Spectrophotometric Estimation of Total Carotenoids in Cereal Grain Products

摘要

Total carotenoids (TC) were determined as a measure of total xanthophylls in grain flours and grits, by new validated spectrophotometric method based on A_(1cm)~(1%)-approach. The general analytical procedure is easily adjustable to different samples, the number of extraction steps depending on TC concentration in the sample. Basically, two methods have been suggested: the rapid one for low-TC samples (white corn, wheat, soybean, sorghum) including one to two extractions, and the one for high-TC samples (yellow corn) needing three to four extractions. Method's accuracy was proven against the reference standard material (102.1±3.9%) and the reference method. Good precision (repeatability and intermediate precision of upto 9% for yellow corn products) and sensitivity with LOD (limit of detection) and LLOQ (lower limit of quantitation) of 0.2 and 0.6 mg kg~(-1) TC, resp., were estimated. The method was applied to the control of nutritional value of cereal grain products. TC concentration (in mg kg~(-1)) in the samples ranged from 11-23 in yellow corn flours, 0.7-0.9 in white corn flours, 17-22 in yellow corn grits, 1.1-1.3 in wheat flours, 1.6 in wheat grits and 1.5 in sorghum flour, to 0.9-9.9 in soybean flours.