Postharvest Biology and Quality Preservation of Vasconcellea pubescens: Challenges and Opportunities for Reducing Fruit Losses

Abstract

Vasconcellea pubescens (mountain papaya) is an underutilized Andean fruit with distinctive nutritional and functional properties, yet its rapid softening and short shelf-life result in significant postharvest losses. This review summarizes current knowledge on the physiology of fruit development and ripening, with emphasis on cell wall disassembly, color changes, and ethylene regulation as determinants of postharvest quality. Advances in postharvest management strategies, including temperature control, packaging, and ethylene-modulating treatments (such as 1-MCP), are discussed in the context of preserving fruit firmness, extending shelf life, and reducing food waste. Furthermore, the high content of bioactive compounds—such as papain, phenolics, and flavonoids—underscores the potential of valorizing by-products through sustainable biotechnological applications. Despite recent progress, critical gaps remain in genomic resources, predictive quality monitoring, and large-scale implementation of preservation techniques. Addressing these challenges could enhance the economic and ecological value of V. pubescens, positioning it as both a model species for postharvest research and a promising fruit for reducing food losses in horticultural supply chains.

1. Introduction

Papaya is an angiosperm plant belonging to the Caricaceae family, which comprises approximately 35 species-two natives to tropical Africa and about 33 endemics to Central and South America. This family includes six genera: Cyclimorpha, Jacaratia, Jarilla, Vasconcellea, Horovitzia, and Carica [1], and is part of the Brassicales order, which also includes species such as mustard and Arabidopsis thaliana. Among these, Carica papaya L. is the most commercially important cultivated species and ranks as the fourth most significant tropical fruit crop worldwide [2,3].

In South America, several species within the genus Vasconcellea-a group formerly considered part of Carica-are recognized as one the closest wild relatives of common papaya. Vasconcellea is considered the oldest genus within the Caricaceae family and is primarily distributed along the Andes Mountain at elevations ranging from 1500 to 3000 m above sea level [4]. The term “highland papaya” refers to its origin in these mountainous regions, where it is predominantly cultivated above 1000 m. The greatest diversity of Vasconcellea species is found between Colombia and Ecuador, with Ecuador harboring 16 of the 27 known species [5].

Globally, postharvest losses account for 30–50% of total fruit and vegetable production, representing a critical challenge for food security and sustainability. In this context, underutilized species such as V. pubescens offer valuable opportunities to diversify horticultural systems, reduce pressure on conventional crops, and contribute to more sustainable agricultural practices through their adaptation to marginal environments and potential for value-added applications.

Chile, a long and narrow country with marked climatic diversity, presents suitable conditions for papaya cultivation in specific regions. Two papaya species are currently found in Chile: the introduced Vasconcellea pubescens and the native Chilean papaya (Vasconcellea chilensis). The latter, commonly referred to as “palo gordo”, “native papaya”, or “southern papaya”, is a shrub endemic to Chile, growing to variable in shape-oval, deltoid, heart-shaped. It produces small purple flowers (5–6 mm) in winter and is a polygamous species, bearing male, female, and hermaphroditic individuals. It grows slowly, generates limited biomass, and produces small fruits (1–3 cm in diameter) with minimal pulp and low papain content in the latex. Fruits typically contain between 5 and 10 seeds. Natural populations are restricted to semi-arid rocky areas coastal area between the Atacama (28°39′ S; 71°42′ W) and Valparaíso (33°09′ S; 71°42′ W) regions [6].

The second species, Vasconcellea pubescens, also known as “mountain papaya” or “papayuela”-is native to South America and has been introduced into various regions. Taxonomically, it belongs to the Plantae Kingdom, Brassicales Order, Caricaceae Family, Vasconcellea Genus, Vasconcellea pubescens Species. Vasconcellea pubescens. It is cultivated in several South American countries [1]. Although the exact date of its introduction to northern Chile is unknown, early Spanish chronicles indicate that the local populations were cultivating this species before the arrival of the conquistadors around 1535 [7].

V. pubescens is an open-pollinated species exhibiting sexual polymorphism, which male, female, and hermaphrodite plants. Traditionally, farmers have propagated the species using seeds for selected plants within their own orchards. These local cultivation practices and environmental conditions have likely shaped the species’ genetic diversity and population structure in Chile [8,9].

Over the years, V. pubescens has been described under various synonymous names, including Carica candamancensis, Carica pubescens, and Vasconcellea cundinamarcensis (

Table 1. Synonyms and taxonomic classification of Vasconcellea pubescens reported in the botanical literature.

Scientific Name	Other Names	Synonimus	Extension
Vasconcellea pubescens [10,11,12,13]	Chamburo, chilacuán, mountain pawpaw, papayer de la montagne, chamburo, papaya de tierra fría, chihualcán, siglalón, chichuacacón, titi-ish, bonete, papaya de altura, papayuela, tapaculo, ababai, bonete.	Vasconcellea cundinamarcensis [14,15], Carica candamarcensis Hook. F [16], Carica cestriflora (A. DC.) Solms, Carica chiriquensis Woodson [16], Carica pubescens (A. DC.) [17], Carica pubescens Lenné & C. Koch, Carica cundinamarcensis Linden, Papaya cundinamarcensis (Linden) Kuntze, Papaya pubescens (A. DC.) Kuntze, Vasconcellea cestriflora A. DC.	Colombia, Ecuador, Venezuela, Peru, Bolivia, Panama, Chile, Costa Rica

). The species is characterized by an arborescent growth habit, reaching 8–10 m in height, with few branches and large leaves [8]. It produces yellow, ovoid fruits (5–6 cm in diameter and 6–14 cm length), containing numerous seeds within a central cavity. The pulp is juicy, yellow, and intensely aromatic, and it is rich in papain-a proteolytic enzyme widely used in the food industry as a meat tenderizer.

V. pubescens holds significant ecological and agri-food value in the Andean region. In Chile, interest in this species has grown due to its versatility in the production of value-added products such as gummies, canned papaya, juices, syrups, and jams. Furthermore, it has demonstrated antifungal, anti-inflammatory, and wound-healing properties. Its latex contains high levels of papain, which plays a crucial role in protein digestion by breaking down highly resistant peptide bonds [18].

The objective of this review is to highlight the agro-industrial and nutritional potential of Chilean papaya, with an emphasis on V. pubescens. The review will address aspects related to its origin, nutritional characteristics, medicinal properties, industrial applications, life cycle, and key physiological characteristics relevant to its cultivation and postharvest potential.

1.1. Physiology of Vasconcellea pubescens: Plant and Fruit

1.1.1. Morphological and Reproductive Characteristics

Botanically, mountain papaya (Vasconcellea pubescens) is a diploid, dicotyledonous species with nine chromosomes (2n = 18) [19]. It is a polygamous species and present monoecious or dioecious individuals. Plants typically between 3 and 10 m tall, with stout, succulent, medullose stems and few branches. Three floral types are present: female, male and hermaphrodite [8]. Consequently, male, female, and hermaphroditic trees can all be found in cultivation [20].

V. pubescens is distinguished from other fruit trees cultivated in Chile by its herbaceous growth habit, early bearing, year-round fruit production, and low production cost [15]. A single plant can produce up to 200 fruits, with a life span ranging from 20 to 25 years. The fruits are obovoid, slightly apiculate, yellow, acidic, fragrant, obtusely pentagonous or five-sulcate, typically 7–10 cm long and 3–6 cm wide, although larger fruits have been reported. The average fruit weight is approximately 200 g [17,21,22,23].

Seeds are numerous, glossy, and pungent. The sarcotesta is smooth, while sclerotesta is reddish-brown with broad, low, interrupted ribs. Seeds account for nearly 22% of the fresh fruit weight, and a fruit can contain up to 150 seeds [24]. In some cases, fruits from monoecious plants may appear oblique in shape. Mountain papaya is a climacteric fruit that displays a typical increase in ethylene production during ripening, accompanied by fruit softening, skin color changes, and the development of a strong and distinctive aroma [15,25,26].

Notably, V. pubescens has papain content up to five times higher than Carica papaya. Additionally, depending on the drying method used, the antioxidant content can be significantly enhanced. Antimicrobial activity has also been observed, especially when ethanolic extracts are obtained at high temperatures [22,23].

1.1.2. Geographic Distribution and Agroecological Adaptation

V. pubescens is primarily cultivated at high altitudes, similar to Carica papaya L., and is native to several countries in South and Central America, including Colombia, Ecuador, Venezuela, Peru, Bolivia, Panama, Costa Rica. In Chile, the species is distributed along coastal zones (Figure 1). Although the plant is sensitive to low temperatures [13,27], it demonstrates tolerance to extreme environmental conditions such as salinity and drought.

In Chile, approximately 225 hectares are dedicated to the cultivation of V. pubescens, mainly spanning from the Coquimbo to the BioBio regions (34°41′ and 36°33′ south latitude) [23,28,29]. Most orchards in this area are relatively large (10–40 hectares) and are managed using standard fruit production practices, including terracing, fertigation, pest control, and pruning. These orchards supply both local and international markets [23].

In Coquimbo Region, particularly around La Serena, papaya production tends to be more commercially oriented. In contrast, in southern regions such as Maule and Biobío, cultivation is often more artisanal. In these areas, many families process mountain papaya fruits into value-added products such as preserves, liqueurs, jams, and candied fruits [17].

1.1.3. Reproductive Biology and Propagation Strategies

Most papaya plants are dioecious; however, a wide range of hermaphroditic phenotypes can be identified in the field. Consequently, V. pubescens is considered a subdioecious species, exhibiting three distinct phenotypes: female, male, and hermaphrodite phenotypes [24,29,30]. V. pubescens exhibits andromonoecious reproductive behavior, characterized by a high proportion of male and hermaphroditic flowers. Bisexual flowers are morphologically to male flowers but contain viable ovules, resulting in the production of small fruits [3].

Sex determination in V. pubescens involves two main genetic components: the Ypm chromosome and the pm cytoplasmic factor-both considered primitive sex-determining elements [24]. These elements are believed to have diverged into distinct genomic sequences responsible for sexual differentiation in male and female individuals [31].

Sexual polymorphism is increasingly relevant in orchard management because fruit number and quality—two key production traits—are strongly influenced by the sex of the plant. In V. pubescens, female plants are generally preferred due to their superior fruit quality. This contrasts with C. papaya, where hermaphroditic plants are favored for their fruit shape [13]. Currently, sex identification in V. pubescens is only possible at the onset of the reproductive stage, making early identification a valuable tool for growers and medium-sized businesses.

The main mode of reproduction of V. pubescens is sexual, through seeds. Plants require approximately 10–12 months to reach reproductive maturity and typically remain productive for commercial purposes for around five years. After this period, fruit yield gradually declines in both quantity and quality. The species is characterized by slow growth and continuous development of leaves and flowers. As basal leaves senesce, they detach naturally and fall to the ground [8].

Various studies have explored vegetative propagation techniques, including plant regeneration from anther-derived callus. The most effective media for shoot induction have been Murashige and Skoog (MS) and Woody Plant Medium (WPM) supplemented with maltose as a carbon source and a combination of 8.88 μM of 6-BAP, 5.71 μM of IAA and 2.28 μM of zeatin (MSM and WPM) [1].

Additionally, species within the Vasconcellea genus have been used as rootstocks for Carica species to improve agronomic traits. Interspecific hybrids have also been developed, such as those between C. papaya and V. cauliflora or V. pubescens, the latter being more compatible. However, many of these hybrids present different degrees of incompatibility, on the other hand introgression has been tested in search of improving some characteristics [2,9,32,33,34,35,36,37,38,39] (

Table 2. Reproductive strategies and interspecific hybridization of Vasconcellea pubescens with Carica papaya and related species.

Female Parent	Male Parent	Mortality Rate in Glasshouse [39]	Color Flower	Color Fruit	Article
Carica papaya	Vasconcellea cauliflora	high	-	-	[9,34]
Carica papaya	Vasconcellea parviflora	low	pink	-	[32,34]
	Vasconcellea pubescens		yellow or cream		[34]
	Vasconcellea quercifolia		yellow		[34]
	Vasconcellea spitulata				[34]
Carica papaya	Vasconcellea goudotiana	high	yellow-purple		[34]
	Vasconcellea monoica				[34]
	Vasconcellea monoica				[34]
Vasconcellea spitulata	Vasconcellea pubescens	-	orange, green or greenish-yellow		[2,35]
V. heilbornii var. chrysopetala	Vasconcellea pubescens	high	-		[2,35,39]

).

1.1.4. Postharvest Physiology and Shelf Life

Postharvest losses in fruits can range from 30% to 80%, depending on the crop. In papaya, significant losses are often attributed to inadequate postharvest handling practices and technologies, including poor temperature control throughout the cold chain, rising logistical costs, and inappropriate packaging. These deficiencies contribute to both economic losses and food safety concerns [40,41].

Postharvest handling begins immediately after harvest, and harvesting methods are typically adapted to the specific characteristics of the crop and available resources. In the case of papaya, fruits are commonly harvested using long sticks or poles. Due to the fruit’s limited shelf life and climacteric nature, it is crucial to harvest at the optimal stage of ripeness to ensure good postharvest performance. Both fruit quality and shelf life are strongly influenced by harvesting practices and subsequent handling and treatments.

Temperature is a critical factor influencing the postharvest physiology of papaya. Technologies that regulate temperature during storage and transport have been widely adopted to extend shelf life and maintain fruit quality (4 °C). Storage temperature directly affects metabolic activity and the integrity of cellular structures in the fruit [42]. In some cases, the fruit is treated by hot water immersion or vapor heat to protect from pathogen attack but are some changes in the skin [43].

Nevertheless, multiple factors contribute to postharvest losses in papaya and other fruits. These include preharvest conditions, environmental stress, inadequate marketing and distribution chains, poor storage infrastructure, suboptimal transport conditions, postharvest pathogens, physiological disorders, chilling injury, and natural senescence. These factors can result in a wide range of quality issues, including changes in nutritional composition, deterioration of texture and firmness, discoloration, and flavor loss. Ultimately, such changes reduce fruit marketability and economic value [42].

After harvesting, papaya is highly perishable due to its rapid ripening and softening 4 or 5 days postharvest in the case of V. pubescens without chilling, the treatment to 1-MCP (for 16 h) extends almost 2 days [21,25], which leads to a decline in firmness, development of surface blemishes, skin discoloration, and an overall reduction in visual and sensory quality [22].

The annual production of papaya in Colombia according to studies reported until 2010, is 30 thousand tons per year and is equivalent to 10.20% of the fruits produced in the country; it is known that the exocarp (fruit peel). Some years ago, studies have been carried out on what to do with some agro-industrial waste or how to give them another use, such as wood substitutes from pits, cellulose nanocrystals (NCC) 45–46 from nuts and rice stover, and coconut shell, on the other hand, magnetite nanoparticles have been made from the skin of Carica. While in Vasconcellea, world papaya production has been decreasing so far during the period 2015–2022; however, in that period of time, around 35 million tons of papaya seeds were generated worldwide, where the contribution of Chilean production is just over 6 thousand tons in that same period and considering that 54% of the fruit is discarded. Studies have been conducted on the production of oil from seeds, microcapsules of active compounds from skin and seeds, and agglomerates for housing construction from seeds, as represented in

Table 3. Examples of some species in which different fabrics that usually end up as waste are used, and their applications [43].

Specie	Tissue	Application
Prunus domestica	Carozo	Chipboard [44,45]
Oryza sativa	Rice husk
	Rice straw
Juglans regia	Nut shell
Oryza sativa	Rice straw	NCC [44,46]
Cocos nucifera	Coconut shell
Carica papaya	Papaya peel extract	Magnetite nanoparticles [47]
	Peels and seeds	Oil from Unripe and ripe papaya seeds [11,48]
Vasconcellea pubescens	Peel and seeds	Microencapsulation of bioactive extracts [12]
	Mucilage and seeds Seeds	Antiglycans, [45] Chipboard [45]

.

1.2. Aroma, Phenolic Compounds and Antioxidants Capacity

The characteristic aromas of fruits are due to a complex mixture of volatile organic compounds (VOCs) that, along with acids and sugars, give each fruit its unique flavor [49]. The characteristic aroma of this papaya is a fructose-citrus blend of pineapple, apple, banana, and apple, due to 37 main compounds, including terpenes, ketones, esters, alcohols, and some hydrocarbons [10].

In the case of papaya fruit, its aroma is primarily due to esters and their esterification by acetyl-CoA. The structural model of an alcohol acyltransferase enzyme of V. pubescens (VpAAT1) [26] was previously described showed that the enzyme can interact with a big number of substrates, and produce the different corresponding esters, additionally, the relative expression of the gene that codified to VpAAT1 enzyme showed in particular an important increase during fruit ripening [25].

V. pubescens fruits cultivated in Chile exhibit a remarkable diversity of phenolic compounds, prominently featuring hydroxycinnamic acids such as p-coumaric acid, as well as various glycosylated derivatives, including sinapyc acid-hexosides and hexosides of ferulic and isoferulic acids [16,23]. Notably, the total phenolic content reached 129.1 mg gallic acid equivalents (GAE) per 100 g fresh weight (FW) when extracted using a combination of ultrasound and high hydrostatic pressure techniques, indicating the efficacy of advanced extraction methods in maximizing bioactive yield [16]. These compounds are well-established antioxidants capable of scavenging reactive oxygen species (ROS), thereby mitigating oxidative stress and contributing to cellular protection mechanisms [23].

The flavonoid composition of V. pubescens is equally noteworthy, with multiple quercetin glycosides such as rutin (quercetin-3-O-rutinoside) and manghaslin (quercetin-3-O-(2′-rhamnosyl)-rutinoside) being structurally confirmed via NMR and HPLC-ESI-MS analyses [16]. By the other hand, from waste like seeds and mucilage, the contribution percentage of bioactive compounds like flavonoids (rutin and quercetin) to the total phenolics was greater than that of phenolic acids [18]. These flavonoids substantially enhance the antioxidant capacity of methanolic fruit extracts, with total flavonoid contents reaching up to 24.83 g quercetin equivalents (QE)/100 g dry weight in certain active fractions [16]. Moreover, their bioactivity extends beyond direct antioxidant action, as evidenced by a significant reduction in malondialdehyde (MDA) levels, an indicator of lipid peroxidation, in rat liver tissues treated with ethanolic extracts of the fruit [50].

Antioxidant activity has been rigorously quantified using assays such as DPPH, ORAC, and voltammetry, with values as high as 20.6 mM Trolox equivalents (TE)/100 g FW (DPPH) and 141.0 mM TE/100 g FW (voltammetry) reported under optimized extraction conditions [23]. While antioxidant levels decrease after dehydration [22,51], a strong correlation between DPPH activity and antimicrobial potency underscores the resilience and functional synergy of phenolic and flavonoid constituents in oxidative stress mitigation [23,50,52].

1.3. Objective Color Assessment in Vasconcellea pubescens Fruits

Until 2010, the color of papaya fruits was evaluated qualitatively, either by estimating the percentage of surface coloration or by using the Munsell color chart [24]. The color of this papaya in day 5 postharvest is yellow and luminous but in day 7 to 12 becomes opaque [21] and the aroma changes. However, more recently, instrumental methods have been adopted, particularly the use of colorimeters that quantify color using the CIE Lab* color space [53].

In this system, L* represents lightness (ranging from black to white), a* ranges from green (−) to red (+), and b* from blue (−) to yellow (+), providing a more objective and reproducible assessment of fruit color. Based on these colorimetric values, several derived parameters have been developed to interpret and compare color differences. These include: (a) Total color difference (ΔE): used to assess the perceptual difference between two color readings. (b) *Chroma (C)**: a measure of color saturation or intensity. (c) Hue angle (h°): indicates the specific shade or tone of the color. These parameters allow for a more accurate classification of color changes, particularly during ripening, storage, or processing [54,55]. The threshold values for ΔE have been used to categorize the degree of perceptible color change in papaya, supporting quality control and consumer acceptance studies [56], based on the criterion of variation in the total color value to classify the intensity of the change [22,23,57].

1.4. Cell Wall Disassembly and Softening Mechanisms in Vaconcellea Pubescens

During post-harvest During postharvest ripening, fruit softening in V. pubescens is primarily driven by progressive disassembly of the cell wall, a process that begins with the dissolution of the middle lamella [22,23,58,59,60]. The plant cell wall, a complex matrix of polysaccharides and structural proteins, provides mechanical strength and defines cell shape and size [61,62]. This structure dynamically remodels throughout development, and its integrity varies among species, tissues, developmental stages, and under stress conditions. Loss of turgor pressure—a major determinant of texture—is also a critical factor in fruit softening, commonly referred to as loss of firmness [21,60,63]. Cell wall disassembly is mediated by a wide array of enzymes and proteins, particularly hydrolases, lyases, and transglycosylases [64,65,66]. These enzymes are typically categorized as pectolytic or non-pectolytic, depending on their substrate specificity Pectolytic enzymes include: endo- and exo-polygalacturonases (PG), pectate lyase (PL), pectin methyl esterase (PME), pectin acetyl methyl esterase (PAE), β-galatosidase (beta-GAL), L-arabinofuranosidase. These enzymes either modify the polysaccharide backbone or remove neutral sugars from branched side chains. Non-pectolytic enzymes target hemicellulose and include: endo-1,4 β-glucanase (EG), endo-1,4-β-xylanase, β-xylanase, xyloglucan endotransglycosidase/hydrolase (XTH) and expansins. The specific activity and expression of these enzymes can vary widely among fruit species [60,67,68].

Although studies using ethylene and 1-MCP treatments have been conducted in mountain papaya [10,63], only expansin (EXPA) has been, only expansin (EXPA) has been conclusively associated with wall softening in this species. Transcript accumulation of EXPA is significantly higher in ripe fruits compared to other tissues (flowers, leaves, stems). Interestingly, its expression peaks on the first day of ethylene treatment, while in untreated controls, peak expression occurs on days 3 and 5 postharvest [21,69].

In addition to structural changes in the wall, mountain papaya is a rich source of bioactive and nutritional compounds. The fruit pulp contains high levels of vitamins C and A, potassium, sugars, dietary fiber, and antioxidants, while the seeds—representing 8–15% of the fruit’s fresh weight-are rich in proteins, fiber, fatty acids, calcium, and phosphorus [22,23].

Another component of interest is plant mucilage, a heterogeneous mixture of water-soluble polysaccharides, glycoproteins, and bioactive compounds. Mucilages in V. pubescens are mainly composed of rhamnogalacturonan I (RG-I), xylan, cellulose, and small amounts of homogalacturonan (HG), with a high degree of methyl-esterified galacturonic acid (GalA) as a primary component [13]. These properties make papaya mucilage an attractive candidate for applications in the food and pharmaceutical industries.

Among the cellular components of mountain papaya, it has been established that changes in fruit texture are the result of modifications in polysaccharides, which in turn lead to the breakdown of primary cell wall and middle lamella structures. This has been postulated to be a consequence of hydrolytic enzyme activity in carbohydrate polymers [13].

Postharvest losses in tropical fruits such as Vasconcellea pubescens and Carica papaya can exceed 30–40%, with fungal pathogens, improper handling, and lack of infrastructure being the main causes. Mitigation requires a comprehensive approach that combines good agricultural practices, postharvest handling, and appropriate technologies (

Table 4. Major causes of losses mainly detected in Vasconcellea pubescens and Carica papaya.

Main Causes of Post-Harvest Loss		Mitigation Strategies
Pathogenic fungi and others	Colletotrichum spp. Fusarium spp. Phytium spp. Oidium spp. Alternaria spp. Mycosphaerella spp. Meloidogyne incognita Tetranychus urticae [70] Aphis spp. [70] Erwinia papaya [71] Meloidogyne incognita [71] Rotylenchulus reniformis [71]	Hot water immersion ozonation, radiation, cold storage, chitosan, essential oils and silicones, Application of a hydrothermal-calcium chloride [43,72,73,74,75,76,77,78]
Mechanical damage	Bumps and bruises during harvesting, transport, and handling increase susceptibility to infection and accelerate deterioration.	Careful harvesting, sorting, ergonomic packaging and suitable transport [42,72,73]
Environmental factors	Improper temperatures, low humidity and light exposure can increase susceptibility to damage.
Physiological disorders	Accelerated ripening, excessive softening and storage problems.	Use of 1-methylcyclopropene (1-MCP) to delay ripening and modified atmosphere technologies [10,43,72,79,80,81,82]

). Some causes are more aggressive in Carica, which is why so many crossbreeding attempts have been made.

2. Bioinformatics and Molecular Approaches in Vasconcellea pubescens

To date, a single transcriptome has been published for Vasconcellea pubescens, which includes gene expression data from fruits, leaves, and roots [28]. Interestingly, mountain papaya has also been proposed as a potential reservoir for Kashmir bee virus.

In addition to transcriptomic studies, other genetic approaches have focused on molecular marker analyses using PCR-RFLP based on chloroplast genomic DNA. These studies targeted two non-coding regions of cpDNA (trn M- rbc L y trn K1- trn K2) and one non-coding region of mitochondrial DNA (nad 4/1- nad 4/2), mainly for phylogenetic and evolutionary analyses [35]. However, comprehensive omics studies in this species remain limited, making V. pubescens a promising candidate for future integrative molecular research.

There is no Vasconcellea pubescens genome, so Carica papaya is mostly used as a reference genome, so several of the genomic studies may or may not work, for example mutation studies with CRISPR/Cas9 have focused on genes such as CpPDS [83], CpMLO6, eIF (iso) 4E, ꞵ-1,3-Glucanase [84]. On the other hand, genes that could be interesting to see in mountain papaya related to the degradation of the cell wall during fruit ripening and that have been studied in tropical papaya are CpEBF1, CpMADS [80], genes of the ethylene biosynthesis pathway, phenylpropanoid, as well as other hormones such as auxin, ABA, salicylic acid [85,86].

3. Hormone Treatments and Future Perspectives

Ethrel (an ethylene-releasing compound) and 1-MCP (1-methylcyclopropene, an ethylene action inhibitor) are the primary hormone-based treatments applied in V. pubescens for postharvest studies [10,21,63], as well as in plant regeneration protocols [1]. Despite these initial efforts, the physiological responses of mountain papaya to a wider range of phytohormones—such as auxins, cytokinins, abscisic acid (ABA), gibberellins, and jasmonates—remain largely unexplored. This opens a promising research avenue for evaluating how different hormones and their concentrations might modulate developmental, stress-related, and postharvest processes in this species.

Although research on hormonal treatments in V. pubescens has so far been limited primarily to ethylene and its inhibitor 1-MCP, evidence from other climacteric and non-climacteric fruits suggests promising avenues for future exploration, in other climacteric fruits ABA and ethylene orchestra fruit ripening under abiotic stress like drought, temperature stress, salt [87]. In strawberry and blueberry, exogenous applications of abscisic acid (ABA) have been shown to modulate ripening, enhance anthocyanin accumulation, and improve postharvest quality by reinforcing antioxidant capacity. Similarly, treatments with methyl jasmonate (MeJA) [88] have been reported to delay softening, reduce microbial decay, and preserve nutritional attributes in berries and tomatoes. In Solanum lycopersicum, treatment with MeJA maintained lycopene and carotenoid and prevented the fruit softening, brassinosteroids induce ripening and respiration rate [89,90]. In Carica, auxin interact to CpEIL1 and CpARF2 [90]. Given that V. pubescens exhibits a rapid loss of firmness and significant postharvest susceptibility, these hormonal strategies could represent valuable tools to complement ethylene modulation. Moreover, the integration of such treatments with existing temperature and packaging technologies could provide synergistic benefits for extending shelf life and reducing losses. Future research should therefore prioritize testing ABA, MeJA, and related phytohormones in V. pubescens, as their successful application in other horticultural commodities suggests high potential for adaptation to this underutilized Andean fruit.

4. Biomedical and Antimicrobial Potential of Vasconcellea pubescens: From Enzymatic Activity to Functional Ingredients

The antimicrobial and bioactive properties of Vasconcellea pubescens, particularly its proteolytic enzyme papain, have been demonstrated in various studies (

Table 5. Key bioactive compounds and their effects.

Compound Category	Specific Compounds	Concentration (Per 100 g)	Main Reported Biological Roles	Reference
Vitamins	Vitamin C (Ascorbic acid)	448.30 mg (JKUAT 8 variety)	Antioxidant, supports immune function and prevents oxidative damage.	[97,98]
	β-Carotene (Provitamin A)	68.75 mg (Solo variety)	Antioxidant, retina and epithelial health via vitamin A conversion.	[99]
	Vitamin E	Variable concentrations	Antioxidant, membrane protection and lipid peroxidation prevention.	[98]
	B-Complex vitamins	Present in moderate amounts	Metabolic support, energy production. Cofactor in enzymatic reactions.	[98]
	Folate	Present	Metabolic support, DNA synthesis, cell division.	[98]
Minerals	Potassium	1145.10 mg (JKUAT 8)	Electrolyte balance, cardiovascular benefits. Regulates blood pressure, nerve function.	[98,99]
	Calcium	Variable	Structural support, signaling. Bone health, muscle function.	[98,99]
	Magnesium	Variable	Enzyme cofactor, muscle function, activates over 300 enzymes.	[98,99]
Carotenoids	Lycopene	25.47 mg (Solo variety)	Antioxidant, associated with cardioprotective and anticancer properties.	[98,99]
	Lutein/Zeaxanthin	Present	Macular protection, ocular health (blue light filtering).	[98]
	α-Carotene	Present	Antioxidant, free radical scavenging	[98]
Enzymes	Papain	Variable (enzyme activity units)	Protein hydrolysis, tissue debridement, digestive aid, anti-inflammatory, wound healing.	[100]
	Chymopapain	Variable	Peptide bond cleavage, proteolytic activity, inflammation reduction	[100]
Phenolic Compounds	Chlorogenic acid	Identified via LC-ESI-QTOF-MS/MS	Antioxidant, anti-inflammatory, inhibits ROS production, NF-κB suppression	[101,102]
	Neochlorogenic acid	Present	Antioxidant, free radical neutralization	[102]
	Cynarin	Present	Hepatoprotective, antioxidant, liver enzyme protection	[102]
	Eupatorine	Present	Anti-inflammatory, cytokine modulation	[102]
	Vicenin II	Present	Antioxidant, cardioprotective, oxidative stress reduction	[102]
Flavonoids	Quercetin derivatives	Present	Anti-inflammatory, antioxidant, NF-κB pathway inhibition	[101,102]
	Kaempferol compounds	Present	Antioxidant, anticancer potential, cell cycle regulation.	[101]
	Rutin	Present	Vascular protection, anti-inflammatory, Capillary strengthening.	[101]
Polysaccharides	Pectin	Significant amounts	Digestive health, cholesterol reduction, gel formation, bile acid binding.	[98,103]
	Other polysaccharides	Present	Antioxidant, anti-inflammatory, NF-κB modulation, immune support	[103]
Alkaloids	Carpaine	Present (mainly in leaves/seeds)	Platelet modulation, antimicrobial, membrane interaction, enzyme inhibition	[100]
Other Compounds	Benzyl isothiocyanate (BITC)	Present in seeds	Antimicrobial, anticancer potential, protein modification, apoptosis induction	[98]
	Glucosinolates	Present in seeds	Detoxification support, phase II enzyme induction	[98]

). One such example is the use of the proteolytic fraction P1G10 as a protective agent against gastric ulcers in mice [91], as well as its ability to stimulate tissue repair following acute UVB radiation exposure [92], anti-inflammatory effect in acute colitis in mice [93], in samples of Botrytis cinerea affecting the mycelia [94]. In turn, the effect of P1G10 was compared, which had a lower growth versus papain from C. papaya in the percentage of fungal growth [95,96].

Ethanolic convective-dried extracts from ripe fruits have also been tested against bacterial strains such as Escherichia coli, Staphylococcus aureus, and Bacillus cereus. These studies found that dried extracts showed higher antimicrobial activity than fresh samples, with the drying method significantly influencing efficacy [22]. Additionally, microcapsules prepared from fruit residues (seeds and peel) were tested in microbial growth media containing E. coli, Salmonella typhi, and S. aureus. Among them, microcapsules derived from seeds exhibited the largest inhibition halos, particularly against S. aureus [12].

Seeds have also been investigated for anthelmintic properties, protective effects against renal toxins, liver detoxification, and for oil production rich in oleic acid (up to 72%) [11]. Seeds have also been investigated for anthelmintic properties, protective effects against renal toxins, liver detoxification, and for oil production rich in oleic acid (up to 72%) [48].

These antimicrobial properties confer a potential natural preservative effect in food systems. Extracts from various tissues of V. pubescens have also been used in dermocosmetic formulations, pharmacological applications, and are the subject of several patents for health-related uses [17,95].

Recent advances in nanotechnology have opened new possibilities for the controlled delivery of phytohormones during postharvest storage. Nanocarriers such as chitosan nanoparticles and or alginate [104,105], lipid-based vesicles [106], and polymeric nanocapsules [107,108] have been successfully employed in other horticultural commodities to improve the stability, bioavailability, and sustained release of signaling molecules, including abscisic acid (ABA) [104,105] and/or hormones. These systems not only allow precise regulation of hormone concentration and release kinetics but also minimize degradation and reduce the amount of active compound required. In strawberries and blueberries, for example, nanoparticle-mediated delivery of ABA and MeJA has been shown to enhance antioxidant defenses, delay senescence, and preserve fruit quality under storage. Although no studies have yet explored this approach in V. pubescens, its rapid postharvest softening and sensitivity to ethylene make it an excellent candidate for testing nanotechnology-based hormone delivery systems. Integrating these approaches with conventional postharvest treatments could provide an innovative strategy to extend shelf life, reduce losses, and valorize this underutilized Andean fruit.

5. Conclusions and Perspectives

Vasconcellea pubescens (mountain papaya) emerges as a promising species due to its unique fruit development physiology, rich phytochemical composition, and broad spectrum of bioactivities with postharvest and biomedical applications (Figure 2). However, its potential remains underexploited due to limited genomic resources, scarce agronomic standardization, and insufficient technological transfer to the productive and industrial sectors. Future research should aim to unravel the molecular and hormonal mechanisms underlying fruit ripening, deepen our understanding of genotype–environment interactions—especially regarding soil and altitude—and expand biotechnological approaches for valorizing by-products. Establishing integrated postharvest management strategies and sustainable extraction protocols for bioactives could enhance its economic value and environmental footprint. In this context, V. pubescens represents not only a niche crop for Andean agriculture, but also a model for innovation at the interface of plant science, food technology, and functional bioproducts.