A qualitative analysis of mango (&lt;em&gt;Mangifera indica&lt;/em&gt; L.) latex and anatomy of latex canals

K O L C Karunanayake

doi:10.4038/jsc.v10i2.21

Abstract

Mango latex is important in the mango industry due to its antimicrobial properties and the burn it causes on the harvested fruits. The present study is a qualitative investigation of the composition of mango latex, the variation in latex volumes among three selected local mango cultivars and the anatomy of fruit pedicel and peel that contain the latex canal system. According to the biochemical tests, the aqueous phase of mango latex contained moderate amounts of carbohydrates and reducing sugars which are disaccharides. Starch and keto-sugars were absent. Small amounts of phenols and proteins were present but not amino acids. Gallotannin antifungal compounds were absent in mango latex while resorcinols were present mostly in the non-aqueous phase of mango latex. The latex canal diameters were larger in a transvers section at and below the abscission zone of fruit pedicel closer to the fruit when compared to that further from the fruit. Cultivars such as ‘Karutha colomban’ and ‘Rata’ more resistant to anthracnose contained higher volumes of the non-aqueous phase of mango latex reported to contain antifungal resorcinols while anthracnose susceptible ‘Willard’ contains less of the non-aqueous phase and more of the aqueous phase of latex.

Highlights

In the mature mango fruit, latex canals occur both in the exocarp and the outer region of the mesocarp
Latex spurts out and is frequently deposited on the surface of the same or neighboring fruits causing sap injury, making the fruit skin brown and un-attractive [3].The non-aqueous phase of mango latex contains antimicrobial substance [5, 6].Mango latex contains antifungal resorcinols in the nonaqueous phase and [6] chitinase enzyme in the aqueous phase [7] that play a defensive role against postharvest pathogens
Since mango latex contains antimicrobial substances, substances that give the typical raw mango aroma and substances that cause sap burn injury to the fruit, it seems worthy to study the properties of latex

Summary

INTRODUCTION

In the mature mango fruit, latex canals occur both in the exocarp and the outer region of the mesocarp. These ducts/canals form a network throughout the fruit, including its base. The non-aqueous phase of Indian mango cultivars contains mostly monoterpenes [2]. The aqueous phase of Indian mango cultivars contains little amounts of protein, which are mostly enzymes. Protein and carbohydrate content in mango latex decrease as fruits mature [3]. Since mango latex contains antimicrobial substances, substances that give the typical raw mango aroma and substances that cause sap burn injury to the fruit, it seems worthy to study the properties of latex. This study was carried out as a preliminary investigation, as no previous studies are available on the composition, antifungal properties and distribution of latex canals of mango cultivars in Sir Lanka

Distribution of latex canals within the stalk and peel of mango fruit

Collection of the aqueous phase of mango latex for biochemical tests

Volumes of latex in selected local mango cultivars

Total soluble solids content in the aqueous phase of mango latex

Antifungal activity in mango latex