Spectrophotometric Estimation of Total Carotenoids in Cereal Grain Products

Total carotenoids (TC) were determined as a measure of total xanthophylls in grain flours and grits, by new validated spectrophotometric method based on A1cm 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.