Determination of available lysine by planar chromatography: a useful tool for protein quality evaluation in fish feed.
Due to the essentiality of lysine for fish, its availability is commonly used as a predictor of the protein nutritional quality of fish feed. The objective of this work was to establish a high-throughput analytical method for protein quality control in fish feed through the measurement of available lysine by planar chromatography. Sample was first incubated with 1-fluoro-2,4-dinitrobenzene to obtain the dinitrophenyl-lysine derivative and then hydrolyzed with hydrochloric acid in order to release the derivative from proteins. Chromatography was performed on silica gel 60 F254 HPTLC plates using n-propanol-25% ammonia (7 + 3, v/v) as mobile phase. Quantitative analysis was performed by densitometry in the absorbance mode at 360 nm. Calibration showed a polynomial relationship with an R2 of 0.9991 in the range of 25 to 125.0 ng/band. Repeatability relative standard deviation (RSD) and intermediate precision (RSD) in matrix were 0.8 and 3.6%, respectively. Recoveries of spiked samples at two levels ranged from 72 to 85% with RSD from 3 to 8%. This method provides the salmon feed industry with a reliable, high-throughput, and low-cost means for routine quality control of available lysine.
Vega
Mario
M
University of Concepcion, Faculty of Pharmacy, Department of Food Science, Nutrition and Dietetic, Barrio Universitario s/n Casilla 237, PO 403-0249 Concepcion, Chile. mveha@udec.cl
Aranda
Mario
M
D000821:Animal Feed / Q000032:analysis / Q000592:standards*; D002855:Chromatography, Thin Layer / Q000379:methods*; D008239:Lysine / Q000032:analysis*; D011506:Proteins / Q000592:standards*; D011786:Quality Control
D011506:Proteins; D008239:Lysine