74 research outputs found

    Non-linear rheological properties of soft wheat flour dough at different stages of farinograph mixing

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    During mixing of wheat flour doughs, the distribution of the gluten network changes as a result of continuously applied large deformations. Especially gliadin, changes its distribution in the whole network during mixing. It is possible to fundamentally explain the role of molecular changes in more detail using large amplitude oscillatory measurements (LAOS) in the non-linear region. Therefore, the purpose of this study is to understand the effect of mixing on the non-linear fundamental rheological behavior of soft wheat flour dough using LAOS. Dough samples were obtained at 4 different phases of the Farinograph mixing and LAOS tests were done on each of them. LAOS tets give in depth intracycle understanding of rheology. All samples showed strain stiffening S and shear thinning T behavior at large strains previously not known in the cereal rheology community. Increasing mixing time (phase 1 to phase 4) and decreasing frequency resulted in retardation in the break of strain stiffening as strain increases. The strain stiffening behavior started to decrease for the dough samples at the 3rd and the 4th phases of mixing. LAOS data enabled us to describe the non-linear rheological changes occurring both in the viscous part largely attributed to the starch matrix and elastic part largely attributed to the gluten network components of the soft wheat flour dough under large deformations. © Appl. Rheol.This research was partly funded by USDA Hatch funds, the William R. Scholle Foundation, a Fellowship to Gamze Yazar from The Scientific and Technological Research Council of Turkey (TUBITAK). The authors gratefully acknowledge all of these funding sources which made this research possible. -

    Influence Of Specific Mechanical Energy On Cornmeal Viscosity Measured By An On-line System During Twin-screw Extrusion

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    The influence of specific mechanical energy (SME) on cornmeal viscosity during the twin-screw extrusion at feed moisture contents of 25 and 30% and screw speeds in the range from 100 to 500 rpm was measured. Cornmeal was extruded in a co-rotating, intermeshing twin-screw coupled to a slit die rheometer. One approach to the on-line rheological measurement is to use a slit die with the extruder. In the present work it was show that shear viscosity decreased as a function of SME. The viscosity of cornmeal at the exit die was influenced by screw speed, rate of total mass flow, mass temperature inside the extruder and SME. An increase in screw speed resulted in an increase in SME and a decrease in viscosity. A reduction in slit die height and an increase in screw speed and mass temperature led to a remarkable macromolecular degradation of the starch, as evidenced by the decrease in viscosity.163285295Bhattacharya, M., Hanna, M.A., Kinetics of starch gelatinisation during extrusion cooking (1987) J. Food Sci., 52, pp. 764-766Basedow, A.M., Edbert, K.H., Hunger, H., Effects of mechanical stress on the reactivity of polymers: Shear degradation of polyacrylamide and dextran (1979) Makromol. Chem., 180, pp. 411-416Bigg, D., Middleman, S., Mixing in a screw extruder. A model for residence time distribution and strain (1974) Ind. Eng. Chem. Fundam., 13, pp. 66-71Casale, A., Porter, R.S., The mechanochemistry of high polymers (1971) Rubber Chem. Technol., 44, pp. 534-538Cervone, N.W., Harper, J.M., Viscosity of intermediate moisture dough (1978) J. Food Process Eng., 2, pp. 83-96Davidson, V.J., Paton, D., Diosady, L.L., Spratt, W.A., Residence time distributions for wheat starch in a single screw extruder (1983) J. Food Sci., 48, pp. 1157-1161Davidson, V.J., Paton, D., Diosady, L.L., Rubin, L.J., A model for mechanical degradation of wheat starch in a single screw extruder (1984) J. Food Sci., 49, pp. 1154-1157Davidson, V.J., The rheology of starch-based materials in the extrusion process (1992) Food Extrusion Science and Technology, pp. 263-275. , J.L. Kokini, J L, C -T. Hao, and M.V. Karwe, eds. Marcel Dekker, New YorkDella Valle, G., Kozlowski, A., Colonna, P., Tayeb, J., Starch transformation estimated by the energy balance on a twin screw extruder (1989) Lebensm Wiss U -Technol., 22, pp. 279-286Ding, X.L., Tang, J., Studies on the extrusion of corn starches. I. Degradation of corn starches in a twin screw extruder and characteristics of extruded starches (1990) J Wuxi Inst Light Ind., 9, pp. 1-11Fletcher, S.I., Richmond, P., Smith, A.C., An experimental study of twin screw extrusion cooking of maize grits (1985) J. Food Eng., 4, pp. 291-312Fujio, Y., Igura, N., Fukuoka, H., Depolymerisation of molten-moisturised starch molecules by shearing-force under high temperature (1995) Starch/Stärke, 47, pp. 143-145Han, C.D., (1976) Rheology in Polymer Processing, , Academic Press. New York, NYHan, C.D., Kim, K.V., (1972) Rheol. Acta, 11, pp. 323-327Han, C.D., (1988) Rheological Measurements, , A. A. Collyer and D. W. Clegg, eds. Elsevier Applied Science, New York, NYHarmann, D.V., Harper, J.M., Modeling a forming foods extruder (1974) J. Food Sc., 39, pp. 1099-1104Harper, J.M., (1981) Extrusion of Foods, 1-2. , CRC Press. Boca Raton, FLJanssen, L.P.B.M., Models for cooking extrusion (1986) Food Engineering and Process Applications. Vol.2: Unit Operations, 2, pp. 115-129. , M. Le Maguer and P. Jelen, eds. Elsevier Applied Science Publ., LondonKalentunc, G., Breslauer, K.J., Glass transitions of extradates: Relationship with processing-induced fragmentation and end-product attributes (1993) Cereal Chem., 70, pp. 548-552Launay, B., Buré, J., Application of a viscosimeter method to the study of. wheat flour dough (1973) J. Texture Stud., 4, pp. 82-101Maga, J.A., Fapojuwo, O.O., Extrusion of corn grits containing various levels of hydrocolloids (1986) J. Food Technol., 21, pp. 61-66Mercier, C., Charbonniere, R., Grebaut, J., De La Gueriviere, J.F., Formation of amylose-lipid complexes by twin-screw extrusion cooking of manioc starch (1980) Cereal Chem., 57, pp. 4-9Von Meuser, F., Van Lengerich, B., Kohler, F., Einflub der Extrusion Extrusionsparameter auf funktionelle Eigenschaften von Weizenstaurke (1982) Starch/Stärke, 34, pp. 366-372Meuser, F., Pfaller, W., Van Lengerich, B., Technological aspects regarding specific changes to the characteristic properties of extrudates by HTST extrusion cooking (1987) Extrusion Tecnology for the Food Industry, pp. 35-53. , C. O'Connor, ed. Elsevier Applied Science Publ. LondonMeuser, F., Wiedmann, W., Extrusion plant design (1989) Extrusion Cooking, pp. 89-155. , C. Mercier, P. Linko, and M. J. Harper, eds. American Association of Cereal Chemists, St. Paul, Minnesota, USAMosso, K., Jeunink, J., Cheftel, J.C., Température, pression et temps de sejour d'un mélange alimentaire dans un cuiseur-extrudeur bi-vis. Influence des paramètres operatoires (1982) Ind. Aliment. Agric., 99, pp. 5-18Remsen, C.H., Clark, J.P., A viscosity model for a cooking dough (1978) J. Food Process. Eng., 2, pp. 39-64Rodis, P., Wen, L.F., Wasserman, B.P., Assessment of. extrusion-induced starch fragmentation by gel permeation chromatography and metylation analysis (1993) Cereal Chem., 70, pp. 152-157Ryu, G.H., Walker, C.E., The effects of extrusion conditions on the physical properties of wheat flour (1995) Starch/Stärke, 47, pp. 33-36Tang, J., (1991) Studies on Extrusion of Corn Starches. I. Physichochemical Changes in Corn Starch during Extrusion and Application in Preparation of a Maltose, , Ph.D. diss. J Wuxi Inst, Light Ind, P R ChinaTsao, T.F., Harper, J.M., Repholz, K.M., The effects of screw geometry on extruder operational characteristics (1978) AlChE Symp., 74, pp. 142-147Van Lengerich, B., Iinfluence of extrusion processing on in-line rheological behavior, structure, and function of wheat starch (1984) Thermal Processing and Quality of Foods, pp. 421-471. , P. Zeuthen, J.-C. Cheftel, C. Eriksson, M. Jul, H. Leniger, P. Linko, G. Varela, and G. Vos, eds. Elsevier Applied Science Publ., LondonWang, S.M., Bouvier, J.N., Gelus, M., Rheological behavior of wheat flour dough in twin-screw extrusion cooking (1990) International Journal of Food Science and Technology, 25, pp. 129-134Wen, L.F., Rodis, P., Wasserman, B.P., Starch fragmentation and protein insolubilization during twin-screw extrusin of. corn meal (1990) Cereal Chem., 67, pp. 268-275Zhen, X., Chiang, W., Wang, S.S., Effect of shear energy on size reduction of starch granules in extrusion (1995) Starch/Stärke, 47, pp. 146-15
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