Combination of Low Fluctuation of Temperature with TiO2 Photocatalytic/Ozone for the Quality Maintenance of Postharvest Peach

Inhibition Effects of Infrared Radiation Prior to Cold Storage Against Alternaria alternata on Yellow Peach (Amygdalus persica)

During postharvest storage, the yellow peach (Amygdalus persica) is susceptible to infection by Alternaria alternata, which causes fruit decay and produces multiple Alternaria toxins (ATs), leading to economic losses and potential health risks. The present study investigated the inhibitory effects of infrared radiation treatment against A. alternata on yellow peaches. Our in vitro experimental results indicated that infrared radiation at 50 °C for 30 min could completely inhibit fungal growth and AT production. Furthermore, infrared treatments prior to cold storage effectively delayed the onset of decay and significantly reduced the lesion diameter, decay rate, and AT levels in the yellow peaches inoculated with A. alternata. After the peaches underwent infrared radiation at 50 °C for 30 min and then cold storage for 60 days, the levels of tenuazonic acid, alternariol, alternariol methyl ether, and altenuene in the yellow peaches decreased by 95.1%, 98.6%, 76.1%, and 100.0%, respectively. Additionally, infrared radiation caused slight changes in their firmness, total soluble solids, and concentrations of sugar and organic acids, indicating minor negative impacts on the quality of the yellow peaches. Therefore, the present work provides a novel strategy for controlling A. alternata and AT contamination, thereby extending the shelf-life of yellow peaches, and improving food safety administration.

Automatic periodical negative air ions reduce postharvest decay and maintain texture and flavor quality of 'Fuji' apple during long-term cold storage

The aim of this study was to explore the effect of periodical negative air ions (NAI) on the quality of 'Fuji' apple fruit after treatment at 0, 30, 60, and 90 min every 4 weeks. NAI for 60 min decreased weight loss, mitigated decay, and maintained hardness of the apple fruit during the 40 weeks of storage. Treatment of fruits with NAI for 60 min enhanced the apple defense ability against pathogens by maintaining the cell wall integrity and improving the related-enzyme activities as well as accumulation of total phenols and flavonoids. Reverse-phase HPLC and solid-phase microextraction GC-MS analysis showed that NAI treatment for 60 min increased the levels of fructose, sucrose, sorbitol, malic acid and volatiles, such as 2-hexenal, 2-methylbutyl acetate, hexyl acetate, and ethyl butanoate. Taken together, NAI is promising for improving the quality 'Fuji' apples during the cold storage.

Photocatalytic Antimicrobials: Principles, Design Strategies, and Applications

Nowadays, the increasing emergence of antibiotic-resistant pathogenic microorganisms requires the search for alternative methods that do not cause drug resistance. Phototherapy strategies (PTs) based on the photoresponsive materials have become a new trend in the inactivation of pathogenic microorganisms due to their spatiotemporal controllability and negligible side effects. Among those phototherapy strategies, photocatalytic antimicrobial therapy (PCAT) has emerged as an effective and promising antimicrobial strategy in recent years. In the process of photocatalytic treatment, photocatalytic materials are excited by different wavelengths of lights to produce reactive oxygen species (ROS) or other toxic species for the killing of various pathogenic microbes, such as bacteria, viruses, fungi, parasites, and algae. Therefore, this review timely summarizes the latest progress in the PCAT field, with emphasis on the development of various photocatalytic antimicrobials (PCAMs), the underlying antimicrobial mechanisms, the design strategies, and the multiple practical antimicrobial applications in local infections therapy, personal protective equipment, water purification, antimicrobial coatings, wound dressings, food safety, antibacterial textiles, and air purification. Meanwhile, we also present the challenges and perspectives of widespread practical implementation of PCAT as antimicrobial therapeutics. We hope that as a result of this review, PCAT will flourish and become an effective weapon against pathogenic microorganisms and antibiotic resistance.

Synergistic Effects of 1-MCP Fumigation and ε-Poly-L-Lysine Treatments on Delaying Softening and Enhancing Disease Resistance of Flat Peach Fruit

Flat peach, a predominant fruit consumed in China, is highly susceptible to softening and perishable. The impact of 1-methylcycloproene (1-MCP) fumigation combined with ε-poly-L-lysine (ε-PL) on softening and postharvest reactive oxygen species (ROS) and phenylpropanoid pathway metabolisms in peaches and its relationship to disease resistance were investigated. Findings revealed that a combination of 1 µL L-1 1-MCP and 300 mg L-1 ε-PL effectively suppressed the activity of cell-wall-degrading enzymes and the disassembly of cell wall structure, thus maintaining higher firmness and lower decay incidence. Compared to the control group, the synergistic approach bolstered enzymatic responses linked to disease resistance and ROS-scavenge system, consistently preserving total phenolics, flavonoids, ascorbic acid, and glutathione levels. Concurrently, the accumulation of hydrogen peroxide and malondialdehyde was significantly diminished post-treatment. These results show that there is good synergistic effect between 1-MCP and ε-PL, which could effectively maintain the quality of flat peach fruit by modulating cell wall metabolism and enhancing the resistance.

Impact of vacuum ultraviolet (VUV) photolysis on ethylene degradation kinetics and removal in mixed-fruit storage, and direct exposure to 'Fuji' apples during storage

Accumulated ethylene in fruit storage/transportation causes rapid senescence resulting in reduced shelf-life and postharvest losses. The aim of this study was to investigate the application of vacuum ultraviolet (VUV) photolysis modular reactor for fruit storage. The first experiment compared the effectiveness of VUV photolysis reactor with the standard fruit industry adsorbent (potassium permanganate, KMnO4) on the removal of ethylene from mixed-fruit loading of apples, banana, and pears stored at ambient temperature (16 °C) for 6 days. Second study evaluated the impact of direct VUV radiation on quality attributes of apples stored at 10 °C for 21 days. Results showed that ethylene produced in mixed-fruit loading storage significantly (p < 0.05) reduced by 86.9% in the storage chamber connected to VUV modular reactor compared to 25.4% for storage under potassium permanganate. Direct exposure of apples to VUV radiation successfully reduced both ethylene and respiration rate but damaged the skin of the apples. Hue angle and lightness (L*) for apples exposed to VUV radiation declined significantly (p < 0.05) from 60.7 ± 1.09 to 33.5 ± 9.51 and 58.1 ± 3.60 to 50.4 ± 1.13, respectively. This study showed the potential of VUV photolysis as an innovative technique for removing ethylene from storage facility.

AcbHLH144 transcription factor negatively regulates phenolic biosynthesis to modulate pineapple internal browning

Internal browning (IB), a major physiological disorder of pineapples, usually happens in postharvest processes, but the underlying mechanism remains elusive. The bHLH transcription factors are involved in regulating various biological processes, but whether they could regulate tissue browning in fruit during storage remains unknown. Here we showed that the phenolic biosynthesis pathway was activated in pineapples showing IB following 9 days of storage. AcbHLH144 expression was the highest of the 180 transcription factors identified, downregulated in pineapple with IB, and negatively correlated with the major phenolic biosynthetic genes. AcbHLH144 was shown to be localized in the nucleus and its transient overexpression in pineapples and overexpression in Arabidopsis decreased phenolic biosynthesis. The yeast one-hybrid assay and electrophoretic mobility shift assay showed that AcbHLH144 directly bound to the Ac4CL5 promoter and the dual-luciferase reporter assay showed that it inactivated Ac4CL5 transcription. These results strongly suggest AcbHLH144 as a repressor for phenolic biosynthesis. Abscisic acid (ABA) alleviated IB, reduced phenolic accumulation, and downregulated phenolic biosynthetic genes, including Ac4CL5. Transcriptomic analysis showed that AcbHLH144 was the most upregulated of all 39 bHLHs in response to ABA. ABA enhanced AcbHLH144 expression, reduced phenolic contents, and downregulated phenolic biosynthetic genes in pineapples transiently overexpressing AcbHLH144. Moreover, ABA enhanced enzyme activity of GUS driven by the AcbHLH144 promoter. These results showed that AcbHLH144 as a repressor for phenolic biosynthesis could be activated by ABA. Collectively, the work demonstrated that AcbHLH144 negatively regulated phenolic biosynthesis via inactivating Ac4CL5 transcription to modulate pineapple IB. The findings provide novel insight into the role of AcbHLH144 in modulating pineapple IB during postharvest processes.

Isothermal Storage Delays the Senescence of Post-Harvest Apple Fruit through the Regulation of Antioxidant Activity and Energy Metabolism

The purpose of this work was to elucidate the influence of TF (5 ± 5 °C, and 5 ± 1 °C) and CT (5 ± 0.1 °C served as an isothermal state) storage environment on the antioxidant ability and energy metabolism in post-harvest apple fruit during storage. Specifically, compared with fruit in TFs groups, the quality attributes of apples in the CT group, including firmness, fresh weight, contents of SSC, and TA were maintained at a higher level. In addition, fruit stored in the CT environment revealed a suppressed respiration rate and EL, lower MDA, O₂·^-, and H₂O₂ accumulation but increased the activities of SOD, CAT, APX, and GR. At the end of storage, the SOD, CAT, APX, and GR activities of fruit in the CT group were 38.14%,48.04%, 115.29%, and 34.85% higher than that of the TF5 group, respectively. Fruit in the CT environment also revealed higher AsA, GSH, total phenols, and total flavonoid content. In addition, fruit stored in the CT environment maintained higher ATP content, EC, and more active H⁺-ATPase, Ca²⁺-ATPase, CCO, and SDH. At the end of storage, the SDH and CCO activities of fruit in the TF0.1 group were 1.74, and 2.59 times higher than that in the TF5 group, respectively. Taken together, we attributed the fact that a constant temperature storage environment can retard the fruit senescence to the enhancement of antioxidant capacities and maintaining of higher energy status in apple fruit.

Influence of ozone treatment on functional and rheological characteristics of food products: an updated review

In this milieu, ozone technology has emerged as an avant-garde non-thermal mode of disinfection with potential applications in the food industry. This eco-friendly technology has a comprehendible adeptness in replacing alternative chemical sanitizers and is recognized as a generally safe disinfectant for fruits and vegetables. Several researchers have been focusing on the biochemical impacts of ozone on different quantitative and qualitative aspects of fruits and vegetables. A collection of those works is presented in this review highlighting the effect of ozone on the functional, antioxidant, and rheological properties of food. This can be a benevolent tool for discovering the processing states of ozone applications and ensuing influence on safety and quality attributes of previously studied foods and opening further research areas. It extends shelf life and never leaves any harmful residues on the product since it decomposes to form oxygen. It was seen that the impact on a specific property of food was dependent on the ozone concentration and treatment time, and the adverse effects of ozone exposure can be alleviated once the processing conditions are optimized. The present review can be used as a baseline for designing different food processing operations involving ozone.

Co-Application of 1-MCP and Laser Microporous Plastic Bag Packaging Maintains Postharvest Quality and Extends the Shelf-Life of Honey Peach Fruit

Honey peach (Prunus persica L.) is highly nutritious; it is an excellent source of sugars, proteins, amino acids, vitamins, and mineral elements. However, it is a perishable climacteric fruit that is difficult to preserve. In this study, “Feicheng” honey peach fruit was used as a test material to investigate the synergistic preservation effect of 1-methylcyclopropene (1-MCP) and laser microporous film (LMF). The peach fruits were fumigated for 24 h with 2 μL L⁻¹ 1-MCP, then packed in LMF. In comparison with the control treatment, 1-MCP + LMF treatment markedly decreased the respiration rate, weight loss, and rot rate of peach fruits. Moreover, the combination of 1-MCP and LMF suppressed the increase in soluble solids (SS) and reducing sugars (RS), as well as the decrease in titratable acid (TA) and ascorbic acid (AsA). The combined application also maintained a high protopectin content and low soluble pectin content; it reduced the accumulation of superoxide anions (O₂⁻) and hydrogen peroxide (H₂O₂). Except in a few samples, the catalase (CAT) and ascorbate peroxidase (APX) activities were higher when treated by 1-MCP + LMF. Conversely, the phenylalanine deaminase (PAL), peroxidase (POD), lipase, lipoxygenase (LOX), polygalacturonase (PG), β-glucosidase, and cellulase (Cx) activities were lower than in the control. Furthermore, 1-MCP + LMF treatment reduced the relative abundances of dominant pathogenic fungi (e.g., Streptomyces, Stachybotrys, and Issa sp.). The combined treatment improved the relative abundances of antagonistic fungi (e.g., Aureobasidium and Holtermanniella). The results indicated that the co-application of 1-MCP and LMF markedly reduced weight loss and spoilage, delayed the decline of nutritional quality, and inhibited the physiological and biochemical metabolic activities of peach during storage. These changes extended its shelf-life to 28 days at 5 °C. The results provide a reference for the commercial application of this technology.

Ozone and Bioactive Compounds in Grapes and Wine

Ozone is widely used in the agri-food and food processing industries mainly as a sanitizing agent. However, it has recently become clear that ozone exposition leads to another important benefit: in living tissues, the induced-oxidative stress triggers the antioxidant response, and, therefore, it enhances the production of antioxidant and stress-related secondary metabolites. As such, ozone can be considered an abiotic elicitor. The goal of the present review was to critically summarize knowledge about the possibility of improving bioactive compounds and, consequently, the health-related properties of grapes and wine, by using ozone. The greatest interest has been given not only to the pre- and post-harvest treatment of table and wine grapes, but also to the explanation of the mechanisms involved in the ozone-related response and the main secondary metabolites biosynthetic pathways. From the literature available, it is clear that the effect of ozone treatment on health-related properties and secondary metabolites accumulation depends on many factors, such as the cultivar, but also the form (water or gaseous), doses, and application method of ozone. Most of the published papers report an increase in antioxidant compounds (e.g., polyphenols) and stress-related volatiles, confirming the hypothesis that ozone could be used to improve berry and wine compositional and sensory quality.

Innovative Preservation Technology for the Fresh Fruit and Vegetables

The preservation of the freshness of fruits and vegetables until their consumption is the aim of many research activities. Quality losses of fresh fruit and vegetables during cold chain are frequently attributable to an inappropriate use of postharvest technologies. Moreover, especially when fresh produce is transported to distant markets, it is necessary to adopt proper postharvest preservation technologies in order to preserve the initial quality and limit microbial decay. Nowadays, for each step of supply chain (packing house, cold storage rooms, precooling center, refrigerate transport and distribution), are available innovative preservation technologies that, alone or in combination, could improve the fresh products in order to maintain the principal quality and nutritional characteristics. The issue groups five original studies and two comprehensive reviews within the topic of preservation technologies related to innovative packaging and postharvest operation and treatments, highlighting their effect on quality keeping.

Ozonation as a Method of Abiotic Elicitation Improving the Health-Promoting Properties of Plant Products-A Review

In this review, the primary objective was to systematize knowledge about the possibility of improving the health-promoting properties of raw plant products, defined as an increase in the content of bioactive compounds, by using ozone. The greatest attention has been paid to the postharvest treatment of plant raw materials with ozone because of its widespread use. The effect of this treatment on the health-promoting properties depends on the following different factors: type and variety of the fruit or vegetable, form and method of ozone treatment, and dosage of ozone. It seems that ozone applied in the form of ozonated water works more gently than in gaseous form. Relatively high concentration and long contact time used simultaneously might result in increased oxidative stress which leads to the degradation of quality. The majority of the literature demonstrates the degradation of vitamin C and deterioration of color after treatment with ozone. Unfortunately, it is not clear if ozone can be used as an elicitor to improve the quality of the raw material. Most sources prove that the best results in increasing the content of bioactive components can be obtained by applying ozone at a relatively low concentration for a short time immediately after harvest.