ISSN 0100-2945 DOI: http://dx.doi.org /10.1590/0100-29452021698 Botany and physiology Anatomical characterization of Passiflora cincinnata Mast. fruit subjected to refrigeration Carolina Rodrigues Victor de Carvalho1, Ana Maria Mapeli2, Andreia Barroncas de Oliveira3 Abstract - Passiflora cincinnata is a species of wild passion fruit whose fruit has potential for use by the food industry. In this context, an anatomical study of the pericarp may help in understanding the changes which occur during the postharvest period. The objective of this work was to anatomically characterize the P. cincinnata pericarp, focusing on the structural changes which occur during refrigerated storage. The selected fruits were kept in net-like packaging at 5°C and evaluated every 15 days for a period of 90 days. Pericarp samples were hand cut on these dates for structural description and to detect starch, phenolic compounds, alkaloids, polysaccharides, proteins, lipids and lignin through histochemical tests. Other samples were analyzed by scanning electron microscope. The fruit is composed of three anatomically distinct regions: exocarp, mesocarp and endocarp. The mesocarp stands out for the presence of sclerified cells and the lax parenchyma, which increased its number of layers during the evaluated period. Idioblasts with prismatic crystals, drusen, silica crystals and raphides were identified, but the amounts reduced over time. This reduction and enlargement of the lax parenchyma were the main changes observed in the postharvest period of P. cincinnata pericarps. Index terms: Calcium oxalate crystals; wild passion fruit; postharvest; histochemical tests; silica. Caracterização anatômica do fruto de Passiflora cincinnata Mast. submetido à refrigeração Resumo - Passiflora cincinnataé uma espécie de maracujá silvestre cujo fruto possui potencial de uso pela indústria de alimentos. Neste contexto, o estudo anatômico do pericarpo pode ajudar na compreensão das mudanças que ocorrem durante o período pós-colheita. O objetivo deste trabalho foi caracterizar anatomicamente o pericarpo de P. cincinnata, com enfoque nas mudanças estruturais que ocorrem durante o armazenamento refrigerado. Os frutos selecionados Corresponding author: foram mantidos em embalagens do tipo rede, a 5oC, sendo realizadas avaliações a cada 15 dias, [email protected] por um período de 90 dias. Nessas datas, amostras do pericarpo foram cortadas à mão para Received: August 15, 2020 descrição estrutural e detecção de amido, compostos fenólicos, alcaloides, polissacarídeos, Accepted: February 15, 2021 proteínas, lipídeos e lignina, através dos testes histoquímicos. Outras amostras foram analisadas no microscópio eletrônico de varredura. O fruto é composto por três regiões anatomicamente Copyright: All the contents of this journal, except where otherwise distintas: exocarpo, mesocarpo e endocarpo. O mesocarpo destaca-se pela presença de células noted, is licensed under a Creative esclerificadas e do parênquima laxo, cujo número de camadas aumentou durante o período Commons Attribution License. avaliado. Foram identificados idioblastos com cristais prismáticos, drusas, cristais de sílica e ráfides, cuja quantidade sofreu redução ao longo do tempo. Essa redução e o aumento do parênquima laxo foram as principais mudanças observadas no período pós-colheita do pericarpo de P. cincinnata. Termos para indexação: Cristais de oxalato de cálcio; maracujá silvestre; pós-colheita; testes histoquímicos; sílica. 1Msc. in Enviromental Science. Researcher. Universidade Federal do Oeste da Bahia, Barreiras-Bahia, Brazil. E-mail: [email protected](ORCID 0000-0003-2259-5394) 2PhD in Plant Physiology. Professor at the Universidade Federal do Oeste da Bahia, Barreiras-Bahia, Brazil. E-mail: [email protected]. (ORCID:0000-0002-6028-1989) 3PhD in Botany. Professor at the Universidade Federal do Oeste da Bahia, Barreiras-Bahia, Brazil. E-mail: [email protected](ORCID 0000-0001-5294-2882) 1 2 C. R. V. de Carvalho et al. Introduction is characteristic of Cerrado fruits (ARAÚJO et al., 2008; SILVA et al., 2008; AZOUBEL et al., 2011; OLIVEIRA, Passiflora L. is the largest genus in the Passifloraceae 2014; SIEBRA et al., 2018). family (GURSKI, 2015). It is estimated that it has more However, although there is no information regarding than 500 species (ARAÚJO et al., 2008; MONTERO et the use of P. cincinnata pericarp by the population or by al., 2016), distributed in tropical and subtropical regions the food industry, data already exist which suggest its use (GURSKI, 2015). This genus is known to group species in manufacturing flour which could be used for therapeutic with economic importance, since some are grown as purposes (PITA, 2012). According to Oliveira et al. ornamental plants (DHAWAN et al., 2004; PEIXOTO, (2002), the yellow passion fruit peels (Passiflora edulis 2005), while others are known for their pharmacological f. Flavicarpa) are basically composed of carbohydrates, properties (ZERAIK et al., 2010; COSTA, 2013; proteins and pectins, making it possible to use them in GAZOLA, 2014; ESTEVAM et al., 2017) or for their manufacturing sweets and flour, which already occurs use in the food industry (OLIVEIRA et al., 2002; with the yellow passion fruit pericarp (OLIVEIRA et al., NASCIMENTO et al., 2013; ZERAIK et al., 2010; 2002; ISHIMOTO et al., 2007; SOUZA et al., 2008). It is COSTA, 2013; SOUZA et al., 2008). However, the focus also worth noting that the use of passion fruit peel flour of academic studies is mainly directed to the Passiflora in diets can assist in treating diabetics and dyslipidemics edulis species, known as yellow passion fruit, due to due to its effect on glycemic control and LDL cholesterol commercial demand (SANTOS et al., 2012). control (SOUZA et al., 2008; PITA, 2012). Passiflora cincinnata Mast. is found in this Furthermore, it is worth mentioning that adequate genus, and is a species of wild passion fruit with wide conservation of the fruit in the post-harvest period geographical distribution in the Brazilian territory preserves the organoleptic properties and the nutritional (Alagoas, Bahia, Ceará, Goiás, Mato Grosso, Mato Grosso quality of vegetables, which important aspects for do Sul, Minas Gerais, Pará, Paraíba, Pernambuco, Piauí, the functionality of the food to remain viable after Rio Grande do Norte, Rio de Janeiro, São Paulo and the its processing (MDITSHWA et al., 2017). One of Federal District) and in other South American countries the techniques used in post-harvest conservation is (Argentina, Bolivia, Colombia, Paraguay and Venezuela) refrigeration, which has already been shown to be efficient (CERVI, 1997; GURSKI, 2015). in preserving the physicochemical characteristics of The aforementioned species has several popular passion fruit (CARVALHO, 2019). In this context, an regional names, such as: maracujá-mochila, maracujá- anatomical study of the P. cincinnata pericarp can act do-mato, maracujá-tubarão, maracujá-brabo, maracujá- as a useful tool in understanding both the senescence de-casca- verde, flor-da-paixão, maracujá, maracujá- process of the fruit and the physiological changes which cultivado and maracujá-de-boi (CERVI, 1997; NUNES, occur during the post-harvest period (ROCHA et al., 2002; OLIVEIRA; RUGGIERO, 2005), being described 2010; LIMA et al., 2013), in addition to complementing as a woody vine, generally entirely glabrous, rarely the already-described anatomical data for the pericarp of velvety-hairy, with cylindrical or subangular stem and this species (GURSKI, 2015). simple leaves, 3-5 palmatipartites, dark green on the It is worth remembering that the fruits of the adaxial face and pale on the abaxial face (ARAÚJO, Passiflora species still require further studies since they 2007). It presents pale pink to violet color and blue violet are not completely known or understood, and therefore flowers, corolla with a purple base, lighter bands in the experiments which find useful information to deepen middle and blue-violet in the upper portion (ARAÚJO, the anatomical data of these plants, as well as to identify 2007; GURSKI, 2015); glabrous ovary and berry type patterns and establish relationships between the characters fruit, globose, dark green; containing ovate, cross-linked, and the environment are necessary for understanding foveolated seeds (NUNES, 2002) and with light yellow and preserving these species, including P. cincinnata aryl (GURSKI, 2015). (GURSKI, 2015). Wild species such as P. cincinnata are threatened Thus, the objective of this work was to anatomically due to habitat fragmentation which has been occurring characterize P. cincinnata pericarp stored under in the region in the Northeastern Semi-arid region; refrigeration, focusing on structural changes which occur a fact which can lead to genetic diversity loss of the during its post-harvest period. species, which supports the need for studies aiming at its description and evaluation (ARAÚJO et al., 2008). In addition, despite being a wild species, P. cincinnata fruit is already commercialized for both fresh consumption at local markets and for use in small processed food industries which use the pulp to produce sweets and jellies (etc.), due to its sui generis (unique) flavor which Rev. Bras. Frutic., Jaboticabal, 2021, v. 43, n. 2: (e-698) Anatomical characterization of Passiflora cincinnata Mast. fruit subjected to refrigeration 3 Material and methods The images were recorded using an iPhone 6 cell phone camera manually attached to the photonic Fruit acquisition