Submitted to: Biomacro Molecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 12, 2002
Publication Date: May 20, 2003
Citation: Biomacromolecules, V.4, No. 4, 2003. p.880-889. Interpretive Summary: The need to provide new markets for low valued by-products derived from the processing of fruit and to produce raw materials from sustainable and renewable resources has prompted us to search for new and improved methods to extract pectin, a polysaccharide found in orange peels. In this work we show that high quality pectin can be extracted rapidly from a portion of the peel, by steam injection heating under pressure in a dilute acid solution. The rapidity of the method and the quality of the pectin produced allows the use of orange peel and pulp as a source of pectin. This research should be of help to fruit growers and processors by increasing the demand and value of their by-products without increasing the cost of the basic commodity to the consumer.
Technical Abstract: Pectin was acid extracted from orange albedo by steam injection heating under pressure. Extraction times ranged from 2 to 6 minutes at a pressure of about 15 psi. Solubilized pectin was characterized by HPSEC with online light scattering and viscosity detection. Molar mass (M), radius of gyration (Rg) and intinsic viscosity ([IV]) all decreased with increasing extraction time when heating temperature was 120 degree C. At heating times of 3.0 minutes, Mw ranged from 4.9 to 4.5 × 10**5, Rgz was about 44 nm and [IV]w ranged from 8.4 to 7.9 dL/g. Chromatography revealed that solubilized pectin distributions were bimodal in nature at 3 minutes extraction time and trimodal when the extraction time was 6 minutes. Scaling law exponents obtained for the highest molar mass fractions were consistent with a very compact spherical structure, for the intermediate fraction scaling law exponents were consistent with a less compact spherical structure comparable to a random coil whereas for low molar mass fractions scaling law exponents were consistent with a structure more asymmetric in shape. These results are consistent with earlier results which indicated that pectin distributions were mixtures of two or more of the following: spherical aggregates, hydrogen bonded network structures; and partially or fullly disaggregated components of network structures which could include branched structures, rods, segmented rods and kinked rods.