Iva Burešová

Influence of selected factors on the content and properties of starch in the grain of non-food wheat

Three non-food cultivars of winter wheat (Biscay, Clarus, Rapsodia) were grown at four locations in the Czech Re public with different agro-ecological conditions in the years 2005–2008 and two levels of nitrogen fertilization – 90 and 120 kg N/ha were used. The influence of growing conditions (year, location, cultivation technology) on grain yield, starch content, protein, gluten, share of amylose in starch, falling number and amylographic characteristics. All qualitative indicators were significantly affected by the weather. Wheat grown in the areas 500 m a.s.l. had lower grain yield of 2.8 t/ha (8.4 t/ha), higher starch content of 2.1% (69.0%) and lower content of proteins by 1.8% (10.2%) in grain than wheat grown in the fertile conditions (below 300 m a.s.l.). The cv. Biscay had the highest starch content of 68%; the proportion of amylose in the starch was in the range 22–27%. The content of proteins was negatively correlated with starch content (r = –0.89). The level of damage of starch α-amylase was most affected by wet weather during ripening – falling number was 62 s, with a very low amylographic gelatinization maximum (30–155 Brabender units) and a low gelatinization temperature at the maximum (67–74°C). The respective values recorded in dry conditions were ca 300 s, AU 600 and 90°C. Most damaged starch was recorded in the cv. Clarus.

Effect of Sulphur Fertilization on Yield and Quality of Wheat Grain

The influence of sulphur fertilization on plant dry weight, grain yield and quality of wheat grain (var. Mulan) was investigated. Wheat was grown in the small plot field experiments conducted in 2011–2012. At the beginning of tillering, the regenerative sulphur fertilization increased dry plant weight and sulphur concentration in dry matter by 28.1–43.2%. Sulphur application reduced the number of unproductive tillers and increased the number of ears per unit area by 10–70%. The highest grain yield was achieved after the application of solid fertilizers YaraBela SULFAN and fertilizer YaraVita Thiotrac applied in the late growing stages. Sulphur fertilization slightly improved the values of grain specific weight, protein content and Zeleny sedimentation volume, but the effect was not significant. The effect of fertilizer application significantly differed between the studied years.

Effect of nitrogen and sulphur fertilization on the quality of barley protein.

A small-plot field experiment was set up during 2011, 2012 and 2013 to test the effect of nitrogen (N) fertilizers and nitrogen fertilizers combined with sulphur (S) in the nutrition of spring barley cv. Bojos. The following parameters were studied, the effect of fertilization on grain yield, specific weight, percentage of the grain retained on a 2.8 mm and 2.5 mm sieve, the content of starch and proteins, and the percentage of protein fractions. Also the influence of weather conditions on the studied parameters was evaluated. Starch content and specific weight of grain were not influenced by the fertilizer applied. Grain yield was rising until the overall dosage reached 50 kg N/ha and 21 kg S/ ha while any higher rate of fertilizer reduced the yield. The percentage of Aand B-hordeins increased and the content of Cand D-hordeins reduced as the fertilizer rate increased. A significant effect of weather on the monitored parameters as well as on the percentage of protein fractions was demonstrated. The results enabled a conclusion that there is no improvement in technological quality of barley grain once the optimal rate of fertilizer has been reached. The optimal rate is influenced by weather conditions during the growing season.

Practical Application of Size-exclusion High Performance Liquid Chromatography in Wheat Analysis

The work was conducted to determine the practical applicability of size-exclusion high performance liquid chromatography in testing wheat bread-making quality and specify which of the peak characteristics, is the best indicator of wheat quality. The research was realized on 29 cultivars of different quality. The wheat quality was evaluated by protein content, content of wet gluten, gluten index, and farinograph rheological characteristics. All of the determined peak characteristics can be used as the indicators of wheat quality but the closest correlations with the quality parameters were found for the absolute peak areas and/or relative peak areas. The area of peak 1 was positively correlated with the dough stability (r = 0.50) and negatively correlated with the degree of dough softening (r = −0.49). The relative and absolute areas of the peak 2 were in positive correlation with sedimentation volume (r = 0.68; 0.68), farinograph water absorption (r = 0.50; 0.57) and protein content (r = 0.56; 0.57). The characteristics of peaks 3 and 4 were in the closest correlation with the investigated parameters of bread-making quality, the correlation coefficients related to the peaks 3 and 4 were nearly equal and reached values 0.58–0.77. The peak height can be used as a supplemental wheat quality indicator especially for determination of certain glutenin subunits. The area/height ratio or the contents of protein fractions are of the minor importance. Then the model predicting bread-making quality from peak characteristics was built. The values of coefficients of determination R2 were the highest for Zeleny sedimentation volume (0.83–0.97). The agreement between predicted and observed values increased when not single characteristics, but their combinations were considered.

Chicory syrup as a substitution of sugar in fine pastry

Fine pastry is a favorite snack but contains big amount fats and sugars. Sugar consumption is a major factor in the development of diabetes and obesity. Because of the growing interest in low-calorie alternatives to sucrose, producers react with different new products which can replace sugar and do not compromise the consumer acceptability of food products. This study deals with replacement of sugar with chicory oligofructose syrup, which provides same sweetness as sugar but contain over 70 % of fiber. Chicory syrup is composed of oligo-fructose and inulin. Inulin-type fructans are beneficial for immune and cardiovascular systems and its prebiotic function can protect colon health. In this study, the influence of sucrose (7 g.100g-1) replacement with chicory oligofructose syrup (0; 3.5; 7 g.100g-1) on the texture, specific loaf volume and sensory acceptability of biologically leavened muffins was tested. The substitution of sugar by the chicory syrup decreased specific loaf volume from 2.15 to 2.01 mL.g-1 while hardness, springiness and chewiness increased. There was no detrimental impact of syrup addition to cohesiveness of fine pastry muffin. It was observed that due to the syrup addition, pastry hardens faster, as showed results of hardnesss measured after 24 h. Bread crumb and crust sensory characteristics were not affected by the syrup addition. Weak impact of sugar replacement on sensory evaluation may be related to a reduced amount of the panelists involved in this study. More extensive study will, however, be performed to describe the impact of sugar replacement of fine biologically leavened muffins in more details. The results of this preliminary study shows, that the substitution of sugar by chicory syrup change textural properties and loaf volume. Despite all, based on sensory analysis the chicory syrup up to amount 7 g.100g-1 seems to be adequate for its use as a sugar replacer in fine pastry as biologically leavened muffins.

Comparison of Gluten-Free Dough Ability to Produce Leavening Gas During Baking and its Impact on Crumb Characteristics

Schopnost těsta tvořit kypřici plyn a jeho vazba na kvalitu peciva byla sledovana u psenicneho, pohankoveho a rýžoveho těsta. Schopnost produkovat kypřici plyn byla sledovana jako změny objemu těsta vyvolane změnami teploty. Nejstrmějsi narůst křivky byl zjistěn u psenicneho těsta α (28∙10-3 mm.s-1), což přispělo take k větsi plose pod křivkou (7 169 mm.s). Průkazně nižsi narůst křivky (10∙10-3 mm.s-1; 5∙10-3 mm.s-1), stejně jako plochy pod křivkou (6 291 mm.s; 53 mm.s) byly zaznamenany u pohankoveho a rýžoveho těsta. Vzrůstajici hodnoty byly v těsne vazbě s kvalitou peciva. Přestože schopnost těsta zadržovat plyn nebyla stanovovana, schopnost těsta produkovat kypřici plyn průkazně ovlivnila kvalitu peciva.

Intersection of mycotoxins from grains to finished baking

This work is focused on the evaluation of the content of deoxynivalenol and zearalenone in samples of winter wheat of the following varieties: Sultan, Cubus, Akteur, Seladon, Mulan, Chevalier, Evina, Hewitt, Bohemia, Baletka. The total amount of 10 samples harvested in 2011 and 2012 was evaluated and included variants both treated and untreated against fungal diseases. The samples were adjusted for mycotoxicological determination and subsequently measured by the ELISA method. The content of deoxynivalenol (DON) and zearalenone (ZEA) was measured in grain, flour and breadrolls in all samples. Out of all samples 43% were found to have positive content of DON and 75% of ZEA. In the treated variants, the average DON content was found to be 115 µg.kg -1 in grain, 77 µg.kg -1 in flour and 97 µg.kg -1 in pastries. In the untreated variants, the average DON content was found to be 208 µg.kg -1 in grain, 103 µg.kg -1 in flour and 128 µg.kg -1 in pastries. Moreover, the average ZEA content in the treated variant was 4.95 µg.kg -1 in grain, 3.38 µg.kg -1 in flour and 4.51 µg.kg -1 in pastries, in the non-treated variant average ZEA content in grain was 3.07 µg.kg -1 , 4.97 µg.kg -1 in flour and 2.81 µg.kg -1 in pastries. The maximal acceptable limits given by the valid legislation were not exceeded in any analysed sample. It can be concluded wheat grain grown in the Czech Republic, whether it is treated or untreated by fungicides, is not dangerous for consumers. The content of both mycotoxins is not dependent on each other, and the untreated variant has a slightly higher dependency between DON and ZEA.