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Compared to control longan, DCC-treated longan had higher pulp breakdown index, lower ATP, ADP and EC levels, and lower H+, Ca2+ and Mg2+-ATPase activities. On day 6, DCC-treated longan presented 18% higher pulp breakdown index, with 44%, 9% and 31% lower levels of ATP, ADP and EC, respectively. Additionally, DCC-treated longan showed 29%, 53%, 37% lower activity of H+-ATPase, 34%, 54%, 4% lower activity of Ca2+-ATPase, and 13%, 21%, 6% lower activity of Mg2+-ATPase in the membranes of plasma, vacuole, and mitochondria, respectively. Whereas, DS-treated longan manifested the opposite trends of DCC treatment. These results suggest that the accelerated pulp breakdown in DCC-treated longan was linked to energy deficiency and reduced energy production. However, DS treatment restrained pulp breakdown occurrence in fresh longan by maintaining a higher energy level through the elevated energy production and ATPase activity.
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Compared to the control longan, DNP treatment elevated pulp breakdown index, reduced the values of pulp firmness, CSP, ISP, cellulose, and hemicellulose by enhancing the activities of PE, PG, Cx, XET, and ß-Gal. Additionally, DNP treatment increased the levels of PLD, lipase, LOX, PA, and SFA, and decreased the values of PC, PI, USFA, U/S, and IUFA, displaying higher cell membrane permeability and more severe cell membrane damage in longan pulp. Furthermore, DNP treatment weakened the levels of SOD, CAT, APX, AsA, GSH, TP, and TF, thereby exacerbating ROS outbreak and MDA production. These results indicate that DNP treatment destroyed the antioxidant system to cause ROS eruption. This disruption further disturbed the metabolisms of membrane lipids and cell wall polysaccharides, leading to the breakdown of cell membrane and cell wall, and eventually aggravated longan pulp softening and breakdown. However, ATP treatment exhibited the opposite effects of DNP treatment.
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Colored corn pericarp contains unusually high amounts of industrially valuable phytochemicals, such as anthocyanins, flavanols, flavonoids, and phenolic acids. Polyphenols were extracted in an aqueous solution and spray-dried to produce microencapsulates using four carrier materials, namely, maltodextrin (MD), gum arabic (GA), methylcellulose (MC), and skim milk powder (SMP) at three concentrations (1, 2, and 3 %, respectively). The encapsulates were evaluated for their polyphenolic contents using spectrophotometric techniques and HPLC analyses, and their antioxidant properties were evaluated using four different assays. The physicochemical properties of encapsulates were analyzed by measuring the zeta potential (ZP), particle size distribution, water solubility index (WSI), water absorption index (WAI), and color parameters. Structural and thermal properties were evaluated using Fourier transform infrared spectroscopy (FTIR), optical profilometry, and differential scanning calorimetry (DSC) analyses. Comparative analysis of structural characteristics, particle size distribution, zeta potential, WSI, WAI, and aw of the samples confirmed the successful formulation of encapsulates. The microencapsulates embedded with 1 % concentrations of MD, MC, GA, or SMP retained polyphenolic compounds and exhibited noteworthy antioxidant properties. The samples encapsulated with GA or MD (1 %) demonstrated superior physicochemical, color, and thermal properties. Comprehensive metabolomic analysis confirmed the presence of 38 phytochemicals in extracts validating the spray-drying process.
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Antioxidantes , Composición de Medicamentos , Polifenoles , Secado por Pulverización , Zea mays , Polifenoles/química , Zea mays/química , Antioxidantes/química , Composición de Medicamentos/métodos , Tamaño de la Partícula , Goma Arábiga/química , Sustancias Macromoleculares/química , Solubilidad , Espectroscopía Infrarroja por Transformada de Fourier , Polisacáridos/químicaRESUMEN
Acidic electrolyzed oxidizing water (AEOW) was applied to suppress disease development and maintain good quality of fresh fruit. However, the involvement of AEOW in improving disease resistance of fresh longan remains unknown. Here, transcriptomic and metabolic analyses were performed to compare non-treated and AEOW-treated longan during storage. The transcriptome analysis showed AEOW-induced genes associated with phenylpropanoid and flavonoid biosynthesis. The metabolome analysis found the contents of coumarin, phenolic acid, and tannin maintained higher levels in AEOW-treated longan than non-treated longan. Moreover, the weighted correlation network analysis (WGCNA) was performed to identify hub genes, and a gene-metabolite correlation network associated with AEOW-improved disease resistance in longan was constructed by the co-analysis of transcriptomics and metabolomics. These findings identified a series of important genes and metabolites involving in AEOW-induced disease resistance of longan fruit, expanding our knowledges on fruit disease resistance and quality maintenance at the transcript and metabolic levels.
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Frutas , Metaboloma , Transcriptoma , Agua , Frutas/química , Frutas/metabolismo , Frutas/genética , Agua/metabolismo , Agua/análisis , Resistencia a la Enfermedad/genética , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Electrólisis , Regulación de la Expresión Génica de las Plantas , Oxidación-Reducción , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
Postharvest harmful pathogenic infestation leads to rapid decay in longan fruit. Compared with P. longanae-infected longans, AEOW alleviated fruit disease severity and diminished the O2-. production rate and MDA content. It also increased APX, CAT, and SOD activities, delayed the decrease in the levels of GSH and AsA, as well as the reducing power and DPPH radical scavenging ability, which resulted in a decline in membrane lipid peroxidation in P. longanae-infected longans. Additionally, AEOW reduced LOX, lipase, PI-PLC, PC-PLC, and PLD activities, maintained higher levels of PC, PI, IUFA, USFAs, and U/S, while reducing levels of PA, DAG, SFAs, and CMP. These effects alleviated membrane lipid degradation and peroxidation in P. longanae-infected longans. Consequently, AEOW effectively maintained membrane integrity via improving antioxidant capacity and suppressing membrane lipid peroxidation. This comprehensive coordination of ROS and membrane lipid metabolisms improved fruit resistance and delayed disease development in longans.
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Frutas , Enfermedades de las Plantas , Especies Reactivas de Oxígeno , Especies Reactivas de Oxígeno/metabolismo , Frutas/química , Frutas/metabolismo , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Oxidación-Reducción , Lípidos de la Membrana/metabolismo , Ascomicetos/química , Agua/metabolismo , Peroxidación de Lípido/efectos de los fármacos , Metabolismo de los Lípidos , ElectrólisisRESUMEN
This study introduces an innovative strategy for the rapid and accurate identification of pesticide residues in agricultural products by combining surface-enhanced Raman spectroscopy (SERS) with a state-of-the-art transformer model, termed SERSFormer. Gold-silver core-shell nanoparticles were synthesized and served as high-performance SERS substrates, which possess well-defined structures, uniform dispersion, and a core-shell composition with an average diameter of 21.44 ± 4.02 nm, as characterized by TEM-EDS. SERSFormer employs sophisticated, task-specific data processing techniques and CNN embedders, powered by an architecture features weight-shared multi-head self-attention transformer encoder layers. The SERSFormer model demonstrated exceptional proficiency in qualitative analysis, successfully classifying six categories, including five pesticides (coumaphos, oxamyl, carbophenothion, thiabendazole, and phosmet) and a control group of spinach data, with 98.4% accuracy. For quantitative analysis, the model accurately predicted pesticide concentrations with a mean absolute error of 0.966, a mean squared error of 1.826, and an R2 score of 0.849. This novel approach, which combines SERS with machine learning and is supported by robust transformer models, showcases the potential for real-time pesticide detection to improve food safety in the agricultural and food industries.
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Oro , Aprendizaje Automático , Nanopartículas del Metal , Plaguicidas , Plata , Espectrometría Raman , Spinacia oleracea , Espectrometría Raman/métodos , Spinacia oleracea/química , Nanopartículas del Metal/química , Plata/química , Oro/química , Plaguicidas/análisis , Contaminación de Alimentos/análisis , Residuos de Plaguicidas/análisisRESUMEN
In recent years, concerns have been raised regarding the contamination of grapes with pesticide residues. As consumer demand for safer food products grows, regular monitoring of pesticide residues in food has become essential. This study sought to develop a rapid and sensitive technique for detecting two specific pesticides (phosmet and paraquat) present on the grape surface using the surface-enhanced Raman spectroscopy (SERS) method. Gold nanostars (AuNS) particles were synthesized, featuring spiky tips that act as hot spots for localized surface plasmon resonance, thereby enhancing Raman signals. Additionally, the roughened surface of AuNS increases the surface area, resulting in improved interactions between the substrate and analyte molecules. Prominent Raman peaks of mixed contaminants were acquired and used to characterize and quantify the pesticides. It was observed that the SERS intensity of the Raman peaks changed in proportion to the concentration ratio of phosmet and paraquat. Moreover, AuNS exhibited superior SERS enhancement compared to gold nanoparticles. The results demonstrate that the lowest detectable concentration for both pesticides on grape surfaces is 0.5 mg/kg. These findings suggest that SERS coupled with AuNS constitutes a practical and promising approach for detecting and quantifying trace contaminants in food. PRACTICAL APPLICATION: This research established a novel surface-enhanced Raman spectroscopy (SERS) method coupled with a simplified extraction protocol and gold nanostar substrates to detect trace levels of pesticides in fresh produce. The detection limits meet the maximum residue limits set by the EPA. This substrate has great potential for rapid measurements of chemical contaminants in foods.
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Nanopartículas del Metal , Residuos de Plaguicidas , Plaguicidas , Fosmet , Vitis , Residuos de Plaguicidas/análisis , Oro/química , Paraquat , Nanopartículas del Metal/química , Plaguicidas/análisis , Espectrometría Raman/métodosRESUMEN
The influences of hydrogen peroxide (H2O2) on the storability and metabolism of disease-resistant substances in fresh longan were investigated. Compared to the control samples, H2O2-treated longan exhibited a higher index of fruit disease, pericarp browning, and pulp breakdown, a higher rate of fruit weight loss, but lower chromaticity values (L*, a* and b*) in pericarp appearance, and a lower commercially acceptable fruit rate. Additionally, H2O2-treated longan showed a lower lignin content, lower activities of enzymes including phenylalnine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumaryl coenzyme A ligase (4-CL), cinnamate dehydrogenase (CAD), peroxidase (POD), chitinase (CHI), and ß-1,3-glucanase (GLU). These data collectively suggest that H2O2 negatively impacted the storability of fresh longan. This can be attributed to H2O2's role in reducing the levels of disease-resistant substances and suppressing the activities of disease-resistant enzymes, implying that H2O2 reduced the postharvest storability of longan by compromising its disease resistance.
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Banana fruit is highly vulnerable to chilling injury (CI) during cold storage, which results in quality deterioration and commodity reduction. The purpose of this study was to investigate the membrane lipid metabolism mechanism underlying low temperature-induced CI in banana fruit. Chilling temperature significantly induced CI symptoms in banana fruit, compared to control temperature (22 °C). Using physiological experiments and transcriptomic analyses, we found that chilling temperature (7 °C) increased CI index, malondialdehyde content, and cell membrane permeability. Additionally, chilling temperature upregulated the genes encoding membrane lipid-degrading enzymes, such as lipoxygenase (LOX), phospholipase D (PLD), phospholipase C (PLC), phospholipase A (PLA), and lipase, but downregulated the genes encoding fatty acid desaturase (FAD). Moreover, chilling temperature raised the activities of LOX, PLD, PLC, PLA, and lipase, inhibited FAD activity, lowered contents of unsaturated fatty acids (USFAs) (γ-linolenic acid and linoleic acid), phosphatidylcholine, and phosphatidylinositol, but retained higher contents of saturated fatty acids (SFAs) (stearic acid and palmitic acid), free fatty acids, phosphatidic acid, lysophosphatidic acid, diacylglycerol, a lower USFAs index, and a lower ratio of USFAs to SFAs. Together, these results revealed that chilling temperature-induced chilling injury of bananas were caused by membrane integrity damage and were associated with the enzymatic and genetic manipulation of membrane lipid metabolism. These activities promoted the degradation of membrane phospholipids and USFAs in fresh bananas during cold storage.
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Frutas , Musa , Frutas/química , Lípidos de la Membrana/análisis , Lípidos de la Membrana/metabolismo , Musa/metabolismo , Almacenamiento de Alimentos/métodos , Ácidos Grasos/análisis , Ácidos Grasos Insaturados/análisis , Lipasa/metabolismo , Poliésteres/análisisRESUMEN
Quantitative polymerase chain reaction as a powerful tool for DNA detection has been pivotal to a vast range of applications, including disease screening, food safety assessment, environmental monitoring, and many others. However, the essential target amplification step in combination with fluorescence readout poses a significant challenge to rapid and streamlined analysis. The discovery and engineering of the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) technology have recently paved the way for a novel approach to nucleic acid detection, but the majority of current CRISPR-mediated DNA detection platforms are limited by insufficient sensitivity and still require target preamplification. Herein, we report a CRISPR-Cas12a-mediated graphene field-effect transistor (gFET) array, named CRISPR Cas12a-gFET, for amplification-free, ultrasensitive, and reliable detection of both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) targets. CRISPR Cas12a-gFET leverages the multiturnover trans-cleavage activity of CRISPR Cas12a for intrinsic signal amplification and ultrasensitivity of gFET. As demonstrated, CRISPR Cas12a-gFET achieves a limit of detection of 1 aM for the ssDNA human papillomavirus 16 synthetic target and 10 aM for the dsDNA Escherichia coli plasmid target without target preamplification. In addition, an array of 48 sensors on a single 1.5 cm × 1.5 cm chip is employed to improve data reliability. Finally, Cas12a-gFET demonstrates the capability to discriminate single-nucleotide polymorphisms. Together, the CRISPR Cas12a-gFET biosensor array provides a detection tool for amplification-free, ultrasensitive, reliable, and highly specific DNA detections.
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Sistemas CRISPR-Cas , Grafito , Humanos , Sistemas CRISPR-Cas/genética , Polimorfismo de Nucleótido Simple , Reproducibilidad de los Resultados , ADN/genética , ADN de Cadena Simple/genética , Escherichia coli/genética , NucleótidosRESUMEN
Postharvest longan fruits are subjected to Phomopsis longanae Chi (P. longanae) infection that lead to fruit quality deterioration. We hypothesized that ε-poly-l-lysine (ε-PL) could enhance fruit disease resistance in longans. Through physiological and transcriptomic analyses, the results showed that, compared to P. longanae-infected longan fruit, ε-PL + P. longanae treatment reduced the disease development of longan fruits. Additionally, ε-PL + P. longanae treatment increased the contents of disease-resistant substances (lignin and H2O2) and the activities of disease-resistance enzymes (CHI, PAL, PPO, C4H, CAD, GLU, 4CL, and POD). Furthermore, the expressions of genes relevant to the phenylpropanoid biosynthesis pathway and plant-pathogen interaction pathway (Rboh, FLS2, WRKY29, FRK1, and PR1) were up-regulated by ε-PL + P. longanae treatment. These findings demonstrated that ε-PL treatment inhibited the disease development of postharvest longan fruits were associated with the increased accumulation of disease-resistant related substances, as well as the raised activities and genes expressions of disease-resistance related enzymes.
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Frutas , Polilisina , Frutas/química , Peróxido de Hidrógeno/metabolismoRESUMEN
This study aimed to illustrate how DNP and ATP affected the pulp breakdown occurrence in P. longanae-infected longan and their relationship with the membrane lipid metabolism. Compared with P. longanae-inoculated samples, the pulp of DNP-treated P. longanae-infected longan exhibited higher cellular membrane permeability, breakdown index, activities of PI-PLC, PLD, PC-PLC, LOX, and lipase, and values of SFAs, PA, and DAG, while lower levels of PI, PC, USFAs, IUFA and U/S. However, the opposite findings were observed in ATP-treated P. longanae-infected longan. The data manifested that DNP-increased the pulp breakdown occurrence in P. longanae-inoculated samples was due to the elevated MLDEs activities that reduced the contents of phospholipids (PI, PC) and USFAs, disrupting the cell membrane structures. Nevertheless, ATP decreased the pulp breakdown occurrence in P. longanae-inoculated samples, which was ascribed to the reduced MLDEs activities that raised phospholipids (PI, PC) and USFAs contents, thus maintaining the cell membrane structures.
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Lípidos de la Membrana , Sapindaceae , Lípidos de la Membrana/metabolismo , Frutas/química , Fosfolípidos/análisis , Sapindaceae/metabolismo , Adenosina Trifosfato/metabolismoRESUMEN
Polymerase chain reaction (PCR)-based nucleic acid testing has played a critical role in disease diagnostics, pathogen surveillance, and many more. However, this method requires a long turnaround time, expensive equipment, and trained personnel, limiting its widespread availability and diagnostic capacity. On the other hand, the clustered regularly interspaced short palindromic repeats (CRISPR) technology has recently demonstrated capability for nucleic acid detection with high sensitivity and specificity. CRISPR-mediated biosensing holds great promise for revolutionizing nucleic acid testing procedures and developing point-of-care diagnostics. This review focuses on recent developments in both fundamental CRISPR biochemistry and CRISPR-based nucleic acid detection techniques. Four ongoing research hotspots in molecular diagnostics-target preamplification-free detection, microRNA (miRNA) testing, non-nucleic-acid detection, and SARS-CoV-2 detection-are also covered.
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Técnicas Biosensibles , COVID-19 , MicroARNs , Humanos , Sistemas CRISPR-Cas , Patología Molecular , SARS-CoV-2 , Prueba de COVID-19RESUMEN
Longan fruit loses its market value rapidly due to postharvest pathogenic infestation and quality deterioration. Here, we hypothesized that acidic electrolyzed water (AEW) could maintain higher quality of P. longanae-inoculated longans via regulating energy metabolism. Results indicated that AEW reduced fruit disease index and decay incidence. Significantly, AEW treatment retained higher levels of ATP, ADP, and energy charge, and higher activities of Ca2+-ATPase, Mg2+-ATPase, and H+-ATPase in the membranes of plasma, vacuole, and mitochondria, which maintained the structural and functional integrity of cell membrane. Furthermore, indirectly sustaining cell membrane function via AEW treatment could maintain the storability and quality properties of longans, including keeping higher values of color chromaticity (L*, a*, and b*), higher amounts of vitamin C, total soluble solids, sucrose, and total soluble sugars, lower titratable acid and reducing sugar contents. This work elucidated the potential regulation of AEW on the balance of energy metabolism and fruit quality.
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Frutas , Purificación del Agua , Frutas/química , Metabolismo Energético , Ácidos/análisis , Adenosina Trifosfatasas/metabolismoRESUMEN
This work studied the difference in pulp breakdown between two cultivars of longan cv. 'Dongbi' and 'Fuyan' from the aspect of metabolisms of lipid and energy. The results reflected that, compared to 'Fuyan' longan, 'Dongbi' longan had higher levels of energy charge, U/S and IUFA, and higher amounts of USFA, PC, PI, ATP and ADP. Moreover, 'Dongbi' longan exhibited lower levels of SFA, PA, AMP and cell membrane permeability. Also, lower PLD, LOX and lipase activities, but higher ATPase activity, lower pulp breakdown index, and better pulp appearance were exhibited in 'Dongbi' longan. These data revealed that the mitigated pulp breakdown in 'Dongbi' longan was due to the comprehensive coordination of metabolisms in lipid and energy through maintaining a higher level of energy, a higher unsaturation degree of fatty acids, delaying the degradation of phospholipids, and better retaining the membrane structural integrity of microsome and entire cell.
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Frutas , Sapindaceae , Adenosina Trifosfatasas/metabolismo , Frutas/química , Fosfolípidos/análisis , Sapindaceae/metabolismoRESUMEN
Boza is an indigenous, traditional, low-alcohol and highly viscous beverage prepared by fermenting cereals. Its thick and gel-like consistency make it suitable for consumption via spoon. Although boza is a nutritious beverage, its protein content is very low (<2%). A new type of boza was developed by incorporating nonfat dry milk (NFDM) to elevate the protein content of the beverage. Different NFDM amounts (10 to 40% w/v) were added to determine the best concentration and fermentation time based on the refractive index and pH values at room temperature (0-48 h). The best sample was further characterized by rheological analyses and Fourier transform infrared (FTIR) spectroscopy. The sample with 10% NFDM was the best, as fermentation was successfully performed, and further addition of NFDM increased the initial pH. The refractive index and pH decreased from 21.9 ± 0.1 to 11.8 ± 0.1 and 5.77± 0.50 to 4.09 ± 0.35 during fermentation, respectively. The samples exhibited shear-thinning, solid-like behavior, and a gel-like structure. FTIR analysis by independent modeling of class analogy (SIMCA) demonstrated that unfermented slurry and the fermented product could be effectively differentiated. With the addition of 10% NFDM, the increase in the protein content of the boza medium became significant.
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Herein, we developed a surface-enhanced Raman spectroscopy (SERS) optofluidic sensor coupled with immunoprobes to simultaneously separate and detect the foodborne pathogens, Escherichia coli O157:H7, and Salmonella in lettuce and packed salad. The method consists of three steps of (i) enrichment to enhance detection sensitivity, (ii) selective separation and labelling of target bacteria by their specific antibody-bearing SERS-nanotags and (iii) detection of tagged bacterial cells using SERS within a hydrodynamic flow-focusing SERS optofluidic device, where even low counts of bacterial cells were detectable in the very thin-film-like sample stream. SERS-nanotags consisted of different Raman reporter molecules, representing each species, i.e., the detection of Raman reporter confirms the presence of the target pathogen. The anti-E. coli antibody used in this study functions against all strains of E. coli O157:H7 and the anti-Salmonella antibody used in this work acts on a wide range of Salmonella enterica strains. Bacterial counts of 1000, 100, and 10 CFU/ 200 g sample were successfully detected after only 15 min enrichment. Our method showed a very low detection limit value of 10 CFU/ 200 g sample for the bacterial mixture in both lettuce and packed salad, proving the efficiency and high sensitivity of our method to detect multiple pathogens in the food samples. The total analysis time, including sample preparation for simultaneous detection of multiple bacteria, was estimated to be 2 h, which is much less than the time required in conventional methods. Hence, our proposed protocol is considered a promising rapid and efficient approach for pathogen screening of food samples.
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Escherichia coli O157 , Microbiología de Alimentos , Inmunoensayo/métodos , Espectrometría Raman/métodos , Lactuca/microbiología , SalmonellaRESUMEN
Compared with P. longanae-infected longan, 2, 4-dinitrophenol (DNP) treatment for P. longanae-infected longan displayed the lower levels of pulp firmness, cell wall materials, ionic-soluble pectin, covalent-soluble pectin, hemicellulose, or cellulose, but the higher amount of water-soluble pectin, the higher activities of cell wall-degrading enzymes (CWDEs) (PG, ß-Gal, PME, Cx, and XET), and the higher transcript levels of CWDEs-related genes (DlPG1, DlPG2, Dlß-Gal1, DlPME1, DlPME2, DlPME3, DlCx1, and DlXET30). On the contrary, ATP treatment for P. longanae-infected longan exhibited opposite effects. The above results imply that DNP accelerated P. longanae-induced pulp softening and breakdown of fresh longan, which was because DNP up-regulated the transcript levels of CWDEs-related genes, enhanced the CWDEs activities, and accelerated the degradation of cell wall polysaccharides (CWP). However, ATP suppressed longan pulp softening and breakdown caused by P. longanae, because ATP down-regulated the transcript levels of CWDEs-related genes, lowered the CWDEs activities, and reduced the CWP degradation.
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Frutas , Pectinas , Adenosina Trifosfato/metabolismo , Pared Celular/genética , Pared Celular/metabolismo , Frutas/genética , Frutas/metabolismo , Pectinas/metabolismo , Phomopsis , Polisacáridos/metabolismo , SapindaceaeRESUMEN
This study developed a useful technique to maintain quality and mitigate chilling injury of cold-stored Chinese olive fruit. Influence of dose (0, 0.5, 1.0, 1.5, 2.0 mM) of γ-aminobutyric acid (GABA) on the quality attributes and chilling damage of Chinese olive when stored at 2 °C for 100 d was investigated. Compared to control samples, GABA-treated fruit displayed lower chilling injury index, cell membrane permeability, and weight loss percentage, but higher hue angle h° value, higher levels of chlorophyll, total soluble sugar, sucrose, total soluble solids, titratable acid, and tannin, and 1.0 mM GABA is the optimal concentration to retain the quality attributes and reduce the chilling injury of Chinese olive fruit during cold storage.
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The influence of melatonin treatment on the quality and chilling injury of guavas during storage at 4 ± 1 °C were evaluated. Compared with control group, fruit of guava cv. Xiguahong exposed to various concentrations (50, 100, 150, and 200 µmol/L) of melatonin showed a significantly lower fruit respiration rate, weight loss, cell membrane permeability, and chilling injury index, but a higher commercially acceptable fruit rate, higher peel L*, h° value, and chlorophyll content. Melatonin treatment also delayed the decreases of fruit firmness, sucrose, total soluble sugar, vitamin C, titratable acidity, and total soluble solids. These data indicate that melatonin treatment could increase chilling tolerance and retain quality of cold-stored guavas. Among various concentrations of melatonin treatment, 100 µmol/L melatonin-treated guavas showed the preferable quality properties and lowest chilling injury index. Thus, melatonin may be a novel method of postharvest handling to enhance cold resistance and extend storage-life of cold-stored guava fruit.