18C-17 |
|
M. V. VENKATACHALAM, Dept. of Food Science, Purdue Univ., Whistler Center for Carbohydrate Research, 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009, K. H. Roux, Dept. of Biological Science, Florida State Univ., 335 Biology Unit 1, Mail Code 4370, Tallahassee, FL 32306-4370, and S. K. Sathe, Dept. of Nutrition, Food & Exercise Sciences, Florida State Univ., 402 Sandels Bldg., Mail Code 1493, Tallahassee, FL 32306-1493. Pecan is an economically important tree nut crop for the U.S. with a range of food applications. Several improved varieties of pecans have been commercially developed in the US for which no comparative chemical composition data exist. Among reported tree nut allergies, pecans ranked fourth. The present study analyzed select US pecan varieties for moisture, lipid, ash, sugars, total tannins and protein content as well as protein polypeptide and antigenic profiles. Pecans (2003 crop) were ground in an Osterizer blender and the full fat flours were analyzed for moisture, lipid, protein (micro-Kjeldahl N x 5.3), and ash content by AOAC (1995) methods 925.40, 948.22, 950.49, and 923.03 respectively. Total soluble sugars were determined by phenol-sulfuric acid method. Tannins were extracted in acidified methanol (1% v/v HCl) and quantified by vanillin assay (expressed as catechin equivalents). Borate Saline Buffer (pH 8.45) solubilized proteins were assessed for polypeptide composition by SDS-PAGE and antigenic profiles by immunoblotting with rabbit polyclonal antibodies that were raised against proteins extracted from defatted flour of “Desirable” pecan variety. On a dry weight basis, pecan moisture, protein, lipid, total soluble sugars and ash content ranged from 2.1 to 6.8%, 6.1 to 11.6%, 69.6 to79.7%, 3.3 to 5.6% and 1.2 to 1.9%; respectively. With the exception of a high tannin (2.7%) native Texas variety, pecan tannin content was in a narrow range (0.6 to 1.85%). Growing location significantly influenced pecan chemical composition. Pecan lipids negatively correlated to proteins (r=-0.663) and total sugars (r=-0.625). In general, there were no significant differences in either the protein polypeptide or the antigenic profiles of the pecan varieties tested.
Session 18C, Food Chemistry: Food composition, analysis and volatiles
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |