Berrin Özkaya

Effects of wheat maturation stage and cooking method on physical and chemical properties of firiks

In this study, samples of two durum wheat cultivars at different maturation stages (13, 16, 19, 22, 25 days post anthesis) were processed into firik using two different cooking processes: roasting (scorching) on flames and boiling at atmospheric pressure. In both cultivars hectolitre weights and 1000 kernel weights of the firiks produced by boiling and roasting increased steadily and significantly (p<0.05) with maturation. The percent of small kernels decreased and the percent of large kernels increased uniformly in the firiks produced by boiling and roasting from both cultivars during ripening. The ash contents of the firiks of both cultivars decreased significantly (p<0.05) with maturation. Fe, Cu, Zn, Mn Na, K and Mg contents of the firiks of both cultivars produced by both methods showed a downward trend within the period of maturation. However, Ca contents of the firiks, first showed a significant (p<0.05) upward trend and then a downward trend during maturation. Significant (p<0.05) reductions in thiamin and riboflavin contents occurred in both cooking methods and both cultivars with maturation. The first two stages of kernel development (13 and 16 days after anthesis) resulted in the highest sensory scores, for the firiks produced by both methods.

Effect of Dephytinization by Fermentation and Hydrothermal Autoclaving Treatments on the Antioxidant Activity, Dietary Fiber, and Phenolic Content of Oat Bran

Fermentation and hydrothermal methods were tested to reduce the phytic acid (PA) content of oat bran, and the effects of these methods on the dietary fiber (DF) and total phenolic (TP) contents as well as the antioxidant activity (AA) were also investigated. Fermentation with 6% yeast and for 6 h resulted in 88.2% reduction in PA content, while it only resulted in 32.5% reduction in the sample incubated for 6 h without yeast addition. The PA loss in autoclaved oat bran sample (1.5 h, pH 4.0) was 95.2% while it was 41.8% at most in the sample autoclaved without pH adjustment. In both methods, soluble, insoluble, and total DF contents of samples were remarkably higher than the control samples. Also for TP in the oat bran samples, both processes led to 17% and 39% increases, respectively, while AA values were 8% and 15%, respectively. Among all samples, the autoclaving process resulted in the lowest PA and the greatest amount of bioactive compounds.

Changes in the Functional Constituents and Phytic Acid Contents of Firiks Produced from Wheats at Different Maturation Stages

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 μmolTE/100 g) besides having lower phytic acid contents (498.6-604.9 mg/100 g).

Effects of concentrated and dephytinized wheat bran and rice bran addition on bread properties

Wheat bran and rice bran were concentrated in terms of dietary fiber and were dephytinized by two different methods (fermentation and hydrothermal). Untreated, concentrated, concentrated-dephytinized by fermentation method, and concentrated-dephytinized by hydrothermal method bran samples were each incorporated into flour at levels of 0, 10, 15, and 20%, and their effects on bread properties were investigated. Unprocessed wheat bran and rice bran addition decreased the volume yield, and the specific volume of the bread depends on the incorporation level. A further decrease was observed with the addition of concentrated bran. However, the dephytinization treatments slightly improved these values. The same pattern was observed for the total number of cells and the total cell area of bread crumbs. Both wheat bran and rice bran were observed to cause a darker crumb color, and the effects of bran samples on crumb color were more pronounced after the dephytinization treatment. The addition of concentrated wheat bran and rice bran significantly increased hardness, as well as decreasing springiness, cohesiveness, and resilience of the bread, depending on the bran levels. Although dephytinization treatments enhanced the textural properties of bread, these results were still inferior to those obtained using bread produced with untreated bran. Regarding the dephytinization treatments, the influence of fermentation treatment on bread properties was slightly beneficial compared to hydrothermal treatment. PRACTICAL APPLICATIONS Consumption of dietary fiber offers a range of health benefits. Cereal bran has great potential as a dietary fiber source. However, this brans high phytic acid content and adverse effects on bread quality limit that potential. It is possible to obtain high dietary fiber and low phytic acid bran samples through bran concentration and dephytinization treatments. The dephytinization treatment is an effective method for degradation of phytic acid. The negative effects of wheat bran and rice bran on bread quality decreased significantly following the dephytinization treatments. This study demonstrated that fiber-enriched bread with low phytic acid content and acceptable texture can be produced using concentrated and dephytinized bran.