ABSTRACT
RESUMEN La papaya es una fruta climatérica altamente perecedera. La antracnosis, enfermedad provocada por hongos, es una de las principales causas de pérdida poscosecha. La actividad de extractos vegetales ha permitido la inhibición del desarrollo de microorganismos, en particular se ha reportado la actividad antifúngica de aceites esenciales. El objetivo de la presente investigación fue evaluar el efecto de un recubrimiento biodegradable a base de quitosano con aceite esencial de cítricos, aplicado en etapa poscosecha, en las propiedades físicoquímicas, fisiológicas e inhibición del crecimiento del hongo Colletotrichum gloeosporioides en frutos de papaya (Carica papaya L.). El recubrimiento se preparó con quitosano, glicerol, ácido acético, aceite esencial de Citrus reticulata (0.5 %, 1.0 % y 1.5 %) y Tween® 80. La solución se aplicó con una brocha en la epidermis de los frutos de papaya y se almacenaron a temperatura ambiente (24 °C ± 2 °C) por 10 d, junto con los frutos testigo. Las variables evaluadas en los frutos fueron color, pH, sólidos solubles totales (SST), firmeza, pérdida de peso, producción de CO2, de etileno y daño por antracnosis. Se utilizó un modelo estadístico completamente al azar. Los datos se sometieron al análisis de varianza (ANOVA) y comparación de medias por la prueba de Tukey (P < 0.05). El recubrimiento aplicado retrasó el cambio de color de la epidermis de los frutos de papaya, la pérdida de peso, firmeza y SST respecto a los frutos testigo. Los cambios estuvieron asociados a la modificación de la tasa de respiración y de producción de etileno de los frutos con recubrimiento. La matriz del quitosano conteniendo aceites escenciales, usada como recubrimiento, mejoró significativamente la vida de anaquel de la papaya y disminuyó más del 80 % el daño por antracnosis.
ABSTRACT Papaya is a highly perishable climacteric fruit. Anthracnose, a disease provoked by fungus, is one of the main causes of postharvest losses. The activity of plant extracts has allowed the inhibition of the development of microorganisms; in particular, the antifungal activity of essential oils has been reported. The aim of this research was to evaluate the effect of a biodegradable antifungal coating based on chitosan with citrus essential oil in the physicochemical and physiological properties and the antifungal activity of postharvest papaya (Carica papaya L.). The coating was prepared with chitosan, glycerol, acetic acid, essential oil of Citrus reticulata (0.5 %, 1.0 % and 1.5 %) and Tween® 80. The solution was applied with a brush to the epidermis of the postharvest papaya fruits and stored at room temperature (24 °C ± 2 °C) for 10 d. The variables evaluated in the fruits were color, pH, °Brix, firmness, weight loss, production of CO2 and ethylene and anthracnose damage. An analysis of variance (ANOVA) was performed under a completely randomized design and a comparison of Tukey means (P < 0.05). The coating applied delayed the color change of the epidermis of the papaya fruits, these maintained the high firmness values with respect to the control fruits. The changes were associated with the modification of the respiration rate and ethylene production of the coated fruits. The chitosan matrix containing essential oils used as a coating significantly improved shelf life of papaya and decreased anthracnose damage by 80 %.
ABSTRACT
Mexico is the world's largest producer, exporter, and consumer of avocados. "Hass" avocado is the most commercialized cultivar, while the native Mexican avocado varieties have been displaced. Thus, studies regarding their chemical and nutraceutical characterization are scarce. We studied the total lipid content, fatty acid profile, carotenoid content, and free radical-scavenging activity of the fruit pulp from 12 accessions of the native Mexican avocado (Persea americana var. drymifolia). The results show that the chemical and nutraceutical characteristics depend on the accession type. The total lipid content ranged from 13.22 to 23.41%. The major saturated fatty acid in all the avocado accessions was palmitic acid (15.54-22.68%). Monounsaturated fatty acids, like oleic (56.58-74.19%), linoleic (5.62-16.85%) and linolenic (0.63-2.85%) acids were the most abundant unsaturated fatty acids in all the native Mexican avocado accessions. The total carotenoid content (1.57 to 7.83 mg eq. of ß-carotene 100 g-1 fresh weight) and the free radical-scavenging activity (7.58-88.62 mMol trolox equivalent 100 g-1 fresh weight) also varied significantly (p < 0.05) among accessions. Native Mexican avocados have a great nutraceutical potential due to their high content of omega-9, omega-6, and omega-3 fatty acids and carotenoids. These compounds have been reported to display antioxidant activities and protect against cardiovascular diseases.
Subject(s)
Persea , Carotenoids , Fatty Acids , Free Radicals , MexicoABSTRACT
Mexican landrace avocados are naturally distributed mainly in high areas of central Mexico, where they have been produced and consumed since pre-Hispanic times. However, trees of these species are being replaced by improved varieties with greater global demand, and many species have been lost due to the destruction of their natural habitats. Many people in Mexico like to consume the pulp and peel of these fruits and have done so since pre-Hispanic times. This is because the peel of Mexican landrace avocados, unlike the peel of Hass avocados, is very thin and flavorful. The peel color may be bluish-purple or dark reddish due to the presence of anthocyanins, which are compounds with antioxidant activity. The objective of this study was to assess the oil and anthocyanin contents and to evaluate the antioxidant activity in fruits of 11 accessions collected from producing-regions of Mexico. The oil content was 16.2 to 32.3 g 100 g-1 in pulp, and the main unsaturated fatty acids were oleic, linoleic and palmitoleic acids, depending on the accession. The anthocyanin contents in peels ranged from 0.64 to 47 mg g-1 fresh weight. The highest antioxidant activity was found in the peel (53.3-307.3 mmol g-1 fresh weight). The results confirm that the pulp and peel of dark-peel Mexican landrace avocados could be important nutraceuticals for humans.
