Zeitschrift für Lebensmittelverarbeitung und -technologie

Abstrakt

Fractionation and Physicochemical Properties of Pectic Substances Extracted from Grapefruit Peels

Huda Abdallah Mohamed and Babiker El Wassila Mohamed

The aim of this work was to extract pectic fractions from grapefruit peels. The Alcohol Insoluble Solids (AIS) were prepared from peels and fractionated sequentially with hot distilled water, ammonium oxalate and hot 0.05 HCl. Water, oxalate and acidextracted peels pectin were obtained and compared in terms of yield, physicochemical properties and neutral sugars. The results showed that the major part of grapefruit peels pectin was extracted in acid fraction. The water soluble fraction gave higher moisture and ash contents and exhibited higher methoxyl content compared to other fractions. The acid soluble fraction afforded higher degree of esterification, anhydrouronic acid, equivalent weight, intrinsic viscosity and molecular weight. Based on degree of estrification and methoxyl content all fractions can be categorized as high methoxyl pectin. The investigation of neutral sugars using TLC showed that all fractions contained similar sugars arabinose, galactose, rhaminose and xylose. Depending on the result obtained it could be concluded that besides material source, pretreatment procedure, temperature, concentration and extractant type the extraction sequence are critical for best extraction conditions and the yield of pectin.