Characterisation of chemical components in manually isolated aleurone and associated layers from maize, wheat and barley kernels
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Date
2013, 2013, 2014, 2015
Authors
Ndolo, Victoria Uchizi
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Health benefits related to consumption of whole grains have been attributed in part to phytochemical and micronutrient composition. Understanding the composition, structure and distribution of these components in different cereal grains is of potential importance in aiding the selection of whole grains and their processed fractions for inclusion in the diet, and as ingredients in development of new food products. The aim of this research was to characterise the chemical components in the botanical fractions of yellow corn, barley, wheat. Manual separation, a tedious and laborious technique that yields pure fractions, suitable for compositional analysis, was used to separate whole grains into pericarp, aleurone layer, germ and endosperm fractions. Component identification and quantification of tissue components was accomplished by several techniques. The study also explored the possibility of using spectral characteristics fluorescence intensity values to provide rapid estimates of the concentrations and distribution of ferulic acid (FA), a major phenolic compound in cereal grains. While composition of phenolic acids and carotenoids was similar, the distribution was significantly different (P < 0.05) among cereal types and grain fractions. Phenolic acids were concentrated in pericarp and aleurone fractions, followed by the germ and the endosperm had the lowest levels. Yellow corn exhibited the highest values. Carotenoids, lutein and zeaxanthin were concentrated in the germ and aleurone layer of wheat and barley while in yellow corn it was in the endosperm and aleurone layer. This is the first study to report on carotenoid composition of aleurone fractions. Mineral elements, thiamine and niacin were higher in wheat aleurone than in purple barley and yellow corn aleurone layers. These findings suggest that yellow corn aleurone layers have potential as a functional food ingredient despite the low micronutrient content. A positive, significant correlation (r= 0.421, p < 0.0001) was found between fluorescence intensity values and ferulic acid concentration. Thus, fluorescence intensity profiles are a promising approach for rapid assessment of FA concentration in grain in-situ. This work has provided information that would act as a database for selection of cereal fractions and guide the miller to obtain grain fractions with enriched levels of phytochemicals and micronutrients.
Description
Keywords
Carotenoids, Cereal grains, Phenolic acids, Aleurone layer, Ferulic acid, Fluorescence intensity profiles, Botanical fractions, Mass spectrometry, Micronutrients
Citation
Ndolo, V. U., & Beta, T. (2013). Distribution of carotenoids in endosperm, germ, and aleurone fractions of cereal grain kernels. Food chemistry, 139(1), 663-671.
Ndolo, V. U., & Beta, T. (2014). Comparative studies on composition and distribution of phenolic acids in cereal grain botanical fractions. Cereal Chemistry, 91(5), 522-530.
Ndolo, V. U., Fulcher, R. G., & Beta, T. (2015). Application of LC–MS–MS to identify niacin in aleurone layers of yellow corn, barley and wheat kernels. Journal of Cereal Science, 65, 88-95.
Ndolo, V. U., Beta, T., & Fulcher, R. G. (2013). Ferulic acid fluorescence intensity profiles and concentration measured by HPLC in pigmented and non-pigmented cereals. Food Research International, 52(1), 109-118.
Ndolo, V. U., & Beta, T. (2014). Comparative studies on composition and distribution of phenolic acids in cereal grain botanical fractions. Cereal Chemistry, 91(5), 522-530.
Ndolo, V. U., Fulcher, R. G., & Beta, T. (2015). Application of LC–MS–MS to identify niacin in aleurone layers of yellow corn, barley and wheat kernels. Journal of Cereal Science, 65, 88-95.
Ndolo, V. U., Beta, T., & Fulcher, R. G. (2013). Ferulic acid fluorescence intensity profiles and concentration measured by HPLC in pigmented and non-pigmented cereals. Food Research International, 52(1), 109-118.