44G-8 |
Effect of extrusion cooking on digestibility of peanut allergenic proteins |
L. CHEN1, R. D. Phillips1, J. A. Nordlee2, S. L. Taylor2, S. L. Hefle2, and M. P. Doyle1. (1) Dept. of Food Science & Technology, Univ. of Georgia, Agricultural Experimental Station, 1109 Experiment St., Griffin, GA 30223, (2) Food Allergy Research & Resource Program, Univ. of Nebraska, Lincoln, Dept. of Food Science & Technology, 143 Food Industry Bldg., Lincoln, NE 68583 Peanut allergy is initiated by peanut allergenic proteins. Extrusion cooking has been used to modify the structural and functional properties of proteins. We have found that both single screw and twin-screw extrusion changes the profile of soluble peanut protein and reduces the allergenic potential of peanut allergens. This study was undertaken to investigate the effect of extrusion on digestibility of peanut proteins and fate of peanut allergens subject to in-vitro digestion. Partially defatted peanut flour was adjusted to moisture of 20 and 40%. These materials were extruded in a twin-screw extruder (APV). Barrel temperature was set to 115 and 135°C and the screw speed applied were 300 and 500rpm. Resulting extrudates were dried, ground and incubated with SGF (Simulated Gastric Fluid, pepsin activity of 8000unit/ml) for various time periods. Soluble protein content of the resulting digestas was measured after 10% of TCA treatment to evaluate the digestibility. Denaturing electrophoresis (SDS-PAGE) was applied to determine the distribution of protein subunits subjected to various time periods of in-vitro digestion. Immunoblotting was used to trace the fate of peanut-specific IgE binding protein subunits. In-vitro digestion using pepsin increased the solubility of peanut protein in 10% TCA solution from 2-6% to 65-75%. Four strong IgE binding subunits (65K, 22K, 17K and 14K) were found. Most of the IgE binding subunits vanished from soluble protein fractions after extrusion cooking. The 65K (putative Ara h 1) subunit was found in SDS&ME soluble fraction and susceptible to pepsin. The IgE binding property of the 14K subunit was stable even after 60 min of pepsin treatment however it was totally destroyed by extrusion. The 22K and 17K(putative Ara h 2) subunits retained a small amount of IgE binding potential and became susceptible to pepsin hydrolysis after extrusion. Extrusion may effectively reduce allergenicity of peanut proteins.
Session 44G, Toxicology & Safety Evaluation
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