Ozone micro-nano bubble water preserves the quality of postharvest parsley

Polarized electric field induced by piezoelectric effect of ozone micro-nano bubbles/spontaneously polarized ceramic to boost ozonolysis for efficient fruit sterilization

Ozone (O3) treatment is an environmentally friendly fruit sterilization strategy. However, the low O3 utilization rate and long-term oxidation lead to O3 waste and fruit damage, respectively. Herein, a sterilization system based on the synergy of O3 micro-nano bubbles (OMNB) and spontaneously polarized ceramic (SPC) was developed to piezoelectrically catalyze ozonolysis for efficient fruit sterilization. OMNB/SPC showed excellent sterilizing activity with 7 lg CFU/mL of E. coli and S. aureus inactivation within 20 min, together with significantly improved fruit quality in Kyoho grapes preservation. The excellent sterilizing performance of OMNB/SPC is attributed to that the piezoelectric SPC (d33 = 103.4 pm/V) formed a strong polarized electric field and rich reactive oxygen species (ROS) under OMNB collapse resulting in O3 absorption/decomposition. The electric field and rich ROS caused membranes in-situ electroporation and irreversible inactivation to the microorganisms on fruits successively. This system is important for more efficient long-term preservation of fruits.

Porous spontaneously polarized ceramic-reinforced ozone micro-nano bubbles for efficient oxidation of starch: Reaction uniformity, physicochemical properties, and mechanism

The preparation of food-grade oxidized starch with eco-friendly ozone (O3) as oxidant is limited by low mass transfer and reaction efficiency. This study proposed a porous spontaneously polarized ceramic-reinforced O3 micro-nano bubbles (PSPC-OMNB) technology to prepare oxidized cassava starch (PSPC-OMCS). Meanwhile, reaction uniformity, physicochemical properties, and formation mechanisms were emphasized for comprehensive investigation. PSPC-OMNB enhanced starch oxidation by improving mass transfer and activating reactive sites in molecular chains. PSPC-OMCS with superior oxidation uniformity exhibited favorable physicochemical properties. The oxidation mechanism illustrates that local electric field of PSPC-OMNB enhanced O3 adsorption-decomposition to generate hydroxyl radicals and simultaneously diminished hydrogen bonding of H2O to form small water clusters, which effectively promoted uniform distribution of oxidized groups in the C2, C3, and C6 sites along starch molecular chains. This study proposes great promise for achieving reaction uniformity in efficient oxidation of starch.

Efficacy of Air and Oxygen Micro-nano Bubble Waters Against Colletotrichum gloeosporioides and Impacts on Postharvest Quality of 'Fan Retief' Guava Fruit

This study focused on the application of micro-nano bubbles (MNBs) water generated using air or oxygen (O2), as an alternative to chlorine-based wash for fruits. For the in vitro and in vivo investigation, 106 spore or conidia/mL Colletotrichum gloeosporioides suspension was used, and treated with solutions of air- or O2-MNB for 30- or 60-min, sodium hypochlorite (NaOCl), and untreated (as control). In the second experiment, freshly harvested guava fruits were washed with tap water (control), NaOCl (standard practice), air-, or O2-MNB (for 15- or 30-min). All samples were packaged, stored for 21 days at 13 °C, and monitored for changes in natural microbial population and quality attributes. Based on the confocal laser and transmission electron microscopy results, exposure of C. gloeosporioides to air-MNB for 60 min resulted in the lowest viable cell count (%) compared to control and other treatments (O2-MNB and NaOCl). Air- and O2-MNB treatments damaged cellular structures, disrupted cell membrane integrity, and deformed hyphal morphology. Washing 'Fan Retief' guava (Psidium guajava L.) in air- or O2-MNB (for 15 and/or 30 min), better-retained tissue strength, delayed changes in color, and total soluble solid (TSS) content. Notably, MNB treatments were as effective as NaOCl washing and significantly reduced microbial load on fruit surface by ≥2 Log (p < 0.05). Micro-nano bubble water treatment offers a new paradigm for decontamination and preservation of guava fruit quality.

Preserving refrigeration and shelf life quality of hardy kiwifruit (Actinidia arguta) with alginate oligosaccharides preharvest application

Alginate oligosaccharide (AOS) is a bioactive carbohydrate known for its preservation properties. However, the efficacy of preharvest AOS treatment in maintaining the postharvest quality of hardy kiwifruit (Actinidia arguta) has not been previously reported. This study explores the effects of preharvest AOS treatment (80 mg L-1) on A. arguta fruit, assessing visual quality, physiological attributes, aroma, and antioxidant capacity during refrigeration and shelf life. Results showed that AOS treatment maintained higher lightness, chroma, firmness, and antioxidant levels (total phenolics, flavonoids, ascorbic acid, and glutathione), along with antioxidant enzyme activities (peroxidase, catalase, and ascorbate peroxidase). Specifically, AOS-treated fruit had 9% higher chroma and double the firmness after 60 days of refrigeration. AOS treatment reduced ripening and senescence, with 25% lower soluble solids content, 22% lower respiration rate, 30% lower ethylene production, and 35% lower malondialdehyde content. Electronic nose analysis indicated that AOS treatment suppressed changes in fruit aroma and off-odor development, maintaining significantly higher quality during the shelf life period. These findings demonstrate the effectiveness of AOS as a sustainable method to extend shelf life and preserve the quality of A. arguta fruit, enhancing its market value and consumer appeal. PRACTICAL APPLICATION: The research on using alginate oligosaccharides (AOS) for preharvest treatment of hardy kiwifruit (Actinidia arguta) has practical applications in the food industry. By extending the shelf life and preserving the quality of the fruit during storage, this method can help reduce postharvest losses and improve the market value and consumer appeal of A. arguta fruit. This sustainable preservation technique offers an eco-friendly alternative to traditional methods, enhancing the freshness and nutritional quality of the fruit available to consumers.

Effects of micro/nano-ozone bubble nutrient solutions on growth promotion and rhizosphere microbial community diversity in soilless cultivated lettuces

Due to its high efficacy as a wide-spectrum disinfectant and its potential for the degradation of pollutants and pesticides, ozone has broad application prospects in agricultural production. In this study, micro/nano bubble technology was applied to achieve a saturation state of bubble nutrient solution, including micro-nano oxygen (O2 group) and micro-nano ozone (O3 group) bubble nutrient solutions. The effects of these solutions on lettuce physiological indices as well as changes in the microbial community within the rhizosphere substrate were studied. The application of micro/nano (O2 and O3) bubble nutrient solutions to substrate-cultured lettuce plants increased the amount of dissolved oxygen in the nutrient solution, increased the lettuce yield, and elevated the net photosynthetic rate, conductance of H2O and intercellular carbon dioxide concentration of lettuce plants. Diversity analysis of the rhizosphere microbial community revealed that both the abundance and diversity of bacterial and fungal communities in the substrate increased after plant cultivation and decreased following treatment with micro/nanobubble nutrient solutions. RDA results showed that the microbial community in the S group was positively associated with EC, that in the CK and O2 groups exhibited a positive correlation with SC, and that in the O3 group displayed a positive correlation with CAT and POD. Overall, the implementation of micro/nanobubble generation technology in soilless substrates can effectively increase the lettuce growth and yield, and O3 had a more pronounced effect on lettuce yield and quality and the microbial community structure in the substrate than O2. Our study would provide a reference and theoretical basis for developing sustainable and green technology for promoting lettuce production and can be a promising alternative to conventional methods for improving crop yields.

Recent advances in activated water systems for the postharvest management of quality and safety of fresh fruits and vegetables

Over the last three decades, decontamination management of fresh fruits and vegetables (FFVs) in the packhouses and along the supply chains has been heavily dependent on chemical-based wash. This has resulted in the emergence of resistant foodborne pathogens and often the deposition of disinfectant byproducts on FFVs, rendering them unacceptable to consumers. The management of foodborne pathogens, microbial contaminants, and quality of FFVs are a major concern for the horticultural industries and public health. Activated water systems (AWS), such as electrolyzed water, plasma-activated water, and micro-nano bubbles, have gained significant attention from researchers over the last decade due to their nonthermal and nontoxic mode of action for microbial inactivation and preservation of FFVs quality. The aim of this review is to provide a comprehensive summary of recent progress on the application of AWS and their effects on quality attributes and microbial safety of FFVs. An overview of the different types of AWS and their properties is provided. Furthermore, the review highlights the chemistry behind generation of reactive species and the impact of AWS on the quality attributes of FFVs and on the inactivation/reduction of spoilage and pathogenic microbes (in vivo or in vitro). The mechanisms of action of microorganism inactivation are discussed. Finally, this work highlights challenges and limitations for commercialization and safety and regulation issues of AWS. The synergistic prospect on combining AWS for maximum microorganism inactivation effectiveness is also considered. AWS offers a potential alternative as nonchemical interventions to maintain quality attributes, inactivate spoilage and pathogenic microorganisms, and extend the shelf-life for FFVs.