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United States Department of Agriculture

Agricultural Research Service

Title: The Effect of Heat Treatment and Ph on the Thermal and Rheological Properties of Lupinus Albus Flour Meal.

Authors
item Mohamed, Abdellatif
item Peterson, Steven
item Biresaw, Girma
item Sessa, David
item Hojilla-Evangelista, Milagros

Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: May 12, 2004
Publication Date: May 12, 2004
Citation: Mohamed, A., Peterson, S.C., Biresaw, G., Sessa, D.J., Hojillaevangelist, M.P. 2004. The effect of heat treatment and ph on the thermal and rheological properties of lupinus albus flour meal [abstract]. Annual Meeting and Expo of the American Oil Chemists' Society. p.124.

Technical Abstract: Lupin is a legume known for 3000 years in the Mediterranean basin. Lupinus albus is known as the old world lupin. Lupin endosperm contains more than 50% protein and no starch. A Lupinus albus sample was hand dissected and dehulled. The endosperm was milled into whole meal and sieved through 40 mesh. A 20% suspension was prepared in phosphate buffers with pH 4, 6.8, and 8. The suspensions were treated at 75, 90 and 100 degrees C for one hour. The heat-treated suspension was centrifuged and the precipitate was freeze-dried. The supernatant was analyzed for protein content to test the effect of heat treatments on protein solubility, while the precipitate was used to determine the surface hydrophobicity, SDS-PAGE, thermal properties and surface tension. The presence of high MW aggregates was apparent on the SDS-PAGE. Higher treatment temperature resulted in higher degree of aggregation. The non-reduced samples showed clearly the effect of pH on the proteins, where at pH 4 and 900C, the bands intensity levels were higher than pH 6.8 and 8 indicating greater aggregation. The DSC analysis of a 3.1% moisture content showed a glass transition around 55ºC and an exothermic transition at 150ºC. The surface hydrophobicity of the heat treated protein decreased as the temperature increased from 75, 90, and 100ºC which agrees with the SDS-PAGE data.

Last Modified: 4/16/2014
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