Composition of pectic polysaccharides in a Portuguese apple (Malus domestica Borkh. cv Bravo de Esmolfe)

Ana S Silva,Luís F Guido,Manuel A Coimbra,Claudia Nunes

doi:10.1590/0103-9016-2013-0333

Abstract

Malus domestica Borkh. cv Bravo de Esmolfe is a typical Portuguese apple cultivar classified as Protected Designation and Origin (PDO). It is a traditional product produced under strict conditions and labelled with a specific law protected designation. This cultivar presents quite good sweetness and flavor. The monosaccharide composition of the pectic polysaccharides from this traditional apple is herein reported for the first time. Based on the molar ratios obtained from the sugar composition, the presumable pectin structure could be inferred. The cell-wall polysaccharides present in the alcohol-insoluble residue (AIR) of unpeeled BE apple were sequentially fractionated. In addition, pectic material was also extracted by citric acid treatment prior to heat extraction at acidic pH. The water soluble pectin, imidazole soluble pectin and sodium carbonate soluble pectin account for 44, 16 and 40 % of the AIR, respectively. The pectic polysaccharides extracted in the presence of citric acid had lower galacturonic acid content and higher neutral sugars content. The homogalacturonan (HG) and less-substituted rhamnogalacturonan (RG) domains are extracted first. Pectin treated with citric acid has been shown to contain more substituted polymers, especially RG-I. In addition, the relatively higher Xylose/Galacturonic acid ratio found in the citric acid extract demonstrates that the xylogalacturonan (XG) domain presumably is present in the pectic material of the unpeeled BE apple.

Highlights

The relatively higher Xylose/Galacturonic acid ratio found in the citric acid extract demonstrates that the xylogalacturonan (XG) domain presumably is present in the pectic material of the unpeeled Bravo de Esmolfe (BE) apple
Malus domestica Borkh. cv Bravo de Esmolfe (BE) is a typical Portuguese apple cultivar classified as Protected Designation and Origin (PDO) since 1994, which means that it corresponds to a traditional product produced under strict conditions and labeled with a specific law protected designation
Characterization of the pectic polysaccharides extracted from BE apple Both the neutral sugar content and the uronic acid content have increased (p < 0.01) with the prehydrolysis with acid (Figure 1)

Summary

Introduction

Malus domestica Borkh. cv Bravo de Esmolfe (BE) is a typical Portuguese apple cultivar classified as Protected Designation and Origin (PDO) since 1994, which means that it corresponds to a traditional product produced under strict conditions and labeled with a specific law protected designation. Cv Bravo de Esmolfe (BE) is a typical Portuguese apple cultivar classified as Protected Designation and Origin (PDO) since 1994, which means that it corresponds to a traditional product produced under strict conditions and labeled with a specific law protected designation This variety is produced in a restricted and small inland region in northern Portugal, corresponding to a production of ca. Pectic polysaccharides comprise associated polysaccharides, such as homogalacturonans (HG), xylogalacturonans (XG), type I rhamnogalacturonans (RG-I), type II rhamnogalacturonans (RG-II), arabinans, and arabinogalactans (Caffall and Mohnen, 2009; Mohnen, 2008; Voragen et al, 2009; Harholt et al, 2010) Pectic substances, such as water-soluble dietary fibers, are not metabolized by endogenous digestive enzymes during passage through the human digestive tract, but they are fermented by the microflora present in the colon (Gulfi et al, 2006; Khondkar et al, 2009). A pectic fraction isolated from guarana powder has recently exhibited antioxidant activity (Dalonso and Petkowicz, 2012), probably contributing to the positive biological effects of guarana

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