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Date fruits (Phoenix dactylifera) of ten varieties, collected in the United Arab Emirates, were studied to determine their dietary fiber content and composition. Fourier transform infrared (FTIR) spectroscopy indicated that the dietary fiber components in all the date fruit varieties was similar. The major dietary fiber components, including cellulose, hemicellulosic components, lignin, and pectin, were analyzed by the Uppsala method. The total dietary fiber content in the date fruits analyzed (5.2%–8.3%) is comparable to commonly consumed dried fruits and is correlated with the content of lignin. The lignin was the main determinant of the total dietary fiber content in dates and its content was higher in semi-hard and hard fruit varieties.

Date fruits vary widely in the hardness of their edible parts and they are classified accordingly into soft, semi-dry, and dry varieties. Fruit texture, a significant parameter in determining consumer acceptance, is related to the tissue structure and chemical composition of the fruit, mainly the ratio of sucrose to reducing sugars. This study aimed to understand the relationship between the chemical composition, microstructure, and texture profile of 10 major Emirati date fruits. The soluble sugars, glucose and fructose, represent ca 80 g/100 g of the fruits on the basis of dry weight (DW) while the dietary fiber contents varied 5.2–7.4 g/100 dg D.W. with lignin being the main determinant of the variability. The textures of the samples were studied using instrumental texture profile analysis. While no correlation was found between the soluble sugar and texture parameters in this study, the different fiber constituents correlated variably with the different parameters of date fruit texture. Lignin, arabinoxylan, galactomannan, and pectin were found to correlate significantly with fruit hardness and the related parameters, gumminess and chewiness. Both lignin and arabinoxylan correlated with resilience, and arabinoxylan exhibited a strong correlation with cohesiveness.

In this study, β-glucan in samples of sifted flour from six barley varieties was sequentially extracted with water and NaOH obtaining three fractions: water-extractable (WE), NaOH- extractable (NaE) and residual (Res). β-Glucan isolates were incubated with lichenase and oligomers released were analysed with high performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). A higher ratio of 3-O-β-cellobiosyl-D-glucose (DP3) to 3-O-β-cellotriosyl-D-glucose (DP4) is reported in WE, NaE and Res fractions in variety SLU 7 (shrunken endosperm) compared to the other varieties, suggesting a more packed β-glucan structure. Water-extractable and water-unextractable β-glucan fractions were incubated with wheat extract and effects of wheat β-glucanase on the structure was assessed after lichenase digestion and analysis with HPAEC-PAD. Findings suggest that wheat β-glucanase manifests a selective hydrolysis towards β-glucan with lower DP3/DP4 ratio and that β-glucan of SLU 7 is composed of a population with higher DP3/DP4 ratio and hence with a more tighten structure which may be more resistant to enzymic action. Overall, the results obtained are of interest to characterise barleys differing in starch and dietary fibre composition, specifically shrunken endosperm barley SLU 7 in the perspective of its inclusion in the production of β-glucan enriched foods.

The effects of genotype and environment on the content of bioactive components in rye were determined with four varieties being grown on one site for three years and on three additional sites in the third year and a fourth variety being included in all trials except year 1. Clear differences were observed in the extent to which the contents of dietary fiber components (arabinoxylan, beta-glucan, total dietary fiber) and phytochemicals (folates, alkylresorcinols, sterols, tocols, phenolic acids) varied between varieties and between the same varieties grown in different sites (United Kingdom, France, Hungary, Poland) and years (2005-2007 in Hungary), with sterols being the most stable and phenolic acids the least. However, no single variety could be selected as having the highest overall level of bioactive components or as being more stable in comparison across environments.

L'article original est publié par The American Society of Plant Biologists; International audience; 1,3;1,4)-(bêta-d-Glucan ((bêta-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 (bêta-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 (bêta-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 (bêta-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 (bêta-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 (bêta-glucan synthase and indicate that transgenic manipulation can be used to enhance the health benefits of wheat products.