Fruit Surface Research Articles

Metabolic fingerprint of ‘WA 38’ green spot symptoms reveals increased production of epicuticular metabolites by parenchyma

Green spot is a pre-harvest physiological disorder of ‘WA 38’ apple fruit that can culminate in corking immediately underneath the peel surface. Unlike bitter pit and many other corking disorders, superficial symptoms emerge in the middle of the growing season as areas of peel discoloration, with the most severe symptoms appearing as parenchyma necrosis or corking that worsens until harvest. Our previous work demonstrated the mitigative effect of early season fruit bagging on green spot appearance, but the mechanism of its onset and the biochemical signatures associated with it remained unknown. We used metabolic profiling to, first, identify metabolites associated with green spot symptoms in the peel and cortex of ‘WA 38’ apples and, then, track changes before and after disorder onset until harvest from apples that were bagged, under a shade net, or uncovered (control). We linked metabolites from multiple metabolic pathways, including carotenoids, phenolics, triglycerides, and triterpenes, with peel and cortex green spot symptoms. Many pigment and triterpene compounds associated with cortex symptoms are typically far less abundant in cortex tissue than in peel. Light-altering treatments also impacted levels of several of these compounds during the growing season; however, the inability to predict which pre-symptomatic tissue would later develop symptoms compromised the establishment of disorder genesis and latent development using this technique. Despite these challenges, we linked novel metabolites and pathways with the disorder, including those that may indicate strengthening and isolation of symptomatic tissue, possibly to provide protections similar to the fruit surface.

Detection of early bruises on apples using hyperspectral reflectance imaging coupled with optimal wavelengths selection and improved watershed segmentation algorithm.

Bruises caused by mechanical collision during the harvesting and storage and transportation period are difficult to detect using traditional machine vision technologies because there is no obvious difference in appearance between bruised and sound tissues. As a result of its fast and non-destructive characteristics, hyperspectral imaging technology is a potential tool for non-destructive detection of fruit surface defects. In the present study, visible near infrared hyperspectral reflectance images of healthy apples and bruised apples at 6, 12 and 24 h were obtained. To reduce hyperspectral data dimension, optimal wavelength selection algorithms including principal component analysis (PCA) and band ratio methods were utilized to select the effective wavelengths and enhance the contrast between bruised and sound tissues. Then pseudo-color image transformation technology combining with improved watershed segmentation algorithm (IWSA) were employed to recognize the bruise spots. The result obtained showed that band ratio images obtained better detection performance than that of PCA. The G component derived from pseudo-color image of followed by IWSA obtained the best segmentation performance for bruise spots. Finally, a multispectral imaging system for the detection of bruised apple was developed to verify the effectiveness of the proposed two-band ratio algorithm, obtaining recognition rates of 93.3%, 92.2% and 92.5% for healthy, bruised and overall apples, respectively. The bruise detection algorithm proposed in the present study has potential to detect bruised apple in online practical applications and hyperspectral reflectance imaging offers a useful reference for the detection of surficial defects of fruit. © 2023 Society of Chemical Industry.

Analysis of mango fruit surface temperature using thermal imaging and deep learning

Abstract Thermal imaging has the potential to measure the object’s surface temperature. This study investigated the thermal behavior of mango fruit stored in a refrigerated environment. Thermal images of the fruit were collected with sufficient quality by supplying hot air to the acquisition environment. Grey-Level Co-occurrence Matrix (GLCM) features of mango images were determined to distinguish the subtle and noticeable changes. The thermal images were analyzed to find the temperature difference between the different regions of the fruit. The temperature of the bruise boundary (T bd ) was higher than the bruised center (T C ) throughout the storage period. In addition, an enhanced deep-learning model was used to predict the damaged mango. Over 10 days, 3500 thermal images were obtained from the 400 mangoes. In that, 80 % of the images were used for training, 10 % for testing, and 10 % for validation. The model achieved a classification accuracy of 99.6 %.

Stone fruit phenolic and triterpenoid compounds modulate gene expression of Monilinia spp. in culture media

Phenolic and triterpenoid compounds are essential components in stone fruit skin and flesh tissues. They are thought to possess general antimicrobial activity. However, regarding brown rot disease, investigations were only confined to a limited number of phenolics, especially chlorogenic acid. The activity of triterpenoids against Monilinia spp., as an essential part of the peach cuticular wax, has not been studied before. In this work, the anti-fungal effect of some phenolics, triterpenoids, and fruit surface compound (FSC) extracts of peach fruit at two developmental stages were investigated on Monilinia fructicola and Monilinia laxa characteristics during in vitro growth. A new procedure for assaying anti-fungal activity of triterpenoids, which are notoriously difficult to assess in vitro because of their hydrophobicity, has been developed. Measurements of colony diameter, sporulation, and germination of second-generation conidia were recorded. Furthermore, the expression of twelve genes of M. fructicola associated with germination and/or appressorium formation and virulence-related genes was studied relative to the presence of the compounds. The study revealed that certain phenolics and triterpenoids showed modest anti-fungal activity while dramatically modulating gene expression in mycelium of M. fructicola on culture medium. MfRGAE1 gene was overexpressed by chlorogenic and ferulic acids and MfCUT1 by betulinic acid, at 4- and 7- days of mycelium incubation. The stage II FSC extract, corresponding to the period when the fruit is resistant to Monilinia spp., considerably up-regulated the MfLAE1 gene. These findings effectively contribute to the knowledge of biochemical compounds effects on fungi on in vitro conditions.

Physicochemical and preservative properties of tyrosinase-crosslinked sodium caseinate-EGCG-carboxymethyl chitosan composite packaging: Comparison of blended and layer-by-layer films

Bio-based packaging materials reduce the interactions of foods with their environment, which improves their quality, safety, and shelf life. Simple blending and layer-by-layer (LBL) deposition methods are commonly used film preparation methods. However, it is not clear which method has a better preservation effect. In this study, differences in the structures and properties of tyrosinase-crosslinked sodium caseinate (SC)-epigallocatechin gallate (EGCG)-carboxymethyl chitosan (CMC) composite packaging materials (coatings and films) prepared by these two methods were compared. Fruit preservation experiments were carried out by applying blend or LBL coatings to banana or strawberry. The structural properties of films prepared by the blend and LBL methods were analyzed to provide insights into their different performances. The adsorption of the coating solution onto the fruit surfaces, as well as the microstructure and properties of the coatings formed, were the main factors affecting fruit preservation. Strawberry or banana coated by blend coatings exhibited a good appearance after 7 or 14 days. Overall, the water vapor barrier properties of the blend films were better than those of the LBL films. Moreover, the mechanical and EGCG-release properties of the blend films were also good. In summary, the properties of the coatings/films prepared by the blending and LBL methods were compared. This study helps to facilitate the rational design of edible packaging materials for different applications.

Effect of Irrigation with Treated Wastewater on Squash Yields, Soil Chemical and Microbial Properties

n this study, the effects of irrigation with treated wastewater (TWW) on soil chemical, microbiological, and yield of squash were investigated. Squash seedlings (Cucurbita pepo) were irrigated using conventional irrigation water (CIW), treated wastewater (TWW), and blended irrigation water (BIW). The drip irrigation system was used to irrigate Squash with CIW, TWW, and BIW. The concentration of all chemical and microbial irrigation water characteristics was falling within the limits of Jordanian standards (JS893/2021), except for turbidity and boron. Pathogens indicators such as Salmonella, and Helminth eggs were not found in TWW. TWW-irrigated plots had significant differences in electrical conductivity, organic carbon, total nitrogen, and sodium adsorption ratio (SAR). Total coliform and Escherichia coli (E. coli) contents increased significantly within TWW-irrigated plots. Squash’s fresh yield weight irrigated with TWW showed no significant difference compared with CIW. TWW and BIW treatments had a tendency toward lower fruit numbers than CIW. E. coli was not significantly different on the surface of squash fruits, while Total coliform increased significantly for fruits within the TWW-irrigated plots.

Overcoming lemon postharvest molds caused by Penicillium spp. multiresistant isolates by the application of potassium sorbate in aqueous and wax treatments.

Penicillium digitatum and Penicillium italicum are the main causal agents of postharvest diseases in lemon. Over the last decades, the appearance of isolates resistant to the main commercial fungicides has been considered one of the most serious problems for the citrus industry. In this work, potassium sorbate (KS) was evaluated as an alternative to chemical fungicides to control postharvest diseases caused by Penicillium isolates resistant to imazalil, thiabendazol, and pyrimethanil. In vitro assays showed that 1% KS inhibited conidia germination and mycelial growth of sensitive and resistant P. digitatum and P. italicum isolates, being this effect stronger at pH 5 than at pH 9. In curative treatments, the immersion of inoculated lemons in 1% KS aqueous solution for 30 s reduced green and blue molds incidences by around 80%. No wound protection effect was observed when wounded lemons were immersed in 3% salt solution before inoculation. Noteworthy, the inclusion of KS in a commercial wax coating effectively controlled green and blue molds, even in decays caused by fungicide resistance isolates. Together, results encourage the use of KS in lemon postharvest treatments to contribute to the management of resistant strains, which represent a major challenge in packinghouses worldwide. PRACTICAL APPLICATION: The use of KS in citrus postharvest treatments would help producers to reduce spoilage caused by Penicillium fungicide-resistant strains. The inclusion of this generally recognized as safe compound in wax coatings improves its persistence on the fruit surface, keeping product quality during long-term overseas transport. In sum, KS constitutes an affordable and eco-friendly option for controlling postharvest molds in lemon fruit.

Physicochemical properties of peach fruit assessed by non-destructive methodology related to the development of Monilinia fructicola during postharvest

ABSTRACT The concomitant evaluation of physicochemical properties and development of important diseases, such as brown rot in peaches postharvest, is hampered by the use of destructive methods for physicochemical analysis. Therefore, this study aimed to evaluate the physicochemical characteristics in wounded and unwounded ‘Chimarrita’ and ‘Maciel’ peaches inoculated with M. fructicola assessed by non-destructive methods. The fruits were stored at room temperature (25 ºC) for 10 days after harvest. Colorimeter, near-infrared spectroscopy and portable spectrophotometer DA-meter® (single index of absorbance difference, IAD index) were used to evaluate the physicochemical changes that naturally occurred in peaches during postharvest and due to pathogen development on the same fruit simultaneously. Incidence and severity of brown rot were evaluated by counting the number of lesions resulting from inoculation at 24, 48 and 60 h post inoculation. Also, the sporulation of M. fructicola on fruit surface was evaluated. The results indicated that differences between wounded and unwounded fruits related soluble solids content, pulp firmness, titratable acidity, dry matter and IAD did not affect the incidence of M. fructicola in both cultivars. However, the interaction between dry matter and colour at the time of inoculation influenced colonisation and consequent lesion size in inoculated wounded ‘Chimarrita’ fruits.

Automated detection of internal fruit rot in Hass avocado via deep learning-based semantic segmentation of X-ray images

Internal rot of avocado fruit (Persea americana), attributable to fungal infection, occurs at the end of the ripening process and causes only minor changes in the appearance and texture of the fruit surface. Manual inspection of rot by sight and touch commonly conducted in countries importing avocado fruit is time-consuming, labor-intensive, and subjective. In this context, X-ray line scanning has been proven as an advantageous method of fruit rot detection because of its speed of data acquisition and the indication of internal rot by bright regions in associated images. However, some fruit internal disorders exhibit only poor changes in contrast, resulting in low detectability by traditional image processing. This study aimed to test the effectiveness of a detection model using deep learning-based semantic segmentation in identifying two types of fruit rot, stem-end and body rot, in Hass avocados. Therefore, U-net+ + was trained and validated via 5-fold cross-validation to classify every pixel in an X-ray image as either infected or not. Then, each X-ray image was binarily classified based on either the presence or absence of internal fruit rots, achieving an accuracy of 0.98. Furthermore, the percentage of infected area was quantified with a root mean squared error (RMSE) of 3.15 %. Lastly, the proposed model detected both stem-end and body rot as well as rot along low-contrast fruit edges. The results of this study indicate that the proposed automatic inspection system using deep learning-based X-ray image analysis can effectively detect internal rot in Hass avocado fruit. This non-destructive, objective detection model can therefore increase efficiency and reduce misclassification in post-harvest avocado inspection. Furthermore, deep learning-based X-ray imaging has potential for applications in fruit inspection for internal cavities attributable to diseases or wounds.

Wafer-Level Highly Dense Metallic Nanopillar-Enabled High-Performance SERS Substrates for Molecular Detection.

Seeking sensitive, large-scale, and low-cost substrates is highly important for practical applications of surface-enhanced Raman scattering (SERS) technology. Noble metallic plasmonic nanostructures with dense hot spots are considered an effective construction to enable sensitive, uniform, and stable SERS performance and thus have attracted wide attention in recent years. In this work, we reported a simple fabrication method to achieve wafer-scale ultradense tilted and staggered plasmonic metallic nanopillars filled with numerous nanogaps (hot spots). By adjusting the etching time of the PMMA (polymethyl methacrylate) layer, the optimal SERS substrate with the densest metallic nanopillars was obtained, which possessed a detection limit down to 10-13 M by using crystal violet as the detected molecules and exhibited excellent reproducibility and long-term stability. Furthermore, the proposed fabrication approach was further used to prepare flexible substrates; for example, a SERS flexible substrate was proven to be an ideal platform for analyzing low-concentration pesticide residues on curved fruit surfaces with significantly enhanced sensitivity. This type of SERS substrate possesses potential in real-life applications as low-cost and high-performance sensors.

Apple Grading Based on Multi-Dimensional View Processing and Deep Learning.

This research proposes an apple quality grading approach based on multi-dimensional view information processing using YOLOv5s network as the framework to rapidly and accurately perform the apple quality grading task. The Retinex algorithm is employed initially to finish picture improvement. Then, the YOLOv5s model, which is improved by adding ODConv dynamic convolution and GSConv convolution and VoVGSCSP lightweight backbone, is used to simultaneously complete the detection of apple surface defects and the identification and screening of fruit stem information, retaining only the side information of the apple multi-view. After that, the YOLOv5s network model-based approach for assessing apple quality is then developed. The introduction of the Swin Transformer module to the Resnet18 backbone increases the grading accuracy and brings the judgment closer to the global optimal solution. In this study, datasets were made using a total of 1244 apple images, each containing 8 to 10 apples. Training sets and test sets were randomly created and divided into 3:1. The experimental results demonstrated that in the multi-dimensional view information processing, the recognition accuracy of the designed fruit stem and surface defect recognition model reached 96.56% after 150 iteration training, the loss function value decreased to 0.03, the model parameter was only 6.78 M, and the detection rate was 32 frames/s. After 150 iteration training, the average grading accuracy of the quality grading model reached 94.46%, the loss function value decreased to 0.05, and the model parameter was only 3.78 M. The test findings indicate that the proposed strategy has a good application prospect in the apple grading task.

TARGET OF EAT3 (TOE3) specifically regulates fruit spine initiation in cucumber (Cucumis sativus L.).

The presence or absence of spines is an important economic trait of cucumber fruit. Spines are believed to be a type of specialized trichome on the fruit surface and all the identified cucumber trichome-less mutants lack fruit spines. However, genes that specifically regulate fruit spine initiation remain to be identified. Here, we found that knocking out cucumber TARGET OF EAT3 homolog (CsTOE3), belonging to the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) family, affected flower development, and more interestingly, inhibited cucumber fruit spine initiation. On analyzing expression patterns by qRT-PCR and in situ hybridization assay, CsTOE3 was found to be highly expressed in male and female flowers, and its mRNA accumulated in the tips of sepal and petal primordia and in the cells of fruit spines and peels. Biochemical analyses indicated that CsTOE3 directly interacts with GLABRA1 (CsGL1) and TRANSPARENT TESTA GLABRA1 (CsTTG1), which are positive regulators of trichome formation. In addition, RNA-seq showed that the transcription levels of eight ERFs were significantly upregulated in CsTOE3 knockout lines. Phytohormone content analysis also revealed a significant increase in the amount of ethylene released by CsTOE3 knockout lines; treatment with the ethylene synthesis inhibitor aminoethoxyvinyl-glycine (AVG) partly restored the spineless phenotype. Our results suggest that CsTOE3 specifically regulates fruit spine initiation but does not affect the formation of trichomes on other organs in cucumber. Our findings may have a far-reaching significance for cucumber germplasm improvement and quality breeding using fruit spines as the target trait.

Subcellular damages of pathogenic fungi combined with gene expression analysis reveals mechanisms that cold plasma controlling apricot disease

Dielectric barrier discharge (DBD) plasma technology has proven effective in controlling postharvest fungus in fruits and vegetables. However, its mechanism of action is rarely reported. In this study, DBD technology was investigated to inhibit apricot diseases under the conditions of shelf simulation, and its mechanism was analysed. Apricot fruits and pathogenic fungal spores were treated with DBD of different voltage intensities（fruits: 80 kV, 90 kV, 100 kV; spores: 80 kV, 100 kV, 120 kV). Experimental data showed that DBD plasma treatment significantly reduced the microbial biomass on the surface of apricot fruit and inhibit Rhizopus oryzae and Alternaria tenuissima. Rhizopus oryzae and Alternaria tenuissima's spore germination decreased by 74.7% and 82.0%, respectively, after 40 s of processing with 100 kV DBD treatment. To investigate DBD plasma's antibacterial mechanism, deoxyribonucleic acid damage and the morphological characteristics of fungal spores were determined; this indicated that DBD plasma treatment resulted in nuclear degradation and cell deformation. In addition, DBD treatment enhanced apricots' expression of phenylalanine ammonia-lyase 1 (PAL1), aldehyde dehydrogenase 2B7 (ALDH2B7) and GDP-L-galactose phosphorylase (VTC2), delayed disease and improved quality under shelf storage conditions. The results demonstrated that DBD plasma treatment could control the primary diseases of apricot fruit and enhance the quality by destroying microbial spores and activating the disease-resistant genes of the fruit.

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.

AUTHENTICATION OF THREE WAX APPLES CULTIVARS (SYZYGIUM SAMARANGENSE (BLUME) MERR. & L.M. PERRY) BASED ON MORPHOLOGICAL CHARACTER AND FRUIT METABOLITE PROFILE

Wax apple is one of the superior fruits of Demak, especially cultivars 'Citra', 'Delima' and ‘Madu Deli Hijau'. Research on the wax apple of the three cultivars is still limited. Therefore, research on the authentication of wax apple cultivars based on morphological characters and metabolite profiles present in one location is important to do. The aims of this study were to identify morphological characters and analyze metabolite profiles, to analyze relationship and to identify morphological characters and metabolite marker profiles in the authentication activities of three wax apples cultivars. Sampling was in Boyolali Village, Demak Regency. The stages of this research included morphological characterization of stem, leaf, fruit and seed organs, phylogeny analysis with MVSP, metabolite profile analysis using GC-MS, and determination of morphological characters and metabolite profiles with PCA. The results showed that there were morphological diversity and metabolite profile variations of the three cultivars. Relationship analysis based on morphological characters and metabolite profiles resulted in different grouping patterns. 'Madu Deli Hijau' and 'Citra' are closely related based on morphological characters and a combination of morphological characters and metabolite profiles. Morphological characters in the authentication of the 'Citra' (dark red exocarp color), 'Delima' (bright red exocarp color, smooth and flat fruit surface, jagged fruit shape), in 'Madu Deli Hijau' (elongated leaf shape and exocarp is green with a pink tinge). Authentication of probable marker metabolite profiles on 'Citra', 'Delima' and 'Madu Deli Hijau' wax apples of 10, 7 and 5 compounds.

Effects of surface micro-structure of fruits on droplet evaporation process: Peach and apple cases

Droplet evaporation at the fruit surface is a common issue related to the efficiency of pesticide spraying as well as freshness preservation. Many works have been carried out demonstrating the impacts of substrate characteristics on the droplet profile, wettability, and evaporation properties in the field of industrial applications. However, the influences of specific fruit skin on the droplet evaporation rate have been rarely studied. Thus, the present works aim to explore the effects of different surface micro-structures of fruits on the droplet properties experimentally through the 3D video microscope, drop shape analyzer, and infrared camera. Apple and peach have been selected respectively as two examples of waxy and hairy skins, and comparisons have been made focusing on the surface roughness, droplet profile including contact angle, contact area, and contact diameter, evaporation rate, and temperature distribution of droplets with a constant initial volume of 2ul. The results show that the differences in micro-structure for apple and peach surfaces have significant impacts on the droplet evaporation performance. A larger evaporation rate has been found for apple skin with three distinct phases including spreading, pinning, and shrinkage periods. However, the pinning phenomenon tends to be broken for the peach case due to the unique properties of super-hydrophobic surfaces and the existence of fluff. Moreover, lower values of temperature at the top center of a droplet can be always observed during the whole evaporating process with peak values of temperature gradient near the triple-phase region.

Influence of long-distance air transport conditions on horticultural product quality: Case study of fresh mango shipment from Thailand to France

Four instrumented boxes of mangoes Mangifera indica L. cv. “Nam Dok Mai” were shipped from Bangkok, Thailand, to Paris, France, without control of the boxes’ positions on the aircraft. Two boxes were shipped via a direct flight and two boxes were shipped via an indirect flight. For each box, the internal air temperature, the external air temperature and relative humidity and surface temperature of two fruits were recorded throughout the supply chain from a packing house in Thailand to a storage room in France. A maximum fruit temperature of 33 °C (during transport from an orchard to the packing house) and a minimum fruit temperature of 8 °C (in a cold room of the logistics company following arrival at the airport in France via the indirect flight) were observed. The slight temperature difference between the air and the fruit surface temperature (< 1 °C on average) for both direct and indirect flights suggests that the air was stagnant inside the box and, thus conduction was the main heat transfer mode. Models of product temperature, mass loss, and peel color changes throughout the supply chain were developed. The numerical and the experimental values were in good agreement. These models were able to predict the product mass loss and peel color evolution as a function of a supply chain scenario.

Interaction between Six Waxy Components in Summer Black Grapes (Vitis vinifera) and Mancozeb and Its Effect on the Residue of Mancozeb.

Mancozeb, an antifungal typically used for the growth of fruits, has the characteristic of non-internal absorption, and has a risk of binding to the waxy components of fruits. This work investigated the interaction of pesticide molecules with the waxy layer on the grape surface and their effects on pesticide residues in grapes. The study observed significant changes in the compositions of the waxy layer on the grape surface after soaking in a mancozeb standard solution. The six substances-oleanolic acid, ursolic acid, lupeol, octacosanol, hexacosanal, and γ-sitosterol-with discernible content differences were chosen for molecular docking. Docking results were further visualized by an independent gradient model based on Hirshfeld partition (IGMH). Hydrogen bonds and van der Waals forces were found between mancozeb and the six waxy components. Moreover, the negative matrix effects caused by the presence or absence of wax for the determination of mancozeb were different through the QuEChERS-HPLC-MS method. Compared with the residue of mancozeb in grapes (5.97 mg/kg), the deposition of mancozeb in grapes after dewaxing was significantly lower (1.12 mg/kg), which further supports that mancozeb may interact with the wax layer compositions. This work not only provides insights into the study of the interaction between pesticides and small molecules but also provides theoretical guidelines for the investigation of the removal of pesticide residues on the surface of fruits.

Postharvest quality and prolong storage time of atemoya (Annona squamosa x A. cherimola hybrids) fruit: coating with D-limonene nanoemulsion edible film

ABSTRACT Atemoya (Annona squamosa x A. cherimola hybrid) is a typical climacteric fruit that has a high respiration rate after harvest, short storage life, and is highly susceptible to fruit cracking and rot. Therefore, this study was intended to apply D-limonene nanoemulsion coating on fruit to prolong the storage life, reduce spoilage, and facilitate the expansion of the market. Green mature atemoya fruit coated with different concentrations of D-limonene nanoemulsion (0.25%, 0.5%, 1.0%, 1.5%, and control) was stored in a 14°C refrigerator for relevant analysis and investigation. The results showed that the use of 0.25% D-limonene nanoemulsion inhibited the browning on the fruit surface, and reduced physiological metabolisms. The browning phenomenon on the fruit surface increased as the D-limonene concentration ratio increases. Since the high concentration caused damage to the peel cells, 0.25% D-limonene was chosen as optimum for atemoya coating. The fruit of atemoya maintained green peel color (L × 28.6, a × 6.63, b × 12.3) after storage at 14°C for 21 days with 0.25% D-limonene nanoemulsion coating. At the same time, after 0.2% D-limonene nanoemulsion coating, the weight loss rate was about % less than that of the control group (0.25% treatment was 11.3%; control was 14.2%) and high pectin content (0.25% treatment was 16.9 mg AGA g−1AIS−1; control was 9.89 mg AGA g−1AIS−1). Coating of D-limonene nanoemulsion can reduce the physiological response of atemoya fruits after harvesting, prolong the storage time, and increase the feasibility of their export. From the experimental results, D-limonene showed the potential to be widely used in fruit preservation agents in the future.

Colletotrichum brevisporum causing anthracnose of papaya (Carica papaya L.) in Mexico

Papaya fruit cv. Maradol showing typical symptoms of anthracnose were observed in a commercial orchard located in the municipality of Pinotepa Nacional at the coastal region of Oaxaca, Mexico in September 2020. The incidence rate of anthracnose reached 60%. The symptoms consisted of sunken, water-soaked lesions with salmon-coloured conidia masses on the surface of papaya fruit. The aim of this study was to identify the causal agent of papaya anthracnose based on the phylogenetic analysis of four concatenated datasets. The isolate exhibited sparse white to greyish aerial mycelium and clearly shaped concentric rings with exudate of orange conidia on potato dextrose agar. The fungus was identified as Colletotrichum brevisporum using sequence data of the internal transcribed spacer (ITS) region, and part of the actin (act), glyceraldehyde-3-phosphate dehydrogenase (gapdh), and chitin synthase (chs-1) genes. The fungus isolated from diseased fruit produced lesions on wounded fruit and unwounded fruit. The pathogen was re-isolated from lesions on inoculated fruit to fulfill Koch’s postulates. To our knowledge, this is the first report of C. brevisporum causing anthracnose disease on papaya fruit in Mexico.