Their reactions cause a release of carboxylic acids and galacturonic acids
. This leads to a decrease in puree viscosity and pH of juice, but a significant increase in titratable acidity and juice yield (Tadakittisarn et al., 2007).
Pectic substances were characterized by titration of acidic functions of galacturonic acid
before and after saponification.
Utilisation of bipolar electrodialysis for recovery of galacturonic acid
According to Evangelista, Chitarra, and Chitarra (2000), PG catalyzes the hydrolysis of the [beta]-1,4 bonds between the galacturonic acid
residues in the pectin chain and consequently promotes the reduction of firmness in the fruits.
The uronic acid contents were determined using the m-hydroxydiphenyl method with galacturonic acid
as the standard.
The soluble and total pectin contents were 0.17-0.18 and 0.95% galacturonic acid
100 [g.sup.-1] pulp, respectively.
Glycerol, mannitol and sorbitol concentrations increased significantly in infected berries along with free galacturonic acid
, arabinose, galactose, rhamnose, mannose and xylose.
A standard curve was established with different concentrations (0.2, 0.5, 1, 5, and 10 mg/mL) of mixed standard solutions including glucose (Glu), mannose (Man), galactose (Gal), L-arabinose (Ara), [alpha]-L-rhamnose (Rha), fructose (Fru), galacturonic acid
(Gal acid), and glucuronic acid (Glu acid).
The total uronic acid content of pectin fraction was determined by an automated m-hydroxydiphenyl assay using an autoanalyser Skalar [San.sup.++] system (Skalar Analytical BV, Breda, Netherlands) controlled by FlowAccessV3 software (version 3.1.18), and galacturonic acid
(12.5-100.0 [micro]g/mL) was used for calibration curve construction .
Pectin is a kind of cell wall polysaccharide that mainly consists of a linear chain of covalently linked galacturonic acid
. Various amounts of neutral sugars are attached to these regions as side chains, including fucose, rhamnose, arabinose, galactose, and xylose.
For the analysis of dietary fibre, pepsin was obtained from Merck (Darmstadt, Germany), pancreatin from Fluka (Sigma-Aldrich), and galacturonic acid
, chloroform, monohydrate and myo-inositol (internal standard) from Sigma Chemical Co.
The digestion of the samples with pectinase led to the release of free galacturonic acid
and insoluble polysaccharides.