Phenolic Composition and Arabinoxylan Characterization of Pearled Barley Fractions

ABSTRACTThe phenolic acid composition and concentration of four manually separated fractions (pericarp, aleurone layer, germ, and endosperm fractions) as well as whole grains of yellow corn, wheat, barley, and oats were analyzed by HPLC‐MS/MS following microwave‐assisted alkaline aqueous extraction. Phenolic acid compositions in whole grains and their fractions were similar, with minor differences among the grain fractions. Significant differences (P < 0.05), however, were observed in phenolic acid concentrations among cereal types, within cereal varieties, and among grain fractions, with yellow corn exhibiting the highest values. The concentrations of p‐coumaric and syringic acid in the pericarp were 10‐ to 15‐fold and 6‐ to 10‐fold higher, respectively, in yellow corn than in wheat, barley, and oats. In the aleurone layer, sinapic and vanillic acids in yellow corn were about 8‐ and 30‐fold more than in wheat. The germ fraction of wheat had 1.8 times more syringic acid than yellow corn germ. Grain fractions, excluding endosperm, had enhanced levels of phenolic acids compared with whole grain. Sinapic acid was more concentrated in the pericarp and germ of wheat, whereas isoferulic acid was concentrated in the germ of purple barley. Syringic and vanillic acids were concentrated in the pericarp and sinapic acid in the aleurone layer of yellow corn. These findings are important in understanding the composition and distribution of phenolic acids, and they act as a guide in identification of grain fractions for use as food ingredients. In addition, yellow corn fractions (aleurone and pericarp) may be potential alternative phenolic‐rich functional food ingredients in grain‐based food products.

Impact of flour particle size on nutrient and phenolic acid composition of commercial wheat varieties

A study was conducted to evaluate the effect of diets based on hulled or hulless (normal- and low-amylose) barley varieties on growth performance and carcass characteristics in heavy growing-finishing pigs for the production of protected designation of origin (PDO) Italian products. The study was performed with 40 gilts and 40 barrows (Italian Duroc × Italian Large White). Four diets were formulated: 1) corn-based diet (control), 2) control diet with 80% of a normal-amylose hulled barley variety named Cometa (Cometa), 3) control diet with 80% of a normal-amylose hulless barley variety named Astartis (Astartis), and 4) control diet with 80% of a low-amylose hulless barley variety named Alamo (Alamo). The diets were formulated according to 3 growth phases (P1, 40 to 80 kg BW; P2, 80 to 120 kg BW; and P3, 120 to 170 kg BW), with the same Lys:DE ratio (2.60, 2.20, and 1.80, respectively in P1, P2, and P3) according to the NRC requirements for P1 and P2 and according to requirements for high-performing pigs for P3. The diets were analyzed for their in vitro starch digestion potentials (predicted glycemic index, pGI) and for their resistant starch (RS) contents. In P1, P2, and P3, the Alamo diet had the numerically lowest RS contents and greatest pGI values, whereas the control diet had the numerically greatest RS contents and the lowest pGI values. Throughout the study, the pigs fed Cometa and Alamo diets grew faster (P < 0.01) than those fed the control diet, whereas pigs receiving Astartis diet grew in a similar manner to those receiving all the other diets. Pigs fed Cometa and Alamo achieved greater final BW (P < 0.01) compared with those fed the control diet. The pigs receiving the Astartis diet had a mean final BW similar to that of the pigs fed other diets. Throughout the study, the control group had a lower grams per megacalorie DE (P < 0.01) compared with the pigs fed diets with barley, whereas the gain per megacalorie of DE (G/Mcal DE) was greater (P < 0.01) for the pigs fed hulled barley compared with the pig fed hulless barleys. No difference in carcass characteristics was found among treatments (P > 0.05). This study showed that diets based both on hulled and hulless barley might be suitable for the heavy pig breeding intended to the production of Italian PDO products. In addition, hulled or low-amylose hulless barley could be valuable to support maximum pig growth performance without affecting carcass composition.

Composition and distribution of phenolic acids in Ponkan ( Citrus poonensis Hort. ex Tanaka) and Huyou ( Citrus paradisi Macf. Changshanhuyou) during maturity

Phenolic acid profiles and antioxidant activities of outer bran, coarse bran, and shorts from blue, black, and purple wheat were analyzed. Phenolic acids were mainly in the bound form in pigmented wheat bran fractions. Phenolic acid content decreased in the order of outer bran, coarse bran, and shorts for the three pigmented wheat varieties. HPLC analysis of phenolic extracts demonstrated that the bound form of phenolic acids contained more ferulic, isoferulic, and p-coumaric acids compared to their free counterparts. Among the three pigmented wheat varieties, the bran fractions from blue wheat contained higher bound phenolic acids than the other two pigmented wheat bran fractions, except for purple coarse bran. The blue wheat outer bran had the highest total bound phenolic acid of 3458.71 μg/g while the purple wheat shorts had the lowest of 1730.71 μg/g. The contribution of bound phenolic acids to the total phenolic content and antioxidant activity was significantly higher than that of free phenolic acids. Blue wheat bran fractions had the highest radical scavenging activity against DPPH∙ while those of purple wheat gained the highest ABTS∙+ scavenging activity. High correlations were observed between TPC and radical scavenging capacities for DPPH and ABTS (R2&gt;0.85, P&lt;0.05).

Free, esterified, glycosided, and insoluble-bound forms of eight phenolic acids in pulp, seed, and peel of jujube are separated and quantified by high performance liquid chromatography with electrochemical detection (HPLC-ECD). In the whole jujube, p-hydroxybenzoic and cinnamic acids are the most abundant phenolic acids. All quantified phenolic acids are mainly present in jujube peel. Phenolic acids in seed and peel are present in the insoluble-bound form, while, in pulp in the glycosided form, the glycosided and insoluble-bound phenolic acid fractions in jujube pulp represent the highest total phenolic content and the strongest antioxidant activity determined by DPPH and FRAP assays. Our results show that most phenolic compounds with antioxidant activity in different tissues of jujube are present as the glycosided and insoluble-bound forms.

It is well documented that blueberry phenolic compositions, such as phenolic acids and flavonoids differ based on species and cultivars. However, phenolic compositions in Florida blueberries have been little explored. Information on Florida blueberries are of interest as they are harvested earlier than other areas of the United States, which may result in compositional differences due to shorter daylight hours and cooler temperatures. Samples were harvested from University of Florida grower-cooperator farm near Gainesville, FL. After liquid-liquid extraction and C-18 SPE cartridge purification, concentrations of phenolic acids and flavonoids of twenty two blueberry cultivars (20 highbush and 2 rabbiteye) were measured using HPLC. Five phenolic acids (gallic acid, protocatechuic acid, chlorogenic acid, caffeic acid and ferulic acid), two flavan-3-ols (catechin and epicatechin) and five flavonols (quercetin-3-galactoside or quercetin-3-glucoside, quercetin-3-arabinoside, myricetin, quercetin and kaempferol) were identified and quantified. Chlorogenic acid was the major component in highbush blueberries. Flavonoid and phenolic acid composition were profoundly different among Florida blueberries and these differences have not been previously reported. The first two components of PCA explained 95% of the variation totally; it showed clear differentiation of blueberry cultivars based on phenolic composition. The majority of the variation between the cultivars was due to variation in quercetin-3-galactoside or glucoside, quercetin-3-arabinoside and chlorogenic acid, which are most likely due to genetic and maturity differences. Complete-linkage clustering analysis displayed five significantly different (p<0.05) clusters of blueberries, which were in agreement with PCA results, although some small differences were noted. Furthermore, Florida blueberries can be differentiated based on phenolic composition between highbush and rabbiteye species and varieties. Low flavanol content in rabbiteye blueberries may be related to maturity as these compounds typically decrease as berries ripen. Although the concentrations for phenolic compositions were lower than found in other reports, Florida blueberries contained a greater range of phenolic compounds. This information is valuable for blueberry breeding programs and growers for development of higher phenolic composition cultivar.

An investigation on minerals, arabinoxylans and other fibres of biofortified hull-less barley fractions obtained by two milling systems

The core objective of the current research was to determine the phenolic acids through High performance liquid chromatography (HPLC) in milling fractions of spring wheats, i.e., bran, shorts, break, and reduction flour. In wheat bran, caffeic, p-coumaric, syringic, and ferulic acid ranged from 0.93 to 1.5, 24 to 32.00, 55.30 to 94, and 137.25 to 180.30 μg/g, respectively. Maximum caffeic acid (0.33 μg/g), p-coumaric acid (12.12 μg/g), and ferulic acid content (29.12 μg/g) were found in the reduction flour of Sehar-2006. Furthermore, whole wheat flour of Shafaq-2006 revealed maximum caffeic acid (1.8 μg/g), p-coumaric acid (22.3 μg/g), and syringic acid (47.07 μg/g). Since antioxidant activity is directly related with phenolic acids, it was decreased (43.26 to 74.40%) in cookies with the decrease in phenolic acids during storage. Moreover, phenolic acids hold potential to be extracted and utilized in cereal-based products for best quality and value addition.

In vitro evaluation of the fermentation characteristics of the carbohydrate fractions of hulless barley and other cereals in the gastrointestinal tract of pigs

Polyamine and phenolic acid levels as well as activities of some enzymes of their biosynthetic metabolism were examined in two sugarcane (Saccharum officinarum) cultivars differing in susceptibility to leaf scald, a disease caused by the bacterium, Xanthomonas albilineans. Juice obtained from both infected cultivars showed significantly increased levels of free putrescine and ornithine decarboxylase activity. However, the pathogen induced different changes in the two cultivars in subsequent metabolic steps. Whereas acid insoluble conjugated spermidine completely disappeared from the highly susceptible cv. C 439-52, an increase in acid insoluble conjugated polyamines was observed in the moderately susceptible cv. L 55-5. Phenolic acid metabolism also differed in the two cultivars. Since total phenolic acid content and phenylalanine ammonium lyase activity was greater in both cultivars after infection, distribution of phenolic acids between free or conjugated forms diverted into different pathways. The level of susceptibility of the two cultivars is discussed in terms of changes in these compounds.

Localization of phenolic acids and antioxidant activity in sorghum kernels

The distribution of phenolic acids in pumpkin’s hull-less seed, skin, oil cake meal, dehulled kernel and hull

The distribution of phenolic acids in rice

The influence of cropping system, weather conditions and genotype on arabinoxylan content in wheat and barley grains