Isolation, modification and characterization of soluble arabinoxylan fractions from rye grain

The Influence of Arabinoxylans on the Properties of Wheat Bread Baked Using the Postponed Baking Method

Bread is a basic element of the human diet. To counteract the process of its going stale, semi-finished bakery products are subjected to cooling or freezing. This process is called postponed baking. The aim of this work was to investigate the effect of the molar mass of rye arabinoxylans (AXs) on the properties of wheat breads baked using the postponed baking method. Breads were produced using the postponed baking method from wheat flour without and with 1 or 2% share of rye AXs clearly differing in molar masses-non-modified or modified AXs by means of partial hydrolysis and cross-linking. The molar mass of non-modified AXs was 413,800 g/mol, that of AXs after partial hydrolysis was 192,320 g/mol, and that of AXs after cross-linking was 535,630 g/mol. The findings showed that the addition of all AX preparations significantly increased the water absorption of the baking mixture, and the increase was proportional to the molar mass of AXs used as well as the share of AX preparation. Moreover, for the first time, it was shown that 1% share of partly hydrolyzed AXs, of a low molar mass, in the baking mixture had the highest effect on increasing the volume of bread and reducing the hardness of the bread crumb of bread baked using postponed baking method. It was also shown that the AXs had a low and inconclusive effect on the baking loss and moisture content of the bread crumb.

The cultivation of rye in marginal Alpine environments: a comparison of the agronomic, technological, health and sanitary traits of local landraces and commercial cultivars

Rye is a secondary crop that is characterized by a higher tolerance to climatically less favorable conditions than other cereal species. For this reason, rye was historically used as a fundamental raw material for bread production and as a supply of straw in northern parts of Europe as well as in mountain environments, such as Alpine valleys, where locally adapted landraces have continued to be cultivated over the years. In this study, rye landraces collected in different valleys in the Northwest Italian Alps have been selected as the most genetically isolated within their geographical contexts and cultivated in two different marginal Alpine environments. The traits concerning their agronomy, mycotoxin contamination, bioactive content, as well as their technological and baking quality were assessed to characterize and compare rye landraces with commercial wheat and rye cultivars. Rye cultivars showed the same grain yield level as wheat in both environments. Only the genotype selected from the Maira Valley was characterized by tall and thin culms and a proneness to lodging, thereby resulting in a lower yield capacity. Among the rye cultivars, the hybrid one presented the highest yield potential, but also the highest susceptibility to the occurrence of ergot sclerotia. However, the rye cultivars, especially the landraces, were characterized by higher concentrations of minerals, soluble fibers, and soluble phenolic acids, and thus both their flours and breads had superior antioxidant properties. A 40% substitution of refined wheat flour with whole-grain rye flour led to a higher dough water absorption and a lower stability, thereby resulting in lower loaf volumes and darker products. Agronomically and qualitatively speaking, the rye landraces diverged significantly from the conventional rye cultivars, thus reflecting their genetic distinctiveness. The landrace from the Maira Valley shared a high content in phenolic acids and good antioxidant properties with the one from the Susa Valley and, when combined with wheat flour, turned out to be the most suitable for bread making. Overall, the results have highlighted the suitability of reintroducing historic rye supply chains, based on the cultivation of local landraces in marginal environments and the production of value-added bakery goods.

Rye: A wonder crop with industrially important macromolecules and health benefits

Rye (Secale cereale) is a rich source of macromolecules, especially starch, fiber, and proteins which encourages the researchers and industries to use it for various purposes including bakery products, beverages and edible films formulation. However, despite many nutritional and health benefiting properties, rye has not been explored up to its full potential. Interest of consumers in formulating foods with high fiber and phenolic compounds has generated our interest in compiling the detailed information on rye. The present review on rye grains summarizes the existing scientific data on rye macronutrients (starch, arabinoxylan, β-glucan, fructan and proteins) and their corresponding industrial importance. Detailed description in this review unfolds the potential of rye grains for human nutrition. This review provides comprehensive knowledge and fills the remaining gap between the previous and latest scientific findings. Comprehensive information on rye nutrients along with health benefits will help to open a new era for scientific world and industrial sectors.

Impact of arabinoxylan on characteristics, stability and lipid oxidation of oil-in-water emulsions: Arabinoxylan from wheat bran, corn bran, rice bran, and rye bran

To investigate the impact of arabinoxylan (AX) on the physical and oxidative stability of oil-in-water emulsions, AX from wheat bran, corn bran, rice bran, or rye bran was incorporated into the production of whey protein isolate-stabilised emulsions. Decreased interfacial charge and increased mean particle diameters were recorded in all fresh emulsions with 0.1%-0.5% AX, as recorded by the ζ-potential and particle size measurement, indicating the adsorption of AX onto the oil droplets. No phase separation was observed in all emulsions with ≤0.3% AX after 14-day storage in dark. Spectrophotometric analysis demonstrated that all AX lowered the peroxide value and thiobarbituric acid reactive substance concentration in emulsions, with AX from rice bran being slightly more effective. Consequently, AX has the potential to be used as a natural interfacial antioxidant in emulsions, and the antioxidant capacity of AX varies with its source.

Heterologous expression, purification and characterization of a highly thermolabile endoxylanase from the Antarctic fungus Cladosporium sp

Numerous endoxylanases from mesophilic fungi have been purified and characterized. However, endoxylanases from cold-adapted fungi, especially those from Antarctica, have been less studied. In this work, a cDNA from the Antarctic fungus Cladosporium sp. with similarity to endoxylanases from glycosyl hydrolase family 10, was cloned and expressed in Pichia pastoris. The pure recombinant enzyme (named XynA) showed optimal activity on xylan at 50 °C and pH 6-7. The enzyme releases xylooligosaccharides but not xylose, indicating that XynA is a classical endoxylanase. The enzyme was most active on xylans with high content of arabinose (rye arabinoylan and wheat arabinoxylan) than on xylans with low content of arabinose (oat spelts xylan, birchwood xylan and beechwood xylan). Finally, XynA showed a very low thermostability. After 20-30 min of incubation at 40 °C, the enzyme was completely inactivated, suggesting that XynA would be the most thermolabile endoxylanase described so far in filamentous fungi. This is one of the few reports describing the heterologous expression and characterization of a xylanase from a fungus isolated from Antarctica.

Extraction and characterization of rye grain starch and its susceptibility to resistant starch formation

The aim of this work was to isolate starch from different parts of rye grain by a traditional and newly developed enzymatic method, and to compare the physical, chemical and molecular properties of isolated starches, especially focusing on susceptibility to resistant starch (RS) formation. Enzymatic treatment provided a high yield of starch which differed in granularity depending on the parts of grain used for isolation. A share of extreme size granules in starches have a strong impact on swelling and pasting properties. The differences could be explained by molecular properties of starch fractions in the examination of which HPSEC with post-column derivatization was especially helpful showing higher dispersity and molar mass of amylose in starches obtained by the enzymatic method. The derivatized SEC profiles of RS have not been reported earlier. Starches isolated by enzymatic method with a high share of small starch granules were less susceptible to a RS formation.

Characterization of water and alkali extractable arabinoxylan from wheat and rye under standardized conditions

Arabinoxylans (AXs) are an important component of wheat and rye dough. They bind water, contribute to the formation of viscous dough and improve the quality of bread. For the application of AX fractions in bread making process, it is useful to record a quality profile of wheat fractions compared to the quality profile of rye fractions under standardized conditions. In this work water and alkali extractable AX containing fractions, from wheat- and rye wholemeal, were extracted under standardized conditions and characterized. For analysis of composition, structural features, and molecular dimension a combination of chemical, physicochemical, enzymatic and chromatographic techniques was applied. The molar mass distributions obtained by means of an innovative colorimetric pentose detection in the eluted SEC fractions were comparable for all under standardized conditions extracted AXs. The determined molar masses of AXs extracted both from wheat- and from rye grain were close to 2.0 × 10(5) g/mol for water extractable AXs and 3.0 × 10(5) g/mol for alkali extractable AXs. Different susceptibility to endoxylanase treatment, having been observed as differences in the SEC profiles, may be evidence of structural differences between AXs depending on their origin. The viscosities of AX solutions were strongly influenced by their molar mass and structure; samples being less susceptible to endoxylanase provided solutions of higher viscosity.

Purification and structural characterization of an α-glucosidase inhibitory polysaccharide from apricot (Armeniaca sibirica L. Lam.) pulp

In this study, the crude polysaccharide (APPS) from the fruiting bodies of apricot (Armeniaca sibirica L. Lam.) was isolated and fractionated by ultrafiltration and Sephadex G-75 gel chromatography. The hypoglycemic activities of all fractions were determined by α-glucosidase inhibitory activity in vitro. The fraction APPS1-2 showed the best activity with an IC50 of 6.06 mg/mL. The properties and chemical compositions of this fraction were analyzed with high-performance liquid chromatography, gel permeation chromatography-eighteen angle laser light scattering instrument, UV spectroscopy, infrared spectroscopy, and NMR spectroscopy ((1)H). The results demonstrated that APPS1-2 was a neutral glycoconjugate with a molecular weight of 25.93 kDa. It comprised rhamnose, glucose, mannose, and galactose, with a relative molar ratio of 1.34:2.01:0.48:0.35. The backbone of APPS1-2 may consist of rhamnose and glucose, but its branches may consist of mannose and galactose. The IR and UV spectrum of APPS1-2 revealed the typical characteristics of heteropolysaccharide. (1)H NMR spectrum showed that APPS1-2 contained α-configurations.

Production and anti-diabetic activity of soluble dietary fiber from apricot pulp by Trichoderma viride fermentation

Soluble dietary fiber (SDF) was prepared by Trichoderma viride fermentation by using apricot pulp as the raw material.

Rye flour enriched with arabinoxylans in rye bread making

The aim of the study was to investigate physical and chemical properties of preparations of water soluble arabinoxylans (arabinoxylan-enriched flour) obtained by industrial method and their derivatives (obtained by hydrolysis and cross-linking of aranbinoxylans), as well as their impact on baking properties of rye flours. Additionally, these results were compared with highly purified arabinoxylans prepared by laboratory method and well characterized in the literature. Flour enriched with arabinoxylans was obtained by industrial method involving air separation of flour particles. It was characterized by 8.6% arabinoxylan content, lack of insoluble material and substantial residue (67%) of starch and dextrins. The addition of all industrial method preparations in amount of 10% (i.e. approx. 1% water soluble arabinoxylans), to rye flours resulted in an increase in water absorption, bread volume and decrease in hardness of the bread crumb and the effect was especially strong in the case of flour type 720. Due to the easiness of isolation procedure, industrial method preparation could be advised as an improver for rye bread making.