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A practical method for extending the biuret assay to protein determination of corn-based products

Liu, Zelong, Pan, Junhui
Food chemistry 2017 v.224 pp. 289-293
absorbance, biuret, bovine serum albumin, corn, corn gluten meal, food industry, heat treatment, prediction, protein content, sodium dodecyl sulfate, solubilization, zein
A modified biuret method suitable for protein determination of corn-based products was developed by introducing a combination of an alkaline reagent with sodium dodecyl sulfate (reagent A) and heat treatments. The method was tested on seven corn-based samples. The results showed mostly good agreement (P>0.05) as compared to the Kjeldahl values. The proposed method was found to enhance the accuracy of prediction on zein content using bovine serum albumin as standard. Reagent A and sample treatment were proved to effectively improve protein solubilization for the thermally-dried corn-based products, e.g. corn gluten meal. The absorbance was stable for at least 1-h. Moreover, the whole measurement of protein content only needs 15–20min more than the traditional biuret assay, and can be performed in batches. The findings suggest that the proposed method could be a timesaving alternative for routine protein analyses in corn processing factories.