Sud' apples.