Cereal Chemistry. The potential utilization of Mixolab for the quality evaluation of bread wheat genotypes

Transcription

1 The potential utilization of Mixolab for the quality evaluation of bread wheat genotypes Journal: Cereal Chemistry Manuscript ID: draft Manuscript Type: Research Date Submitted by the Author: Complete List of Authors: Koksel, Hamit; Hacettepe University, Food Engineering Dept. Kahraman, Kevser; Hacettepe University, Food Engineering Dept. Sanal, Turgay; Central Field Crop Research Institute Sivri, Dilek; Hacettepe University, Food Engineering Dept Dubat, Arnaud; Flour and Food Department Chopin Technologies Area of Expertise: Baking, Bread, Cookies and Cakes, Dietary Fiber, Starch, Wheat, Rheology, Pasta, Gluten, Enzyme

2 Page of Cereal Chemistry The potential utilization of Mixolab for the quality evaluation of bread wheat genotypes Hamit Koksel, Kevser Kahraman, Turgay Sanal, Dilek Sivri Ozay, Arnaud Dubat * Corresponding author: Hamit Koksel, Professor Address: Hacettepe University, Faculty of Engineering, Department of Food Engineering, 000 Beytepe, Ankara, Turkey Phone : Fax : koksel@hacettepe.edu.tr Hacettepe University, Faculty of Engineering, Department of Food Engineering, 000 Beytepe, Ankara, Turkey Central Field Crop Research Institute, Ankara, Turkey Flour and Food Department, Chopin Technologies, Villeneuve la Garenne, France

3 Page of ABSTRACT The aim of this study was to determine the possibility of using Mixolab to assess the quality of different wheat genotypes. Mixolab data were compared with various flour quality characteristics and bread volume. The samples were chosen to represent a wide range in terms of grain and rheological properties and baking quality. There were significant correlations between two Mixolab parameters (Stability and C) and Zeleny sedimentation and Alveograph W values (p<0.0). Some of the Mixolab parameters (C, C, C) were correlated with Alveograph G and P/L value (p<0.0). Mixolab values are generally in agreement with Farinograph values. There were significant negative correlations between most of the Mixolab parameters (Stability, C, C, C) and Farinograph softening degree. Stability and C parameters of Mixolab were also significantly correlated with Farinograph stability values (p<0.0). The correlation between Mixolab stability and Farinograph stability was found to be considerably high (r=0.0, p<0.00). The Mixolab parameters C, C and C were significantly correlated with the bread volume. Significant correlations were observed between the slope α and Zeleny sedimentation (p<0.0), Alveograph W (p<0.0), Farinograph softening degree (p<0.00) and stability (p<0.00) values. Keywords: Mixolab; Alveograph; Farinograph; Bread wheat quality

4 Page of Cereal Chemistry Test baking has been found to be one of the best methods to predict the suitability of flour samples for the production of high quality bread. However, the baking test is time consuming, requires skilled personnel and difficult to use for commercial purposes. Therefore, other methods are needed to test the suitability of flours in terms of baking quality in a shorter period of time. The determination of rheological properties of wheat flour dough is essential for the successful manufacturing of various bakery products because they determine the behavior of dough during mechanical handling, thereby affecting the quality of the finished products (Bloksma and Bushuk ). Rheological properties of wheat flour dough as well as the information on the pasting properties of starch might also give useful information related to the quality of bakery products such as bread. Therefore, these properties should be investigated to establish alternative methods for the prediction of baking quality. Mixolab, a new instrument developed by Chopin Technologies Company, has the capabilities to measure physical dough properties like dough strength and stability, and also to measure the pasting properties of starch on actual dough. It is used to characterize the rheological behavior of dough subjected to a dual mixing and temperature constraint. Therefore, it is possible to record the mechanical changes due to mixing and heating simulating the mechanical work as well as the heat conditions that might be expected during the baking process. It measures in real time the torque (Nm) produced by mixing of the dough between the two kneading arms (Anonymous 00). Since it is a new instrument the information related to its utilization on different aspects of wheat flour quality is quite limited. It is used for the evaluation of pasta making quality of various wheats (Manthey et al 00). It is also utilized to investigate the effects of hydrocolloids (Rosell et al 00) and flaxseed on the rheological properties of dough (Tulbek and Hall 00). Kahraman et al (00) and Ozturk et al (00) tested the possibility of using Mixolab to predict the cake baking and cookie quality of different wheat flours. Bonet et al (00) investigated the effectiveness of

5 Page of transglutaminase for the formation of heteropolymers of wheat and wheat-exogenous proteins by using Mixolab. Pena et al (00) found that the Mixolab dough development time, stability and breakdown parameters showed high correlation with the dough strength parameter Fb of the Alveograph when testing the whole grain flour. However we have not encountered any study related to the utilization of Mixolab to evaluate the bread making quality of flours. A typical Mixolab curve is shown in Figure. It is separated to five different stages. At the first stage the dough mixing characteristics such as stability, elasticity and water absorption can be measured. During this stage an increase in the torque is observed until a maximum is reached and dough can resist the deformation for some time (Anonymous 00; Rosell et al 00). Consistency of the dough decreases with excessive mixing which is an indication of protein weakening (Stage ). At the beginning of the heating, proteins underwent an additional decrease in dough consistency, the thermal weakening (Rosell et al 00). The greater the decrease in consistency, the lower is the protein quality. As the temperature increases first a decrease and then an increase in consistency is observed. The increase in consistency is mainly due to the starch gelatinization (Stage ). During this stage, starch granules swell and absorb water and amylose molecules leach out resulting in an increase in the viscosity. At the fourth stage consistency decreases as a result of amylolytic activity. The intensity of the decrease depends on amylase activity. At the fifth stage, the decrease in the temperature causes an increase in the consistency as a result of gel formation. This stage is also related to retrogradation of starch. There are eight parameters (C-C and slopes α, β, γ) used to evaluate Mixolab curve. These are illustrated on Figure. C represents the maximum point of the first mixing stage. On the other hand, the points C to C represent the end point of the corresponding mixing stage. Slope α is the slope of the curve between the end of the 0 C period and C and it is an indicator of the speed of the weakening of the protein network due to the effects of heat. Slope β is the slope of the curve between C and C and it is an

6 Page of Cereal Chemistry indicator of pasting speed. Slope γ is the slope of the curve between C and C and shows the enzymatic (α-amylase) degradation speed (Anonymous 00). The aim of this study was to test the possibility of using Mixolab to evaluate the quality of different wheat genotypes. For this purpose, Mixolab data were compared with some flour quality characteristics (e.g. Zeleny sedimentation, Alveograph and Farinograph values and bread volume). To test the suitability of Mixolab for the estimation of wheat quality correlation coefficients were calculated between Mixolab parameters and the other flour quality characteristics. MATERIALS AND METHODS Materials bread wheat samples ( cultivars, advanced lines) obtained from Field Crops Research Center, Ankara, Turkey were used. Wheat samples were milled to flours in a Buhler laboratory mill (MLU 0, Uzwil, Switzerland) to obtain straight-grade flour according to AACCI Method No: - A (AACC International 000). Methods Wheat samples were analyzed for moisture, protein (N x.) and hectoliter weight by using AACCI Methods No: -A, -A and -0, respectively (AACC International, 000). Hardness of the grains was also determined according to PSI method with Near Infrared Spectroscopy (FOSS NIRS 00, Höganäs, Sweden). The weight per thousand kernels was determined by counting the number of seeds in 0 grams of grain and reported on a dry basis. The moisture and Zeleny sedimentation of the flour samples were determined according to AACCI Methods No: -A and -0, respectively (AACC International 000). Farinograph characteristics were determined according to AACCI Method No: - (AACC International 000). From the Farinograph curves, the water absorption (the

7 Page of percentage of water required to yield a dough consistency of 00 BU, Brabender Units), development time (time to reach consistency of 00 BU), softening degree and stability were obtained. Alveograph characteristics were determined according to AACCI Method No: - 0 (AACC International 000). The Alveograph characteristics were automatically recorded by the Alveolink-NG software (Chopin Technologies, Villeneuve La Garenne, France) including maximum over-pressure (P) needed to blow the dough bubble, the average abscissa (G) at bubble rupture, the deformation energy (W) relates to the surface under the curve indicating the necessary work input needed to inflate the dough, and the P/L ratio. P, G and W are the indices of resistance to extension, dough extensibility and dough strength, respectively. Test baking was performed with the flour samples according to the AACCI Method No: 0- (AACC International 000). The volumes of bread samples were determined by rape seed displacement method. Dough mixing and pasting behaviours of the wheat flour samples were studied using the Mixolab (Chopin Technologies, Villeneuve La Garenne, France). 0 gr of sample was used for each analysis. Mixolab analysis was carried out at the water absorption level determined by the Farinograph following the AACCI Method No: - (AACC International 000). Despite the fact that the Mixolab can measure water absorption, it was decided to use the Farinograph water absorption for convenience since Farinograph water absorption values were available prior to the Mixolab analysis. For the analysis of the mixing and pasting behaviour the standard Chopin+ protocol at 0 rpm mixing speed was followed: initial equilibrium at 0 C for min, heating to 0 C over min (at a rate of C/min), holding at 0 C for min, cooling to 0 C over min (at a rate of C/min) and holding at 0 C for min.

8 Page of Cereal Chemistry RESULTS AND DISCUSSION Grain hardness, hectoliter weight, 000 kernel weight and protein content values of the wheat samples were in the range of.-0.%,.-. kg,.-. g,.-., respectively (Table I). The results indicated that the selected samples showed a great variation in terms of grain properties. Zeleny sedimentation, Alveograph and Farinograph characteristics of the flour samples and bread volume values are presented in Table II. Zeleny sedimentation values of the flour samples were in the range of -0 ml. Alveograph P, G, W and P/L values were in the range of - mm H 0,.-. mm, - x0 - J, 0.-. respectively. Farinograph water absorption, softening degree, dough development time and stability values were in the range of 0.-.%, -0 BU,.-.0 min,.-. min, respectively. Bread volumes were changed in the range of - ml. The samples generally represented a wide range in terms of rheological properties and baking quality. Mixolab data of the flour samples are presented in Table III. Typical Mixolab curves for medium strong (Sample ) and weak bread wheat flours (Sample ) are presented in Figure. Mixolab values are generally in agreement with farinograph values. Five samples with the lowest Mixolab stability values (S, S, S0, S, S) also had the lowest Farinograph stability values. Furthermore, five samples with the highest Mixolab stability values (S, S, S, S, S) also had the highest Farinograph stability values except the sample S. The difference between Mixolab C and C values is related to gluten quality and higher values indicate weaker gluten properties. Five samples which had the largest difference between C- C values (S, S0, S, S, S) had the lowest Farinograph stability values except the sample S. Table I Table II Table III

9 Page of Correlation coefficients were calculated between Mixolab parameters and the flour quality characteristics (e.g. Zeleny sedimentation, Alveograph and Farinograph values) to test the suitability of Mixolab to predict gluten quality of the samples (Table IV). The correlation between Mixolab parameters and bread volume were also calculated to test the suitability of Mixolab for the estimation of bread making quality of the flour samples. Table IV There were significant correlations between two Mixolab parameters (Stability and C) and Zeleny sedimentation value (p<0.0). These Mixolab parameters were also significantly correlated with Alveograph W and Farinograph stability values (p<0.0). The correlation between Mixolab stability and Farinograph stability was found to be considerably high (r=0.0, p<0.00). There were significant negative correlations between most of the Mixolab parameters (Stability, C, C, C) and Farinograph softening degree. Some of the Mixolab parameters (C, C, C) were significantly correlated with Alveograph G and P/L value (p<0.0). Among the Mixolab parameters only C was significantly correlated with Alveograph P value (p<0.0). Since the Mixolab is a new instrument, there is limited information published related to the importance of different parameters obtained by Mixolab. Therefore, it was decided to check the correlation coefficients between the differences of certain points (C C, C C, C C, C C) and wheat quality characteristics. The difference between Mixolab C and C values can be referred to as the resistance of the dough through mixing. C C difference is highly correlated with the Farinograph softening degree (r=-0., p<0.0). C C is also significantly correlated with Zeleny Sedimentation (r=0.), Alveograph W (r=0.) and Farinograph stability value (r=0.). Significant correlations were also calculated between C C and C C differences and Alveograph P, G and P/L values. Although it was indicated in the literature that Mixolab C, C and C values were related to starch gelatinization, pasting and retrogradation properties (Anonymous

10 Page 0 of Cereal Chemistry ; Rosell et al 00), in the present study these values are also found to be correlated with the Alveograph G and P/L and bread volume values. Therefore, further studies are required to investigate the relationship between Mixolab C, C and C values and protein quality. The slope α is related to protein weakening (Bonet et al 00). In the present study, significant correlations were observed between the slope α and Zeleny sedimentation (r= 0., p<0.0), Alveograph W (r=-0., p<0.0), Farinograph softening degree (r=0., p<0.00) and stability (r= 0., p<0.00) values (Table IV). The correlations between slope β and other flour quality parameters were not significant. Manthey et al (00) evaluated the rheological and gelatinization properties of durum wheats grown in the USA with Mixolab, their results showed variability in terms of protein quality and starch pasting properties, which indicated that Mixolab could be used to determine durum wheat quality. Pena et al (00) found that the Mixolab dough development time, stability and breakdown parameters showed high correlation with the Alveograph W value when testing the whole grain flour. However, the studies related to the utilization of Mixolab to evaluate the bread making quality of flours are limited. Overall results of the present study indicated that Mixolab can be used to predict the bread wheat quality and Mixolab can be used to differentiate wheat genotypes in terms of different quality characteristics. CONCLUSION The present study showed that Mixolab has ability to generate correlated data for some of the Farinograph and Alveograph characteristics, Zeleny sedimentation and bread volume values. It performs mixing and heating to determine starch properties and alpha-amylase activity as well as protein quality. It can be concluded that Mixolab is a reliable instrument to screen for gluten strength in wheat cultivars. However, further work is required to expand the information obtained in the present study by using a large number of wheat cultivars grown in different locations.

11 Page of ACKNOWLEDGEMENT We would like to thank Chopin Technologies for lending us the Mixolab instrument. LITERATURE CITED AACC International Approved Methods of the American Association of Cereal Chemists, 0th Ed. Methods 0-, - A, -A, -A, -, -0, -0, -0. The Association: St. Paul, MN, USA. Anonymous. 00. Mixolab User s Manual. CHOPIN Technologies, France. Bloksma, A.H., and Bushuk, W.. Rheology and chemistry of doughs. Pages in: Wheat: Chemistry and Technology, Y. Pomeranz, ed., rd Ed. AACC, St. Paul, MN, USA. Bonet, A., Blaszczak, W., and Rosell, C.M. 00. Formation of homopolymers and heteropolymers between wheat flour and several protein sources by transglutaminasecatalyzed cross-linking. Cereal Chemistry. : -. Kahraman K., Sakiyan, O., Ozturk S., Koksel, H., Sumnu G., and Dubat, A. 00. Utilization of Mixolab to predict the suitability of flours in terms of cake quality. European Food Research and Technology. :-0 Manthey, F., Tulbek, M.C., and Sorenson, B. 00. Evaluation of U.S. durum wheat with Mixolab. Page in: Proc. AACC International Annual Meeting: World Grain Summit: Foods and Beverages September 0th 00, San Francisco, CA, USA,. Ozturk, S., Kahraman, K., Tiftik, B., and Koksel, H. 00. Predicting the cookie quality of flours by using Mixolab. European Food Research and Technology. :-.

12 Page of Cereal Chemistry Pena, R.J., Cervantes-Espinoza, M.I., Ortiz-Monasterio, J.I., and Dubat, A. 00. Gluten composition, gluten quality, and dough mixing properties (National-Mixograph; Chopin- Mixolab) of high yielding wheats derived from crosses between Common (T. aestivum) and Synthetic (Triticum dicoccon x Aegilops tauschii) wheats. In Proc. EUCARPIA 00. Rosell, C. M., Collar, C., and Haros, M. 00. Assessment of hydrocolloid effects on the thermo-mechanical properties of wheat using the Mixolab. Food Hydrocolloids. :. Tulbek, M. C., and Hall, C. 00. Mixolab as a tool to investigate the effects of flaxseed on rheological properties of dough. Page 0 in: Proc. AACC International Annual Meeting: World Grain Summit: Foods and Beverages September 0th 00, San Francisco, CA, USA.

13 Page of FIGURE CAPTIONS Fig.. A typical Mixolab curve Fig.. Typical Mixolab curves for medium strong (Sample ) and weak bread wheat flours (Sample )

14 Page of Cereal Chemistry Torque (Nm) Block Temperature Fig.. A typical Mixolab curve C α β C Time (min) C γ C C Temperature ( o C)

15 Page of Torque (Nm) Medium Strong wheat flour Weak wheat flour Time (min) Fig.. Typical Mixolab curves for medium strong (Sample ) and weak bread wheat flours (Sample ) Temperature ( o C)

16 Page of Cereal Chemistry Table I. Grain hardness, hectoliter weight, 000 kernel weight and protein content values of the wheat samples Sample No Grain Hectoliter 000 kernel weight Protein Hardness Weight (g, dry basis) content (%) (kg) (%) S S..0.. S.... S S.... S.... S....0 S.0... S.... S S...0. S.... S S.... S S....

17 Page of Table II. Zeleny Sedimentation, Alveconsistograph Characteristics, Farinograph Characteristics of Flour Samples and Bread Volume Alveoconsistograph Characteristics Farinograph Characteristics Zeleny Sample P Sedimentation No (mm H O) (ml) G W (mm) (x0 - J) Water Softening Bread Development Stability P/L Absorbtion Degree Volume Time (min) (min) (%) (BU) (ml) S S S S S S S S S S S S S S S S

18 Page of Cereal Chemistry Table III. Mixolab Characteristics of Flour Samples Sample C C C-C C C-C C C-C C C-C Stability (min:sec) No (N) (N) (N) (N) (N) (N) (N) (N) (N) S 0: S 0: S 0: S 0: S 0: S 0: S 0: S 0: S 0: S0 0: S 0: S 0: S 0: S 0: S 0: S 0: Average Standard deviation CV% 0.%.% -.%.%.%.% -00.%.%.%

19 Page of Table IV. Correlation Coefficients Between Mixolab Characteristics and Zeleny Sedimentation, Alveoconsistograph and Farinograph Characteristics of flour samples and Bread Volume Alveoconsistograph Characteristics Farinograph Characteristics Mixolab Zeleny Characteristics Sedimentation P G W (mm H O) (mm) (x0 - J) Softening Stability Bread P/L Degree Volume Stability 0.** NS NS 0.** NS -0.0*** 0.0*** NS C NS NS NS NS NS NS NS NS C 0.0** NS 0.* 0.** NS -0.** 0.** NS C NS NS 0.** NS -0.*** -0.* NS -0.* C NS NS 0.** NS -0.*** -0.* NS -0.* C NS -0.** 0.** NS -0.*** NS NS -0.** α -0.* NS NS -0.** NS 0.*** -0.*** NS C-C 0.** NS NS 0.** NS -0.** 0.*** NS C-C NS -0.** 0.* NS -0.** NS NS NS C-C NS NS NS NS NS NS NS NS C-C NS -0.0** 0.* NS -0.** NS NS -0.0* *Correlation is significant at p< 0.0, **Correlation is significant at p< 0.0, ***Correlation is significant at p< 0.00 NS: Not significant