Título da Tese: Estudo de pós-colheita de pitaia (Hylocereus undatus Haw.): avaliação da atividade antifúngica de óleos essenciais, caracterização de micotoxinas e uso da casca para a produção de geleia

Orientador: Prof. Dr. Benício Alves de Abreu Filho

 Data da Defesa: 18/07/207



Hylocereus undatus (Haw.), dragon fruit, exotic fruit and introduced in Brazil a short time ago, has beneficial health properties and high antioxidant power. However, dragon fruits are susceptible to attack by deteriorating microorganisms, already cited in literature, which lead to poor fruit quality and shorter shelf life. From the need to understand the contamination of fungi responsible for deterioration postharvest of H. undatus fruits, their development, and possible inhibition through natural compounds, this study allowed to isolate and identify the fungus that causes postharvest disease in dragon fruits (Hylocereus undatus Haw.). The in vitro and in vivo antifungal activity of some essential oils were evaluated against the fungus. Morphophysiological and molecular identification confirmed the fungus was Alternaria alternata. The essential oils of Cinnamomum zeylanicum, Cymbopogon flexuosus, Eucalyptus globulus, Eugenia caryophyllus, and Rosmarinus officinalis were evaluated by the microdilution broth technique, disc diffusion, scanning electron microscopy, and fluorescence microscopy. Evaluation of the composition of the essential oils by gas chromatography/mass spectrometry revealed substantial amounts of eugenol as a major constituent of E. caryophyllus and C. zeylanicum (90.50% and 80.70%, respectively). The other essential oils of R. officinalis contained α-pinene (24.50%) and camphor (22.00%) as major components. E. globulus contained 1,8-cineole (78.90%). C. flexuosus contained neral (35.10%) and geranial (42.60%). C. zeylanicum and E. caryophyllus were the most active against the isolated fungi at minimum inhibitory concentrations of 250 and 500 μg/ml, respectively, causing morphological changes in the hyphae.The in vivo assay indicated that the fruits that were treated with E. caryophyllus at concentrations of 500 and 1000 μg/ml exhibited a 31% reduction of mycelial growth compared with the control. These results suggest that the essential oils of C. zeylanicum and E. caryophyllus are active against A. alternata both in vitro and in vivo, which may be promising for control of the microorganism. It is known that this fungus, A. alternata is responsible for producing mycotoxins in several cultures, the importance in characterizing and identifying possible formation of these secondary metabolites in this isolated species and to determine the same in vitro and in vivo in the fruits of H. undatus (Haw.) were evaluated. Although H. undatus (Haw.) is a crop susceptible to attack by microorganisms such as A. alternata, there are no reports on the production of mycotoxins in this fruit. The objective of the present study was to identify mycotoxins produced by A. alternata previously isolated from H. undatus (Haw.) fruit, and A. alternata ATCC 46582, in vitro and in vivo. Compounds were identified using liquid chromatography-mass spectrometry (LC-MS/MS). Alternariol (AOH), alternariol monomethyl ether (AME), tentoxin (TEN) and altertoxins (ATX) I, II, III were detected in vitro for A. alternata, and ATX I and ATX II for the reference strain, A. alternata ATCC 46582. Mycotoxins characteristics of A. alternata were not detected in vivo in the fruit. The use of LC-MS/MS facilitated rapid and efficient mycotoxin identification, contributing significantly to the evaluation of food safety. It is known that the fruits of H. undatus are seasonal, and present a short shelf life, as well as factors that contribute to their rapid deterioration, such as deteriorating fungi, practices and production of products from this fruit are important to make the fruit available throughout the year, in the form of a byproduct. The processing of food in the industries and the in natura consumption generate residues that entail with the increase of organic material to the environment. Currently, the use of food growns frequently, and 10 contributes to increase the nutritional value of processed foods. Dragon fruit (H. undatus Haw.), presents pectin, fructose, sucrose and oligosaccharides, as well as antioxidant compounds in the composition. The objective of this study was to develop jam formulations with pulp and peel from the dragon fruit, to evaluate nutritional compounds, texture properties: sensorial, instrumental, physical, chemical, biochemical and microbiological analyzes of the final product. The fruits were selected, sanitized, pulped, ground and the formulations with different concentrations of pulp and peel were developed and evaluated. The jam formulations presented within the conformities and current legislation, before the microbiological evaluation. Increased peel concentration in the jam formulations contributed to better consumer acceptance, increased concentration of phenolic compounds and antioxidants, as well as favoring an acceptable and pleasant texture. The addition of peel made possible the integral use of the food, besides favoring the enrichment of the byproduct with compounds of interest for the health of consumers, as antioxidants. Key words: Hylocereus undatus (Haw.), Alternaria alternata, micotoxins, jam.


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