Characterization and Protein Composition Of Food Allergen Extracts

Abstract

RationaleFood diagnostic extracts used in the USA are non-standardized with no measurement of potency. Most food diagnostics have not been extensively characterized or allergen proteins identified. This study analyzed the protein composition of several foods extracted under varying conditions.MethodsAnimal and plant foods were defatted with acetone and extracted overnight in 50% glycerin or aqueous extraction fluid using multiple extraction techniques. Extractions were performed at 4°C or room temperature and blended or stirred. Following extraction, all samples were adjusted to contain 50% glycerin, centrifuged and sterile filtered. The extracts were then evaluated for protein profiles and concentrations using Coomassie or silver stained SDS-PAGE and Bradford methods.ResultsThe food extracts showed a wide range of protein content. For example, tree nut allergens, almond and Brazil nuts were over 10 mg/mL whereas pecan and walnut were 1-3 mg/mL. For most foods the protein profiles within the same species were similar for the differing extraction conditions and correlated with the final protein concentrations. Walnut extraction, however, produced final protein concentrations that varied significantly according to the extraction method. Glycerin extraction resulted in an average final concentration of 2-3mg/ml, versus 0.3mg/ml for aqueous extraction. Room temperature extraction resulted in higher protein yields (2.8mg/ml), when compared to extraction at 4°C (1.7mg/ml), and persistent stirring was the superior method of agitation.ConclusionsSDS-PAGE profiles and total protein content were obtained for many food extracts in several food groups in order to optimize extraction conditions and to eventually monitor for allergen content, potency and stability. RationaleFood diagnostic extracts used in the USA are non-standardized with no measurement of potency. Most food diagnostics have not been extensively characterized or allergen proteins identified. This study analyzed the protein composition of several foods extracted under varying conditions. Food diagnostic extracts used in the USA are non-standardized with no measurement of potency. Most food diagnostics have not been extensively characterized or allergen proteins identified. This study analyzed the protein composition of several foods extracted under varying conditions. MethodsAnimal and plant foods were defatted with acetone and extracted overnight in 50% glycerin or aqueous extraction fluid using multiple extraction techniques. Extractions were performed at 4°C or room temperature and blended or stirred. Following extraction, all samples were adjusted to contain 50% glycerin, centrifuged and sterile filtered. The extracts were then evaluated for protein profiles and concentrations using Coomassie or silver stained SDS-PAGE and Bradford methods. Animal and plant foods were defatted with acetone and extracted overnight in 50% glycerin or aqueous extraction fluid using multiple extraction techniques. Extractions were performed at 4°C or room temperature and blended or stirred. Following extraction, all samples were adjusted to contain 50% glycerin, centrifuged and sterile filtered. The extracts were then evaluated for protein profiles and concentrations using Coomassie or silver stained SDS-PAGE and Bradford methods. ResultsThe food extracts showed a wide range of protein content. For example, tree nut allergens, almond and Brazil nuts were over 10 mg/mL whereas pecan and walnut were 1-3 mg/mL. For most foods the protein profiles within the same species were similar for the differing extraction conditions and correlated with the final protein concentrations. Walnut extraction, however, produced final protein concentrations that varied significantly according to the extraction method. Glycerin extraction resulted in an average final concentration of 2-3mg/ml, versus 0.3mg/ml for aqueous extraction. Room temperature extraction resulted in higher protein yields (2.8mg/ml), when compared to extraction at 4°C (1.7mg/ml), and persistent stirring was the superior method of agitation. The food extracts showed a wide range of protein content. For example, tree nut allergens, almond and Brazil nuts were over 10 mg/mL whereas pecan and walnut were 1-3 mg/mL. For most foods the protein profiles within the same species were similar for the differing extraction conditions and correlated with the final protein concentrations. Walnut extraction, however, produced final protein concentrations that varied significantly according to the extraction method. Glycerin extraction resulted in an average final concentration of 2-3mg/ml, versus 0.3mg/ml for aqueous extraction. Room temperature extraction resulted in higher protein yields (2.8mg/ml), when compared to extraction at 4°C (1.7mg/ml), and persistent stirring was the superior method of agitation. ConclusionsSDS-PAGE profiles and total protein content were obtained for many food extracts in several food groups in order to optimize extraction conditions and to eventually monitor for allergen content, potency and stability. SDS-PAGE profiles and total protein content were obtained for many food extracts in several food groups in order to optimize extraction conditions and to eventually monitor for allergen content, potency and stability.