title: Comparative study of the cell wall composition of broccoli, carrot, and tomato: structural characterization of the extractable pectins and hemicelluloses.
abstract: This study delivers a comparison of the pectic and hemicellulosic cell wall polysaccharides between the commonly used vegetables broccoli (stem and florets separately), carrot, and tomato. Alcohol-insoluble residues were prepared from the plant sources and sequentially extracted with water, cyclohexane-trans-1,2-diamine tetra-acetic acid, sodium carbonate, and potassium hydroxide solutions, to obtain individual fractions, each containing polysaccharides bound to the cell wall in a specific manner. Structural characterization of the polysaccharide fractions was conducted using colorimetric and chromatographic approaches. Sugar ratios were defined to ameliorate data interpretation. These ratios allowed gaining information concerning polysaccharide structure from sugar composition data. Structural analysis of broccoli revealed organ-specific characteristics: the pectin degree of methoxylation (DM) of stem and florets differed, the sugar composition data inferred differences in polymeric composition. On the other hand, the molar mass (MM) distribution profiles of the polysaccharide fractions were virtually identical for both organs. Carrot root displayed a different MM distribution for the polysaccharides solubilized by potassium hydroxide compared to broccoli and tomato, possibly due to the high contribution of branched pectins to this otherwise hemicellulose-enriched fraction. Tomato fruit showed the pectins with the broadest range in DM, the highest MM, the greatest overall linearity and the lowest extent of branching of rhamnogalacturonan I, pointing to particularly long, linear pectins in tomato compared with the other vegetable organs studied, suggesting possible implications toward functional behavior.
authors.affiliation: Laboratory of Food Technology and Leuven Food Science and Nutrition Research Centre, Department of Microbial and Molecular Systems (M2S), Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, PB 2457, B-3001 Leuven, Belgium.
authors.forename: Ken
authors.initials: K
authors.lastname: Houben
authors.forename: Ruben P
authors.initials: RP
authors.lastname: Jolie
authors.forename: Ilse
authors.initials: I
authors.lastname: Fraeye
authors.forename: Ann M
authors.initials: AM
authors.lastname: Van Loey
authors.forename: Marc E
authors.initials: ME
authors.lastname: Hendrickx
mesh_terms: D001937:Brassica / Q000737:chemistry* / Q000166:cytology; D002236:Carbohydrate Conformation; D002473:Cell Wall / Q000737:chemistry*; D005591:Chemical Fractionation; D018552:Daucus carota / Q000737:chemistry* / Q000166:cytology; D018551:Solanum lycopersicum / Q000737:chemistry* / Q000166:cytology; D010368:Pectins / Q000737:chemistry* / Q000302:isolation & purification*; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D011134:Polysaccharides; C007916:hemicellulose; D010368:Pectins