Quantification and partial characterization of the residual protein in fully and partially refined commercial soybean oils.
A method has been developed to determine residual protein in refined oils, a potential trigger of allergic reactions. High-pH bicarbonate or borate buffers were found to be the most effective extractants, residual oil protein comprising a mixture of proteins of M(r) 6000-100000. Extracted protein could be quantified with superior precision using 3-(4-carboxybenzoyl)quinolone-2-carboxaldehyde (CBQCA). Residual protein content determined in a set of oils using the borate extraction-CBQCA assay was positively correlated with contents determined using a bicarbonate-total amino acid analysis method. Oil refining substantially reduced the oil protein content determined by the borate-CBQCA assay with neutralized/refined, bleached, and deodorized (fully refined) oils containing 62-265 ng/g oil, whereas crude un-degummed oils contained 86000-87900 ng/g of protein. These analyses and published data on cumulative threshold doses for soybean suggest that even the most sensitive individuals would need to consume at least 50 g of highly refined oil to experience subjective symptoms.
Institute of Food Research , Norwich Research Park, Colney, Norwich NR4 7UA, United Kingdom.
Neil M
NM
Rigby
Ana I
AI
Sancho
Louise J
LJ
Salt
Rob
R
Foxall
Steve
S
Taylor
Ana
A
Raczynski
Stella A
SA
Cochrane
Rene W R
RW
Crevel
E N Clare
EN
Mills
D000596:Amino Acids / Q000032:analysis; D001565:Benzoates; D001639:Bicarbonates; D001881:Borates; D005511:Food Handling; D005512:Food Hypersensitivity / Q000276:immunology; D011804:Quinolines; D015203:Reproducibility of Results; D013024:Soybean Oil / Q000737:chemistry*; D030262:Soybean Proteins / Q000032:analysis* / Q000276:immunology
D000596:Amino Acids; D001565:Benzoates; D001639:Bicarbonates; D001881:Borates; D011804:Quinolines; D030262:Soybean Proteins; C069617:3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde; D013024:Soybean Oil