Evaluation of Carbohydrates in Pukekohe Longkeeper and Grano Cultivars of Allium cepa

Abstract

The storage, soluble, and structural carbohydrates of two onion cultivars, the hard, pungent Pukekohe Longkeeper (PLK) and the softer, milder Houston Grano, were analyzed to determine differences that might be related to their response to sulfur nutrition received during growth as well as their postharvest attributes and end-use suitability. PLK tissue contained 1.37 times more dry matter than Grano and was composed of more fructan and sucrose and less glucose and fructose than Grano [corrected] There were also differences in neutral sugar content, especially galactose, and the amount, size, and content of pectin fractions soluble in chelator and weak alkali. These two onion cultivars differed in their capacity to take up sulfur, but there was no statistical association between sulfur supply and any measured dry matter component.

The Antioxidant Properties of Pectin Fractions Isolated from Vegetables Using a Simulated Gastric Fluid

“…These differences may result from the ultrafiltration procedure used in the present study, which leads to the removal of components with low molecular weight and insoluble fibre. The Mw of the obtained pectins (Table 1) were similar to those of the sodium carbonate-soluble pectins of white cabbage, carrot, and onion obtained in previous studies [32][33][34]. BO-P, DC-P, AC-P, and CA-P were hydrolyzed with 2 M TFA to release the monosaccharides typically present in pectins.…”

“…From this ratio, it was obvious that BO-P and DC-P were most enriched in RG with Rha/GalUA ratios of 0.08-0.09, whereas CA-P contained the most HG regions with a Rha/GalUA ratio of 0.02. Corresponding Rha/GalUA ratios for the pectins of white cabbage [34], carrot [38], onion [32], and sweet pepper [39] have been previously reported. The Gal residue content was higher in the pectin fraction obtained from onion compared to the fractions from other vegetables.…”

Structural and chemical differences in the cell wall regions in relation to scale firmness of three onion (Allium cepa L.) selections at harvest and during storage

“…38 It has been reported that higher concentrations of cellulose were detected in a firm onion cultivar 'Pukekohe Longkeeper' than in a softer 'Houston Grano' bulb. 39 However, there were no differences in cellulose concentrations among the cultivars tested in this experiment. Furthermore, all cultivars experienced a significant decrease in cellulose concentrations between harvest and 4 weeks of storage, but only bulbs from Pegasus and MSU4535B underwent significant softening during the same period.…”

Fructans and major compounds in onion cultivars (Allium cepa)

“…Non-structural and soluble carbohydrates form a substantial part of onion dry matter, mainly as fructooligosaccharides (FOS) and monosaccharides (glucose, fructose and sucrose) (Darbyshire and Henry, 1979;Darbyshire and Henry, 1981;Jaime et al, 2001;O'Donoghue et al, 2004;Susuki and Cutliffe, 1989). The non-digestible carbohydrates have recently been shown to be of particular interest for human health.…”