Annica A.M. Andersson

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.

Phytochemicals and dietary fiber components in rye varieties in the HEALTHGRAIN diversity screen

Ten rye varieties grown in one location were analyzed for their contents of dietary fiber (arabinoxylan and beta-glucan) and phytochemicals (folate, tocols, phenolic acids, alkylresorcinols, and sterols). The varieties included old and modern varieties from five European countries. Significant differences were observed in the contents of all phytochemicals in whole grains and in the fiber contents in the flour and bran. The old French varieties Haute Loire and Queyras had high contents of most phytochemicals, whereas the Polish varieties Dankowskie-Zlote and Warko were relatively poor in phytochemicals. The varieties with a high content of folate tended to have low alkylresorcinol contents and vice versa. Furthermore, high contents of arabinoxylans were associated with high contents in tocols and sterols. The 10 selected rye samples comprising old populations and old and modern varieties from different ecological regions of Europe demonstrate high natural variation in their composition and show that landraces and old populations are useful genetic resources for plant breeding. The contents of single phytochemicals can likely be affected by breeding, and they may be adjusted by the right selection of genotype.

The HEALTHGRAIN Wheat Diversity Screen: Effects of Genotype and Environment on Phytochemicals and Dietary Fiber Components

Analysis of the contents of bioactive components (tocols, sterols, alkylresorcinols, folates, phenolic acids, and fiber components) in 26 wheat cultivars grown in six site x year combinations showed that the extent of variation due to variety and environment differed significantly between components. The total contents of tocols, sterols, and arabinoxylan fiber were highly heritable and hence an appropriate target for plant breeding. However, significant correlations between the contents of bioactive components and environmental factors (precipitation and temperature) during grain development also occurred, with even highly heritable components differing in amount between grain samples grown in different years on different sites.

Determination of β-Glucan Molecular Weight Using SEC with Calcofluor Detection in Cereal Extracts

ABSTRACT A high-performance size-exclusion chromatography system (HPSEC) was set up with detection based on the specific binding of Calcofluor to β-glucan for determination of amount and molecular weight of β-glucan in different cereal extracts. To calibrate the HPSEC system, a purified β-glucan was fractionated into narrow molecular weight ranges and the average molecular weight was determined before analysis on the HPSEC system. The detector response was similar for β-glucans from oats and barley and appeared to be independent of molecular weight. Four different methods for extraction of β-glucan from different cereal products were tested: two alkaline, one with hot water and added α-amylase, and one with water and added xylanase. Inactivation of endogenous β-glucanase was crucial for the stability of the extracts, even when extracting at high temperature or pH. Yields varied widely between the different extraction methods but average molecular weight and molecular weight distribution were similar. Extr...

Phytochemical and fiber components in oat varieties in the healthgrain diversity screen

The levels and compositions of a range of phytochemicals (sterols, tocols, avenanthramides, folates, phenolic acids) and dietary fiber components were determined in five oat cultivars (four husked and one naked) grown on a single site in 2005. The total levels of tocols, phenolic acids, and avenanthramides varied by over 2-fold between cultivars, but less variation occurred in total sterols and total folates. Limited variation was also observed in the dietary fiber content and composition of the four husked lines. These results indicate that it may be possible to selectively breed for lines with high contents of dietary fiber and specific groups of phytochemicals.

Down-Regulation of the CSLF6 Gene Results in Decreased (1,3;1,4)-β-d-Glucan in Endosperm of Wheat

(1,3;1,4)-β-d-Glucan (β-glucan) accounts for 20% of the total cell walls in the starchy endosperm of wheat (Triticum aestivum) and is an important source of dietary fiber for human nutrition with potential health benefits. Bioinformatic and array analyses of gene expression profiles in developing caryopses identified the CELLULOSE SYNTHASE-LIKE F6 (CSLF6) gene as encoding a putative β-glucan synthase. RNA interference constructs were therefore designed to down-regulate CSLF6 gene expression and expressed in transgenic wheat under the control of a starchy endosperm-specific HMW subunit gene promoter. Analysis of wholemeal flours using an enzyme-based kit and by high-performance anion-exchange chromatography after digestion with lichenase showed decreases in total β-glucan of between 30% and 52% and between 36% and 53%, respectively, in five transgenic lines compared to three control lines. The content of water-extractable β-glucan was also reduced by about 50% in the transgenic lines, and the Mr distribution of the fraction was decreased from an average of 79 to 85 × 104 g/mol in the controls and 36 to 57 × 104 g/mol in the transgenics. Immunolocalization of β-glucan in semithin sections of mature and developing grains confirmed that the impact of the transgene was confined to the starchy endosperm with little or no effect on the aleurone or outer layers of the grain. The results confirm that the CSLF6 gene of wheat encodes a β-glucan synthase and indicate that transgenic manipulation can be used to enhance the health benefits of wheat products.

Chemical and physical characteristics of different barley samples

Eight different barleys, including covered and naked samples containing low, normal and high amylose starches as well as a sample with low starch and high β-glucan content and a malting barley, were examined both from a chemical and physical perspective. In the chemical characterisation of the samples, analyses of nutrients were performed, while in the physical characterisation, weight of individual kernels, sieving fractions, bulk density, terminal velocity by pneumatic classification and parameters from a Single Kernel Characterization System (SKCS) were analysed. Results were evaluated by principal component analysis (PCA). The major trend found was that hull content and endosperm composition varied independently of each other. Constituents found mainly in the hull were positively correlated with each other, but negatively with bulk density and the 95% quantile of terminal velocity. There was a positive correlation between average value and standard deviation of grain mass, fat and starchy endosperm components such as extractable dietary fibre residues and β-glucan. The latter variables were negatively correlated to β-glucan extractability.

Alkylresorcinols in wheat varieties in the HEALTHGRAIN Diversity Screen.

The contents of alkylresorcinols (AR) were analyzed in 131 winter wheats, 20 spring wheats, 10 durum wheats, 5 spelt wheats, and 10 early cultivated forms of wheat (5 diploid einkorn and 5 tetraploid emmer), which are part of the HEALTHGRAIN diversity screen. AR were analyzed by gas chromatography (GC), which provides both total contents and relative homologue compositions, as well as with a Fast Blue colorimetric method that provides only total contents but which is fast and easily screens a large number of samples. There was considerable variation in the total AR content analyzed with GC: winter wheat (220-652 microg/g of dm), spring wheat (254-537 microg/g of dm), durum wheat (194-531 microg/g of dm), spelt (490-741 microg/g of dm), einkorn (545-654 microg/g of dm), and emmer wheat (531-714 microg/g of dm). The relative AR homologue composition was different for different types of wheat, with a C17:0 to C21:0 ratio of 0.1 for winter, spring, and spelt wheats, 0.04 for einkorn and emmer wheat, and 0.01 for durum wheat. The total AR content analyzed with the Fast Blue method was lower than that analyzed with GC but there was a good correlation between the two methods (R(2) = 0.76).

Natural variation in grain composition of wheat and related cereals

The wheat grain comprises three groups of major components, starch, protein, and cell wall polysaccharides (dietary fiber), and a range of minor components that may confer benefits to human health. Detailed analyses of dietary fiber and other bioactive components were carried out under the EU FP6 HEALTHGRAIN program on 150 bread wheat lines grown on a single site, 50 lines of other wheat species and other cereals grown on the same site, and 23-26 bread wheat lines grown in six environments. Principal component analysis allowed the 150 bread wheat lines to be classified on the basis of differences in their contents of bioactive components and wheat species (bread, durum, spelt, emmer, and einkorn wheats) to be clearly separated from related cereals (barley, rye, and oats). Such multivariate analyses could be used to define substantial equivalence when novel (including transgenic) cereals are considered.

Chemical composition of the potential new oilseed crops Barbarea vulgaris, Barbarea verna and Lepidium campestre

Barbarea vulgaris, Barbarea verna and Lepidium campestre were selected as potential new oilseed crops. To evaluate the nutritional and technological quality of the seeds, the chemical composition was studied. The major constituents found were dietary fibre, crude fat and crude protein. Barbarea contained about 350 g kg−1 dietary fibre, 295 g kg −1 crude fat and 170 g kg−1 crude protein, while Lepidium contained about 400 g kg−1 dietary fibre, 200 g kg−1 crude fat and 190 g kg−1 protein. The amino acid composition was found to be suitable for human consumption when comparison with the amino acid pattern for high quality protein was made. Fatty acid composition was dominated by erucic acid in B vulgaris (28%) and B verna (50%) and by linolenic acid in L campestre (34%). Insoluble dietary fibres were dominated by Klason lignin in both Barbarea and Lepidium. Uronic acid and glucose residues were also found in large amounts. Soluble dietary fibres were dominated by uronic acid, arabinose and galactose residues. The major glucosinolates found were glucobarbarin in B vulgaris (108 μmol g−1), gluconasturtiin in B verna (106 μmol g−1) and sinalbin in L campestre (110 μmol g−1). No cyanogens were found in any of the seeds. © 1999 Society of Chemical Industry