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Abstract Background Kiwifruit, belonging to the genus Actinidia, represents a unique fruit crop characterized by its modern cultivars being genetically diverse and exhibiting remarkable variations in morphological traits and adaptability to harsh environments. However, the genetic mechanisms underlying such morphological diversity remain largely elusive. Results We report the high-quality genomes of five Actinidia species, including Actinidia longicarpa, A. macrosperma, A. polygama, A. reticulata, and A. rufa. Through comparative genomics analyses, we identified three whole genome duplication events shared by the Actinidia genus and uncovered rapidly evolving gene families implicated in the development of characteristic kiwifruit traits, including vitamin C (VC) content and fruit hairiness. A range of structural variations were identified, potentially contributing to the phenotypic diversity in kiwifruit. Notably, phylogenomic analyses revealed 76 cis-regulatory elements within the Actinidia genus, predominantly associated with stress responses, metabolic processes, and development. Among these, five motifs did not exhibit similarity to known plant motifs, suggesting the presence of possible novel cis-regulatory elements in kiwifruit. Construction of a pan-genome encompassing the nine Actinidia species facilitated the identification of gene DTZ79_23g14810 specific to species exhibiting extraordinarily high VC content. Expression of DTZ79_23g14810 is significantly correlated with the dynamics of VC concentration, and its overexpression in the transgenic roots of kiwifruit plants resulted in increased VC content. Conclusions Collectively, the genomes and pan-genome of diverse Actinidia species not only enhance our understanding of fruit development but also provide a valuable genomic resource for facilitating the genome-based breeding of kiwifruit.

Real-time detection of kiwifruits in natural environments is essential for automated kiwifruit harvesting. In this study, a lightweight convolutional neural network called the YOLOv4-GS algorithm was proposed for kiwifruit detection. The backbone network CSPDarknet-53 of YOLOv4 was replaced with GhostNet to improve accuracy and reduce network computation. To improve the detection accuracy of small targets, the upsampling of feature map fusion was performed for network layers 151 and 154, and the spatial pyramid pooling network was removed to reduce redundant computation. A total of 2766 kiwifruit images from different environments were used as the dataset for training and testing. The experiment results showed that the F1-score, average accuracy, and Intersection over Union (IoU) of YOLOv4-GS were 98.00%, 99.22%, and 88.92%, respectively. The average time taken to detect a 416x416 kiwifruit image was 11.95 ms, and the model's weight was 28.8 MB. The average detection time of GhostNet was 31.44 ms less than that of CSPDarknet-53. In addition, the model weight of GhostNet was 227.2 MB less than that of CSPDarknet-53. YOLOv4-GS improved the detection accuracy by 8.39% over Faster R-CNN and 8.36% over SSD-300. The detection speed of YOLOv4-GS was 11.3 times and 2.6 times higher than Faster R-CNN and SSD-300, respectively. In the indoor picking experiment and the orchard picking experiment, the average speed of the YOLOv4-GS processing video was 28.4 fps. The recognition accuracy was above 90%. The average time spent for recognition and positioning was 6.09 s, accounting for about 29.03% of the total picking time. The overall results showed that the YOLOv4-GS proposed in this study can be applied for kiwifruit detection in natural environments because it improves the detection speed without compromising detection accuracy. [ABSTRACT FROM AUTHOR]

Background: Kiwifruit, belonging to the genus Actinidia, represents a unique fruit crop characterized by its modern cultivars being genetically diverse and exhibiting remarkable variations in morphological traits and adaptability to harsh environments. However, the genetic mechanisms underlying such morphological diversity remain largely elusive. Results: We report the high-quality genomes of five Actinidia species, including Actinidia longicarpa, A. macrosperma, A. polygama, A. reticulata, and A. rufa. Through comparative genomics analyses, we identified three whole genome duplication events shared by the Actinidia genus and uncovered rapidly evolving gene families implicated in the development of characteristic kiwifruit traits, including vitamin C (VC) content and fruit hairiness. A range of structural variations were identified, potentially contributing to the phenotypic diversity in kiwifruit. Notably, phylogenomic analyses revealed 76 cis-regulatory elements within the Actinidia genus, predominantly associated with stress responses, metabolic processes, and development. Among these, five motifs did not exhibit similarity to known plant motifs, suggesting the presence of possible novel cis-regulatory elements in kiwifruit. Construction of a pan-genome encompassing the nine Actinidia species facilitated the identification of gene DTZ79_23g14810 specific to species exhibiting extraordinarily high VC content. Expression of DTZ79_23g14810 is significantly correlated with the dynamics of VC concentration, and its overexpression in the transgenic roots of kiwifruit plants resulted in increased VC content. Conclusions: Collectively, the genomes and pan-genome of diverse Actinidia species not only enhance our understanding of fruit development but also provide a valuable genomic resource for facilitating the genome-based breeding of kiwifruit. [ABSTRACT FROM AUTHOR]

Soluble solid content (SSC), firmness, and color (L*, a*, and b*) are important physicochemical indices for assessing the quality and maturity of kiwifruits. Therefore, this research aimed to realize the nondestructive detection and visualization map for the physicochemical indices of kiwifruits at different maturity stages by hyperspectral imaging coupled with the chemometrics. To further improve the detection accuracy and working efficiency of the models, competitive adaptive reweighted sampling (CARS) and successive projection algorithm were employed to choose feature wavelengths for predicting the physicochemical indices of kiwifruits. Multiple linear regression (MLR) was designed to develop simplified detection models based on feature wavelengths for determining the physicochemical indices of kiwifruits. The results showed that 32, 18, 26, 29, and 32 feature wavelengths were extracted from 256 full wavelengths to predict the SSC, firmness, L*, a*, and b*, respectively, with the CARS algorithm. Not only was the working efficiency of the CARS-MLR model improved, but the prediction accuracy of the CARS-MLR model for determining the physicochemical indices was also at its relative best. The residual predictive deviations of the CARS-MLR model for determining the SSC, firmness, L*, a*, and b* were 3.09, 2.90, 2.32, 2.74, and 2.91, respectively, which were all above 2.3. Compared with the model based on the full spectra, the CARS-MLR model could be used to predict the physicochemical indices of kiwifruits. Finally, the visualization map for the physicochemical indices of kiwifruits at different maturity stages was generated by calculating the spectral response of each pixel on the kiwifruit samples with the CARS-MLR model. This made the detection for the physicochemical indices of kiwifruits more intuitive. This study demonstrates that hyperspectral imaging coupled with the chemometrics is promising for the nondestructive detection and visualization map for the physicochemical indices of kiwifruits, and also provides a novel theoretical basis for the nondestructive detection of kiwifruit quality.

Kiwifruits are often exposed to various temperature fluctuations (TFs) during postharvest transportation and storage. To evaluate the effect of TFs on the qualities of kiwifruits during storage, kiwifruits were stored at 2 °C, 2 °C or 5 °C (TF2 °C–5 °C, alternating every 12 h), 2 °C or 7 °C (TF2 °C–7 °C, alternating every 12 h) for 3 d before long time storage at 2 °C. Observations revealed that kiwifruits stored at a constant 2 °C showed the lowest loss of weight and vitamin C because of minimized ethylene production and respiratory rate compared with that of TF2 °C–5 °C and TF2 °C–7 °C. Moreover, the results of RT-qPCR verified that the expression levels of genes encoding polygalacturonase, β-galacturonidase, and pectin methylesterase were significantly increased by the treatment of TF. Hence, TF accelerated the degradation of cell walls, softening, translucency, and relative conductivity of the flesh of kiwifruits. In addition, the impact of TF2 °C–7 °C on kiwifruits was more significant relative to TF2 °C–5 °C. The present study provides a theoretical basis for kiwifruit during cold storage. [ABSTRACT FROM AUTHOR]

About ten species of the genus Actinidia Lindl. are known as cultivated plants—alongside the most known A. chinensis var. deliciosa, there are many others, including Far-Eastern cold-hardy kiwifruits such as A. arguta, A. kolomikta, and A. polygama. Unlike most plant species, in which the chloroplast genome is maternally inherited, the family Actinidiaceae possesses a complex system of plastid inheritance with possible transmission through both maternal and paternal lines. The main aim of this work was the assembly of the plastid genomes of three species of Actinidia, their comparison with already-available sequences from databases, and evolutionary analyses. We discovered that the gene composition and gene sequences are conserved; the studied species are either subject to purifying selection or not subject to selection at all (with some exceptions, such as the ycf2 gene). However, the chloroplast chromosomes of some Actinidia species have undergone significant structural rearrangements, leading to the persistence of two main forms, both on an intrageneric and intraspecific level. These results expand our understanding of plastid genomics and genetic diversity within the genus Actinidia, providing a basis for future research in molecular marker development, phylogenetic analysis, and population studies. [ABSTRACT FROM AUTHOR]

The nondestructive detection of the quality attributes and maturity of kiwifruits by using hyperspectral imaging technique and chemometric algorithms were investigated. Two models of the partial least square regression and principal components regression were built up based on full variables. The multiple linear regression (MLR) was designed to develop the simplified detection models based on feature variables chosen by the successive projection algorithm and competitive adaptive reweighted sampling (CARS). Results showed that the optimal CARS‐MLR model was designed to determine the quality attributes with RPD above 2.2. Particularly, about SSC (R2P = 0.896, RMSEP = 0.628%, RPD = 3.121), about firmness (R2P = 0.871, RMSEP = 1.065 kg/cm2, RPD = 2.809). The partial least square discriminant analysis and simplified k nearest neighbor models were designed to discriminate the kiwifruits maturity stages with a classification accuracy of 93.3% and 98.3%. This research demonstrates that the hyperspectral imaging technology coupled with chemometric algorithms is promising for the quality assessment and maturity discrimination of kiwifruits. Practical applications: The quality and maturity of kiwifruits have a direct relationship with the indicators of the SSC, firmness and color. Traditional methods for predicting the quality and maturity of kiwifruits are destructive, time‐consuming, and unusually affected by subjective factors. Hyperspectral imaging technique has the advantages of nondestructive, rapid, non‐pollution, and so on. The results demonstrated that the hyperspectral imaging technique coupled with chemometric algorithms can predict the quality and maturity of kiwifruits, which provides a theoretical basis to develop a real‐time detection system to predict the quality and maturity of fruits. [ABSTRACT FROM AUTHOR]

Botryosphaeria dothidea is the source of the deadly kiwifruit disease known as soft rot. In order to explore the role of melatonin in regulating the postharvest quality and disease resistance of kiwifruit at different growth and development stages, in this study, we applied melatonin at different concentrations to kiwifruit at the young fruit, expansion, and late expansion stages to assess its effect on fruit resistance to B. dothidea, minimize soft rot, and maintain postharvest fruit quality. The results showed that melatonin significantly suppressed the mycelial growth of B. dothidea, with 1.0 mmol/L melatonin inhibiting it by up to 50%. However, 0.1–0.3 mmol/L melatonin had the best control over soft rot. Furthermore, spraying MT during kiwifruit growth can successfully increase fruit weight; preserve postharvest fruit firmness; reduce respiration intensity in the early stages of storage; delay the rise in soluble solids, while maintaining a high titratable acid content to ensure suitable solid acid ratio; increase total phenol, flavonoid, chlorophyll, carotenoid, and ascorbic acid contents; and delay the rise in soluble sugar contents in the late stages of storage. These results have a positive effect on maintaining the nutritional composition of kiwifruit. However, the effects on weight loss, dry matter content, and soluble protein content were not significant. In addition, the results of the principal component analysis demonstrated that 0.3 mmol/L MT increased kiwifruit's resistance to soft rot while preserving postharvest fruit quality. [ABSTRACT FROM AUTHOR]

Kiwifruits are often exposed to various temperature fluctuations (TFs) during postharvest transportation and storage. To evaluate the effect of TFs on the qualities of kiwifruits during storage, kiwifruits were stored at 2 °C, 2 °C or 5 °C (TF2 °C–5 °C, alternating every 12 h), 2 °C or 7 °C (TF2 °C–7 °C, alternating every 12 h) for 3 d before long time storage at 2 °C. Observations revealed that kiwifruits stored at a constant 2 °C showed the lowest loss of weight and vitamin C because of minimized ethylene production and respiratory rate compared with that of TF2 °C–5 °C and TF2 °C–7 °C. Moreover, the results of RT-qPCR verified that the expression levels of genes encoding polygalacturonase, β-galacturonidase, and pectin methylesterase were significantly increased by the treatment of TF. Hence, TF accelerated the degradation of cell walls, softening, translucency, and relative conductivity of the flesh of kiwifruits. In addition, the impact of TF2 °C–7 °C on kiwifruits was more significant relative to TF2 °C–5 °C. The present study provides a theoretical basis for kiwifruit during cold storage.

About ten species of the genus Actinidia Lindl. are known as cultivated plants—alongside the most known A. chinensis var. deliciosa, there are many others, including Far-Eastern cold-hardy kiwifruits such as A. arguta, A. kolomikta, and A. polygama. Unlike most plant species, in which the chloroplast genome is maternally inherited, the family Actinidiaceae possesses a complex system of plastid inheritance with possible transmission through both maternal and paternal lines. The main aim of this work was the assembly of the plastid genomes of three species of Actinidia, their comparison with already-available sequences from databases, and evolutionary analyses. We discovered that the gene composition and gene sequences are conserved; the studied species are either subject to purifying selection or not subject to selection at all (with some exceptions, such as the ycf2 gene). However, the chloroplast chromosomes of some Actinidia species have undergone significant structural rearrangements, leading to the persistence of two main forms, both on an intrageneric and intraspecific level. These results expand our understanding of plastid genomics and genetic diversity within the genus Actinidia, providing a basis for future research in molecular marker development, phylogenetic analysis, and population studies.

Background: Kiwifruit is a popular fruit consumed worldwide and is also used as a cosmetic ingredient. However, it is known to cause allergic reactions in humans. Recent studies have suggested an association between food allergy and food allergens entering the body via the skin. However, percutaneously sensitizing kiwifruit allergens have not been identified in human studies or in animal models. Objective: This study aimed to identify kiwifruit proteins that percutaneously sensitized mice through the epidermal application of crude extracts from green and gold kiwifruit on the dorsal skin, and serum IgE and IgG1 levels were used as sensitization markers. Design: BALB/c mice were back-shaved and their skin was exposed to crude extracts from green and gold kiwifruit that contained sodium dodecyl sulfate. Specific IgE and IgG1 antibodies generated and secreted in response to antigens were measured using enzyme-linked immunosorbent assay or immunoblotting. Results: Skin exposure to kiwifruit extract induced an increase in the levels of kiwifruit-specific IgE and IgG1, which are helper T cell 2-related allergenic antibodies in mice. These antibodies reacted with 18, 23, and 24 kDa proteins found in both green and gold kiwifruits. Thus, three percutaneously sensitizing allergens were identified and purified. Their amino acid sequences partially matched with that of kiwellin (Act d 5). Discussion and conclusion: Kiwellin has been identified as a plant defense-related protein. Interestingly, many plant allergens are biodefense-related proteins belonging to the pathogenesis-related protein family. Kiwellin, which was discovered to be a transdermal sensitizing antigen, might also be categorized as a biodefense-related protein. This study is the first to identify kiwellin (Act d 5) as a percutaneously sensitizing kiwifruit allergen in a mouse model.

Botryosphaeria dothidea is the source of the deadly kiwifruit disease known as soft rot. In order to explore the role of melatonin in regulating the postharvest quality and disease resistance of kiwifruit at different growth and development stages, in this study, we applied melatonin at different concentrations to kiwifruit at the young fruit, expansion, and late expansion stages to assess its effect on fruit resistance to B. dothidea, minimize soft rot, and maintain postharvest fruit quality. The results showed that melatonin significantly suppressed the mycelial growth of B. dothidea, with 1.0 mmol/L melatonin inhibiting it by up to 50%. However, 0.1–0.3 mmol/L melatonin had the best control over soft rot. Furthermore, spraying MT during kiwifruit growth can successfully increase fruit weight; preserve postharvest fruit firmness; reduce respiration intensity in the early stages of storage; delay the rise in soluble solids, while maintaining a high titratable acid content to ensure suitable solid acid ratio; increase total phenol, flavonoid, chlorophyll, carotenoid, and ascorbic acid contents; and delay the rise in soluble sugar contents in the late stages of storage. These results have a positive effect on maintaining the nutritional composition of kiwifruit. However, the effects on weight loss, dry matter content, and soluble protein content were not significant. In addition, the results of the principal component analysis demonstrated that 0.3 mmol/L MT increased kiwifruit’s resistance to soft rot while preserving postharvest fruit quality.

The developed edible coating with curcumin facilitated iron functionalized cellulose nanofiber (f- CNF) reinforced chitosan (CS) were applied on kiwifruits for maintaining the quality during storage life. The f- CNF was fabricated via anchoring iron particles onto the surface of CNF as evident by FESEM, FETEM, and XRD analysis. The inclusion of f- CNF and curcumin as a component of edible coating can provide a synergistic effect in maintaining the quality of kiwifruits. The f- CNF (1.5 wt%) dispersed CS edible coating assisted by curcumin provided a lamellar and heterogonous surface morphology with a hazy appearance. The used edible coating materials were effective in reducing mass loss, firmness loss, respiration rate, and microbial count of the kiwifruits during storage life (10 days at 10 °C). Additionally, color, and physiological properties of kiwifruits can be modified by using the addressed edible coating materials. • Iron particles are decorated onto CNF surfaces to develop iron functionalized CNF. • Cur doped functionalized CNF/Chitosan are effective in edible coating of kiwifruits. • Cur and nanofiller are uniformly dispersed in chitosan improving kiwifruits storage. • Addition of Cur aided nanocomposite helps to reduce microbial count during storage. • Firmness of the kiwifruit products improved due to edible coating materials. [ABSTRACT FROM AUTHOR]

BACKGROUND: The application of exogenous plant growth regulator, for example forchlorfenuron (CPPU), on kiwifruits has become an important factor that influences kiwifruit economic efficiency and the health development of the kiwifruit industry. Owing to the slight difference in calyx shape between the kiwifruits treated with CPPU (CPPU‐treated kiwifruits) and the kiwifruits without CPPU treatment (CPPU‐untreated kiwifruits), this study aims to provide a cheap, quick, convenient, and non‐destructive method for identifying CPPU‐treated kiwifruits based on the images of kiwifruits captured at visible lights. RESULTS: The identification method includes three steps. Firstly, the kiwifruit was extracted from the background by using Otsu algorithm, hole filling operation and 'bwareaopen' function. Secondly, the calyx was extracted by using corrosion, image enhancement, hole filling and closing operations. Finally, the length/width ratio of the minimum enclosing rectangle of calyx region was calculated. The kiwifruit was regarded as a CPPU‐treated kiwifruit if the length/width ratio of the rectangle was higher than 1.6. Otherwise, the kiwifruit was regarded as a CPPU‐untreated one. The method had the total identification accuracy rate of 90.0% when the kiwifruit images were captured either by utilizing a smartphone at normal lighting condition or by using an image acquisition system. CONCLUSION: The programs run on computer and smartphone were developed, and they could realize kiwifruit identification in 0.6 s and 2 s, respectively. The study makes identifying CPPU‐treated kiwifruits in online processing be realizable, and offers a convenient method for kiwifruit consumers. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Highlights • Thinned Young Kiwifruits (TYK) was studied as a potential agricultural resource. • TYK have significantly higher phenolic contents than the mature fruits. • TYK showed very high antioxidant powers which also correlated to phenolic contents. • A UPLC-QqQ-MS/MS method was set up to quantify the phenolics in TYK. • Epicatechin was the most prevailing phenolic compound in TYK. Abstract For the first time, thinned young kiwifruits (TYK) have been investigated as a source of deserted agriculture resource and evaluated for their phenolic characteristics along with antioxidant capacity. Two batches of TYK in different maturity stages (TYK1 and TYK2) and mature kiwifruits (MK) were sourced from three New Zealand cultivars. Comparing with MK, the TYK, especially TYK1, exhibited significantly higher contents of total phenolics (7.92 fold), total flavonoids (17.56 fold) and total flavanols (10.11 fold) as well as elevated and phenolic-correlated antioxidant capacities. A novel UPLC-QqQ-MS/MS method with low limit of detection (0.010–0.240 mg/L) and high accuracy (RSDs < 6.79%) was established to quantify 15 phenolics in the kiwifruit extracts. Epicatechin was the prevailing antioxidant in both TKY and MK, with the highest level of 2989.23 μg/g FDW present in TYK1 of 'Zesy002' cultivar. These results provide good evidence for the development and utilization of TYK of these cultivars in food and nutraceuticals. [ABSTRACT FROM AUTHOR]

The present work was conducted to find the physicochemical properties, chemical components and antioxidant capacity of kiwifruit hydroalcoholic extracts (B-31, HO-1-14, J-242, Bruno, Greenlight, Hayward, Monty, Topstar) grown Yalova, Turkey. Phytochemical tests were performed to determine total phenolic, flavonoid and ascorbic acid. Moreover, the kiwifruit extracts were subjected to evaluate their antioxidant potential using different in vitro assays such as total antioxidant, inhibition of lipid peroxidation, reducing power, metal chelating, free radical, H2O2 and superoxide anion scavenging activities at 50–500 μg mL−1, and also found EC50 and IC50 values. The soluble solid content (SSC), titratable acidity (TA) and pH were analyzed in all the genotypes and cultivars. The highest total phenolic, flavonoid and ascorbic acid content were found in J-242 (89.53 mg GAE/100 g), J-242 (109.13 mg QE/100 g) and HO-1-14 (64.15 mg/100 g), respectively. The linoleic, palmitic, stearic and oleic acid methyl esters were detected in all kiwifruit extracts by GC/MS. Significant differences were found between genotypes and cultivars in the antioxidant tests. The extracts showed high inhibition of lipid peroxidation and compared to standards, significantly (p < 0.05). The GC/MS analyses confirmed quantitative variability in the antioxidant profiles. The SSC, TA and pH of kiwifruit genotypes and cultivars showed a moderate level. The key parameters for the most active kiwifruit included the following: total antioxidant activity for B-31, H2O2 scavenging activity for J-242 and metal chelating activity for Topstar. In conclusion, this study exhibited the important role played by the genotypes and cultivars background on the chemical content and antioxidant profiles. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Fungal development in agricultural products may cause mycotoxin contamination, which is a significant threat to food safety. Patulin (PAT) and PAT‐producer contamination has been established as a worldwide problem. The present study aimed to investigate the mycoflora and PAT‐producers present in kiwifruits and environmental samples collected from orchards and processing plants in Shaanxi Province, China. RESULTS: Variations in mycoflora were observed in different samples, with penicillia and aspergilli as the predominant genera. Approximately 42.86% of dropped fruits were contaminated with PAT‐producers, which harbored the 6‐methylsalicylic acid synthase and the isoepoxydon dehydrogenase genes that are involved in PAT biosynthesis. The growth of Penicillium expansum, Penicillium griseofulvum and Penicillium paneum in kiwi puree agar (KPA) medium and kiwi juice well fitted the modified Gompertz and Baranyi and Roberts models (R2 ≥ 0.95). A significant positive correlation between colony diameter and PAT content in KPA medium of P. expansum and P. griseofulvum was observed (P < 0.05). CONCLUSIONS: The present study analyzed the mycofloral composition and the potential risk for PAT and PAT‐producer contamination in kiwifruit, which may be utilized in the establishment of proper management practices in the kiwifruit industry. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In the present study, a liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method with a minimal matrix effect (ME) was developed and validated for simultaneous determination of a diverse range of pesticides (49) in kiwifruit. Samples extracted by the quick, easy, cheap, effective, rugged, and safe (QuEChERS) citrate-buffered method were analyzed either without purification or following purification (with primary secondary amine (PSA) or PSA + graphitized carbon black (GCB)). With the addition of a clean-up step, the suppression of the ME decreased, with a higher number of pesticides determined by the application of PSA + GCB. The method exhibited good linearity with coefficients of determination ( R 2 ) ≥ 0.9972 and satisfactory recoveries (70–120%) with a relative standard deviations (RSDs) <10%. The limits of quantification (LOQ) were lower than the maximum residue limits (MRLs) set by the Korean Ministry of Food and Drug Safety (MFDS) and the CODEX Alimentarius. The developed method was applied to the real samples and the results indicated that the quantitated levels of all pesticides, except for pyraclostrobin and carbendazim, are lower than the MRLs set by the regulatory authorities. The percentage of the acceptable daily intake was <20%, suggesting that there is no risk associated with the intake of residual pesticides through kiwifruit. [ABSTRACT FROM AUTHOR]

The use of natural compounds to preserve fruit quality and develop high value functional products deserves attention especially in the growing industry of processing and packaging ready-to-eat fresh-cut fruit. In this work, potential mechanisms underlying the effects of postharvest biofumigation with brassica meal-derived allyl-isothiocyanate on the physiological responses and quality of 'Hayward' kiwifruits were studied. Fruits were treated with 0.15 mg L of allyl-isothiocyanate vapours for 5 h and then stored in controlled atmosphere (2% O, 4.5% CO) at 0 °C and 95% relative humidity, maintaining an ethylene concentration <0.02 μL L. The short- and long-term effects of allyl-isothiocyanate on fruit quality traits, nutraceutical attributes, glutathione content, antiradical capacity and the activity of antioxidant enzymes were investigated. The treatment did not influence the overall fruit quality after 120 days of storage, but interestingly it enhanced the ascorbic acid, polyphenols and flavan-3-ol content, improving the antioxidant potential of kiwifruit. The short-term effect of allyl-isothiocyanate was evidenced by an increase of superoxide dismutase activity and of oxidative glutathione redox state, which were restored 24 h after the treatment. The expression levels of genes involved in detoxification functions, ethylene, ascorbate and phenylpropanoid biosynthesis, were also significantly affected upon allyl-isothiocyanate application. These results suggest that allyl-isothiocyanate treatment probably triggered an initial oxidative burst, followed by an induction of protective mechanisms, which finally increased the nutraceutical and technological value of treated kiwifruits. [ABSTRACT FROM AUTHOR]

Storage of harvested agricultural products under optimum storage conditions is very important for selling them as an intended price in the market and for the maintenance of their quality longer. On the other hand, different storage techniques effects the resistance properties of products. In this research, some rupture properties like, maximum force and bioyield force, stress, maximum energy in maximum force, maximum energy in bioyield point, modulus of elasticity, bioyield deformation, maximum breaking dilatation and minimum damage height, of 'Hayward' kiwifruits stored under four different storage conditions (Normal Atmosphere; 21 % O + 0 % CO (NA as Control), NA storage after 1-Methylcyclopropene treatment (1-MCP + NA), NA storage with ethylene control (NA + EC), Controlled Atmosphere storage (2 % O + 5 % CO) with ethylene control (CA + EC) and under two different load conditions were evaluated. Both under two load conditions rupture properties of kiwifruits stored under CA + EC conditions were measured higher than other storage conditions. In particular, maximum force and modulus of elasticity values of CA-stored kiwis were found to be statistically important. [ABSTRACT FROM AUTHOR]

To investigate the differences among kiwifruits from six different cultivars (Actinidia chinensis , Actinidia delicosa and Actinidia arguta), UPLC-QTOF-MS and UPLC-ESI-MS/MS coupled to multivariate statistical analysis were applied to untargeted metabolites and targeted analysis of kiwifruit samples for the first time. In untargeted analysis, the metabolome of kiwifruits was exhibited by principal component analysis (PCA), a total of 44 up-regulated feature compounds were screened based on the orthogonal partial least squares-discriminant analysis (OPLS-DA) and identified as glycosyl compounds, hydrocinnamic acids and various flavonoids. Furthermore, the contents of 27 targeted procyanidins, flavonoids and hydrocinnamic acids were analyzed by a UPLC-ESI-MS/MS method. It was indicated that phenol glycosides were much higher in A. arguta , responsible for the aroma of kiwifruits, various quercetin glycosides were higher in A. arguta , and much higher flavan-3-ols and hydrocinnamic acids were rich in A. Chinensis cv. Hongyang (red) kiwifruits. In addition, the results of chemometric analysis showed the untargeted metabolites and targeted compounds were responsible for the classification on the kiwifruits, which can benefit the scientific understanding of chemical diversity for kiwifruits, and improve the investigation of new wild kiwifruit cultivars, especially red kiwifruit and A. arguta. • UPLC-Q-TOF-MS was used for untargeted analysis of kiwifruits. • 44 metabolites up-regulated corresponding to each kiwifruit were determined. • 27 phenols in kiwifruits were targeted analyzed by UPLC-ESI-MS/MS. • Feature metabolites can discriminate kiwifruits of six cultivars. [ABSTRACT FROM AUTHOR]

In this research, the volatile profile of Actinidia deliciosa (A. Chev) C.F. Liang and A.R. Ferguson var. deliciosa cv. Hayward fresh fruits (pulp) coming from two different training systems, picked at different harvest times were characterized by HS-SPME-GC-IT/MS before and after storage. Forty-seven compounds were identified and distributed by distinct chemical classes (aldehydes, alcohols, ketones, esters, monoterpenes, norisoprenoid and hydrocarbons), with 24 being reported for the first time in this variety. The major volatiles found were: hexanal, ( E)-2-hexenal and methylbutyrate. A principal component analysis showed that fruits from pergola training system are very well distinguished from those coming from T-bar training system by their abundance of monoterpenes and norisoprenoids. In general, fruits after storage have higher amounts of esters. All these results were confirmed by sensory analysis, having the T-bar kiwifruits higher notes in 'pungent' descriptor, and fruits stored higher values of 'ripened fruit odour' and 'sweetness'. [ABSTRACT FROM AUTHOR]

Abstract: We used Magnetic Resonance Imaging spectroscopy to reveal the use of two Plant Growth Regulators (PGRs), i.e. cytokinin and auxin, on Hayward kiwifruits, at any stage of cultivation, and post-harvest ripening and storage. The internal morphology was non-destructively determined in order to depict structural features related to hormones treatments and we found that T2-weighted MRI images showed different internal tissue organisations depending upon the use and the type of PGR. Transverse relaxation times allowed the recognition of cytokinin-treated samples, whilst image analysis was used to identify auxin-treated kiwifruits. We also exploited the post-harvest conditions, i.e. normal refrigeration and controlled atmosphere, on PGRs treated kiwifruits, and found that auxin shortened the shelf-life, with normal refrigeration exerting a stronger effect. The kiwifruit pulp was also investigated by means of Scanning Electron Microscopy, highlighting significant differences at a cellular level amongst treatments, in terms of pore size and vacuoles number, both probably playing a fundamental role in the evaporation activity. [ABSTRACT FROM AUTHOR]

Abstract: The device used in the present study consists of a conveyer belt that throws the fruit onto a flat horizontal plate connected to a load cell. The vertical distance between plate and conveyer belt (drop height) as well as the speed of the belt can be continuously adjusted. Tests were carried out by selecting three different values of drop height and speed. The Magness-Taylor (MTf) index was used as reference, destructive parameter, to describe the flesh firmness and to set-up predictive models. The digitalized time history of the force was analysed to extract some mechanical indices (peak force, impact duration and impulse) used to predict MTf by simple or multiple regression analyses. Moreover, each point of the entire time history was processed by artificial neural network (ANN) software to predict MTf. The goodness of fit, expressed as R 2, was up to 0.823 with the regression models. On the whole, the peak force was the best predictor. The ANNs did not involve a substantial increase in goodness of fit with respect to the best regression models: +8.3%, as mean, 37% as maximum. The speed or position at which the fruit impacts the plate can represent an important parameter influencing the MTf prediction. Free dropping of the fruit instead of throwing onto the plate by the conveyer did not provide a better prediction. The impact device did not cause mechanical damage to the kiwifruits. [Copyright &y& Elsevier]

Abstract: Parts of irradiated kiwifruits were investigated for radiation-induced markers. The DNA comet assay on seeds showed that non-irradiated cells appeared as intact nuclei without tails, while irradiated cells displayed comets with long tails. Tail length of seeds increased significantly up to 1kGy (p <0.05), showing a positive correlation (R 2 =0.9084) between the irradiation dose and tail length. The triplet signals from cellulose radicals observed in electron spin resonance (ESR) analysis on the core or flesh of kiwi enabled irradiated samples to be distinguished from the non-irradiated samples. The ESR signals increased in correlation with the irradiation doses with R 2 =0.9071 in the core and R 2 =0.9730 in flesh. Both methods were found suitable for the detection of irradiated kiwi during the six-week shelf-life period. [Copyright &y& Elsevier]

Retention of ascorbic acid (AA) in dried kiwifruit in storage is studied. The effects of storage temperature (30°C–50°C) and water activity (aw: 0.51–0.82) are investigated. The degradation of AA follows a first order reaction. A decrease of approximately one order of magnitude in AA is observed when aw is increased from 0.51 to 0.82 with the activation energy in the range of (38.0–62.3) kJ/mole. The effect of temperature on the rate constant followed the Arrhenius relationship. An empirical equation combining temperature, water activity rate constant has been developed. [ABSTRACT FROM AUTHOR]