Iwona Rabalski

Bioactive Compounds and their Antioxidant Capacity in Selected Primitive and Modern Wheat Species

Whole grain foods have been recommended for healthy diets as being recognized sources of dietary fiber and antioxidants. A diverse array of wheat was evaluated in terms of bioactive compounds and antioxidant capacity. The bio- active compounds examined include phenolic acids, carotenoids and tocols which were determined by HPLC. Antioxidant was based on the determination of scavenging capacity of DPPH . and ABTS .+ radicals and total phenols assay. Significant differences were observed in total phenols and ferulic acid between wheat species. Wheat species contained four major to- cols including 2 tocopherols and 2 tocotrienols with � -tocotrienol being the most abundant tocol. Lutein, the primary caro- tenoid in wheat, significantly differed among wheat species ranging from 1.0 to 8.1 mg kg -1 . Scavenging capacity of DPPH . and ABTS .+ radicals significantly varied being 1.97-3.20 and 17.1-24.7 μmole g -1 , respectively. The results show the presence of considerable variability among wheat species in antioxidant composition and capacity with certain wheats hold promise for the development of functional foods for health promotion.

Stability of lutein in wholegrain bakery products naturally high in lutein or fortified with free lutein.

Lutein is a yellow pigment found in common foods that promotes the health of eyes and skin and is associated with reduced risk of age-related macular degeneration and cataracts. In the present study, selected high-lutein wheat and corn were milled into wholegrain flours by two mills to improve flour uniformity. The high-lutein and lutein-fortified wholegrain flours were processed into breads, cookies, and muffins to study lutein stability during baking and subsequent storage. Lutein and its isomers were separated, identified, and quantified by LC-UV/vis and LC-MS following extraction with water-saturated 1-butanol. Baking resulted in a significant reduction in all-trans-lutein and the formation of cis-lutein and cis-zeaxanthin isomers. Subsequent storage at ambient temperature had a slight impact on the content of all-trans-lutein. Effects of processing were more pronounced in lutein-fortified products, and the degradation rate of lutein was influenced by concentration and baking recipe. Fortified cookies and muffins showed greater lutein reduction compared with bread. Despite the significant reduction in lutein, the fortified bakery products still possessed reasonable amounts per serving that would enhance daily intake and consumption of wholegrain foods.

Free and Bound Phenolic Acids and Total Phenolics in Black, Blue, and Yellow Barley and Their Contribution to Free Radical Scavenging Capacity

ABSTRACT Barley is considered a healthy food because of its high content of β-glucan and phenolic antioxidants. In the current study, 28 black, blue, and yellow barleys were investigated in terms of their composition of free and bound phenolic acids and 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity. Free phenolics were based on aqueous methanol extraction, whereas bound phenolics were extracted following alkaline hydrolysis. Phenolics were then separated and quantified by liquid chromatography and the Folin–Ciocalteu method. Significant differences were observed between the three barley color groups, and within each color group a wide range of phenolics concentrations existed. Ferulic acid was the predominant phenolic acid in free and bound extracts, followed by p-coumaric acid in all the barleys investigated. Total phenols content and individual phenolic acids strongly correlated with free radical scavenging capacity of barley. Black and blue barley were found to be related and distinct from ...

Accelerated, Microwave‐Assisted, and Conventional Solvent Extraction Methods Affect Anthocyanin Composition from Colored Grains

Anthocyanins are important dietary components with diverse positive functions in human health. This study investigates effects of accelerated solvent extraction (ASE) and microwave-assisted extraction (MAE) on anthocyanin composition and extraction efficiency from blue wheat, purple corn, and black rice in comparison with the commonly used solvent extraction (CSE). Factorial experimental design was employed to study effects of ASE and MAE variables, and anthocyanin extracts were analyzed by spectrophotometry, high-performance liquid chromatography-diode array detector (DAD), and liquid chromatography-mass spectrometry chromatography. The extraction efficiency of ASE and MAE was comparable with CSE at the optimal conditions. The greatest extraction by ASE was achieved at 50 °C, 2500 psi, 10 min using 5 cycles, and 100% flush. For MAE, a combination of 70 °C, 300 W, and 10 min in MAE was the most effective in extracting anthocyanins from blue wheat and purple corn compared with 50 °C, 1200 W, and 20 min for black rice. The anthocyanin composition of grain extracts was influenced by the extraction method. The ASE extraction method seems to be more appropriate in extracting anthocyanins from the colored grains as being comparable with the CSE method based on changes in anthocyanin composition. The method caused lower structural changes in anthocaynins compared with the MAE method. Changes in blue wheat anthocyanins were lower in comparison with purple corn or black rice perhaps due to the absence of acylated anthocyanin compounds in blue wheat. The results show significant differences in anthocyanins among the 3 extraction methods, which indicate a need to standardize a method for valid comparisons among studies and for quality assurance purposes.

Compositional Differences in Anthocyanins from Blue- and Purple-Grained Spring Wheat Grown in Four Environments in Central Saskatchewan

Anthocyanins are important dietary components that play significant roles in human health because of their antioxidant and anti-inflammatory properties. In the present study nine anthocyanin-pigmented spring wheat lines grown at two sites in central Saskatchewan, Canada, were evaluated in terms of anthocyanin composition in comparison with four wheat checks over a two-year period. The genotypes studied were blue-aleurone and purple-pericarp wheat. The anthocyanin pigments were quantified and identified with liquid chromatography and mass spectrometry. Two anthocyanin profiles were identified in the breeding lines, namely, blue profile and purple profile. Wheat lines with a purple profile had overall higher anthocyanin concentrations and more pigments than the blue-aleurone lines. The purple profile was also characterized by the presence of acylated anthocyanins containing malonyl and succinyl substituents, but no acylated pigments were found in the blue profile. Delphinidin was the dominant aglycone in th...

Compositional and antioxidant properties of anthocyanin-rich products prepared from purple wheat

Demands for anthocyanin-rich ingredients are steadily growing due to their positive functions in human health and food coloration. Commercially available purple wheat was evaluated as a source of functional ingredients based on anthocyanin composition and antioxidant properties. Anthocyanins were concentrated in the bran fraction by about 2-fold and then the bran was further processed into anthocyanin-rich powder using ethanol extraction and column purification. Batch studies showed that anthocyanin concentration factor increased by about 81- to 135-fold in the powder depending on batch size. Characterization of anthocyanins with a triple quad mass spectrometry showed a complex anthocyanin profile with 5 pigments making up 93-96% of the total anthocyanin content. These pigments were cyanidin-3-glucoside, cyanidin-3-(6-malonyl glucoside), cyanidin-3-rutinoside, peonidin-3-glucoside and peonidin-3-(6-malonylglucoside) but their concentrations varied between bran and powder. The purple wheat bran and powder exhibited exceptional antioxidant capacity based on scavenging of DPPH, ABTS and peroxyl radicals holding a promise as functional ingredients.

Effect of processing on phenolic acids composition and radical scavenging capacity of barley pasta

Phenolic acids, total phenolics content and DPPH radical scavenging capacity in raw ingredients, fresh and dried spaghetti, and in uncooked and cooked spaghetti were evaluated and compared with semolina spaghetti as a reference. Ferulic acid was the major phenolic acid found in the free and bound phenolic extracts in all the investigated pasta samples. The addition of barley flour into pasta at incorporation levels of 30, 50 and 100% increased phenolic acids and total phenolics content. Pasta processing did not significantly affect the total phenolics content and free radical scavenging capacity, but a significant reduction in total phenolic acids measured by HPLC was found. Drying process differently affected individual phenolic compounds in the free and bound fractions, and thus, the total phenolic acids content. Free vanillic, caffeic and p-coumaric acids did not significantly change, while p-hydroxybenzoic and ferulic acids of the free extracts showed higher values compared to the corresponding fresh pasta. Cooking did not greatly affect total phenolic acids, more leading to conserving free and bound phenolic compounds.