Quality Of Papaya Fruit Research Articles

Postharvest Application of Different Coatings to Improve the Quality and Storage Stability of Papaya Fruit (Carica papaya L.) Cv. Red Lady

The Present investigation was carried out on title “Study on different post-harvest treatment for improving shelf life and quality of Papaya fruit (Carica papaya L.) cv. Red lady”. The Experiment was conducted in a Completely Randomized Design with 10 treatments viz. T0-Control, T1- Ethrel 500 ppm, T2- Ethrel 700 ppm, T3- Aloevera gel 1.0%, T4- Aloevera gel 1.5%, T5- Corn Starch 1.0%, T6- Corn Starch 1.5%, T7- Cassava Starch 1.0%, T8- Cassava Starch 1.5%, T9- (Corn Starch 1.5% + Cassava Starch 1.5%) and their three replications, during the year 2023. Aloevera gel 1.5% treated fruits showed the better results followed by the Aloevera gel 1.0%. This coating reduced the transpiration rate and slowed down the ethylene production and formed a layer on the surface of papaya fruits which helped in protection from microorganisms, fungus resulting in the increase in shelf life of fruits and storage quality. The Papaya fruits treated with Corn Starch 1.5% was also found to be significantly good treatments over the Control in respect of storage quality and shelf life of Papaya fruits during the storage. Based on the results obtained, it can be concluded that Aloevera gel 1.5% was found to be most appropriate treatment in papaya cv. Red Lady. Therefore, it can be used in Papaya cv. Red Lady for physiochemical traits ie., Physiological loss in weight, Decay percent, Fruit Firmness, Sensory Evaluation, Visual Appearance, TSS.

Nanocomposite Coatings of Pectin and Oxide Zinc Nanoparticles to Increase Papaya Shelf Life

Nanocomposite coatings functionalized with antimicrobial nanoparticles could be a promising alternative for the postharvest preservation of fruits. This study aimed to develop nanocomposite coatings based on pectin incorporated with zinc oxide (NPZ) nanoparticles to preserve the postharvest quality of papaya fruits. The coatings were prepared using pectin (3%) and NPZ (0%–0.4%). The materials were characterized for water-related properties (water solubility and water vapor permeability) as well as physical, mechanical, morphological, rheological, and structural properties. The coatings were applied to papaya fruits, which were analyzed for weight loss, firmness, titratable acidity, and soluble solids over nine days of storage. Incorporating NPZ (0%–0.4%) did not affect the films’ water solubility and vapor permeability. However, films with NPZ exhibited lower mechanical properties than pure pectin films. Rheological behavior testing indicated that the pectin solution was a Newtonian fluid, whereas pectin solutions with zinc nanoparticles were non-Newtonian fluids. The pectin coating with 0.2% NPZ was the most effective in preserving the postharvest quality of papaya by reducing fruit weight loss and acidity content. Therefore, the developed coatings incorporated with NPZ showed promise for the postharvest preservation of papaya fruits.

Spraying with encapsulated nitric oxide donor reduces weight loss and oxidative damage in papaya fruit

The combination of nitric oxide (NO) donors with nanomaterials has emerged as a promising approach to reduce postharvest losses. The encapsulation of NO donors provides protection from rapid degradation and controlled release, enhancing the NO effectiveness in postharvest treatments. Moreover, the application method can also influence postharvest responses. In this study, two application methods were evaluated, spraying and immersion, using S-nitrosoglutathione (GSNO, a NO donor) in free and encapsulated forms on papaya fruit. Our hypothesis was that GSNO encapsulated in chitosan nanoparticles would outperform the free form in delaying fruit senescence. In addition, this study marks the pioneering characterization of chitosan nanoparticles containing GSNO within the framework of a postharvest investigation. Overall, our findings indicate that applying encapsulated GSNO (GSNO-NP-S) through spraying preserves the quality of papaya fruit during storage. This method not only minimizes weight loss, ethylene production, and softening, but also stimulates antioxidant responses, thereby mitigating oxidative damage. Consequently, it stands out as the promising technique for delaying papaya fruit senescence. This innovative approach holds the potential to enhance postharvest practices and advance sustainable agriculture.

The effect of indigenous Arbuscular mycorrhizal fungi (AMF) on phyto-accumulation in Carica papaya hybrids

Papaya (Carica papaya L.) is a climacteric fruit with a resilient and distinctive aroma. The consumption of the fruit is global due to its high nutritive and medicinal values. However, there has been low production of quality papaya fruits due to unavailability of crucial mineral elements in the soils. The current study therefore, focuses on the effect of indigenous arbuscular mycorrhizal fungi (AMF) as a biofertilizer on the quality of papaya fruits. In order to verify AMF effectiveness on papaya fruits, four treatments were used: AMF inoculum only, composted farm yard manure (FYM) only, combination of AMF inoculum and compost FYM and control where only soil and sand media were used at a ratio of 1:1. Jomo Kenyatta University of Agriculture and Technology (JKUAT) and Malkia papaya hybrids were used. The papaya seeds from JKUAT and Malkia papaya hybrids were sown in trays and transplanted at 3 leaves stage into 5 litre pots within a green house. The AMF spores were bulked using sorghum plants to obtain the AMF inoculum. The treatments were added into the soil media of the papaya plantlets at a ratio of 1:3, every 4 weeks after first transplanting until they were 20 weeks old. They were then transplanted to 100 litre containers, where completely randomized design was used and replication of six papaya plants for each treatment and hybrid. Watering, weeding and cooling the green house with water fumes was carried out when necessary; as the papaya plants grew until the fruits attained physiological maturity. The fruits were separately harvested and ripened to a predetermined stage. They were then analysed for moisture content, crude fibre, minerals (nitrogen, phosphorous, potassium, magnesium, calcium, iron and zinc), ascorbic acid, total carotenoids and total polyphenols. Data obtained was subjected to two-way ANOVA at p ≤ 0.05 significance level; means were separated using Tukey's HSD test in Genstat's 15th edition. JKUAT hybrid with AMF inoculum treatment had 3.07%crude fibre and 8.42mg/100g phosphorous content while JKUAT hybrid with both AMF inoculum and manure treatments had 4.9 % crude fibre and 9.88 mg/100g phosphorous content. Malkia and JKUAT hybrids with compost FYM treatment had potassium content of 98.31mg/100g and 109.4 mg/100g respectively while the controls had 31.58 mg/100g and 35.32mg/100g respectively. Incorporating soil media with manure and AMF inoculum improved the nutritive quality of papaya fruits and this was contingent on papaya hybrids. Key words: biofertilizer, inoculum, mineral elements, nutritive quality, physiological maturity

Effect of lactic acid bacteria and Bacillus on anthracnose disease in postharvest papaya fruit

Abstract. Thi QVC, Dung TQ, Huynh NTN, Truc NT, Thuy NP. 2023. Effect of lactic acid bacteria and Bacillus on anthracnose disease in postharvest papaya fruit. Biodiversitas 24: 5883-5894. Anthracnose disease of papaya fruit caused by Colletotrichum (isolate TD1), identified by 5.8S rRNA sequence homology, is a main obstacle in papaya fruit, influencing fruit quality and minimizing shelf life. Therefore, to diminish the disease and sustain the fruit quality, the impact of Lactic Acid Bacteria (LAB) and Bacillus on the growth of anthracnose disease and fruit quality was investigated in vitro and in vivo. Furthermore, 13 LAB and 12 Bacillus isolates were collected from traditional fermented vegetables and papaya rhizospheric soils. The results showed that 13 LAB isolates and 6 isolates of Bacillus were inhibitory against Colletotrichum in an in vitro test. Two isolates of LDC11 and BHL21 with the highest antifungal activity were selected to evaluate their effect on Colletotrichum growth and papaya fruit quality under in vivo conditions. These findings indicated that the isolates LDC11 and BHL21 at a density of 106 CFU/mL reduced the disease incidence and severity. The LAB and Bacillus treated papaya fruit increased a number of parameters, such as weight loss, TSS, and L*, a*, and b* values. However, vitamin C content, TA, and fruit firmness were reduced compared to the control. The research shows a potential applications of LAB and Bacillus in the postharvest preservation of papaya fruit. To our knowledge, this is the first study to apply Bacillus and LAB bacteria to control diseases in postharvest papaya in Vietnam.

Effect of Humidity-Triggered Controlled-Release 1-Methylcyclopropene (1-MCP) on Postharvest Quality of Papaya Fruit

Papaya (Carica papaya L.) is a valuable economic crop that is widely cultivated in tropical and subtropical regions but has a short storage and shelf life. Exploring effective strategies to improve the postharvest quality of papaya is important. This study explored the effect of humidity-triggered controlled-release 1-methylcyclopropene (1-MCP) sheets on the postharvest quality of papaya fruit. ‘Rainbow’ papayas underwent cold storage at 10 ± 0.5 °C, RH 85% ± 2% for 14 days, and then were transferred to 20 ± 0.5 °C, RH 85% ± 2% for 10 days to simulate shelf life. The 1-MCP sheets were cut into different sizes and placed in storage containers in advance to create corresponding concentrations at 0.5, 1.0, 2.0, and 4.0 ppm. Results showed that 1-MCP treatment inhibited fruit softening, and reduced weight loss and peel color deterioration without causing any physiological disorders. The 1.0–2.0 ppm 1-MCP-treated fruit received the highest score for papaya flavor and sweetness respectively and the lowest score for off-flavor. The humidity-triggered controlled-release 1-MCP sheets are effective and convenient, and they can serve as an important tool for regulating postharvest papaya ripening with economic benefits.

Secondary Metabolites Application of Two Pseudomonas fluorescens isolates and Two Trichoderma Harzianum Isolates in Combination Against Postharvest Anthracnose in Papaya

The occurrence of papaya anthracnose is a significant post-harvest ailment, necessitating the effective disease management. The aim was to determine the ability of secondary metabolites combination of Pseudomonas fluorescens and Trichoderma harzianum isolates against the disease. A completely randomized design was used for in vitro experiments and a randomized block design for in vivo experiments. The treatments consisted of P. fluorescens P60 and T. harzianum T10, P. fluorescens P60 and T. harzianum T213, P. fluorescens P32 and T. harzianum T10, P. fluorescens P32 and T. harzianum T213 secondary metabolites and fungicides (a.i. maneb). The observed variables included the pathosystem component and papaya character and organoleptic test. The in vitro test results showed that P. fluorescens P60 and T. harzianum T10 and P. fluorescens P60 and T. harzianum T213 secondary metabolites inhibited the pathogen growth by 48.1075 and 43.4625%, respectively. The secondary metabolites of P. fluorescens P60 and T. harzianum T10 in vivo test results could delay the germination time by 12.63% and reduce the invasion area by 44.29%. All secondary metabolites had no effect on sugar content, hardness and sensory test. The combined secondary metabolites of P. fluorescens and T. harzianum are safe and does not affect papaya fruit quality.

Effect of Edible Coatings of Cassava Starch Incorporated with Clove and Cinnamon Essential Oils on the Shelf Life of Papaya.

Applying edible coatings added with plant essential oils is a strategy used to delay ripening processes in climacteric fruits such as papaya. Formulations comprising 3% or 4% cassava starch (w/v), added with clove or cinnamon essential oils (2 mL/L), were tested for microbial inhibition (in vitro) purposes. Moreover, these fruits' physicochemical and microbiological aspects were assessed at 25 °C, for 12 days. Slight variations in pH and Brix values were observed during storage. On the other hand, there were no significant variations in carotenoid contents over storage time. The papaya fruits' coating contributed to reducing their weight loss from 40.66% (uncoated sample) to 24.10% on the 12th storage day, as well as delayed changes often observed during the ripening process. The 4% cassava starch coatings added with essential oils were more efficient in reducing microbiological levels. The herein proposed treatments reduced aerobic mesophilic bacteria, as well as molds and yeast counts, by 1.48 and 1.95 log CFU/g, on average, respectively, in comparison to the control sample. The assessed microorganism counts were higher in the uncoated sample than in the coated papaya fruits, after 12 days of storage. Thus, the tested coatings can potentially delay the emergence of post-harvest changes; consequently, they can help improve the quality of papaya fruits and extend their shelf life.

Prototype Detection System Of Papaya Murability Using Fuzzy Logic Method Based On Color Sensor

Product selection based on the ripeness quality of papaya fruit is one of the stages in the processing of plantation products. At this time, the process of sorting papaya fruit is still using manual methods, especially in estimating the level of ripeness. Papaya is considered a climacteric fruit where respiration occurs and its ethylene production suddenly increases and then rapidly falls off. Fruit with a low respiration rate has a longer shelf life than fruit with a high respiration rate. To overcome this problem, this research created a prototype of a papaya fruit ripeness detection system using a color sensor-based fuzzy logic method. This fruit maturity detector can provide information related to fruit ripeness (unripe, half ripe, and ripe) which is determined from the color of the papaya fruit which is then processed using the Mamdani fuzzy logic method. The results of the prototype design can measure fruit with an accuracy rate of 93.33% of the 30 data tested by using tools that are in a cool place, with low intensity of incoming sunlight.
 Keywords: Papaya fruit ripeness, TCS3200 Sensor, Mamdani Fuzzy Logic.

Classification for Papaya Fruit Maturity Level With Convolutional Neural Network

Papaya California (Carica papaya L) is one of the agricultural commodities in the tropics and has a very big opportunity to develop in Indonesia as an agribusiness venture with quite promising prospects. So the quality of papaya fruit is determined by the level of maturity of the fruit, the hardness of the fruit, and its appearance. Papaya fruit undergoes a marked change in color during the ripening process, which indicates chemical changes in the fruit. The change in papaya color from green to yellow is due to the loss of chlorophyll. The papaya fruit is initially green during storage, then turns slightly yellow. The longer the storage color, the changes to mature the yellow. The process of classifying papaya fruit's ripeness level is usually done manually by business actors, that is, by simply looking at the color of the papaya with the normal eye. Based on the problems that exist in classifying the ripeness level of papaya fruit, in this research, we create a system that can be used to classify papaya fruit skin color using a digital image processing approach. The method used to classify the maturity level of papaya fruit is the Convolutional Neural Network (CNN) Architecture to classify the texture and color of the fruit. This study uses eight transfer learning architectures with 216 simulations with parameter constraints such as optimizer, learning rate, batch size, number of layers, epoch, and dense and can classify the ripeness level of the papaya fruit with a fairly high accuracy of 97%. Farmers use the results of the research in classifying papaya fruit to be harvested by differentiating the maturity level of the fruit more accurately and maintaining the quality of the papaya fruit.

Classification for Papaya Fruit Maturity Level with Convolutional Neural Network

Papaya California (Carica papaya L) is one of the agricultural commodities in the tropics and has a very big opportunity to develop in Indonesia as an agribusiness venture with quite promising prospects. So the quality of papaya fruit is determined by the level of maturity of the fruit, the hardness of the fruit, and its appearance. Papaya fruit undergoes a marked change in color during the ripening process, which indicates chemical changes in the fruit. The change in papaya color from green to yellow is due to the loss of chlorophyll. During storage, the papaya fruit is initially green, then turns slightly yellow. The longer the storage color, the changes to mature the yellow. The process of classifying papaya fruit's ripeness level is usually done manually by business actors, that is, by simply looking at the color of the papaya with the normal eye. Based on the problems that exist in classifying the ripeness level of papaya fruit, in this research, we create a system that can be used to classify papaya fruit skin color using a digital image processing approach. The method used to classify the maturity level of papaya fruit is the Convolutional Neural Network (CNN) Architecture to classify the texture and color of the fruit. This study uses eight transfer learning architectures with 216 simulations with parameter constraints such as optimizer, learning rate, batch size, number of layers, epoch, and dense and can classify the ripeness level of the papaya fruit with a fairly high accuracy of 97%. Farmers use the results of the research in classifying papaya fruit to be harvested by differentiating the maturity level of the fruit more accurately and maintaining the quality of the papaya fruit.

Papaya Fruit Quality Classification Based on Lab Color and Texture Features Using Artificial Neural Networks (ANN)

The process of sorting the quality of papaya fruit is a postharvest problem. So far, humans still do the quality sorting process conventionally or manually. It certainly has weaknesses and limitations, which require a large workforce, and the level of human perception of the quality of papaya varies. Several studies have been carried out regarding the classification of papaya fruit quality, but these studies have accuracy that can still be improved. Therefore, in this study, it is proposed to determine the quality of papaya fruit based on LAB colour and texture features using an Artificial Neural Network (ANN) algorithm. This research consists of six stages: image acquisition, pre-processing, segmentation, morphology, feature extraction and classification. The classification process for the training stage produces the highest level of accuracy in three training scenarios; namely, two techniques have 100% accuracy and 99.58% in the third scenario. Based on the best training scenario selected, the testing process produces 98.88%, the highest accuracy rate with a misclassification error of 1.12% and 69 seconds of computing time. These results indicate that the proposed method can accurately classify papaya quality based on LAB colour and texture features.

Effect of Calcium Nitrate and Calcium Carbonate on Plant Growth, Fruit Quality and Yield of Papaya Cv. Red Lady

A field experiment was performed to study the effects of foliar applications of CaCO3 and Ca(NO3)2 on growth, quality, yield, and shelf life of papaya (Carica papaya) Cv. Red lady. Calcium (Ca) is one of the major plant nutrients which affects significantly the formation of the cell walls and cell membranes and also enables the production of biomass with proper plant growth and function. In the current experiment, papaya seedlings were well established in the orchard, well-irrigated with standardized nutrient solutions with all required inter-culture activities. Four different pre-harvest foliar application sprays were provided with two varying sources of Ca (CaCO3 and Ca(NO3)2) at three concentrations of each with CaCO3 (2%, 1%, 0.5%) Ca(NO3)2 (2%, 3%, 4%) at different stages of growth like flowering stage, fruit set stage, pre-harvest stage. The study revealed that foliar spray of above mentioned concentrations showed a profound improvement in vegetative growth of plants in terms of their height and diameter as compared to the plants in control treatment and also affected the fruit quality of papaya fruit.

Effect of combined application of carbonate salts and hot water treatment for the management of postharvest anthracnose (Colletotrichum gloeosporioides) of papaya.

Postharvest anthracnose (Colletotrichum gloeosporioides Penz.Sacc) is the most economically important biological constraint to papaya production and consumption, which causes substantial yield loss worldwide. The effect of combined application of carbonate salts and hot water treatments on the development of postharvest anthracnose and maintenances of postharvest quality of papaya fruit was studied in completely randomized design (CRD) under laboratory condition. The results revealed that combined application of hot water treatment and carbonate salts significantly (p < .05) reduced the incidence and severity of postharvest papaya anthracnose disease. The disease incidence reached 100% 21 days after inoculation in the control treatment; this level was significantly reduced to 26.70% by dipping the fruits in NH4CO3 at 50°C and NH4CO3 at 54°C. Similarly, treatments significantly (p < .05) reduced the disease severity in different degrees from the first day of disease appearance to the date of 100% unmarketability of control fruits. Furthermore, the combined application of carbonate salt and hot water treatments significantly improves fruit marketability by 93.33%. Moreover, the treatments showed significant (p < .05) effect on maintaining pH, TSS, TA, and reducing postharvest weight loss of papaya fruit. In conclusion, postharvest treatment of papaya fruit with NH4CO3 at 54°C, NH4CO3 at 52°C, and NaCO3 at 54°C can significantly reduce anthracnose development and improve marketability of the fruits without pronounced effect on their edible qualities.

Hydrolate and EO Application to Reduce Decay of Carica papaya during Storage

Postharvest fruit loss is caused by the absence of advanced handling and storage technologies and the quiescent presence of fungal pathogens. Therefore, there is a growing demand for sustainable decisions for the planet. This study focused on the use of two types of edible coatings: one was based on the essential oil of Origanum vulgare L. subsp. viridulum with Aloe arborescens Mill. gel (EC1), and the other was based on the hydrolate only (EC2). These treatments were applied to provide defense against fungal infections in papaya (Carica papaya L. cv Solo), and the storage time was 25 days (T5 ± 1 °C). Fruits coated with EC1 were more contaminated with fungal pathogens than both control (CTR) and EC2 fruit. EC2 showed a statistically lower decay index than CTR and EC1 and maintained its organoleptic characteristics better, showing a 15% loss of firmness after 25 days of storage. Furthermore, the lowest decay index (1.14 after 25 days) was found for the EC1 and CTR. These findings suggest that the use of hydrolate can be useful for extending the shelf life and maintaining the quality of papaya fruit, representing an alternative to the use of synthetic fungicides for food safety.

Exogenous melatonin treatment reduces postharvest senescence and maintains the quality of papaya fruit during cold storage.

Exogenous melatonin (EMT) application has been used to reduce postharvest senescence and improve the quality and antioxidant enzyme activities of papaya fruits during cold storage. The effects of exogenous melatonin application (1. 5 mM) were investigated on papaya fruits during cold storage (10°C ± 2°C) for 28 days in the present study. The EMT treatment delayed postharvest senescence significantly with lower maturing status compared with untreated papaya fruits (control). In addition, EMT treatment maintained substantially higher titratable acidity values and ascorbic acid content but significantly lower soluble solids content and lower weight loss compared with the untreated fruits. Concerning the antioxidant capacity, the EMT-treated papaya fruit exhibited markedly higher total phenolic content and, consequently, higher DPPH-radical scavenging activity than the control group. The EMT treatment not only kept a higher enzyme activity of superoxide dismutase, peroxidase, and catalase but also significantly inhibited the accumulation of hydrogen peroxide and malondialdehyde, along with satisfying sensory attributes. The findings of this study indicated that EMT application could be commercially used as an eco-friendly strategy to reduce postharvest senescence and maintain the fresh-like quality traits of papaya fruit during cold storage.

The combined effect of ascorbic acid and chitosan coating on postharvest quality and cell wall metabolism of papaya fruits

Papaya fruit easily decays and prematurely senescence after harvest. Studies have shown that adding ascorbic acid to chitosan can improve postharvest quality and extend the shelf life of coated fruits. Therefore, the effect of 1.5% (w/v) ascorbic acid (AsA), 1.0% (w/v) chitosan (CTS), and 1.5% (w/v) ascorbic acid + 1.0% (w/v) chitosan (AsA + CTS) treatment on the storage quality of papaya fruits was studied. The results showed that AsA + CTS treatment reduced the weight loss, malondialdehyde, and hydrogen peroxide content of papaya fruit. AsA + CTS treatment improved the antioxidant capacity of papaya fruits by increasing the activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase), soluble sugar and total phenol content, as well as by maintaining color and delaying senescence of fruits. AsA + CTS treatment also inhibited fruit softening by reducing cell-wall- degrading enzymes activities and by encoding gene transcript levels for cellulase, polygalacturonase, pectin methylesterase, and β-galactosidase. In summary, AsA + CTS treatment was an effective technique for maintaining the postharvest storage quality of papaya fruits.

Plant extract and essential oil coating prolongs shelf life and maintains keeping quality of papaya fruit during storage

Plant extract and essential oil coating prolongs shelf life and maintains keeping quality of papaya fruit during storage

Effects of Ethanol Treatment on Storage Quality and Antioxidant System of Postharvest Papaya.

Papaya is the fourth most favored tropical fruit in the global market; it has rich nutrition and can be used for medicine and food processing. However, it will soften and mature in a short time after harvest, resulting in a lot of economic losses. In this study, papaya fruits were soaked in 0, 12.5, 25, 50, and 100 ml/L ethanol solutions for 2 h and stored at 25°C for 14 days, by which we explored the effects of ethanol treatment in papaya after harvest. At an optimal concentration of ethanol treatment, color changing of the papaya fruits was delayed for 6 days, and decay incidence and average firmness of the fruits were shown as 20% and 27.7 N, respectively. Moreover, the effect of ethanol treatment on antioxidant systems in the papaya fruits was explored. It was observed that ethanol treatment contributed to diminish the development of malondialdehyde (MDA), ethylene, and superoxide anions. Furthermore, the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) were promoted than those of control group, while the activities of peroxidase (POD), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) were brought down. In addition, the principal component analysis (PCA) showed that PAL, ethylene, and superoxide anions were the main contributors for the maturity and senescence of postharvest papaya. In this experiment, ethanol treatment had the potential of delaying the ripening and maintaining the storage quality of papaya fruits.

Melatonin Maintains Fruit Quality and Reduces Anthracnose in Postharvest Papaya via Enhancement of Antioxidants and Inhibition of Pathogen Development.

Papaya fruit is widely grown in tropical regions because of its sweet taste, vibrant color, and the huge number of health benefits it provides. Melatonin is an essential hormone that governs many plants′ biological processes. In the current study, the impact of melatonin on fruit ripening and deterioration in postharvest papaya fruit was explored. An optimum melatonin dose (400 μmol L−1, 2 h) was found to be effective in delaying fruit softening and reducing anthracnose incidence. Melatonin enhanced antioxidant activity and decreased fruit oxidative injury by lowering superoxide anion, hydrogen peroxide, and malondialdehyde content by enhancing the enzymatic and non-enzymatic antioxidants, and by improving the antioxidant capacity of papaya fruit. Melatonin increased catalase, ascorbate peroxidase, NADH oxidase, glutathione reductase, polyphenol oxidase, superoxide dismutase, and peroxidase activity, as well as induced total phenol, total flavonoid, and ascorbic acid accumulation. Melatonin also enhanced the activity of defense-related enzymes, such as chitinase, 4-coumaric acid-CoA-ligase, and phenylalanine ammonia lyase, while it repressed lipid metabolism. Additionally, melatonin inhibited the development of anthracnose in vitro and in vivo. These findings suggest that exogenous melatonin application improves papaya fruit quality by boosting antioxidant and defense-related mechanisms.