Laser-Induced Microporous Modified Atmosphere Packaging and Chitosan Carbon-Dot Coating as a Novel Combined Preservation Method for Fresh-Cut Cucumber

Synergistic inactivation effect and mechanism of ultrasound combined with Zanthoxylum schinifolium essential oil nanoemulsions against Escherichia coli O157:H7 and its application on fresh-cut cucumber

Fresh-cut produce is often contaminated with Escherichia coli O157, posing a significant risk to public health. This study investigated the synergistic inactivation effect and underlying mechanism of ultrasound (US) combined with Zanthoxylum schinifolium essential oil nanoemulsion (ZEO-NE) against E. coli O157:H7, and explored its potential application in fresh-cut cucumbers. The results demonstrated that combined treatment of US and ZEO-NE significantly reduced the viable counts of E. coli O157:H7 compared to treatment with US or ZEO-NE alone. In particular, US (20 kHz, 345 W/cm2) + ZEO-NE (1.0 mg/mL) treatment for 12 min achieved an 8.91 log colony-forming units (CFU)/mL reduction in viable counts of E. coli O157:H7. Moreover, biofilm formation assay revealed that US+EO-NE treatment significantly reduced mobility, altered surface properties, and inhibited biofilm formation of E. coli O157:H7 cells compared to single treatments. The synergistic inactivation mechanism of US+ZEO-NE treatment against E. coli O157:H7 was revealed to involve increased cell membrane permeability, resulting in leakage of nucleic acids, proteins, and LDH, AKP, and ATP, disruption of cell membrane integrity, and alterations in membrane potential. Additionally, the US+ZEO-NE treatment induced reactive oxygen species accumulation and disrupted cell morphology, ultimately leading to E. coli O157:H7 cell death. Notably, the US+EO-NE treatment also significantly reduced the E. coli O15:H7 counts in fresh-cut cucumbers compared to single treatments, without adversely affecting the quality and sensory properties of the produce during storage at 4 °C for 12 days. Overall, these findings suggest that US+EO-NE is a promising technique for bacterial inactivation, and holds potential for improving microbial safety in fresh-cut produce.

Modification of microporous bionanocomposite films with visible light-activated photocatalytic antimicrobial TNT-CuO nanoparticles for active fruit packaging

Active packaging technologies are evolving to enhance the preservation of fresh produce by fighting against microbial contamination and controlling internal packaging atmospheres. This study introduced an active fruit packaging called MT film, created by modifying a microporous polyvinyl alcohol/chitosan/cellulose nanocrystal bionanocomposite film with CuO-doped titania nanotubes. The MT film, with an average micropore size of 2.4 μm, displayed excellent mechanical properties and hydrophobicity due to its crosslinked structure. When exposed to visible light, the MT film could produce reactive oxygen species, effectively inhibiting the growth of Staphylococcus aureus and Escherichia coli O157:H7. Moreover, experiments on blueberry preservation demonstrated that the MT film could remove excess CO2 and maintain a higher O2 level. Under visible light, this film significantly reduced total viable count (4.6 ± 0.2 log CFU/g) and mold colony count (2.6 ± 0.1 log CFU/g), with Bacillus and Ascochyta being the primary inhibited genera. These findings highlight the potential of MT film in utilizing visible light to prevent microbial growth on blueberries and regulating the gas exchange of food packaging. MT film holds promise as an active packaging solution to improve the quality and shelf life of fresh produce while reducing food losses in the supply chain.

Edible coating using carbon quantum dots for fresh produce preservation: A review of safety perspectives

Fresh produce deteriorates and spoils after harvest due to its perishable nature. Deterioration in quality over time has become a major problem for the food industry, placing an undue burden on the economy and agriculture. Food scientists have developed various methods and technologies to prevent spoilage of fruits and vegetables during storage and logistics. Utilizing carbon quantum dots (CQDs) in the form of active packaging and coatings has been a popular strategy recently. CQDs have recently attracted attention as sustainable and functional nanomaterials. CQDs are popular among food scientists due to their easy and economical synthesis, sustainability, non-toxicity, biocompatibility, edibility, UV protection, and antibacterial and antioxidant activities. Although many studies have been conducted and reviewed on the utilization of CQDs in the manufacture of flexible active packaging materials, relatively few studies have investigated the use of CQDs in edible coating formulations for fresh produce. The main reasons for this are concerns about the potential toxicity and edibility of CQDs if they are coated directly on fresh produce. Therefore, this review aims to address these issues by investigating the dose-dependent non-toxicity and biocompatibility of sustainable CQDs along with other important properties from a food packaging perspective. Additionally, this review focuses on the studies performed so far on the direct coating of CQD-based formulations on fresh and fresh-cut fruits and vegetables and discusses the important impact of CQDs on the quality of coated agricultural products. This review is intended to provide food packaging researchers with confidence and prospects for utilizing sustainable CQDs in direct coating formulations for food.

Effect of Chitosan and Hyperbranched Poly-L-Lysine Treatment on Quality of Cucumber (Cucumis sativus L.) during Storage

To enhance the storage time of cucumbers, this research investigated the impact of chitosan (CS) and hyperbranched poly-L-lysine (HBPL) on the quality and nutritional attributes of cucumbers when stored at a temperature of 25 °C. The results demonstrated that sensory evaluation scores for cucumbers treated with a CS-HBPL combination were significantly higher than the control (CK), CS, and HBPL groups. On the 18th day of storage, cucumbers in the CK group exhibited significant decay and softening; however, there was a decrease in hardness observed in the CS-HBPL group and no decay or noticeable sour taste was detected. Furthermore, compared to the CK group, treatment with CS-HBPL effectively delayed cucumber decay and weight loss rate while significantly inhibiting decreases in cucumber hardness and growth of surface microorganisms. Additionally, it substantially reduced losses of soluble protein content as well as vitamin C (Vc), reducing sugars, and total phenolic compounds within cucumbers, which were 4.7 mg/g, 4.7 mg/g, 0.94 mg/g, and 0.52 mg/kg, respectively. Moreover, compared to the CK group, combined treatment with CS-HBPL significantly inhibited malondialdehyde (MDA) accumulation and reducing relative electrolyte permeability within cucumbers, which were 1.45 μmol·g-1FW and 29.82%. Furthermore, it notably enhanced activities of superoxide dismutase (SOD) and catalase (CAT), while exerting a significant inhibitory effect on polyphenol oxidase (PPO). In summary, the combined CS-HBPL treatment successfully prolonged cucumber shelf life at room temperature, enabling new possibilities for extending cucumber shelf life.

Applicability and Freshness Control of pH-Sensitive Intelligent Label in Cool Chain Transportation of Vegetables

Freshness is one of the main factors affecting consumers' purchase of food. The freshness indicator labels of packaged fresh green bell pepper (Capsicum annuum L.) and greengrocery (Brassica chinensis L.) were constructed, and pH-sensitive indicator labels based on the dye of anthocyanin and the mixing dye of methyl red and bromothymol blue were prepared in this study. At the same time, the color, chlorophyll content and vitamin C content of vegetables were measured in order to explore the applicability of indicator labels in the cool chain transportation of vegetables. Compared with the nature dye, the chemical dye-type indicator labels are more sensitive to pH changes. The results showed that the mixed indicator intelligent label had the best indication effect, and the MB 2 (mixing 1 g/L methyl red and bromothymol blue solutions at a ratio of 3:2 with a concentration of 70 mL/L in indicator film solution) indicator label could effectively indicate the freshness changes in vegetables during storage. Meanwhile, the color changes of the MB 2-type indicator label were correlated with the colors change of the sample, changes in nutrients, and changes in CO2 content inside the packaging. In addition, freshness detection models for green bell pepper and greengrocery by using color information of MB 2 intelligent labels were established. Hence, this pH-sensitive label can be applied as a promising intelligent packaging for non-destructively monitoring the freshness of respiratory and non-respiratory climacteric vegetables.

Laser Light as an Emerging Method for Sustainable Food Processing, Packaging, and Testing

In this review article, we systematically investigated the diverse applications of laser technology within the sphere of food processing, encompassing techniques such as laser ablation, microbial inactivation, state-of-the-art food packaging, and non-destructive testing. With a detailed exploration, we assess the utility of laser ablation for the removal of surface contaminants from foodstuffs, while also noting the potential financial and safety implications of its implementation on an industrial scale. Microbial inactivation by laser shows promise for reducing the microbial load on food surfaces, although concerns have been raised about potential damage to the physio-characteristics of some fruits. Laser-based packaging techniques, such as laser perforation and laser transmission welding, offer eco-friendly alternatives to traditional packaging methods and can extend the shelf life of perishable goods. Despite the limitations, laser technology shows great promise in the food industry and has the potential to revolutionize food processing, packaging, and testing. Future research needs to focus on optimizing laser equipment, addressing limitations, and developing mathematical models to enhance the technology's uses.

Chitosan Based Biodegradable Composite for Antibacterial Food Packaging Application

A recent focus on the development of biobased polymer packaging films has come about in response to the environmental hazards caused by petroleum-based, nonbiodegradable packaging materials. Among biopolymers, chitosan is one of the most popular due to its biocompatibility, biodegradability, antibacterial properties, and ease of use. Due to its ability to inhibit gram-negative and gram-positive bacteria, yeast, and foodborne filamentous fungi, chitosan is a suitable biopolymer for developing food packaging. However, more than the chitosan is required for active packaging. In this review, we summarize chitosan composites which show active packaging and improves food storage condition and extends its shelf life. Active compounds such as essential oils and phenolic compounds with chitosan are reviewed. Moreover, composites with polysaccharides and various nanoparticles are also summarized. This review provides valuable information for selecting a composite that enhances shelf life and other functional qualities when embedding chitosan. Furthermore, this report will provide directions for the development of novel biodegradable food packaging materials.

Evaluation of a Packaging System in Pallets Under Modified Atmosphere to Extend the Shelf-life of ‘Padrón’ Peppers Stored at Refrigeration Temperature

A modified atmosphere packaging (MAP) system in pallets was developed for ‘Padrón’ peppers as a way to extend their shelf-life while maintaining good fruit quality. Peppers were stored at 6 °C in cardboard boxes arranged on pallets wrapped in micro-perforated low-density polyethylene (LDPE) bags. Physico-chemical (moisture, firmness, color, chlorophylls, carotenoids, ascorbic acid, and total phenolic content) and sensory analysis were carried out after 0, 7, 14, and 21 days of storage. An initial mixture of 11.8% O2–8.5% CO2 prevented anaerobic conditions and kept suitable CO2 levels throughout the entire storage period. Silica gel was tested as a moisture absorbent and considerably reduced water vapor condensation inside packaging bags. The MAP system developed maintained the shelf-life of peppers until the end of the 21-day storage period. The fruit always showed a good appearance and color. No rotting or other types of undesirable alterations were observed. MAP markedly reduced the fraction of peppers with water loss as evidenced by a minimum percentage of fruit with wrinkles (12.5%) as compared to unpackaged samples (75%). Good pigment stability was also observed.

Chitosan-Based Carbon Dots with Applied Aspects: New Frontiers of International Interest in a Material of Marine Origin

Carbon dots (CDs) have attracted significant research attention worldwide due to their unique properties and advantageous attributes, such as superior optical properties, biocompatibility, easy surface functionalization, and more. Moreover, biomass-derived CDs have attracted much attention because of their additional advantages related to more environmentally friendly and lower-cost synthesis. In this respect, chitosan has been recently explored for the preparation of CDs, which in comparison to other natural precursors exhibited additional advantages. Beyond the benefits related to the eco-friendly and abundant nature of chitosan, using it as a nanomaterial precursor offers additional benefits in terms of structure, morphology, and dopant elements. Furthermore, the high content of nitrogen in chitosan allows it to be used as a single carbon and nitrogen precursor for the preparation of N-doped CDs, significantly improving their fluorescent properties and, therefore, their performances. This review addresses the most recent advances in chitosan-based CDs with a special focus on synthesis methods, enhanced properties, and their applications in different fields, including biomedicine, the environment, and food packaging. Finally, this work also addresses the key challenges to be overcome to propose future perspectives and research to unlock their great potential for practical applications.

Effect of Cold Shock Pretreatment Combined with Perforation-Mediated Passive Modified Atmosphere Packaging on Storage Quality of Cucumbers

This study evaluated the application of cold shock combined with perforation-mediated passive modified atmosphere packaging technology (CS-PMAP) for cucumber preservation through physicochemical, sensory, and nutritional qualities. The effectiveness of CS-PMAP in maintaining the quality of fresh cucumbers was studied; cucumbers were pretreated with cold shock and then packed into perforated polyethylene bags (bag size of 20 × 30 cm; film thickness of 0.07 mm; and two holes in each bag with a diameter of 6 mm), while the cucumbers without cold shock were considered as the control. Storage of the samples was performed at (13 ± 2) °C for 20 days to determine the quality changes in terms of gas composition, weight loss, skin color, texture, total soluble solids (TSS), ascorbic acid, malondialdehyde (MDA), and volatile organic compounds (VOCs). The CS-PMAP showed a significant improvement in maintaining firmness, TSS, ascorbic acid, and flavor profile of cucumbers; the control samples without cold shock showed higher weight loss and MDA levels. Results of this study confirmed that CS-PMAP has potential use in the storage of cucumbers.