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Bakery characteristics of wheat dough and the final product and their predictability by NIR technique was investigated using 231 variety and commercial wheat samples (crop years 2003-2005). The behaviour of doughs was assessed with Brabender maturograph and OTG (Germany), the final product quality was evaluated by the baking test and image analysis. NIR spectra of flours were acquired on a NIRSystem 6500 spectrometer. Calibration equations for the selected rheological characteristics were computed by WINISI II using mPLS regression. The quality of prediction was evaluated by means of coefficients of correlation between measured and predicted values from cross and independent validation. A statistically significant dependence (with probability higher than 99%) was found with all rheological characteristics. The standard errors of cross-validation were achieved as follows: dough elasticity 16 BU, bread volume (11 min) 58 BU, specific loaf volume 34 cm 3 /100 g, bread cut area 2.6 cm 2 , penetration 4.1 mm, average cell area 0.4 mm 2 and cells per cm 2 7.4.

The milling and baking parameters of flours from foreign and Czech varieties were determined and related to milling and baking performance by correlation analysis. Twenty samples of wheat from the international breeding test CIMMYT (harvest year 2003) were used. Standard milling test at CD1 auto mill confirmed expressive different milling parameters of single varieties. Rheological properties of flours in dough were assessed at farinograph, extensigraph, fermentograph SJA, maturograph and oven spring apparatus. Baking test was also performed. Significant correlation was obtained between the milling parameters, grain hardness, flour water absorption and specific bread volume. The significant correlation was found between water absorption and yield of semolina (r = 0.79); fermentograph gases volume and yield of semolina (r = 0.89), farinograph water absorption (r = 0.77), kernel hardness (r = 0.76); specific bread volume and flour protein content (r = 0.57), the yield of semolina (r = 0.57). The most related section correlation was found between maturograph dough resistance and final dough volume on fermentograph (r = 0.70).

Fermentograph and baking properties of 98 wheat flour samples (two sets of commercial and one set of variety) were evaluated in the form of fermented dough. Analytical traits (ash and protein contents, wet gluten, FallingNumber, Zeleny sedimentation value), fermentograph parameters (gases volume, the volume of dough and the time of its max. increase), and the laboratory baking test were used for the characterisation of flours and doughs. Differences found between the two commercial flour sets were small and were influenced by the year of harvest. Significant differences were found between commercial and variety flours both in the fermentograph behaviour and in the baking test results. Lower dough volumes and lower bread specific volumes for variety flours in comparison with commercial ones were caused by a worse quality of proteins. Statistical analysis on significance level 99% showed correlations between the gases volume and the dough volume (r = 0.5264), between the gases volume and the time of dough maximum (r = -0.7689), and between the dough volume and the specific volume of bread (r = 0.5452).

The bread-making quality of forty three wheat flour samples, divided into two groups according to the ash content (up to 0.6% and 0.7%), and its changes by fortification with malt flour were studied in the form of fermented dough. Standard analytical measurements (ash and protein contents, wet gluten, falling number, Zeleny sedimentation value), rheological investigations (amylograph, maturograph, oven rise recorder), and laboratory baking test were used for the characterisation of flour and dough. The influence of the malt flour addition on the fermented dough behaviour depends on the flour composition and was found more significant in flours with a lower ash content ("bright" type). Amylograph characteristics of flour-water suspensions were affected in the same extent by the malt addition. Maturograph behaviour changed significantly only in proofing stability (without influence by the flour type) and dough firmness was affected by malt only in the case of flours with lower ash contents. Oven rise characteristics of dough and the specific bread volume showed important changes in both sets of samples with significant differences between flours with lower and higher ash contents. A strong correlation (r = 0.62-0.75) significant at 0.01 level exists between the specific bread volume and all oven rise parameters of dough from both sets of samples.

Summary Addition of non-traditional raw-materials and flours into wheat flour follows contemporary trend of manufacturing nutritionally healthier fermented bakery products. Aim of the study follows this tendency, evaluating nutritional improvement of composite flour and baking potential of prepared wheat-hemp flour composites. Hemp products addition significantly increased both protein and dietary fibre contents. Between five types of hemp flour, differences were observed according to incorporated amount (wheat flour substitution from 5% to 20%). In composites containing 20% of hemp flour and dehulled hemp wholemeal, protein content increased to 14.9% and to 15.7%, respectively (compared to 12.5% proteins in control wheat flour). Dietary fibre content change was governed unequivocally by addition level for both hemp flour and hemp wholemeal. Hemp wholemeal affected the solvent retention capacity (SRC) profile of the wheat flour used in a broader extent than hemp flour done, interacting moreover with addition level applied. Significant diminishing was measured for the sucrose and the lactic acid SRC, which describe physicochemical stage of starch and proteins in prepared composites. Addition of 5% and 20% of dehulled hemp wholemeal decreased the formed SRC from 112.0% to 102.3% and to 64.1%, and the latter SRC from 182.6% to 108.0 and to 78.3%, respectively. Smaller bread volume and worse shape were evaluated as the amount of hemp flour gradually increased; wholemeal form had more or less a positive effect. Correspondingly to that, crumb firmness measured by penetration test was found approximately half for hemp flour composite bread than for the hemp wholemeal ones.

The mixolab, a rheological device developed recently, combines approved farinograph and amylograph test procedures. Analysing wheat flour composites with hemp, teff, or chia in terms of all three mentioned rheological methods, correspondence of farinograph, and amylograph versus mixolab features was examined by principal component analysis. The first two principal components, PC1 and PC2, explained 75% of data scatter and allowed a satisfying confirmation of presumed relationships between farinograph or amylograph and mixolab parameters. Dough development time and stability were associated with gluten strength (C1 torque point) and also dough softening (mixing tolerance index) had a link to protein weakening (C1-C2 difference). In the second mentioned case, amylograph viscosity maximum and amylase activity (C3-C4) closeness was verified. Starch and starch gel properties during mixing (C3, C3-C2, and C4) affect dough viscosity (C1) and rheological behaviour (dough development time and stability). Another important finding is unequivocal distinguishing of the composite subsets (of hemp, teff, and chia ones) by the used rheological methods and statistical treatment of multivariable data.

Chia flour from white and brown seeds were tested in dry and hydrated form. In flour composites, ash and protein content was verifiably increased by both chia types (up to about 2%). Non-starch polysaccharides content also increased, as the sucrose SRC confirmed. Protein technological quality was affected by alternative plant materials, measured as Zeleny value diminishing. Water suspension viscosity and dough elasticity increased during amylograph and extensigraph tests. For composites including hydrated chia form, somewhat higher elasticity was determined; the change was positively reflected in baking test results (bread volume increased about 20% at least). Bread crumb morphology changed gradually, determined by deeper penetration rate. Higher elasticity of dough containing hydrated chia form limited small pores coalescence into larger ones, resulting into firmer crumb compared to bread with dry chia flour. That was verified by soft diminishing of mean pores area and reversely by increase in pores density within order of samples wheat bread – dry chia flour bread – hydrated chia flour bread. Pore sizes distribution was varied, too – by chia flour, counts of small and large pores (area smaller than 1.5 mm2 and larger than 4.2 mm2, respectively) were magnified approximately twice and lowered to ca half, respectively.

Hruskova M., Svec I., Sekerova H. (2011): Colour analysis and discrimination of laboratory prepared pasta by means of spectroscopic methods. Czech J. Food Sci., 29: 346–353. For the CIE Lab colour profile determination of laboratory prepared pasta, two sample granulations and two spectral methods were tested. Pasta was manufactured progressively from semolina, common wheat, and corn flour. Sufficient colour spectra ranges were ensured by means of fortification with 9 non-traditional cereals in the first case, 8 natural colorants in the second one, and with 12 gluten-free pasta recipes in the last case. Both factors (i.e. granulation and spectral method) were proved as statistically significant by the cluster, variance and principal component analyses. In the comparison of the effects on the pasta composition and the spectral method, the latter demonstrated a stronger impact on the pasta colour profile measured.

Wheat flour was fortified by 2.5, 5.0 or 10 wt. per cent of linseed fibre, gained from seeds of golden flax varieties Amon and Raciol and brown one Recital (granulation 500 - 700 m), prepared from 2015 and 2016 harvests. Using analytical tests, namely sedimentation according to Zeleny and Falling Number, basic technological quality of flour composites was mostly independent on all three observed factors (harvest year, linseed variety and addition). Rheological tests included the farinograph, the extensigraph and the amylograph proofs. Enhancement by brown and yellow flax fibre significantly contributed to rise of farinograph water absorption and to dough stability shortening, directed mainly by addition level. Extensigraph curves course depended on dough resting time, higher differences between wheat control and flour composites were observed after 60 min dough resting. Linseed fibre weakened dough extensibility, and energy as area under curve also partially decreased about 3, 8 and 25% in average as portion of alternative materials in dough has risen. Compared to control, suspension viscosities of tested flour composite generally increased; the strongest effect was recorded for composite samples from harvest year 2016. During dough leavening, tested samples were differentiated according to maturograph dough resistance, and interaction of all three factors was identified. Regardless to variantion in dough machinability, specific volumes of composite bread samples were similar through whole sample set - any unequivocal trend was found. Somewhat worse vaulting of bread was calculated for buns manufactured from raw materials of 2016 harvest. Reversely, linseed fibre produced in 2015 improved crumb softness, especially at 5% enhancement (about ca 50% in average). The lowest addition of linseed fibre resctricted biscuits spread during baking in the highest extent, but rising level of enhancement suppressed elevated dough elasticity. Both cereal products were considered as acceptable for common consumers. Multivariate PCA method verified changes mainly in protein visco-elastic properties, which were reflected in bread and biscuits quality in an opposite manner. Based on this statistics, quality of wheat controls was comparable in both harvest year if related to changes induced by linssed fibre. In opposite to this, technological and consumer's parameters of flour composites and manufactured cereal products were statistically dependent of harvest year of linseed. As presumed, the lowest addition level brough the smallest changes; multiplied fortification caused gradual variation in results of all conducted proofs. Owing to high dietary fibre content in linseed fibre (over 50%), the medium dosage of the alternative material (i.e. 5% addition) could be recommended for praxis.

Bread and bread crumb characteristics as the results of laboratory baking test were used to assess bread profile. Its texture was quantified by image analysis technique, performed by using the Kaiser reproset (stand, lighting), the COHU CCD camera and the NIS Elements 2.0 AR software. In the case of common cereals fortification (wheat, rye, barley, oat and corn wholemeal flours), tested substitution level were chosen from 10% to 50% of commercial wheat flour standard “M’09”. Its analytical parameters correspond with satisfying bakery quality (protein content 14.1%, Zeleny's value 36 ml, Falling Number 396 s). Non-fortified bread from M’09 reached specific volume of 365 mL/100 g, and bread texture was described by 14 cell/cm2 and mean cell area (MCA) 2.538 mm2. The second fortification attempt included four non-traditional wheat (spelt, dicoccum, spring wheat ‘Trinaldina’, one with purple grain) and millet. These recipe components were tested on two commercial wheat samples, marked as “M’06” and “M’07”. Their baking values differed in protein content only (12.3% vs. 11.5%, respectively), while the Zeleny's sedimentation and the Falling Number test results were comparable (49 ml vs. 49 ml and 324 s vs. 363 s, respectively. Lower protein content as well as higher Falling Number contributed to lower bread volume from M’07 flour (252 mL/100 g vs. 343 mL/100 g), and also its texture was less open (20 cells/cm2 at mean cell area 1.160 mm2 against 15 cells/cm2 at 1.520 mm2). Statistical approach comprised correlation and variation analyses (Tukey's test) on significance level of 95% for both methods. Addition of common cereals wholemeal caused progressive changes of both specific bread volumes and crumb morphology, i.e. volume of bread with 10% and 50% of rye wholemeal fell from z 235 mL/100 g up to 155 mL/100 g. An extraordinary position was revealed out for wheat wholemeal, which did not affect dough volume rise at baking stage due to similar protein structure (specific values of 233 mL/100 g a 259 mL/100 g, respectively). Cell densities were 21 cells/cm2 and 25 cells/cm2 for recipes with 10% and 50% of rye, respectively. Corresponding MCA's were evaluated on levels of 1.617 mm2 and 1,365 mm2, respectively. Compared to standard M’09, a decrease about 25% was registered. Influence of wheat wholemeal was equivocal likewise the specific bread volume – numbers of cell in bread crumb with 10% and 50% of that component were 18 per cm2 for both cases, whereas the proper MCA's were 1.830 mm2 in the former and 2.128 mm2 in the latter case (72% and 83% of standard M’09). Texture of the selected samples is documented on Fig. 1. Bread prepared from “M’07” was affected differently due to lower baking quality – crumb texture changes oscillated up to 20%. Figure 2 shows major influence for bread with TSP (77% increase in mean cell area, 23% decrease in number of cells/cm2). The most levelled change in these two bread crumb parameters was observed for bread with WPG – mean cell area increased about 20%, while number of cells/cm2 decreased about 23%.

In wheat and flour processing many traits have to be investigated for quality control. However, conventional methods available for technological quality assessment of wheat grain and flour are generally tedious and/or requiring expensive equipment. To overcome these drawbacks in common use, alternative methods using spectroscopy have been developed. The objective of this study was to utilize near-infrared reflectance spectroscopy (NIR) to analysis of milling and baking parameters: flour extraction, protein content, Zeleny sedimentation, deformation energy, gas volume and baking volume. Samples including Czech and international varieties were collected from a field experiments (crop years 2002–2005) and laboratory milled on Chopin CD1. Spectra were acquired on a scanning monochromator NIRSystems 6500 in the range from 400 to 2500 nm. Calibration equations were obtained both with classical and modified partial least square (PLS) regression analysis of conventional laboratory analysis values on 168 selected NIR spectra using WinISI computer software. Those were externally validated with additional samples from commercial wheats. Prediction of flour extraction, Zeleny sedimentation and protein content in particular gave a very good accuracy. The results indicate that NIRS can also determine some rheological traits (deformation energy, gas volume and specific loaf volume) at least with a screening performance.