•Ten phenolic compounds have been identified for the first time in finger millet.•Catechin and epicatechin are the major extractable flavonoids in finger millet.•Ferulic acid is the major bound ...phenolic compound in finger millet.•Colored finger millets have higher phenolic compounds than non-colored ones.
The profiles of phenolic compounds and antioxidant capacities of four finger millet varieties harvested in northern Malawi were investigated. The total phenolics, flavonoids and condensed tannins in the free fractions ranged from 114.43 to 179.19 mg ferulic acid equivalent (FAE)/100 g, 90.24 to 202.94 mg catechin equivalent (CE)/100 g and 31.76 to 83.59 mg CE/100 g, respectively. Total phenolic contents of the bound fractions ranged from 58.27 to 123.23 mg FAE/100 g. Twenty phenolic compounds were identified in the free fractions including eighteen flavonoids, with catechin and epicatechin being the predominant flavonoids. Seventeen phenolic compounds were identified in the bound fractions, with ferulic acid being the predominant one. Ten of the identified polyphenols were firstly reported in finger millet. Darker colored finger millet varieties had higher phenolic contents and antioxidant properties than the lighter colored ones. Finger millet can be used as healthy food material and natural antioxidant resource.
► TCC, lutein and zeaxanthin levels are unevenly distributed in the grain kernels. ► Lutein and zeaxanthin were found in aleurone layer of non-corn and corn cereals. ► Non-corn germ had higher levels ...of lutein and zeaxanthin than yellow corn germ. ► Antioxidant activity of carotenoids from aleurone was 50% of the germ fraction.
To compare the distribution of carotenoids across the grain, non-corn and corn cereals were hand dissected into endosperm, germ and aleurone fractions. Total carotenoid content (TCC) and carotenoid composition were analysed using spectrophotometry and HPLC. Cereal carotenoid composition was similar; however, concentrations varied significantly (p<0.05). Endosperm fractions had TCC ranging from 0.88 to 2.27 and 14.17 to 31.35mg/kg in non-corn cereals and corn, respectively. TCC, lutein and zeaxanthin in germ fractions were higher in non-corn cereals than in corn. Lutein and zeaxanthin contents were lower in non-corn cereal endosperms. The aleurone layer had zeaxanthin levels 2- to 5-fold higher than lutein among the cereals. Positive significant correlations (p<0.05) were found between TCC, carotenoids analysed by HPLC and DPPH results. This study is the first to report on carotenoid composition of the aleurone layer. Our findings suggest that the aleurone of wheat, oat, corn and germ of barley have significantly enhanced carotenoid levels.
•Provitamin A potential of landrace orange maize variety (MW5021) was studied.•Carotenoid content of orange maize differed significantly with growing location.•Color values of orange maize correlated ...with β-cryptoxanthin (r>0.36).•Provitamin A content of orange maize met the target (15μg/g) of biofortification.•Maize with higher lutein and zeaxanthin levels had higher antioxidant capacity.
The provitamin A potential of landrace orange maize from different locations (A, B, C and D) of central Malawi has been evaluated. Physicochemical compositions, color, total carotenoid content (TCC), carotenoid profiles, and oxygen radical absorbance capacity (ORAC) and 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging activity as antioxidant capacities of maize were determined. Color values of orange maize had correlations with β-cryptoxanthin (r>0.36). TCC of white and orange maize averaged 2.12 and 59.5mg/kg, respectively. Lutein was the most abundant carotenoid (47.8%) in orange maize, followed by zeaxanthin (24.2%), β-carotene (16.4%) and β-cryptoxanthin (11.6%). Location D showed the highest levels of lutein, zeaxanthin and antioxidant capacity. Provitamin A content of orange maize met the target level (15μg/g) of biofortification. Retinol activity equivalent (RAE) from β-cryptoxanthin and β-carotene in orange maize averaged 81.73μg/100g. In conclusion, orange maize has the potential to be a natural source of provitamin A.
A total of 45 finger millet samples from seven different growing regions of central and northern Malawi were analyzed in terms of the total phenolic content (TPC), individual phenolic compounds using ...high performance liquid chromatography (HPLC) and Q-TOF mass spectrometry (MS), and in vitro antioxidant capacity using ABTS+ and oxygen radical absorbance capacity (ORAC) assays. Finger millet samples from central (n = 22) Malawi (Makowe, Mphathi, Chuma-Chitsala and Khulungira) presented higher (p < 0.05) TPC, ABTS+ radical-scavenging activity and ORAC values compared to those from northern (n = 23) Malawi (Kabanda, Edundu and Kabwanda) and this was related to the higher (p < 0.05) contents of catechin, epicatechin, and ferulic acid in the former. Antioxidant capacity significantly (p < 0.01) correlated with TPC (r = 0.836; r = 0.948, respectively). The main phenolic compounds, including catechin, epicatechin, caffeic acid, ferulic acid showed significant (p < 0.01) correlations with the antioxidant capacity of finger millet samples. Principal component analysis (PCA), which was used to investigate further for similarities among finger millet samples, explained up to 68.54% of the data variability. Finger millets from Malawi could serve not only as whole grain foods but also as natural sources of antioxidants.
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•Phenolic compounds of finger millets from seven regions in Malawi were characterized.•Catechin and ferulic acid were the predominant phenolic compounds in finger millets.•The antioxidant capacity of finger millet was strongly correlated with phenolic compounds.•Two principal components explained 68.54% of the total variance in finger millets.
The aims of the current work were: (1) to study the influence of variety and geographical production area on the total phenolic content, total anthocyanin content, total flavonoid content, total ...carotenoid content and antioxidant activity in bean varieties (Dimeta, Napirira and Nanyati) from different growing areas in central Malawi, and (2) to evaluate the possibility of establishing a classification based on the geographical areas of the growing regions. A total of 47 bean samples were collected from Makowe, Mphathi, Chuma-Chitsala and Khulungira Zone. These four locations were segregated based on altitude, latitude and longitude. Principal component and hierarchical cluster analysis were used to distinguish and classify among these samples. Significant differences (
P
< 0.05) in total phenolic content (2.92–4.97 mg/g), total anthocyanin content (14.52–152.31 μg/g), total flavonoid content (2.01–6.38 mg/g) and oxygen radical absorbance capacity (16.75–24.51 μmol/g) were found among the different sampled villages, showing a significant effect of the producing region on these parameters. The beans in Makowe had lower polyphenols than in other locations. Results of principal component analysis indicate that phytochemicals and antioxidant capacity could serve as parameters to establish a bean classification according to the geographical area of production.
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