Posts Tagged ‘Lysine’

Método económico y eficiente para la cuantificación colorimétrica de lisina en grano de maíz. Inexpensive and efficient colorimetric method for the lysine cuantification on whole maize grain

Posted by Carelia Juarez on , in Journal Articles

Published in  Revista Fitotecnia Mexicana 34(4): 285-289, 2011

Método económico y eficiente para la cuantificación colorimétrica de lisina en grano de maíz. Inexpensive and efficient colorimetric method for the lysine cuantification on whole maize grain

Luis A. Galicia-Flores, Catalina Islas-Caballero, Aldo Rosales-Nolasco and Natalia Palacios-Rojas

Quality protein maize (QPM, Zea mays L.) has higher content of‑ lysine and tryptophan, two essential amino acids usually present in low quantities in maize kernels. The colorimetric method used currently to measure lysine in maize is time consuming and poorly‑ reproducible. This paper describes a modi­fication to the methodology for colorimetric determination of lysine in whole grains of maize.‑ Reduction of costly reagents, risks for operators and reduction in the number of steps to prepare the calibration curve are the main modi­fications done to the previous protocol and which largely improve the efficiency and cost of the analysis. The alternative methodology was validated by comparison with the reference colorimetric method and NIR, obtaining high coefficients of determination (R2)‑0.97 and 0.85, respectively. The modi­fied method is inexpensive, reliable and fast, and can be used for the determination of lysine in large number of samples for breeding programs.

 

Near-Infrared Reflectance Spectroscopy (NIRS) for Protein, Tryptophan, and Lysine Evaluation in Quality Protein Maize (QPM) Breeding Programs

Posted by on , in Journal Articles

Published in Journal of Agricultural and Food Chemistry 59(20): 10781-10786, 2011

Near-Infrared Reflectance Spectroscopy (NIRS) for Protein, Tryptophan, and Lysine Evaluation in Quality Protein Maize (QPM) Breeding Programs

Aldo Rosales, Luis Galicia, Ezequiel Oviedo, Catalina Islas and Natalia Palacios-Rojas

Quality protein maize (QPM) has approximately twice the tryptophan (Trp) and lysine (Lys) concentrations in protein compared to normal maize. Because several genetic systems control the protein quality of QPM, it is essential to regularly monitor Trp and/or Lys in breeding programs. Our objective was to examine the potential of near-infrared reflectance spectroscopy (NIRS) to enhance the efficiency of QPM research efforts by partially replacing more expensive and time-consuming wet chemistry analysis. More than 276 maize samples were used to develop NIRS models for protein content (PC), Trp, and Lys. The standard error of prediction (SEP) for the calibration and the coefficient of determination for validation (R2v) were 0.26 and 0.96 for PC, 0.005 and 0.85 for Trp, and 0.02 and 0.75 for Lys. When the NIRS models were used to evaluate 266 S2 lines from five QPM breeding populations, the coefficients of determination between NIRS and the chemical data were 0.94, 0.76, and 0.80 for PC, Trp, and Lys, respectively. Therefore, the NIRS models can be used to support the QPM breeding efforts.