Anatomical and physiological studies of persimmon fruits (Diospyros kaki L.) on the tannin accumulation and deastringency processes

Author(s)

Magda Andréia Tessmer

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2014-04-25

Examining board members

Beatriz Appezzato da Gloria; Angelo Pedro Jacomino; Giuseppina Pace Pereira Lima; Ben hur Mattiuz; Marilia Contin Ventrella

• Advisor: Beatriz Appezzato da Gloria; Ricardo Alfredo Kluge

Abstract

This study purpose was the comparison between the physiological and structural changes of astringent persimmons (PVA) and non-astringent (PCNA) from the start of development to advanced maturation. Furthermore, postharvest treatments of deastringency were made and tested for different storage conditions at \"Giombo\". This work is presented in six Chapters, and the last five chapters refer to experiments conducted between 2010 and 2013. Chapter 2 describes the development of persimmons \"Giombo\" (PVA) and \"Fuyu\" (PCNA). It was observed that the differentiation of tannin cells and the accumulation process of tannin in vacuole did not vary among cultivars, but there was a significant difference in the density of tannin cells and soluble tannins. Chapter 3 presents the comparative study of seven stages of ripening persimmons \"Giombo\" and \"Rojo Brillante\" (PVA), and \"Fuyu\" and \"Hana Fuyu\" (PCNA). Reduction of mesocarp firmness of both groups of persimmons is related to maturation advance and not due to natural loss of astringency. Antioxidant capacity and total soluble solids of persimmons from both groups indicate a possible relation with the natural loss of astringency, once only PVA cultivars showed astringency decrease during ripening. The tannins delimited in tannin cells for the test with vanillin hydrochloric, and the contents of the vacuole with alveolus aspect observed by Cryo-SEM may be related to tannin polymerization during fruit ripening. In the experiment described in Chapter 4, persimmons \"Giombo\" from late and early harvest were submitted to different periods of exposure to ethanol (1.70 mL kg-1). Fruits obtained at late harvest presented index astringency and soluble tannin content suitable for consumption within 24 hours, while early harvest in 36 hours. Chapter 5 regards to the influence of pectins in astringency removal of persimmons \"Giombo\" under cold storage at 5?C. Results indicated no interaction of pectins with soluble tannins astringency removal, because even with the reduction of flesh firmness and increased solubilization of pectins, the index of astringency and soluble tannins remained high in fruits not deastringenced. The influence of temperature (1, 5 and 10?C) storage on the quality of persimmons \"Giombo\" treated or not with 1-MCP is presented in Chapter 6. Better quality was observed when the fruits were deastringenced, treated with 1-MCP and stored at 1°C for up to 35 days. Fruits that had been only deastringenced had bigger changes on their mesocarp cellular structure and firmness at all temperatures experimented. The temperature of 5°C may be responsible for making fruitsmore susceptible to chilling injury with structural changes and a drastic reduction of the firmness. (AU)

• FAPESP's process: 10/16392-7 - Anatomical and physiological studies of persimmon fruits (Diospyros kaki L.) on the accumulation of tannins and processes to remove astringency
• Grantee: Magda Andréia Tessmer
• Support Opportunities: Scholarships in Brazil - Doctorate