46I-17 |
Determination of proteins in soybean oil from distinct processing steps |
J. A. NORDLEE1, L. M. Niemann, S. L. Hefle, and S. L. Taylor. (1) Food Allergy Research & Resource Program, University of Nebraska, Department of Food Science & Technology, 143 Food Industry Building, Lincoln, NE 68583 Soybean oil is derived from a commonly allergenic food. The soybean allergens are certain naturally-occurring proteins found in the seed. A modicum of literature exists regarding the protein content of edible oils. It is presumed that the protein level decreases as the oil becomes more processed. The protein level of the oil would presumable correlate with the allergen content. A method now exists, albeit expensive and time consuming, to determine the apparent protein content of oils. The objective of this research was to determine the protein level in 30 different soybean oils at four stages of processing (120 samples) and observe the protein reduction in each step of refining. Since the method is expensive and time consuming, free fatty acid determinations were compared to protein content in an attempt to have a more rapid, reliable indicator of the protein level in finished oils. Soybean oils from worldwide processing facilities were obtained from the degumming, refining, bleaching and deodorization steps. For protein analyses the oils were extracted by vigorous agitation with 0.2 M ammonium bicarbonate. The aqueous layers were dried in a concentrator and washed with water and formic acid, then analyzed for amino acid content. Apparent micrograms of protein per gram oil were calculated. American Oil Chemists' Society Official Method Ca 5a-40 was used to determine percent free fatty acid in the deodorized oils. Apparent protein ranges for the four processing steps were: Degummed, 0.16-20.8 µg/g oil; Refined, 0.043-6.8 µg/g oil; Bleached, 0.033-3.1 µg/g oil; Deodorized, 0.021-0.443 µg/g oil. Free fatty acid levels ranged from 0.011 to 0.111%. No correlation was observed between the apparent protein and the free fatty acid levels. This is the first full scale analysis of protein levels in oils at various steps of processing. These oils represent worldwide production methods. This information will assist the food industry in production and labeling issues
Session 46I, Toxicology & Safety Evaluation
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