Improving Storability of Fresh Strawberries with Controlled Release Chlorine Dioxide in Perforated Clamshell Packaging

Sustained release of gaseous chlorine dioxide from alpha-cyclodextrin: An innovative method for strawberry preservation

The traditional method of generating chlorine dioxide (ClO2) involves reacting sodium chlorite with acid on-site, posing high safety risks of concentrated ClO2. This study encapsulates ClO2 molecules directly in α-cyclodextrin (α-CD) to form inclusion complexes (ClO2@α-CD). This approach enables stable storage and safe handling of gaseous ClO2, while its sustained-release property also provides long-term microbial inhibition. Fumigation with 0.25 g of ClO2@α-CD completely inhibited Aspergillus niger growth on potato dextrose agar (PDA). A 0.5 g dose reduced the 6-day decay incidence of A. niger-inoculated strawberries from 91.67 % (control) to 5.00 % and the severity from 58.75 % (control) to 1.25 %. In commercial storage simulations, 5 g of ClO2@α-CD reduced the natural incidence from 53.33 % (control) to 26.67 %, while preserving the weight, color, firmness, and total soluble solids (TSS)/titratable acidity (TA) ratio of strawberries. These findings suggest that ClO2@α-CD is a viable approach for controlling postharvest diseases and prolonging fruit shelf-life.

Polylactic acid-based microcapsules for moisture-triggered release of chlorine dioxide and its application in cherry tomatoes preservation

Polylactic acid (PLA)-based microcapsules, capable of releasing chlorine dioxide (ClO2) upon exposure to moisture, have been developed for fruits and vegetables preservation. The microcapsules were prepared by emulsion solvent evaporation, utilizing PLA as the wall material, and NaClO2 as the core material. After optimization, NaClO2 microcapsules exhibited an encapsulation efficiency of 55.75% and an average particle size of 498.08 μm. Citric acid microcapsules were prepared using the same process, but with citric acid as the core material. When the two kinds of microcapsules were mixed, gaseous ClO2 was released in a highly humid environment. The release rate could be adjusted by temperature and the ratio between the two microcapsules, and the release period could be as long as 17 days at 20 °C. With a certain amount of microcapsules placed in the package of cherry tomatoes, the decay rate and weight loss rate of the fruits were reduced by 63 % and 34 %, respectively, compared to the control group. The microcapsules also helped to maintain the good appearance, hardness, and the content of total soluble solid content and titratable acid content of cherry tomatoes. Therefore, the PLA-based microcapsules have satisfied convenience and effectiveness for application in fruit and vegetables preservation.

Chlorine Dioxide Treatment Modulates Ripening-Related Genes and Antioxidant System to Improve the Storability of Tomato

Chlorine dioxide (ClO2) is used to maintain quality and safety of fresh produce. However, ClO2 action mechanism in fresh produce is unknown. In this study, firstly, we evaluated the efficacy of ClO2 treatment on the quality, chilling injury, and calyx molding of tomatoes stored at two different temperatures. Then, ClO2 effect on the expression of cell wall- and ripening-related genes and on the activity of antioxidant enzymes was investigated. Tomatoes were treated with gaseous ClO2 for 15 min before transferring them to 13°C for 12 days and/or 4°C for 14 days, followed by 5 days at 20°C (shelf-life conditions). ClO2 treatment marginally reduced the rate of respiration but did not affect ethylene production at 13°C and 4°C storage or at shelf-life conditions. When stored at 13°C, treatment with ClO2 reduced the loss of firmness, with concomitant repression of pectin esterase 1, a cell wall-related gene. Additionally, at 13°C storage conditions, ClO2 treatment maintained tomato quality in terms of soluble solid content, titratable acidity, and color and was associated with the downregulation of the ripening-relatedethylene response factors B3/C1/E1 and the induction of antioxidant genes encoding catalase and ascorbate peroxidase. At 4°C storage conditions, ClO2 at a concentration of 15 ppm not only maintained the firmness and quality of tomatoes but also inhibited pitting during shelf-life with a concomitant increase of catalase activity. Moreover, treatment with 15 ppm ClO2 significantly reduced the calyx molding that is generally observed in fruits stored at 13°C and under shelf-life conditions. Hence, our results indicate that ClO2 treatment effectively maintained tomato quality and inhibited calyx molding by partially regulating ripening-related genes and antioxidant systems, thereby improving the storability of postharvest tomatoes.

Fresh Produce Safety and Quality: Chlorine Dioxide's Role

Maintaining microbial safety and quality of fresh fruits and vegetables are a global concern. Harmful microbes can contaminate fresh produce at any stage from farm to fork. Microbial contamination can affect the quality and shelf-life of fresh produce, and the consumption of contaminated food can cause foodborne illnesses. Additionally, there has been an increased emphasis on the freshness and appearance of fresh produce by modern consumers. Hence, disinfection methods that not only reduce microbial load but also preserve the quality of fresh produce are required. Chlorine dioxide (ClO₂) has emerged as a better alternative to chlorine-based disinfectants. In this review, we discuss the efficacy of gaseous and aqueous ClO₂ in inhibiting microbial growth immediately after treatment (short-term effect) versus regulating microbial growth during storage of fresh produce (long-term effect). We further elaborate upon the effects of ClO₂ application on retaining or enhancing the quality of fresh produce and discuss the current understanding of the mode of action of ClO₂ against microbes affecting fresh produce.

Preparation of Coated Corrugated Box for Controlled-Release of Chlorine Dioxide and Its Application in Strawberry Preservation

Chlorine dioxide (ClO2) has received great attention as a nontoxic and efficient antimicrobial agent for the preservation of fresh fruits and vegetables. A novel two-layer coated corrugated box was developed to release gaseous ClO2 under the trigger of moisture in this study. The inner surface of the box was firstly coated with a mixture of polyvinyl alcohol-NaClO2-diatomite and then with chitosan acetic acid solution. Results showed that ClO2 was successfully released under high humidity due to the reaction of NaClO2, water vapor and acid. The concentration of released ClO2 increased with the increasing NaClO2 content in the coating, while the addition of diatomite stabilized and extended the release. To evaluate the preservation effect, strawberries were packed in the coated box and stored at room temperature. Compared with the control, the decay rate and weight loss of the strawberries packed in the coated box (9 g/L NaClO2) were reduced up to 21.88% and 6.84%, respectively. The surface color, firmness and nutrients content were also better maintained. Therefore, this coated corrugated box with the capability to release ClO2 under the trigger of moisture has great potential to be applied as an antimicrobial packaging for fresh fruits and vegetables.

Application of chlorine dioxide microcapsule sustained-release antibacterial films for preservation of mangos

In this study, fresh mangos were packed using a custom-made antimicrobial film coated with sustained-release chlorine dioxide microcapsules. We then compared physical and chemical indexes, such as weight loss rate, firmness, chromatic aberrations, soluble solids, vitamin C, titratable acid, and other nutritional indicators, to examine changes in the mango and film during storage. Our findings revealed that control mango showed loss of edible value and commercial value after 21 days of storage, and the chlorine dioxide microcapsule antibacterial film group still retains food value and commercial value. Cross-sectional scanning electron microscopy images of the used film showed that the polylactic acid film was smooth and flat, whereas cross-sections of the antimicrobial film showed that the film was covered with voids due to deliberate release of chlorine dioxide gas during the packaging process. Thus, the antibacterial film exhibited erosion and degradation. These findings provided important insights into the use of antimicrobial films for the packaging of fruits during storage, which is essential for promoting the application of solid chlorine dioxide antimicrobial film in packaging preservation.

Microwave-dried or air-dried? Consumers' stated preferences and attitudes for organic dried strawberries. A multi-country investigation in Europe

Non-thermal food processing technologies are becoming more important in the organic food sector because, beyond preserving the organic feature, they could offer organic products with additional benefits in terms of enhanced nutritional content and healthiness as well as better sensory properties that could satisfy the more complex demands of organic consumers. Berries have a well-known health benefits and show increasing market shares in European markets while dehydration can increase the food convenience in terms of extended shelf-life. This study investigates for the first time organic consumers' stated preferences, attitudes and individual differences for a non-thermal organic processing technology. Specifically, we investigated consumers' preferences for organic dried strawberries varying in drying technology used, such as the most conventional (i.e. thermal) air drying and the most innovative (i.e. non-thermal) microwave drying, origin, price levels, and nutrient contents in three European countries: Norway, Romania and Turkey. Data from a total of 614 consumers were collected through an online choice experiment. Results show that on average consumers prefer organic dried strawberries produced with air drying technology that have national origin, with natural nutrient content and at low price, but country and individual differences are identified. Consumers who showed least rejection for microwave dried products are young, mostly from Norway and have higher positive attitudes towards new food technologies. Consumers who showed most rejection for microwave dried products are older, mostly from Turkey and have higher positive attitudes for organic, natural and ecological products. Organic producers who adopt microwave drying might better inform consumers about the characteristics, the process and highlight the nutritional benefits of such technology. Finally, this research informs policy makers about the need to define and regulate more clearly microwave drying as an organic technology, as well as to regulate labelling to ensure that consumers are not misled and correctly informed about the new technology.

Degradable and Photocatalytic Antibacterial Au-TiO₂/Sodium Alginate Nanocomposite Films for Active Food Packaging

A degradable and antibacterial sodium alginate film containing functional Au-TiO₂ nanocomposites for food packaging was successfully developed. The Au-TiO₂ nanocomposites are synthesized hydrothermally and mixed with the alginate solution to form the film by a casting method. The Au-TiO₂ nanocomposites enable the film with excellent visible light absorption and transfer ability with the light absorption rang covering UV–visible wavelength (300–800 nm) and induce the increase of the film water contact angle from 40° to 74°, which contributes to the film shape stability. Furthermore, compared to the TiO₂ nanoparticle-incorporated film, the antibacterial ability of Au-TiO₂/sodium alginate composite film is improved approximately by 60% and 50% against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively, in light conditions. The antibacterial property of the film arises from the increased production of reactive oxygen species (ROS) induced by the surface plasmonic resonance of Au nanoparticles. The degradable and antibacterial properties render the composite film of great application potential in food packaging industry.

Chlorine dioxide fumigation generated by a solid releasing agent enhanced the efficiency of 1-MCP treatment on the storage quality of strawberry

The effect of 1-methylcyclopropene (1-MCP) and chlorine dioxide (ClO₂) on fruit quality during storage was investigated. Strawberries were treated with 1-MCP alone or in combination with ClO₂ gas generated by a releasing agent, and the quality, fruit decay, microbial inhibition, and enzyme activities [polyphenol oxidase (PPO), superoxide dismutase (SOD), ascorbate peroxidase (APX), and phenylalanine ammonia lyase (PAL)] at 4 °C were measured for 16 days. 1-MCP alone could maintain the fruit quality during storage but had little effect on microbial growth, resulting in quick decay during storage. ClO₂ treatment effectively inhibited microbial growth during storage and improved shelf life with no visual damage. Moreover, 1-MCP in combination with ClO₂ was superior in maintaining quality attributes as compared with 1-MCP alone, as significant differences were found in some indices. Furthermore, 1-MCP in combination with ClO₂ maintained higher SOD, APX, and PAL activities and lower PPO activity as compared with the control and 1-MCP alone. Overall, ClO₂ enhanced the effect of 1-MCP on strawberries during storage and shelf life, possibly through the inhibition of microbial growth and regulation of enzyme activity. The combination of 1-MCP and ClO₂ may serve as a potential strategy with dual physiological and antimicrobial effects for the preservation of perishable products.