Comparative evaluation of phytochemical profiles and identification of flavonoids in cereal grains

The phytochemicals including flavonoids and phenolic acids mainly contained in the outer layer of the kernels are key factors responsible for the biofunctionality of whole grains. The phytochemical profiles of twelve grain samples comprising 6 wheats, 3 barleys and 3 oats were studied for comparative evaluation of their antioxidant properties. Total phenolic content (TPC) and antioxidant activities (DPPH and ORAC) of the grain extracts were measured. The bound phenolic acids were identified and quantified using HPLC and mass spectrometry. The flavonoids in different grain were analyzed using HPLC and tandem mass spectrometric techniques. TPC in acidified methanol extracts ranged from 164 to 226, 264-391, and 308-331 mg/100 g for wheat, oats and barley, respectively. Similarly TPC in acetone extracts were 78 to 118, 223 to 351 and 367 to 433 mg/100 g. Acetone extracts had significantly (p < 0.05) higher TPC than acidified methanol extracts for barley samples. On the contrary, acidified methanol extracts from wheat and oats had higher TPC than their acetone extracts. The results showed that for both acetone and acidified methanol extracts, barley samples had significantly higher antioxidant activity than oats and wheat samples although even some of the oats had similar or even higher TPC compared to barley samples. Wheat extracts had low antioxidant activity assayed using both DPPH and ORAC assays. Oats had the highest levels of bound phenolic acids (431 to 656 mg/100 g) followed by wheat samples (91 to 153 mg/100 g). The bound phenolic acid contents of barley samples ranged from 81–105 mg/100 g. The major flavonoids in barley samples are dimers and trimers of proanthocyanidins, while flavone glucosides are the major flavonoids for wheat. The phytochemical including flavonoid profile may explain the antioxidant activity for different cereal grain rather than TPC

Isolation and identification of feruloylated arabinoxylan mono- and oligosaccharides from undigested and digested maize and wheat

AbstractFeruloylated arabinoxylan mono- and oligosaccharides (F-AXOS) are a subject of interest because of their prebiotic and antioxidant properties. We aimed at isolating and identifying F-AXOS from maize, wheat, wheat bran and wheat aleurone using HPLC and LC-MS/MS. Prior to extraction of F-AXOS, samples were subjected to either simulated gastric fluid with enzymes (gastric) or without enzymes (pH) or water (aqueous) at 37 °C. F-AXOS present in all samples were identified as 5-O-feruloyl-α-L- arabinofuranose and possibly 5-O-feruloyl-α-L-arabinofuranosyl-(1 → 3)-O-β-D-xylopyranose. Their mean content, measured as esterified ferulic acid (FA), was 2.5 times higher in maize (10.33 ± 2.40 μg/g) compared to wheat. Digestion under gastric or pH conditions resulted in a two-fold increase in F-AXOS in all samples. The level of F-AXOS produced during gastric or pH condition was positively correlated to the insoluble bound FA content of the sample (R2 = 0.98). 5-O-Feruloyl-α-L- arabinofuranose was the only identifiable F-AXOS released during gastric digestion. Our results suggest feruloyl arabinose is the most abundant form of F-AXOS in maize and wheat

The potential of Manitoba chokecherry as a source of high natural antioxidants

Consumption of fruits and vegetables is shown to be beneficial for protecting health and preventing some chronic diseases such as cancer, cardiovascular disease, and stroke. The positive health effects have been mainly due to the contributions of their natural antioxidant capacity. Chokecherry (Prunus virginiana), a unique fruit, is a member of the Rose family and native to North America. Here we demonstrate that chokecherry fruit with strong antioxidant capacity is available in Manitoba, and that its potent antioxidant potential can be developed for health benefits in value-added applications.These findings are useful for developing novel value-added antioxidant products from chokecherry because of its phytochemical profile associated with health protection and prevention of disease. The results provide evidence essential for breeding novel cultivars of fruit plants with strong natural antioxidants

High-Amylose Corn Exhibits Better Antioxidant Activity than Typical and Waxy Genotypes

The consumption of fruits, vegetables, and whole grains rich in antioxidative phytochemicals is associated with a reduced risk of chronic diseases such as cancer, coronary heart disease, diabetes, Alzheimer\u27s disease, cataract, and aged-related functional decline. For example, phenolic acids are among the main antioxidative phytochemicals in grains that have been shown to be beneficial to human health. Corn (Zea mays L.) is a major staple food in several parts of the world; thus, the antioxidant activity of several corn types was evaluated. The 2,2-Diphenyl-1-picryhydrazyl free radical (DPPH•) scavenging activity, total phenolic content (TPC), antioxidant capacity of lipid-soluble substances (ACL), oxygen radical absorbance capacity (ORAC), and phenolic acid compositions of typical and mutant genotypes (typical-1, waxy, typical-2, and high-amylose) were investigated. The DPPH• scavenging activity at 60 min was 34.39−44.51% in methanol extracts and 60.41−67.26% in HCl/methanol (1/99, v/v) extracts of corn. The DPPH• scavenging activity of alkaline hydrolysates of corn ranged from 48.63 to 64.85%. The TPC ranged from 0.67 to 1.02 g and from 0.91 to 2.15 g of ferulic acid equiv/kg of corn in methanol and HCl/methanol extracts, respectively. The TPC of alkaline hydrolysates ranged from 2.74 to 6.27 g of ferulic acid equiv/kg of corn. The ACL values were 0.41−0.80 and 0.84−1.59 g of Trolox equiv/kg of corn in methanol and HCl/methanol extracts, respectively. The ORAC values were 10.57−12.47 and 18.76−24.92 g of Trolox equiv/kg of corn in methanol and HCl/methanol extracts, respectively. ORAC values of alkaline hydrolysates ranged from 42.85 to 68.31 g of Trolox equiv/kg of corn. The composition of phenolic acids in alkaline hydrolysates of corn was p-hydroxybenzoic acid (5.08−10.6 mg/kg), vanillic acid (3.25−14.71 mg/kg), caffeic acid (2.32−25.73 mg/kg), syringic acid (12.37−24.48 mg/kg), p-coumaric acid (97.87−211.03 mg/kg), ferulic acid (1552.48−2969.10 mg/kg), and o-coumaric acid (126.53−575.87 mg/kg). Levels of DPPH• scavenging activity, TPC, ACL, and ORAC in HCl/methanol extracts were obviously higher than those present in methanol extracts. There was no significant loss of antioxidant capacity when corn was dried at relatively high temperatures (65 and 93 °C) postharvest as compared to drying at ambient temperatures (27 °C). Alkaline hydrolysates showed very high TPC, ACL, and ORAC values when compared to methanol and HCl/methanol extracts. High-amylose corn had a better antioxidant capacity than did typical (nonmutant) corn genotypes

Microwave-assisted extraction of bound phenolic acids in bran and flour fractions from sorghum and maize cultivars varying in hardness

To release bound phenolic acids, a microwave-assisted extraction procedure was applied to bran and flour fractions obtained from eight sorghum and eight maize cultivars varying in hardness. The procedure was followed by HPLC analysis, and the identities of phenolic acids were confirmed by MS/MS spectra. The extraction of sorghum and maize bound phenolic acids was done for 90 s in 2 M NaOH to release ferulic acid and p-coumaric acid from bran and flour. Two diferulic acids, 8-O-4′- and 8-5′-benzofuran form, were identified and quantitated in sorghum bran, and only the former was found in maize bran. The contents of ferulic acid and diferulic acids in sorghum bran were 416−827 and 25−179 μg/g, respectively, compared to 2193−4779 and 271−819 μg/g in maize. Phenolic acid levels of sorghum were similar between hard and soft cultivars, whereas those of maize differed significantly (p < 0.05) except for ferulic acid in flour. Sorghum phenolic acids were not correlated with grain hardness as measured using a tangential abrasive decortication device. Maize ferulic acid (r = −0.601, p < 0.01), p-coumaric acid (r = −0.668, p < 0.01), and 8-O-4′-diferulic acid (r = −0.629, p < 0.01) were significantly correlated with hardness.The Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant program and the Canada Foundation for Innovation (New Opportunities Fund and Leaders Opportunity Fund).http://pubs.acs.org/journal/jafcauhb2017Food Scienc

Phenolic acid content of sorghum and maize cultivars varying in hardness

The role of phenolic acids on sorghum and maize hardness was evaluated among eight cultivars of each of the cereals representing hard and soft classes. Bran and flour fractions were evaluated for monomeric and diferulic phenolic acids using high performance liquid chromatographic and mass spectrometric (LC–MS/MS) techniques. Bran samples of harder grains had more phenolic acids than those of soft types. Intra-class testing showed slight differences in cultivars within the hard and soft classes. The content of phenolic acids was a useful indicator of hardness distinguishing between hard and soft maize and sorghum cultivars. Correlation coefficients between monomeric acids of maize bran, mostly ferulic acid, and grain hardness were higher than those of sorghum. Maize bran ferulic acid content was strongly correlated with Tangential Abrasive Dehulling Device (TADD) hardness (r = - 0.776, p < 0.001). This study is the first to show that there is a relationship between bran phenolic acid content and sorghum and maize hardness.The Natural Science and Engineering Research Council of Canada (NSERC) Discovery Grant Program, Canada Foundation for Innovation (CFI) -New Opportunities Fund (CFI-NOF) and CFI-Leaders Opportunity Funds (CFI-LOF) .http://www.elsevier.com/locate/foodchemhb2016Food Scienc

Increasing the utilisation of sorghum, millets and pseudocereals : developments in the science of their phenolic phytochemicals, biofortification and protein functionality

There is considerable interest in sorghum, millets and pseudocereals for their phytochemical content, their nutritional potential and their use in gluten-free products. They are generally rich in a several phenolic phytochemicals. Research has indicated that the phenolics in these grains may have several important health-promoting properties: prevention and reduction of oxidative stress, anti-cancer, antidiabetic, anti-inflammatory, anti-hypertensive and cardiovascular disease prevention. However, increased research on the actual health-promoting properties of foods made from these grains is required. Biofortified (macro and micronutrient enhanced) sorghum and millets are being developed through conventional breeding and recombinant DNA technology to combat malnutrition in developing countries. Enhanced nutritional traits include: high amylopectin, high lysine, improved protein digestibility, provitamin A rich, high iron and zinc, and improved mineral bioavailability through phytate reduction. Some of these biofortified cereals also have good agronomic characteristics and useful commercial end-use attributes, which will be important to their adoption by farmers. Knowledge of the structure of their storage proteins is increasing. Drawing on research concerning maize zein, which shows that it can produce a visco-elastic wheat-like dough, it appears that the storage proteins of these minor grains also have this potential. Manipulation of protein b-sheet structure seems critical in this regard.http://www.elsevier.com/locate/jcshb201