Ripe Papaya Fruit Research Articles

Resposta da aplicação do 1-MCP em frutos de mamoeiro 'Golden' em diferentes estádios de maturação

O estudo de fatores que influenciam no processo de amadurecimento é fundamental para o planejamento do processo de comercialização, principalmente em frutos com padrão de respiração climatérico e perecível, como é o caso do mamão. Nesse trabalho, avaliou-se o efeito da aplicação do 1-MCP (1-metilciclopropeno) sobre o amadurecimento de frutos de mamoeiro nos estádios 0; 1 e 2 de maturação. O 1-MCP diminui a produção de etileno (≈79%) e a taxa respiratória (≈45%), principalmente em frutos no estádio 0 de maturação. O uso deste inibidor da ação do etileno retardou a perda de coloração verde da casca dos frutos, principalmente em frutos nos estádios 0 e 1 de maturação. Houve redução na perda de firmeza do fruto e do mesocarpo nos estádios 1 e 2. Entretanto, em frutos no estádio 0 de maturação, a firmeza do mesocarpo manteve-se alta, o que pode comprometer a aceitação destes frutos pelo consumidor. O teor de sólidos solúveis não foi influenciado pela aplicação do 1-MCP. O efeito do 1-MCP na redução da atividade das enzimas PME e PG foi maior em frutos nos estádios 0 e 1 de maturação em comparação a frutos no estádio 2 de maturação. A atividade da PME demonstrou crescente aumento ao longo do período de armazenamento, porém a atividade da PG permaneceu baixa ao longo dos cinco primeiros dias, com aumento posterior. Os resultados mostraram que a PME exerce influência significativa na perda de firmeza da polpa nos primeiros dias, com atuação posterior da PG. O 1-MCP mostrou-se eficiente em retardar o processo de amadurecimento de frutos de mamoeiro, tornando-se mais eficiente quando associado a estádios de maturação iniciais.

Managing Oriental Fruit Fly (Diptera: Tephritidae), With Spinosad-Based Protein Bait Sprays and Sanitation in Papaya Orchards in Hawaii

The efficacy of GF-120 NF Naturalyte Fruit Fly Bait in combination with field sanitation was assessed as a control for female oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in papaya (Carica papaya L.) orchards in Hawaii. Three different bait spray regimes were evaluated: every row (high use of the bait), every fifth row (moderate use), and every 10th row (low use). Orchard plots in which no bait was applied served as controls. For five of the seven biweekly periods that followed the first bait spray, trapping data revealed significantly fewer female B. dorsalis captured in plots subject to high and moderate bait use than in control plots. Differences in incidence of infestation among treatments were detected only by the third (12 wk after first spray) fruit sampling with significantly fewer infested one-fourth to one-half ripe papaya fruit in plots subject to high and moderate bait use than in control plots. Parasitism rates by Fopius arisanus (Sonan) (Hymenoptera: Braconidae) were not negatively affected by bait application. Results indicate that foliar applications of GF-120 NF Naturalyte Fruit Fly Bait either to all rows (every other tree), or to every fifth row (every tree) in combination with good sanitation can effectively reduce infestation by B. dorsalis in papaya orchards in Hawaii.

Ripening in papaya fruit is altered by ACC oxidase cosuppression

Papaya (Carica papaya) is a very important crop in many tropical countries but it is highly susceptible to parasitic diseases, physiological disorders, mechanical damage and fruit overripening. Here we report a study on ACC oxidase cosuppression and its effects on papaya fruit ripening. Papaya ACC oxidase was isolated using PCR and embriogenic cells transformed by biolistic using the CaMV 35S promoter to drive the expression of the PCR fragment in sense orientation. Fifty transgenic lines were recovered and 20 of those were grown under field conditions. Southern analysis showed incorporation of the transgene in different copy numbers in the papaya genome. Fruits were evaluated in terms of texture (firmness), colour development, respiration and ethylene production. A sharp reduction in ethylene and CO2 production was detected, whereas softening and colour development of the peel were also altered. Overall, transgenic fruits showed a delay in ripening rate. A reduction in mRNA level for ACC oxidase in transgenic fruit was clearly detectable by northern blot. More studies are necessary before this technology can be used to extend the shelf life of papaya fruit.

Papaya Fruit Ripening: Response to Ethylene and 1-Methylcyclopropene (1-MCP)

Ripening affects the quality and nutritional contents of fleshy fruits, and papayas are climacteric fruits very susceptible to postharvest losses due to the fast softening caused by ethylene. This paper reports the changes in respiration, ethylene production, and pulp color and firmness, along with the contents of soluble sugars and major carotenoids, during ripening of 'Golden' papaya, an important Brazilian cultivar that has been exported to North American and European markets. The results obtained for nontreated and ethylene- or 1-MCP-treated papaya suggest that 1-MCP can decrease the quality of treated fruit and that even the use of ethylene for triggering or inducing homogeneous ripening can result in lower quality when compared to that of fruit allowed to ripe naturally.

Extended Shelf Life and Quality of Fresh-cut Papaya Derived from Ripe Fruit Treated with the Ethylene Antagonist 1-Methylcyclopropene

The purpose of the present study was to investigate the role of ethylene action, via use of the ethylene antagonist 1-methylcyclopropene (1-MCP), on the senescence and quality of fresh-cut ripe papaya (Carica papaya L. `Sunrise Solo') fruit. Ripe papaya fruit were treated with 2.5 μL·L-1 1-MCP and immediately processed into fresh-cut slices or left intact. At 2-day intervals over 10 days at 5 °C, continuously stored slices were monitored for ethylene production, firmness, electrolyte leakage, color, sensory changes, and pathogen incidence. Slices freshly prepared from intact fruit stored under identical conditions were measured similarly. Ethylene production did not differ significantly between the treatments, although production rates were slightly but consistently higher in slices from intact control compared with intact 1-MCP-treated fruit. Mesocarp firmness of continuously stored slices and slices from fruit stored intact was significantly retained by 1-MCP. Firmness of continuously stored slices from 1-MCP-treated fruit declined 50% compared with 75% for control slices. Firmness of fresh-cut slices prepared from intact control and 1-MCP-treated fruit at each sampling interval declined 26% and 15%, respectively. Electrolyte leakage remained low and changed little in slices freshly prepared from fruit stored intact. Leakage from continuously stored papaya slices increased after 4 days, and after 6 days controls increased significantly compared with stored slices derived from papaya fruit initially treated with the ethylene antagonist. The flesh color of continuously stored slices or slices prepared from fruit stored intact was influenced by 1-MCP only during the later periods of storage. Microbial counts in stored slices or slices prepared at each sampling were generally unaffected by 1-MCP. Informal sensory analysis indicated that the edible shelf life was 6 days in stored slices from 1-MCP-treated fruit compared with 2 to 3 days for stored slices from control fruit.

Characterisation of an α-galactosidase with potential relevance to ripening related texture changes

α-Galactosidase (EC 3.2.1.22) from ripe papaya ( Carica papaya L.) fruit was fractionated by a combination of ion exchange and gel filtration chromatography into three forms, viz., α-galactosidase 1, 2 and 3. The predominant isoform, α-gal 2, was probably a tetramer with a native molecular mass of about 170 kDa and 52 kDa-sized subunits and an estimated p I of 7.3. The subunit’s N-terminal amino acid sequence shared high identity (97%) with the deduced sequence of a papaya cDNA clone (accession no. AY25329) encoding a putative α-galactosidase PAG2 as well as with an Ajuga reptans L. GGT1 clone (accession no. AY386246) encoding a galactan: galactan galactosyltransferase (66%). During ripening, α-galactosidase activity increased concomitantly with firmness loss and this increase was largely ascribed to α-gal 2. The protein level of α-gal 2 as estimated by immunoblot was low in developing fruits and generally increased with ripening. α-Galactosidase 2 also had the ability to markedly catalyse increased pectin solubility and depolymerisation while the polymers were still structurally attached to the cell walls mimicking, in part, the changes that occur during ripening. The close correlation between texture changes, α-gal 2 activity and protein levels as well as capability to modify intact cell walls suggest that the enzyme might contribute to papaya fruit softening during ripening. The purported mechanism of α-gal 2 action as a softening enzyme was discussed in terms of its functional capacity as a glycanase or perhaps, as a transglycosylase.

Effect of the potassium permanganate during papaya fruit ripening: Ethylene production

The effect of potassium permanganate (KMnO 4 ) on the ripening process of papaya fruits by monitoring the ethylene emission rates is reported. The ethylene emission was monitored by a photoacoustic spectrometer. Two experimental conditions were applied, being one of them just putting the fruit alone inside the sampling chamber and the second, modifying the atmosphere by the presence of KMnO 4 . The use of the ethylene absorber reduces the autocatalytic process of ethylene during papaya fruit ripening. For 20 g of KMnO 4 the maximal intensity of the ethylene emission decreases by a factor two. Using the same amount of KMnO 4 , a reduction of about 2.2 % in the concentration of ethylene for a mixture of 1ppmv of ethylene in synthetic air was observed.

Association of Enterobacter cloacae with Rhizome Rot of Edible Ginger in Hawaii.

Edible ginger is a popular spice crop that is grown in Hawaii primarily for the fresh market, and as such, rhizome quality is of paramount importance. In our studies, a Gram-negative, facultative anaerobic, rod-shaped bacterium was consistently isolated from decayed as well as symptomless ginger rhizomes. The bacterium was identified as Enterobacter cloacae by biochemical assays and 16S rDNA sequence analysis. Rot symptoms, which usually occurred in the central cylinder of the rhizome, were characterized by yellowish-brown to brown discolored tissue and firm to spongy texture. In inoculation experiments, ginger strains of E. cloacae produced basal stem and root rot, with foliar chlorosis and necrosis in tissue-cultured ginger plantlets, and discolored and spongy tissue in mature ginger rhizome slices and whole segments. In other hosts, ginger strains of E. cloacae caused internal yellowing of ripe papaya fruit and internal rot of onion bulbs. All strains that caused symptoms in inoculated plants were reisolated and identified as E. cloacae. Our studies suggest that E. cloacae can exist as an endophyte of ginger rhizomes, and under conditions that are favorable for bacterial growth, or host susceptibility, including maturity of tissues, rhizome rot may occur. Rhizome quality may be impacted by the presence of E. cloacae under conditions such as high temperature, high relative humidity, and low oxygen atmosphere that may affect the development of decay, and such conditions should be avoided during post-harvest handling and storage. The association of E. cloacae with a rhizome rot of ginger is a new finding.

Chlorophyll fluorescence as a tool to evaluate the ripening of ‘Golden’ papaya fruit

Abstract Fruit classification based on one or more physical or physiological attributes is important to improve quality during storage and marketing. Our objectives were to evaluate changes in chlorophyll fluorescence of papaya fruit ( Carica papaya L. cv. Golden) at different ripeness stages and during the ripening to determine if this non-destructive technique might assist the evaluation of fruit ripeness. Maximal ( F m ), minimal ( F o ), variable ( F v ), variable:maximal ( F v / F m ) and maximal:minimal ( F m / F o ) chlorophyll fluorescence, fruit firmness, and skin color ( H °) were evaluated at three ripeness stages and during the ripening of papaya fruit. Simple and multiple empirical regressions assessed the relationships among all measured parameters. The three ripeness stages were differentiated using the chlorophyll fluorescence parameters. All chlorophyll fluorescence parameters declined with the progress of fruit ripening, where F m and F o showed the best correlation with changes in skin color and fruit firmness. This suggests a relationship between the fluorescence and the level of papaya fruit senescence. Chlorophyll fluorescence decline was probably due to chlorophyll degradation and also to the degree of chloroplast membrane injury due to fruit ripeness and senescence. Chlorophyll fluorescence associated with chloroplast function, declined in parallel with the decline of other quality characteristics during papaya fruit ripening. The use of a single parameter to determine the overall quality of papaya fruit may be unreliable, and the chlorophyll fluorescence technique may be a helpful, complementary, non-destructive technology that can be combined with other quality measurement techniques.

Cell-wall polysaccharide modifications during postharvest ripening of papaya fruit (Carica papaya)

Abstract Modifications of cell-wall polysaccharides and flesh firmness, as a measure of texture, were evaluated during postharvest ripening of papaya fruit (Carica papaya). Cell-wall material (CWM) was isolated from pericarp at different ripening stages. Three pectic and one hemicellulosic fractions, as well as a cellulosic residue, were obtained from CWM. A water soluble fraction contained pectins presumably not cell wall associated. Imidazole and sodium carbonate soluble fractions contained pectins with low degree of branching from middle lamella and profusely branched structures with neutral sugar chains arising from primary cell walls, respectively. Solubilization and concomitant depolymerization of both kinds of pectin was observed. Loss of galactose at two phases of ripening was detected, one at the beginning, and the other, with a simultaneous release of rhamnose, at the onset of the postharvest period. Polysaccharide analysis of 4 M sodium hydroxide soluble fraction was compatible with a xyloglucan type and a mannose containing polymer. Depolymerization of this hemicellulosic fraction was not evident during ripening. A continuous depolymerization of water-extracted pectins was evident. For this fraction, a polymer containing galacturonic acid and covalently associated rhamnose units, i.e., a rhamnogalacturonan type structure that lost acidic monomeric units during ripening, appeared beyond the exclusion limit of gel filtration resin. Cellulose residue exhibited decreasing quantities of galacturonic acid and non-glucose monosaccharides during ripening indicating that association between polysaccharides from matrix and microfibrilar phases may be involved in the softening process. Methyl esterification decreased for middle lamella and primary cell wall pectins while it increased steadily for water soluble pectins. Finally, a scheme of suggested temporal events undergone by cell-wall polysaccharides and the possible enzymes involved along with firmness variation during postharvest ripening of papaya fruit is presented.

CLONING AND MOLECULAR CHARACTERIZATION OF RIPENING-RELATED ACC SYNTHASE FROM PAPAYA FRUIT (CARICA PAPAYA L.)

Papaya is a climacteric fruit and like other climacteric fruits in the tropics, one of the main problems is the significant post-harvest loss due to uncontrolled ripening. One molecular strategy to control ripening after the climacteric rise in ethylene is to down-regulate ethylene biosynthesis through antisense expression of the ripening-related ACC synthase gene. Total RNA was isolated from 100% ripe papaya fruit and reverse transcriptase polymerase chain reaction (RT-PCR) was used to amplify ripening-related ACC synthase cDNAs. Two pairs of degenerate primers (oligonucleotides) derived from conserved regions of ACC synthase from several plant sources were used for RT-PCR. Two different members of the ACC synthase multigene family were isolated and characterized from ripe tissues of papaya whose expression patterns differ greatly from each other. The two ACC synthase cDNAs, ACS1 and ACS2 differ from each other in terms of restriction digest patterns, DNA and amino acid sequence analysis and expression during ripening. ACS2 expression pattern in papaya cv Solo Kapoho exhibits a striking similarity to that of leacs2 in tomato whose transcript levels are high during ripening. ACS2 is a good candidate gene of ACC synthase for antisense strategies to regulate or control fruit ripening. ACS2 was inserted in an antisense orientation in two types of vector constructs for papaya transformation via particle bombardment.

Evolution of Soluble Sugars During Ripening of Papaya Fruit and its Relation to Sweet Taste

ABSTRACT: Fruit ripening is closely associated with compositional and structural changes which can occur before or after harvesting. In papaya fruit, the period of sugar synthesis and accumulation remains poorly understood. The correlation between soluble sugar content and sweetness during papaya ripening was investigated in this study. Soluble sugars accumulated mainly when the papaya fruit was still attached to the plant. After harvest, however, there was still sucrose synthesis, and the sucrose‐phosphate synthase activity was highly correlated to the sucrose content, indicating the importance of this enzyme in the process. Sensory analysis showed that there was a dissociation between sugar content and sweet sensory perception, while the pulp softening showed high correlation with the sweetness process, probably due to the easier release of cellular contents in the fully ripened tissue.

Oviposition Behavior of Ceratitis capitata Wiedemann (Diptera: Tephritidae): Association Between Oviposition Preference and Larval Performance in Individual Females

The oviposition preference and larval performance of females of Ceratitis capitata (Wiedemann) were examined. Wild or laboratory-reared females were tested for oviposition preference in relation to papaya fruit in different stages of ripeness, as well as to two different fruits: papaya and apple. The results demonstrated that both laboratory-reared and wild females preferred ripe papaya fruit compared to unripe fruit for oviposition, and that ripe papaya was the best for larval performance. When oviposition preference was tested with different fruits (papaya and apple), both wild and laboratory-reared larvae developed better in papaya. However, only wild females showed a preference for oviposition on papaya as opposed to apple. Laboratory-reared females showed no oviposition preference on fruits that resulted in better larval performance.

Papaya Fruit Growth, Calcium Uptake, and Fruit Ripening

The uptake of Ca by `Sunset' papaya (Carica papaya L.) fruit and its role in ripening was studied. The highest mesocarp Ca uptake rate occurred in fruit that were <40 days postanthesis when fruit transpiration was probably highest. Ca uptake rate by the mesocarp was low, from 60 to 80 days postanthesis when fruit fresh and dry weight increased. Mesocarp Ca uptake rate increased again from 100 to 140 days postanthesis when fruit fresh weight growth rate declined and dry weight growth rate increased. Mesocarp Ca concentration did not significantly differ from the peduncle to the blossom end. although Ca was significantly higher in the outer than inner mesocarp at the fruit equator. Mesocarp Ca concentration fluctuated significantly throughout the year ranging from 68 to 204 μg·g-1 fresh weight (FW). Soil Ca application did not always increase fruit mesocarp Ca concentration, while K and N fertilization decreased mesocarp Ca concentration. Attempts to increase mesocarp Ca concentration by spraying CaCl2 onto papaya fruit during growth and by postharvest vacuum infiltration and dipping of the cut peduncle into CaCl2 were unsuccessful. Mesocarp Ca concentration was positively correlated to the firmness of ripe papaya fruit and the rate of softening of mesocarp plugs. Less correlation was found between fruit firmness and the ratio of Ca concentration to K or Mg concentration, or to Mg plus K concentrations. Mesocarp Ca concentration of 130 μg·g-1 FW or above was associated with slower fruit softening rate than fruit with a lower concentration.

Fruit trap: A detection and collection tool for opiine parasitoids (Hym.: Braconidae) of the oriental fruit fly,Bactrocera dorsalis (Dipt.: Tephritidae)

A fruit trap was developed for detection and collection of the opiine parasitoids of the oriental fruit fly,Bactrocera (=Dacus)dorsalis (Hendel). Gravid females ofBiosteres arisanus (Sonan), an egg-larval parasitoid, orDiachasmimorpha longicaudata (Ashmead) andPsytallia incisi (Silvestri), both larval parasitoids, were lured to parasitize the eggs or larvae ofB. dorsalis inoculated in ripe papaya fruits,Carica papaya L. Progenies ofB. arisanus were consistently recovered from papaya fruits inoculated withB. dorsalis eggs (subsequently referred to as egg fruit traps). Except in Moloaa on Kauai (6%), higher percentage ofB. dorsalis parasitization (range=38–43%) was recorded in Hilo, island of Hawaii and Waimanalo and Poamoho, island of Oahu. Progenies ofD. longicaudata and a fewP. incisi were recovered from papaya fruits artificially infested withB. dorsalis larvae (subsequently referred to as larval fruit traps). The recovery of parasitoid progenies from larval fruit traps suspended from papaya trees did not differ significantly from larval fruit traps placed on the ground. In both methods of trap placement, percent parasitization ofB. dorsalis byD. longicaudata (predominant species) ranged from 58–60%. On the other hand, significantly moreB. arisanus thanD. longicaudata andP. incisi adults (larval parasitoids) were recovered from fully ripened to highly deteriorated papaya fruits collected from papaya trees or ground (fallen fruits).

Skin freckles on solo papaya fruit

Freckle-like blemishes occur on ripe papaya fruit; the cause and the factors that influence their occurrence are unknown. No freckles were detected on young fruit (less than 40 days old); the skin area affected and freckle diameter (FD) increased during the last phase of fruit growth as the fruit approached maturity. More freckles were seen on the exposed side of the fruit away from the stem. Fruit freckle index and FD were lowest during the late summer-autumn part of the year in Hawaii. Freckle parameters were negatively correlated with minimum and maximum temperatures, especially during the second month before fruit were harvested. Rainfall in the second month before harvest had a significant positive correlation with freckle diameter. There was no correlation between cuticle thickness and freckle appearance. During growth latex volume declined, while latex total soluble solids and freckle incidence increased, suggesting that latex osmotic pressure and fruit growth stresses may play a role in freckle development. Application of anti-transpirants onto young fruits did not reduce the incidence of skin freckles in mature fruit. Wrapping young fruits in white paper bags significantly reduced freckle incidence.

Isolation and Characterization of Pectin Methylesterase from Papaya

Pectin methylesterase (PME) (EC 3.1.1.11) has been purified to apparent homogeneity from ripe papaya fruits. The purification protocol consisted of ammonium sulphate precipitation (60-80%) and cation exchange chromatography in CM Sepharose CL-6B and Mono S. Papaya PME consists of two components (PME 1 and PME 2), which have been shown to be isoenzymes by Ferguson plot analysis. The molecular weight of the enzyme is 27,000 while its isoelectric point is greater than pH 9.0. The N-terminal sequences of PME 1 and PME 2 are SVVTPNAVVADDGVFXFKTG. Both PME 1 and PME 2 showed optimum activities at pH 8.0 and 35°C. The average K m s of PME 1 and PME 2 are 0.0071 and 0.0166 g/liter pectin respectively, while the corresponding average V maxs are 741 and 800 μmol methanol/min/mg protein, respectively. Papaya pectin methylesterase is activated by cations, but the effect is more pronounced for divalent than monovalent cations. Inhibition studies showed that sucrose is a noncompetitive inhibitor while p-chloromercuribenzoic acid has no significant effect on its activity.

Changes during ripening of papaya fruit in different storage systems

The ripening stages of the papaya fruit can only be precisely determined by using many parameters on the same fruit. Eight physico-chemical measurements (water content, pH, °Brix, acidity, sugar content, neutral detergent fibre, proteins and minerals) have been obtained for Carica papaya Solo grown in the Canary Islands, during 1 month under different storage conditions (1: room temperature, 25°C; 2: domestic refrigerator, 10°C; 3: control chamber, 12°C and 92% H 2O). Analysis of variance, correlation analysis and principal component analysis (PCA) were used to characterize the ripening process of this fruit. The statistical analysis indicates that pH. and °Brix are indices of the ripening of the papaya fruit.

Effect of feeding Carica papaya (Papita) fruits on blood lipid profile of albino rabbits

Effect of feeding ripe and unripe papaya fruit pulps were investigated on blood lipid profile of normal male adult albino rabbits by giving them pulps separately at the dose of 15 and 30g per day along with standard diet over a period of six weeks. As compared to controls both fruit pulps resulted in highly significant (p<0.001) and consistent lowering of serum cholesterol, low density lipoprotein cholesterol and triglycerides and elevation in phospholipids and high density lipoprotein cholesterol levels at 1,3 and 6 weeks of fruit pulp feeding indicating a dose dependent effect. Observations clearly support medicinal value ofC. Papaya in the management of atherosclerosis, fatty liver, ischaemic changes and consequential myocardial infarction.

Effect of Ripeness and Location of Papaya Fruits on the Parasitization Rates of Oriental Fruit Fly and Melon Fly (Diptera: Tephritidae) by Braconid (Hymenoptera) Parasitoids

Parasitization rates of eggs of oriental fruit fly, Dacus dorsalis Hendel, by Biosteres arisanus (Sonan), and larvae of melon fly, Dacus cucurbitae Coquillett. by Psytallia fletcheri (Silvestri) in mature green to fully ripe papaya fruits on trees and in fully ripe fruits on the ground was studied. Parasitization of oriental fruit fly eggs by B. arisanus was greater in fully ripe fruits than in one-quarter to half-ripe fruits on trees; B. arisanus never parasitized oriental fruit fly eggs in mature green to color-break fruits. No difference was observed in the density of emergent B. arisanus adults from oriental fruit fly pupae recovered from fully ripe fruits on trees and on the ground. Parasitization of melon fly larvae by P. fletcheri was observed in only one fully ripe, fallen fruit. Results in relation to the effect of host plants on the foraging behavior of adult parasitoids and to the biological control of oriental fruit fly and melon fly in an agricultural ecosystem were discussed.