Composition of Functional Lipids in Hulled and Hulless Barley in Fractions Obtained by Scarification and in Barley Oil

Two cultivars of hulled barley (Thoroughbred and Nomini) and two cultivars of hulless barley (Doyce and Merlin) were scarified to abrade the outer layers of hull and pericarp. The resulting scarification fines fractions were evaluated as potential sources of functional lipids (phyto‐sterols, tocopherols, and tocotrienols). The levels of total phytosterols and total tocotrienols in the barley scarification fine fractions were probably not high enough to justify their use as functional foods. However, the levels of total phytosterols and total tocotrienols in the oils extracted from both whole kernels and scarified fines were both sufficiently high to make it reasonable to consider their potential use as new functional oils. Indeed, the levels of total tocotrienols in barley oils (2,911–6,126 mg/kg of oil) are several‐fold higher than those reported in two other oils that are being marketed as high in tocotrienols: palm oil (530 mg/kg) and rice bran oil (770 mg/kg). The levels of total phytosterols in barley oils range from 1.20 to 9.60 g/100 g of oil.     

Tocopherols and Tocotrienols in Barley Oil Prepared from Germ and Other Fractions from Scarification and Sieving of Hulless Barley

Two cultivars of hulless barley (Doyce and Merlin) were scarified to abrade the outer layers of the kernels (germ, pericarp, and aleurone). The resulting scarification fines fractions were then separated into four particle-size subfractions using sieves. Each of the size subfractions was then extracted with hexane to produce a barley oil, and the levels of free phytosterols, tocopherols, and tocotrienols in the various barley oils were compared. For both cultivars, the fraction with the largest particle size (0.717–1.410 mm) had the highest oil yields (11–12%). Visual examination of this fraction indicated that it consisted almost entirely of small fragments (≈1 mm) of the germ portion of the kernel. The levels of tocopherols were highest in the largest particle-size fraction and their proportion decreased in the fractions with decreasing particle size. In contrast, the levels of tocotrienols were very low in the largest particle-size fraction and increased in the fractions with decreasing particle sizes. Intact germ was also prepared by hand-dissection, extracted, and analyzed. The results indicate that the ≈1 mm germ fragments obtained by scarification-sieving consisted almost entirely of germ fragments, but these fragments represented only 17.5 and 23.7% of the total mass of the germ, from Merlin and Doyce, respectively. These results also suggest that it may be possible to control the concentrations of tocopherols and tocotrienols in barley oil by controlling the particle size of the feedstock used to extract the oil. Germ fragments isolated by such processes could potentially be used as functional food ingredients or extracted to yield oils enriched in health-promoting phytosterols, tocopherols, or tocotrienols.     

The changes in physiological and biochemical traits of Tibetan wild and cultivated barley in response to low phosphorus stress

Low phosphorus (LP) limits crop growth and productivity in the majority of arable lands worldwide. Here, we investigated the changes in physiological and biochemical traits of Tibetan wild barleys (Hordeum vulgare L. ssp. spontaneum) XZ99 (LP tolerant), XZ100 (LP sensitive), and cultivated barley ZD9 (moderately LP tolerant) under two phosphorus (P) levels during vegetative stage. These genotypes showed considerable differences in the change of biomass accumulation, root/shoot dry weight ratio, root morphology, organic acid secretion, carbohydrate metabolism, ATPase (Adenosine triphosphatase) activity, P concentration and accumulation under LP in comparison with CK (control) condition. The higher LP tolerance of XZ99 is associated with more developed roots, enhanced sucrose biosynthesis and hydrolysis of carbohydrate metabolism pathway, higher APase (Acid phosphatase) and ATPase activity, and more secretion of citrate and succinate in roots when plants are exposed to LP stress. The results prove the potential of Tibetan wild barley in developing barley cultivars with high tolerance to LP stress and understanding the mechanisms of LP tolerance in plants.     

Chemical Composition of Barley Cultivars Fractionated by Weighing,Pneumatic Classification,Sieving, and Sorting on a Specific Gravity Table

Five different barley cultivars, including covered and naked samples containing low, normal, or high-amylose starches were fractionated by weighing, pneumatic classification, sieving, or sorting on a specific gravity table, and analyzed for content of starch, protein, ash, and β-glucan. For ash content, almost no variation could be found between different fractions. Protein content was minimum in the intermediate fractions for all cultivars when sorted by weighing. For the other fractionation methods, the differences in protein content were small. A tendency for decreasing content of starch with increasing grain mass and size could be seen when fractionating grains by weighing and sieving, respectively. The clearest trend was seen in differences in β-glucan content for all cultivars and all methods used. The main interpretation of our results is, however, that the chemical composition within the cultivars studied is very similar for all fractions, and that the differences between the unfractionated barley samples are larger.     

Malting Oats: Effects on Chemical Composition of Hull-less and Hulled Genotypes

Samples of hull-less oat genotypes from the Cooperative Naked Oat Test grown in Ottawa, ON, and Aberdeen, ID, were analyzed for their potential as a food malt. Malted oats had a lower concentration of petroleum ether-extractable lipid, but a much higher percentage of the lipid was in the form of free fatty acids. About 5% less starch and slightly more N was found in malted oats than in unmalted. Malted oats contained ≈8% soluble carbohydrate. During the germination phase of malting, nearly all the β-glucan was degraded. α-Amylase activity of malted oats approached that of malting barleys, but diastatic power was much lower. Groats of hulled cultivars grown at Madison, WI, were malted and analyzed with similar results. Because the increased levels of free fatty acids in the malted grains may lead to the development of rancid flavors, a method to curtail their increase or selections of genotypes with a minimum increase during malting may be necessary to produce a useful malted food product.     

Quality of Flours from Waxy and Nonwaxy Barley for Production of Baked Products

One nonwaxy (covered) and two waxy (hull-less) barleys, whole grain and commercially abraded, were milled to break flour, reduction flour, and the bran fraction with a roller mill under optimized conditions. The flour yield range was 55.3–61.8% in whole grain and increased by 9–11% by abrasion before milling. Break flours contained the highest starch content (≤85.8%) independent of type of barley and abrasion level. Reduction flours contained less starch, but more protein, ash, free lipids, and total β-glucans than break flours. The bran fraction contained the highest content of ash, free lipids, protein, and total β-glucans but the lowest content of starch. Break flours milled from whole grain contained 82–91% particles <106 μm, and reduction flours contained ≈80% particles <106 μm. Abrasion significantly increased the amount of particles <38 μm in break and reduction flours in both types of barley. Viscosity of hot paste prepared with barley flour or bran at 8% concentration was strongly affected by barley type and abrasion level. In cv. Waxbar, the viscosity in bran fractions increased from 428 to 1,770 BU, and in break flours viscosity increased from 408 to 725 BU due to abrasion. Sugar snap cookies made from nonwaxy barley had larger diameter than cookies prepared from waxy barley. Cookies made from break flours were larger than those made from reduction flours, independent of type of barley. Quick bread baked from nonwaxy barley had a loaf volume similar to that of wheat bread, whereas waxy barley bread had a smaller loaf volume. Replacement of 20% of wheat flour by both waxy and nonwaxy barley flour or bran did not significantly affect the loaf volume but did decrease the hardness of quick bread crumb.     

Vitamin E Homologs and γ‐Oryzanol Levels in Rice (Oryza sativa L.) During Seed Development

Vitamin E homologs (tocopherols and tocotrienols) and γ‐oryzanol have gained significant attention because of their proposed health benefits and ability to increase vegetable oil stability. Changes in the levels of these phytochemicals were examined during seed development. Rapid accumulation of tocopherols, tocotrienols, and γ‐oryzanol occurred during early seed development. During the middle stage of seed development, the levels of tocopherols decreased sharply, and the levels of tocotrienols either stayed the same or decreased slightly, whereas γ‐oryzanol continued to accumulate until maturity. The levels of these compounds remained constant from maturity to 15 days postmaturity. In conclusion, rice grain for nutraceutical and functional food applications should be harvested during its immature stage to obtain the highest amount of tocopherols, whereas the amounts of the other phytochemicals that were studied can be optimized by harvesting grain at maturity.     

Air Classification of Barley Flours

Flour samples from seven different barleys, including covered and naked barleys and barleys with normal, waxy, and high‐amylose starches, as well as the high fiber barley Prowashonupana, were impact‐milled and air‐classified in a pilot unit. Six fractions (F1–F5 and C5) with increasing particle size were obtained from each barley. All fractions were analyzed for ash, protein, starch, dietary fiber, and total and unextractable β‐glucan. Ash was enriched in C5; covered barleys (4.3–5.7% of dry matter) had a higher ash content than naked barleys (2.1–3.2%). Starch was enriched in F4 for normal and waxy barleys (72–79%) and in F3 for high‐amylose barleys (72–75%). Protein was enriched in F1 (14–26%) for the different barleys. β‐glucan was enriched in F5 and C5 (7–23%), Prowashonupana had the highest value. The extractability of β‐glucan decreased with increasing particle size, probably because of lower amounts of endogenous β‐glucanase and poorer availability of the substrate in larger particles.     

Effect of Barley β-Glucan in Durum Wheat Pasta on Human Glycemic Response

High-fiber, high-carbohydrate diets, including foods with low glycemic index, have been associated with prevention and treatment of diseases such as coronary heart disease and diabetes. β-glucan, a soluble, viscous polymer found in oat and barley endosperm cell wall, was incorporated into pasta test meals. Five fasted adult subjects were fed test meals of a barley and durum wheat blend pasta containing 100 g of available carbohydrate, 30 g of total dietary fiber (TDF) and 12 g of β-glucan, or an all durum wheat pasta containing the same amount of available carbohydrate, 5 g of TDF, and negligible β-glucan. The β-glucan and durum wheat pasta resulted in a lower glycemic response as measured by average total area and maximum increment of the blood glucose curves. Lower insulin response to the β-glucan and durum wheat pasta was also indicated by lower average area and increment characteristics of the insulin curves. Barley β-glucans may be an economical and palatable ingredient for processed food products formulated to modify glycemic and insulin response.     

Molecular Characterization of Barley β-Glucans by Size-Exclusion Chromatography with Multiple-Angle Laser Light Scattering and Other Detectors

Molecular characteristics were determined for mixed-linkage (1→3) (1→4)-β-d -glucans (β-glucans) extracted from Azhul, Crystal, Waxbar, and Prowashonupana barleys. β-Glucans in extracts (with or without α-amylase, protease, hemicellulase, or xylanase treatment) were separated from other components by high-performance size-exclusion chromatography and detected with multiple-angle laser light scattering, refractive index, and fluorometry following postrefractive index treatment with Calcofluor. Pretreatment of barley with 70% ethanol (80°C, 4 hr) reduced β-glucanase activity by ~20%. Hot-alcohol treatment also reduced β-glucan extraction at 23 and 65°C by 42 and 14%, respectively. Molecular weights of β-glucans in the first water extract were generally higher than in succeeding water and alkali extracts. Weight average molecular weights ranged from 0.44 × 10⁶ to 2.34 × 10⁶ g/mol after α-amylase treatment to remove interfering starch. Interference due to pentosans was not demonstrated using enzyme treatments.     

Enzyme-Assisted Wet Separation of Starch from Other Seed Components of Hull-less Barley

A multiple enzyme cocktail containing cellulase, endo-(1→3), (1→4)-β-d -glucanase and xylanase was used in wet separation of starch, protein, β-glucan, bran, and tailings from four hull-less barleys (HB): SB94794 (0% amylose), CDC Candle (5% amylose), CDC Dawn (24% amylose), and SB550831 (40% amylose). Compared to a conventional procedure, the enzyme-assisted wet extraction reduced slurry viscosity by 50–99%, the amount of water and ethanol used in screening and β-glucan precipitation by 30–60%, and screening time by 20–80%. The enzyme-assisted extraction reduced starch contents and yields of tailings and bran fractions, resulting in a 10% increase in average starch extraction efficiency. However, β-glucan yield was reduced in the enzyme-assisted extraction, particularly in high-viscosity HB. The physicochemical properties of isolated starches were not affected by the enzyme-assisted extraction.     

Comparison of Pearled and Unpearled Canadian and Japanese Barleys

Canadian and Japanese barleys were compared for whole and pearled grain composition and starch properties. Whole grain color and composition of the barleys showed large intercultivar differences, but few (color, protein, and total dietary fiber) significant differences between the Canadian and Japanese barleys. The Canadian hull-less barleys (HB) were pearled to 55% yield to match pearl yields of Japanese barleys. In Canadian HB, pearl time was correlated (r² = +0.96**) with grain hardness. There were large intercultivar differences in color and composition of the pearled barleys; only protein, starch, total dietary fiber, and viscosity showed significant differences between the Canadian and Japanese pearled barleys. Pasting properties of the four Canadian pearled barleys (CDC Candle, AC Hawkeye, Falcon, and CDC Richard) and three Japanese pearled barleys (Hinode, Ichiban-Boshi, and Minori) showed Canadian pearled barleys had higher peak viscosity, viscosity at 95°C, and setback viscosity than the Japanese barleys. These differences in pasting properties were not related to amylose or crude lipid contents of Canadian and Japanese pearled barleys, nor to swelling factor and thermal properties of starches isolated from the barleys. They were likely due to higher β-glucan and protein in starch slurries of Canadian HB.     

Starch and By‐Products from a Laboratory‐Scale Barley Starch Isolation Procedure

Starch was isolated from three different barleys with normal, highamylose, or high‐amylopectin (waxy) starch. The laboratory‐scale starch isolation procedure included crushing of grains, steeping, wet milling, and sequential filtration and washing with water and alkali, respectively. Yield and content of starch, protein, and dietary fiber, including β‐glucan, were analyzed in isolated starch and in the by‐products obtained. Starch yield was 25–34%, and this fraction contained 96% starch, 0.2–0.3% protein, and 0.1% ash. Most of the remaining starch was found in the coarse material removed by filtration after wet milling, especially for the high‐amylose barley, and in the starch tailings. Microscopy studies showed that isolated starch contained mostly A‐granules and the starch tailings contained mostly B‐granules. Protein concentration was highest in the alkali‐soluble fraction (54%), whereas dietary fiber concentration was highest in the material removed by filtration after alkali treatment for the normal and waxy barleys (55%). The β‐glucan content was especially high for the waxy barley in this fraction (26%). The study thus showed that it was possible to enrich chemical constituents in the by‐products but that there were large differences between barleys. This result indicates a need for modifications in the isolation procedures for different barleys to obtain high yields of starch and different by‐products. Valuable by‐products enriched in β‐glucan or protein, for example, may render starch production more profitable.     

Study of the main constituents of some authentic hazelnut oils

This paper describes the composition of authentic hazelnut oils obtained from nuts collected from five countries that are major suppliers of hazelnut oil. Oils were analyzed using standard methods for fatty acids, fatty acids in the triacylglycerol 2-position, tocopherols and tocotrienols, triacylglycerols, sterols, steradienes, and iodine value. The results were generally in good agreement with those of other publications. Tocotrienols, previously unreported in hazelnut oil, were detected in one sample. There were no major differences in the composition of oils from different countries. Roasting the nuts prior to pressing had little effect on oil composition.     

Comparisons of β-Glucan Content of Barley and Oat

The cholesterol-lowering effect of cereal grains has been associated with the soluble fiber component of dietary fiber. β-Glucan is the major soluble fiber component of barley (Hordeum vulgare L.) and oat (Avena sativa L.). Much research has been conducted to determine the β-glucan content of barley and oat genotypes from many different countries. However, genotypes of both crops always were grown in separate experiments, making direct comparisons between the two crops difficult. This study compares in the same experiment the β-glucan content of nine barley and 10 oat genotypes grown at two locations in each of two years (i.e., four environments) in North Dakota. Averaged across genotypes, total β-glucan content of barley and oat groat was similar. Soluble β-glucan content of oat groat was greater than barley, and oat groat had a greater ratio of soluble-to-total β-glucan than barley. The soluble β-glucan content and ratio of soluble to total β-glucan content of the “best” barley genotypes were less than that of oat genotypes with the highest levels of these two traits.     

Barley carbohydrate composition varies with genetic and abiotic factors

Abstract

Changes in chemical quality arising from genetic composition of different barley varieties as well as non-genetic factors were investigated by comparing samples from different seasons and locations. The samples (15), consisting of different varieties originating from Norway and Canada, were analysed for polysaccharide composition as well as total protein content. The results revealed differences in chemical parameters between the hulled and hull-less varieties, especially in carbohydrate composition. Also, variations within the types were found, which indicated that factors other than the presence or lack of hull may also influence the carbohydrate composition. As expected, varieties grown at the same location in both seasons had a lesser variation in their grain composition between the growing periods than varieties grown at different locations. Changing the growth location from Canada to Norway also gave an increase in starch and insoluble fibre, but decreased the amount of β-glucan, protein and soluble fibre. Promising varieties for the food industry are samples with an atypical starch characteristic without hull, due to higher levels of the proposed health-beneficial components. Also, the commercial Norwegian variety, Olve, had an advantageous grain composition and is a promising variety for food uses.     

The Potential of Hull-less Barley

Hull-less barley (HB) has been investigated in many countries for use in feed, food, and industry since the publication of the last review in 1986. Literature published since 1990 on various aspects of HB utilization, other than in monogastric feeds, has been reviewed. Several HB cultivars containing low or β-glucan, low or high extract viscosity, and waxy (0–5% amylose) or normal starch are now available. Interest in HB utilization in the food industry developed largely due to its high β-glucan content, particularly in the waxy cultivars. β-Glucan is a major component of soluble fiber implicated in hypocholesterolemia, hypoglycemia, and in reducing incidence of chemically induced colon cancer in experimental animals. However, large-scale clinical trials using human subjects are needed to corroborate these effects. The zero amylose HB starch had low syneresis or a high freeze-thaw stability suitable for use in frozen foods. Single- or double-modified waxy HB starch may replace corn starch in some food applications, and cationized HB starch can replace corn and potato starches in the pulp and paper industry. HB may be milled using conventional wheat milling equipment to yield bran and flour for multiple food uses. Hull-less barley may also be used as a feed stock for fuel alcohol production, for the preparation of food malt with low or high enzyme activities, and for brewer's and distiller's malts.     

Phytochemical and dietary fiber components in barley varieties in the HEALTHGRAIN Diversity Screen

Ten different barley varieties grown in one location were studied for their content of tocols, folate, plant sterols, alkylresorcinols, and phenolic acids, as well as dietary fiber components (arabinoxylan and beta-glucan). The samples included hulled and hull-less barley types and types with normal, high-amylose, and waxy starch. The aim was to study the composition of raw materials, and therefore the hulls were not removed from the hulled barleys. A large variation was observed in the contents of all phytochemicals and dietary fibers. Two varieties from the INRA Clermont Ferrand barley program in France (CFL93-149 and CFL98-398) had high content of tocopherols and alkylresorcinols, whereas the variety Dicktoo was highest in dietary fiber content and phenolics. Positive correlations were found between 1000 kernel weight, alkylresorcinols, and tocols, as well as between dietary fiber content and phenolic compounds. The results demonstrate that the levels of phytochemicals in barley can likely be affected by breeding and that the contents of single phytochemicals may easily be adjusted by a right selection of a genotype.     

Comparison of the phosphorus and mineral concentrations in bran and abraded kernel fractions of a normal barley (Hordeum vulgare) cultivar versus four low phytic acid isolines

Phytic acid consists of 65-80% of the total phosphorus (P) in cereal grains. Its salts are concentrated in the germ and aleurone layers, which are typically removed during milling. We hypothesize that concentrations of different types of P and minerals in milled products will be greatly altered in low phytic acid (lpa) barleys. Seeds of cv. Harrington (control) and four lpa isolines-lpa1-1, lpa2-1, lpa3-1, and M955-were abraded by a laboratory method into five surface layer and four remaining kernel fractions. Results show that phytic acid in the four lpa lines ranged from 75% to 5% of the control. The decrease in phytic acid P concentration was matched almost equally by an increase in inorganic P, so that the rest of P (the sum of all P-containing compounds other than phytic acid P and inorganic P) and total P levels remained relatively unchanged among the five genotypes. These trends were also observed for the processed fractions. The major mineral elements in barley seeds were P, K, Mg, S, and Ca, while minor ones were Fe, Zn, Mn, Cu, and Ba. All types of P and other minerals measured were generally concentrated in the outer layers of the grain. Although there were substantial differences in mineral contents of bran fractions among genotypes, the level of phytic acid P had little effect on mineral contents in whole or abraded kernels. One major exception was Fe, which had the highest level in all tissues of M955 genotype. The above findings were all confirmed by analyzing another set of barley samples grown in a different environment. Thus, in general, breeding lpa barleys does not lead to reduced mineral contents in whole grains or elevated mineral levels in milled products.     

Molecular Weight Distribution and (1→3)(1→4)-β-d-Glucan Content of Consecutive Extracts of Various Oat and Barley Cultivars

The content and molecular weight (MW) of β-glucan in extracts from a selection of oat and barley cultivars were compared using flow-injection analysis and high-performance size-exclusion chromatography. From 60 to 75% of the β-glucan was extracted from oat and waxy barley by hot water (90°C) containing heat-stable α-amylase, whereas just 50–55% was extracted from nonwaxy barley. Consecutive extractions with hot water and dimethylsulfoxide (DMSO) extracted 65% (nonwaxy barley) or 75–80% (oat and waxy barley) of the total β-glucan. An extraction with sodium hydroxide and sodium borohydride (NaOH/NaBH₄) increased the percentage of β-glucan extracted to 86–100% but decreased the MW. The MW of β-glucan in the oat cultivars selected was significantly higher than those in the barley cultivars. The β-glucan extracted from the nonwaxy barley cultivars showed significantly higher peak MW than that from the waxy barley cultivars.