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    Changes in the functional constituents and phytic acid contents of firiks produced from wheats at different maturation stages
    (Elsevier Ltd, 2018) Özkaya, Berrin; Türksoy, Seçil; Özkaya, Hazım; Baumgartner, Burcu; Özkeser, İrem; Köksel, Hamit
    Three different wheat cultivars (Bezostaya, Eser and Cesit-1252) at four maturity stages were processed into firik which is a whole wheat-based ethnic food by using traditional cooking method. Some nutritional and antinutritional (moisture, ash, protein, fructans, dietary fibers, phenolic contents and antioxidant activity) properties of firiks were investigated. A significant increase was observed for the hectoliter and 1000 kernel weights whereas a decrease for ash and protein contents by increased maturation level. It was found that immature wheats especially at early stages of kernel development are rich sources of functional nutrients such as total dietary fiber (17.3–20.4%), fructans (4.1–7.2%), total phenolics (4602.5–4838.3 mgGAE/kg) and antioxidants (729.2–782.8 ?molTE/100 g) besides having lower phytic acid contents (498.6–604.9 mg/100 g). © 2017 Elsevier Ltd
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    Effect of different resistant starch sources and wheat bran on dietary fibre content and in vitro glycaemic index values of cookies
    (Academic Press, 2019) Kahraman, Kevser; Aktaş Akyıldız, Eda; Öztürk, Serpil; Köksel, Hamit
    Cross-linked starches produced in lab-scale from corn and wheat starches with TDF contents of 80.4% and 83.6% were used in cookie formulation to obtain high fibre and low glycaemic index (GI) cookies. Different resistant starch (RS) sources including and wheat bran were also used for comparison. RS sources were added into the formulation at the levels of 25, 50 and 75%. Overall cookie quality (spread ratio, hardness, colour) results showed that among the RS sources and wheat bran, lab-scale produced cross-linked wheat starch (XL-W) had an improving effect on cookie quality, whereas the other sources had detrimental effect. Cookie samples supplemented with XL-W had the highest total dietary fibre (TDF) contents regardless of the addition level. High levels of TDF content were also observed with the wheat bran supplemented cookie samples; however, quality of these cookies were low. RS and wheat bran supplementation caused significant decrease in the in vitro GI of the cookies and the lowest GI value was achieved with the cookie supplemented with XL-W. This study proved that XL-W produced in this study can be used as an alternative ingredient to produce high fibre and low GI cookies without any deteriorative effect on the quality.
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    Effect of extrusion treatment on enzymatic hydrolysis of wheat bran
    (Academic Press, 2020) Aktaş Akyıldız, Eda; Masatcıoğlu, M. Tuğrul; Köksel, Hamit
    Although, wheat bran is a good source of dietary fibre (DF), it has certain disadvantages due relatively lower levels of soluble DF. Therefore, in the current study, the effect of extrusion treatment on microstructure and enzymatic hydrolysis of wheat bran was investigated. Extrusion treatment increased fibre solubility at all process conditions and the screw speed was found to be the most effective parameter. Physicochemical properties of bran were affected from extrusion treatments. While the water-binding capacities of extruded brans were lower than that of non-extruded wheat bran, their water solubilities were higher. Enzymatic hydrolysis increased the soluble DF content of the bran samples as compared to those of respective samples at the beginning of incubation. The results showed that extrusion treatment can be used to disrupt the wheat bran microstructure and thus to increase the soluble fibre content. Enzymatic hydrolysis can also be used for increasing solubility further. The outcomes of this study can be utilized for improving the technological functionality of cereal fibres to develop high fibre ingredients for food applications.
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    Effect of steam explosion on enzymatic hydrolysis and baking quality of wheat bran
    (Academic Press, 2017) Aktaş Akyıldız, Eda; Mattila, Outi; Sözer, Nesli; Poutanen, Kaisa; Köksel, Hamit; Nordlund, Emilia
    In this study, the effect of steam explosion (SE) treatment on microstructure, enzymatic hydrolysis and baking quality of wheat bran was investigated. Coarse and fine bran were treated at different steam temperatures (120–160 °C) and residence times (5 or 10 min) and then hydrolysed with carbohydrase enzymes. The SE treatment increased water extractable arabinoxylan (WEAX) content from 0.75 to 2.06% and reducing sugars from 0.92 to 2.41% for fine bran. The effect was more pronounced with increased SE temperature and residence time. The highest carbohydrate solubilisation was observed in fine bran at SE treatment of 160 °C, 5 min. WEAX content increased to 3.13% when this bran was incubated without enzyme, while WEAX content increased to 9.14% with enzyme addition. Microscopic analysis indicated that cell wall structure of wheat bran was disrupted by severe SE conditions. Supplementation of SE treated (150 °C, 10 min) bran at 20% replacement level decreased the baking quality of bread. However SE followed by enzymatic hydrolysis increased specific volume and decreased crumb hardness (on the day of baking and after three days of storage). Phytic acid content of bread supplemented with SE treated bran was lower than the one supplemented with untreated bran. © 2017 Elsevier Ltd
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    Extraction of soluble ?-glucan from oat and barley fractions: Process efficiency and dispersion stability
    (Academic Press, 2018) Aktaş Akyıldız, Eda; Sibakov, Juhani K.; Nappa, Marja; Hytönen, Eemeli; Köksel, Hamit; Poutanen, Kaisa
    This study comprises laboratory-scale extraction of soluble ?-glucan (BG) from oat (16 and 32% BG) and barley (12 and 32% BG) fractions, investigation of chemical composition and stability of dispersions prepared from water extracts and techno-economic evaluation for small industrial scale production. Oat and barley fractions were hydrolysed with an enzyme preparation and BG was extracted from hydrolysed samples by boiling water. Enzymatic hydrolysis resulted in medium molecular weight (MW = 38,500–69,400 g/mol) after 2 h incubation with 10 nkat ?-glucanase activity/g bran and low MW (11,800–22,600 g/mol) after 4 h incubation with 50 nkat/g bran. MW and concentration of BG affected the stability of dispersions during storage. Barley fractions, after both 2 and 4 h hydrolysis, resulted in higher viscosities than oat fractions. MW of BG in soluble barley fractions was only slightly higher, but the difference in MW does not seem to be adequate to justify the observed viscosity differences. Barley extracts contained higher amounts of starch, however, starch did not have a distinct effect on viscosity. Techno-economic analysis for production process with feedstock design capacity of 100 kg/h showed that production costs varied from 0.06 to 0.11€/g soluble BG. Raw material and capital charge were key cost factors. © 2018 Elsevier Ltd
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    Multi-elemental analysis of flour types and breads by using laser induced breakdown spectroscopy
    (Academic Press, 2020) Arı Akın, Pervin; Sezer, Banu; Sanal, Turgay; Apaydın, Hakan; Köksel, Hamit; Boyacı, İsmail Hakkı
    Bread and flour are most commonly used products in human diet, which makes it susceptible to adulteration, mislabeling and addition of unpermitted amount of different flour types. The objective of this work was to evaluate the potential of employing laser induced breakdown spectroscopy to differentiate different flour types and quantify the white wheat flour addition to rye and oat flour and breads. In the principal component analysis, score plot represents pure flour types with 97.64% of the variance. In the calibration study, the measured coefficient of determination values was 0.989, 0.989, 0.992 and 0.991 for refined wheat flour: rye flour, refined wheat flour: oat flour, breads made with the blend of refined wheat: rye flour and the blend of refined wheat: oat flour, respectively. The limit of detection values were calculated as 3.82, 5.97, 4.59 and 4.92% for refined wheat flour: rye flour, refined wheat flour: oat flour, refined wheat: rye bread and refined wheat: oat bread, respectively.