30C-25 |
Rapid estimation of protein content in enriched corn masa flour |
M. L. YEVERINO and G. E. Arteaga-MacKinney. Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon, Pedro de Alba S/N, Ciudad Universitaria, San Nicolas de los Garza, 66400, Mexico Corn tortillas are the staple food in Mexico. Tortillas are produced from fresh masa or from nixtamalized dry masa flour. The protein quality of tortillas is low due to lack of lysine and tryptophan. Supplementation of corn tortillas with toasted soybean flour has been shown to double the protein quality of the tortillas. This enriched flour is use in a federal program in Mexico to reduced malnutrition. There is a need of the corn flour industry for a rapid method to estimate protein in this enriched flour. Available rapid methods for protein determinations require soluble protein. Using different solvents and conditions it may be possible to solubilize the soy protein to a level where a rapid protein determination method may be applicable. Develop a rapid method to estimate protein content in enriched corn masa flour. Commercial dry masa flour (DMF) and heat-treated soy flour (50% protein content) were used. DMF and soy flour were mixed in different proportions (2, 4,6,8,10% soy flour) and several solvent systems were evaluated for their ability to solubilized the proteins of the mixtures. Four spectrophotometric methods were evaluated to estimate protein content in the extracts and their results were compared to Kjeldahl. Analysis of variance and linear regression were used to analyze the data. The water solubility of the soy flour protein was very low (<10%). A mixture of KOH, detergents and reducing agents was found to solubilize the soy protein. Solubilization was also found with sulfuric acid and urea. After solubilization, the biuret method and UV absorbance could be used to quantify protein in the extracts. The method developed could be use as a quality assurance tool to verify the dosification of soy flour to corn masa flour. The method is simpler and faster than Kjeldahl methodology.
Session 30C, Food Chemistry: Proteins
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