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Nutritional and Medicinal Values of Papaya (Carica papaya L.) Chapter 11
Abstract
Papaya (Carica papaya L.) is a deliciously sweet tropical fruit with musky undertones and a distinctive pleasant aroma. It was first cultivated in Mexico several centuries ago but is currently being cultivated in most of the tropical countries. Everything in papaya plant such as roots, leaves, peel, latex, flower, fruit and seeds have their nutritional and medicinal significance. Papaya can be used as a food, a cooking aid, and in medicine. Papaya is considered as a low calorie nutrient dense fruit. The fresh fruit is commonly used as a carminative, stomachic, diuretic and antiseptic in many parts of the world. The nutrients and phytochemicals contained in papaya help in digestion, reduce inflammation, support the functioning of cardiovascular, immune and digestive systems and may also help in prevention of colon, lung and prostate cancers. Overall, the papaya can act as a detoxifier, activator of metabolism, rejuvenating the body and in the maintenance of body's homeostasis because it is rich in antioxidants, B vitamins, folate and pantothenic acid, and potassium and magnesium as well as fiber. Because of its high vitamin A and carotenoids contents, it can help in preventing the cataract and age-related macular degeneration. Papaya pastes can be used externally as a treatment for skin wounds and burns. This paper discusses the nutritional and medicinal value of papaya (Carica papaya L.) and its relationship to human health.
Recent studies indicated that regular consumption of antioxidant-rich foods reduces cellular oxidative stress and protects against health-related problems. This study aimed to assess the in vitro antioxidant properties of the papaya epicarp extract against hydrogen peroxide (H(2)O(2))-induced oxidative stress in human SH-SY5Y neuronal cells. Our study revealed that papaya epicarp extract acted as a potent free radical scavenger and provided neuroprotection against H(2)O(2)-induced oxidative stress. Papaya epicarp extract ameliorated glutathione depletion, restored total antioxidant capacity and augmented the inhibition of antioxidant enzymes (catalase, glutathione peroxidases and superoxide dismutase). In conclusion, papaya epicarp extract can be used as a functional dietary ingredient that might help in reducing the neurological health problems associated with various oxidative stress insults.
Vitamin A deficiency is a disorder of public health importance in Sri Lanka. A recent national survey revealed that 36% of preschool children in Sri Lanka have vitamin A deficiency (serum retinol <0.2 µg ml−1). In view of its well-established association with child morbidity and mortality, this is a reason for concern. One of the main fruits which has been recommended for prevention of vitamin A deficiency in Sri Lanka is papaya (Carica papaya L). In this study the carotenoid profiles of yellow- and red-fleshed papaya were analysed by medium-pressure liquid chromatography (MPLC) and UV-vis spectrophotometry. A section of yellow-fleshed papaya showed small carotenoid globules dispersed all over the cell, whereas in red-fleshed papaya the carotenoids were accumulated in one large globule. The major carotenoids of yellow-fleshed papaya were the provitamin A carotenoids β-carotene (1.4 ± 0.4 µg g−1 dry weight (DW)) and β-cryptoxanthin (15.4 ± 3.3 µg g−1 DW) and the non-provitamin A carotenoid ζ-carotene (15.1 ± 3.4 µg g−1 DW), corresponding theoretically to 1516 ± 342 µg kg−1 DW mean retinol equivalent (RE). Red-fleshed papaya contained the provitamin A carotenoids β-carotene (7.0 ± 0.7 µg g−1 DW), β-cryptoxanthin (16.9 ± 2.9 µg g−1 DW) and β-carotene-5,6-epoxide (2.9 ± 0.6 µg g−1 DW), and the non-provitamin A carotenoids lycopene (11.5 ± 1.8 µg g−1 DW) and ζ-carotene (9.9 ± 1.1 µg g−1 DW), corresponding theoretically to 2815 ± 305 µg kg−1 DW mean RE. Thus the carotenoid profile and organisation of carotenoids in the cell differ in the two varieties of papaya. This study demonstrates that carotenoids can be successfully separated, identified and quantified using the novel technique of MPLC. Copyright © 2003 Society of Chemical Industry
The storage of shea butter waxed and unwaxed pawpaw Carica papaya fruit at two storage temperatures was investigated with respect to the antinutrient (phytate, oxalate, condensed tannin (CT) and hydrolysable tannin (HT)) and antioxidant (vitamin C, tocopherol, total phenol and carotenoid) properties. Freshly harvested just ripe pawpaw C. papaya fruit was divided into two lots; one was waxed with shea butter, the other was not waxed and they were stored at room temperature (27 ± 1°C) and refrigeration temperature (10 ± 1°C) for 8 days. The antinutrients and antioxidants were subsequently determined. The result of the study shows that the antinutrients decreased significantly (P < 0.05) as the storage period increased in both storage temperature regimes; phytate (1.22 to 0.34%), oxalate (0.45 to 0.13%), hydrolysable tannin (0.021 to 0.000%) and condensed tannin (0.062 to 0.006%). The value of antinutrients of unwaxed sample was lower than that of waxed sample though there was no significant difference (p > 0.05) in the CT and HT. Antioxidants also decreased significantly (P < 0.05) as the storage period increased. Waxed pawpaw recorded the highest antioxidant content at the end of the storage period which was significantly (P < 0.05) higher than the unwaxed in the two storage temperatures.
The volatiles of fresh mountain papaya (Carica candamarcensis, syn. C. pubescens Lenne et Koch) were separated from the fruit pulp by high-vacuum distillation and subsequent solvent extraction (pentane-dichloromethane, 2:1). In three fractions obtained by preseparation of the concentrated extract with adsorption chromatography on silica gel (pentane-diethyl ether gradient) the volatiles were analyzed by capillary gas chromatography and combined capillary gas chromatography-mass spectrometry. From 199 volatiles identified by these methods 103 compounds showed structures of esters, among them some uncommon substances such as, e.g., ethyl 3-mercaptopropanoate, ethyl 4-hydroxy- and 4-acetoxybutanoate, methyl (E)-2- and (E)-3-octenoate, butyl and hexyl (E)-2-butenoate, and butyl 2-furoate and butyl nicotinoate were found.
To facilitate the growth of a commercial pawpaw (Asimina triloba) industry, several problems with harvest and postharvest handling of fruit need to be resolved. Pawpaw fruit ripening is characterized by an increase in soluble solids content, fl esh softening, increased volatile production, and a loss of green color intensity. Within 3 days after harvest, ethylene and respiratory climacteric peaks are clearly evident. Softening of fruit is due to the action of at least four enzymes, with the softening proceeding from the surface to the interior tissue. Fruit on a single tree can ripen over a 2-week period, creating labor prob- lems. When immature fruit is harvested it does not ripen, even if treated with ethephon at 1000 mg·L -1 (ppm), but the use of commercially available growth regulators both pre- and postharvest warrants further study. Fruit soften very rapidly at room temperature after harvest and have a 2-to 4-day shelf life. How- ever, we have stored pawpaw fruit for 1 month at 4 °C (39.2 °F) with little change in fruit fi rmness and fruit apparently continue normal ripening upon removal to ambient temperature. The optimum tempera- ture and duration for holding fruit will need to be determined. Further extension in pawpaw storage life may be feasible with controlled or modifi ed atmosphere storage. Although there are a number of practical problems with pawpaw harvest and postharvest storage that need to be addressed, we hope to develop recommendations for harvest and handling of fruit in the near future.
BACKGROUND: Papaya ( Carica papaya L.) production is limited by over 20 viruses, the most damaging of which is papaya ringspot virus (PRSV). Owing to a lack of suitable PRSV‐resistant sources in Carica germplasm, transgenic resistance using the coat protein ( cp ) gene of a local PRSV strain is being developed to manage the disease in Jamaica. For assurance of food safety, the nutritional and antinutritional composition of transgenic papayas during ripening was compared with that of unmodified control samples.
RESULTS: Mature unripe fruits of transgenic and non‐transgenic papayas were repeatedly harvested and stored at room temperature for 1 week periods, during which random samples were assessed. With the exception of one transgenic line, no significant differences ( P > 0.05) were observed in selected nutrients and antinutrients between the control and test samples at three stages of maturity, although a few random variations were noted.
CONCLUSION: Transformation with viral cp gene and two marker genes did not produce any major unintended alterations in either the nutritional or the antinutritional composition of transgenic papayas. These findings must be compared with other physicochemical and safety assessments to provide a scientific basis for concluding substantial equivalence with conventional papayas available on the market in Jamaica. Copyright © 2008 Society of Chemical Industry
Transgenic papaya (Carica papaya L.) was produced with the introduction of replicase (rep) gene for resistance to papaya ringspot virus (PRSV). In order to investigate the potential unintended compositional changes in transgenic papaya, profiles of volatile organic compounds (VOCs), sugar/polyals, organic acids, carotenoids and alkaloids in transgenic and non-transgenic papaya were obtained respectively by HPLC, GC–MS and LC–MS, and compared mutually by multivariate statistical methods, including principal component analysis (PCA) and similarity analysis method. Results showed that the composition in transgenic papayas exhibited great similarity to non-transgenic counterparts for measured components. The contents of important nutrients of β-carotene and vitamin C and two natural toxicants, including benzyl isothiocyanate (BITC) and carpaine, were compared by analysis of variance (ANOVA). The results also showed that content was similar between transgenic papayas and non-transgenic counterparts for these components. The variation of composition in papaya caused by genetic effect was slight during two harvesting times during our work. It is hoped that this study could provide some reference value for a safety evaluation of transgenic papaya from the compositional point of view, and could also propose a method for discrimination of transgenic food from non-transgenic counterparts.
Papaya does not sufficiently maintain desired fresh fruit quality when shipped long distances due to an easily bruised soft skin and a short shelf life. This leads to both a large supply of pulp from unsightly fruit that is never shipped and low sales due to blemished fruit. Unfortunately, traditional preservation methods (pasteurisation) negatively alter papaya’s fresh flavour. Thus to effectively utilise available papaya pulp, processing requires an approach that enables retention of papaya’s natural flavours without excessive heat. Papaya fruit (Carica papaya L., var.’s Rainbow (yellow-fleshed) and SunUp (red-fleshed)) were pulped, diluted, and processed with mild heat (80 °C, 5 min), irradiation (5 kGy or 7.5 kGy) or combinations of both. Irradiation resulted in a significant reduction in ascorbic acid content. Mild heat treatment significantly reduced pectinesterase activity and microbiological viability. Irradiation followed by heat further enhanced destruction of Listeria innocua and Clostridium sporogenes and retained the flavour and a nutritional profile closest to untreated controls. The product was microbiologically safe with acceptable enzyme levels and would be shippable under refrigeration.
Benzylglucosinolate was detected in all of the tissues of Carica papaya (pawpaw). No other glucosinolates were detected in any tissue of C. papaya. Previous suggestions that indolyl-3-methylglucosinolate might be present could not be confirmed. The highest concentrations of benzylglucosinolate were found in the youngest leaves, but the compound was also detected in leaf stalks, stem internodes and roots. The presence of benzylglucosinolate in shoots was developmentally regulated—high concentrations in young tissues, declining as they matured. The exception was the stem internodes which maintained relatively constant concentrations. Tap roots had higher glucosinolate content than young roots. Cyanide, specifically released from cyanogenic glucosides, was detected in leaves and roots of C. papaya. Cyanide was not detected in comparable glucosinolate-containing tissues from Brassica napus (oilseed rape). The cyanide concentrations were highest in the tap roots and young leaves of C. papaya, suggesting that cyanogenic glucoside accumulation was also developmentally regulated. NADPH-dependent l-phenylalanine monooxygenase activity was detected in leaves of C. papaya catalysing the oxidative decarboxylation of l-phenylalanine. This monooxygenase activity was restricted to leaves, and could not be detected in any other tissues. No other monooxygenase activities were detected, in any tissues, active with any of the amino acids tested. Activity was highest in the young leaves and declined as leaves expanded and matured. This enzyme was significantly inhibited by several cytochrome P450 inhibitors, and to a lesser extent by the flavoprotein-specific inhibitor diphenylene iodonium. No other aromatic amino acids tested were either substrates or inhibitors of this enzyme, suggesting a high degree of substrate specificity. Two other key enzymes involved in the metabolism of l-Phe and l-Phe-derived compounds, phenylalanine-ammonia lyase and peroxidase, were found to be similarly developmentally regulated in tissues of C. papaya. Activities were highest in young tissues and declined as the tissues matured.