The HEALTHGRAIN Cereal Diversity Screen: concept, results, and prospects

One hundred and fifty bread wheat lines and 50 other lines of small-grain cereals (spelt, durum wheat, Triticum monococcum, Triticum dicoccum, oats, rye, and barley) were selected for diversity in their geographical origin, age, and characteristics. They were grown on a single site in Hungary in 2004-2005, harvested, milled, and analyzed for a range of phytochemicals (tocols, sterols, phenolic acids, folates, alkylresorcinols) and fiber components that are considered to have health benefits. Detailed analyses of these components in the different species are reported in a series of accompanying papers. The present paper discusses the comparative levels of the bioactive components in the different species, showing differences in both ranges and mean amounts. Furthermore, detailed comparisons of the bread wheat lines show that it is possible to identify lines in which high levels of phytochemicals and dietary fiber components are combined with good yield and processing quality. This means that commercially competitive lines with high levels of bioactive components are a realistic goal for plant breeders.     

Qualitative characterization of benzoxazinoid derivatives in whole grain rye and wheat by LC-MS metabolite profiling

Benzoxazinoids are metabolites occurring in a restricted group of plant species including crops such as rye, wheat, and maize. Focus on the analysis of benzoxazinoid metabolites has typically been due to their importance to plant biochemistry and physiology as highly bioactive molecules that plants use as alleochemicals to defend themselves against predators and infections. However, the potential dietary contribution of these compounds has not been addressed. This study conducted a detailed qualitative characterization of benzoxazinoid metabolites present in the whole grain rye and processed fractions of rye bran, and their presence was also detected in whole grain wheat samples. Several novel benzoxazinoid metabolites of the hydroxamic acids (2,4-dihydroxy-1,4-benzoxazin-3-one, DIBOA; 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one, DIMBOA), lactams (2-hydroxy-1,4-benzoxazin-3-one, HBOA), and benzoxazolinones (1,3-benzoxazol-2-one, BOA) were identified, including double-hexose derivatives of DIBOA, DIMBOA, and HBOA. This paper presents an important addition to the information on the phytochemical composition of rye and wheat grains, which deserves attention in the discussion of the potential health-promoting effects of these grains.     

Gelation of Waxy Barley Starch Hydrolysates

Thealpha-amylolysis of gelatinized waxy barley starch and the gelation of the hydrolysates was studied. The progress of the hydrolysis was monitored with gel permeation and ion exchange chromatography. Initial attack occurred mainly between the clusters, without significant hydrolysis of the external chains. The stiffness of 20% gels prepared from the polymeric products decreased with increasing hydrolysis of the amylopectin. A linear relationship between the shear modulus and the original high-molecular weight amylopectin content was observed. Although the branched degradation products of amylopectin (average DP <6×10⁴) were not involved in network formation, they retained their ability to recrystallize as analysed by differential scanning colorimetry. For more extensively hydrolysed products (average DP <5000) no recrystallization or gel formation was observed under the conditions tested. Information on the gel structure was obtained with acid hydrolysis and ion exchange chromatography. The structure of the acid-resistant gel residues was complicated, showing a five-peak distribution when analysed with ion exchange chromatography. No differences between the original and hydrolysate gels was observed. The gel residues were resistant to isoamylase.     

Lipid removal enhances separation of oat grain cell wall material from starch and protein

Effects of lipid removal on the fine milling and air classification processing of oats were studied. Lipid removal by supercritical carbon dioxide (SC-CO₂) extraction enabled concentration of the main components of oats - starch, protein, lipids and cell walls - into specific fractions. Using defatted oats as raw material, the highest β-glucan concentration of the cell wall-enriched fraction was 33.9% as compared to 17.1% without lipid removal. This was probably due to more efficient milling yielding smaller particles, and release of starchy material from cellular structures during milling of defatted oats, resulting in better classification. The removal of lipids also enabled separation of an oat protein concentrate with a protein concentration of 73.0% and a mass yield of 5.0%. A trial with 2310 kg of oat groats showed that the process based on defatting and dry fractionation was also industrially applicable.     

Studies of the in vitro intestinal metabolism of isoflavones aid in the identification of their urinary metabolites

Soy isoflavones have recently gained considerable interest due to their possible health benefits. However, detailed studies on the metabolism of isoflavones are lacking. The aims of the investigation presented here were (1) to study the in vitro intestinal metabolism of isoflavones and their hydroxylated analogues 3'-OH-daidzein, 6-OH-daidzein, 8-OH-daidzein, and 3'-OH-genistein and (2) to characterize the structures of some earlier identified urinary metabolites of soy isoflavones, for which no authentic reference compounds have been available. Isoflavone standards (1-2 mg) were fermented with human fecal flora (16.7%) for 24 h. Metabolites formed during the fermentation were tentatively identified by interpretation of the mass spectra of trimethylsilylated compounds obtained by GC-MS. Compounds having hydroxyl groups at 5-position (i.e., genistein and 3'-OH-genistein) were completely converted to metabolites that could not be detected by the methods used in this study. The metabolism of daidzein and its hydroxylated analogues, 3'-OH-daidzein, 6-OH-daidzein, and 8-OH-daidzein, occurred to a much lesser extent. Minor amounts of reduced metabolites (i.e., isoflavanones and alpha-methyldeoxybenzoins) of these compounds were tentatively identified in fermentation extracts. The retention times and the mass spectra of reduced isoflavone metabolites, obtained from in vitro fermentations of pure compounds, were utilized to identify unknown urinary metabolites of soy isoflavones. Four novel isoflavone metabolites were identified in human urine collected after soy supplementation: 3' '-OH-O-desmethylangolensin, 3',4',7-trihydroxyisoflavanone, 4',7,8-trihydroxyisoflavanone, and 4',6,7-trihydroxyisoflavanone.     

The effect of growth temperature on gelatinization properties of barley starch

The effects of growth conditions on the properties of barley starch were studied with the two‐rowed malting barley cultivars “Kustaa”; and “Kymppi”; field‐grown in Finland during a cold summer and a normal summer. In both cultivars, the growth conditions had an effect on the composition and gelatinization behaviour of both small and large granules. In the starches from the cold summer, the lipid content and gelatinization peak temperatures were lower, the gelatinized starch also being more easily hydrolysed by alpha‐amylase.     

Combined enzymatic and high-pressure processing affect cell wall polysaccharides in berries

The effect of high-pressure processing (HPP) on cell wall polysaccharides in berries was investigated. HPP decreased the degree of methyl esterification (DM), probably by activation of pectin methyl esterase (PME), and improved the extractability of pectins. When commercial enzyme mixtures were added to mashed berries, a synergistic effect was observed between treatment with commercial enzymes and HPP. Compared to treatment at atmospheric pressure, pectic polysaccharides were degraded to a larger extent when HPP was used. In contrast, hemicelluloses were hardly affected by the added enzymes when HPP was included, although they were degraded during similar treatment at atmospheric pressure. Additionally, the activity of rhamnose-releasing enzymes present in minor quantities might be enhanced after HPP, resulting in a decrease of rhamnose in the polymeric cell wall material. These results exploring the effect of HPP at representative conditions clearly point out the potential of HPP for polysaccharide modification.     

Developmental lignification and seasonal variation in beta-glucosidase and peroxidase activities in xylem of Scots pine,Norway spruce and silver birch

We examined the relationship between beta-glucosidase and peroxidase activities and xylem lignification in the stems of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) during the 1999 growing season. Examination of stem cross sections stained with safranin and Alcian blue for lignin and cellulose, respectively, indicated that radial growth of pine and spruce xylem began in late May, whereas the growth of birch xylem was initiated 2 weeks later. Lignification began soon after thickening of the newly formed cell walls, i.e., upon deposition of cellulose. Hydrolysis of the synthetic beta-glucosidase substrate p-nitrophenyl-beta-O-D-glucopyranoside was correlated with radial growth and lignification in the xylem of both conifers, but the relationship between lignification and the hydrolysis of coniferin by beta-glucosidase was not obvious. Beta-glucosidase activities in the xylem of silver birch were low and did not correlate with growth or lignification with either substrate. An increase in peroxidase activity was detected at the initiation of growth and lignification in the conifers and during growth and lignification in silver birch, but high peroxidase activities were also measured outside the growth period during late autumn, winter and early spring.