Effect of extraction conditions on the yield and purity of apple pomace pectin precipitated but not washed by alcohol.
A study of the influence of extraction conditions (pH: 1.5 to 2; temperature: 80 to 90 degrees C; extraction time: 1 to 3 h), on the yield and purity of apple pomace pectin without elimination of impurities by alcohol washing was carried out. The alcohol precipitate yields varied from 2.9% to 8.9% depending on the pH. At pH 1.5, these yields were higher than those obtained at pH 2 contrary to the galacturonic acid purity (%w/w). Compounds other than pectins were solubilized from the cell walls of apple pomace at pH 1.5, and they were precipitated with alcohol. The apple pectins obtained from the different extraction procedures were highly methylated (54.5% to 79.5%), especially when the conditions (temperature, pH) were drastic. Similar conclusions can be drawn for the neutral sugar content that decreased at pH 1.5 (arabinose, xylose, and galactose) or at the highest temperatures and extraction times (arabinose and galactose). The phenomenon of demethylation and pectin degradation of neutral sugars chains can be observed at acid pH, and for long extraction times. The presence of high quantities of mannose or fructose, glucose, and xylose in the alcohol precipitate showed that pectin precipitation with ethanol was not specific.
Garna
Haikel
H
Unité de Chimie Biologique Industrielle, Faculté Univ. des Sciences Agronomiques de Gembloux, Passage des Déportés, 2 -B-5030 Gembloux, Belgium. haikel_1999@yahoo.fr
Mabon
Nicolas
N
Robert
Christelle
C
Cornet
Charlotte
C
Nott
Katherine
K
Legros
Hervé
H
Wathelet
Bernard
B
Paquot
Michel
M
D000438:Alcohols / Q000737:chemistry*; D000704:Analysis of Variance; D002241:Carbohydrates / Q000032:analysis*; D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D027845:Malus / Q000737:chemistry; D008745:Methylation; D010368:Pectins / Q000737:chemistry* / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D012995:Solubility; D013696:Temperature; D013997:Time Factors
D000438:Alcohols; D002241:Carbohydrates; D010368:Pectins