CATTERALL, P. (1998) Flour milling, in Technology of Breadmaking, (eds S.P. Cauvain and L.S. Young), Blackie Academic & Professional, London, UK, pp. 296-329.
DOBRASZCZYK, B.J. (1999) Measurement of biaxial extensional rheological properties using bubble inflation and stability of bubble expansion in bread doughs, in Bubbles in Food (eds G.M. Campbell, C. Webb, S.S. Pandiella and K. Niranjan) American Association of Cereal Chemists, St Paul, Minnesota, USA. FARIDIH. and FAUBION,J.M. (1990) Dough Rheology and Baked Product Texture, Van Nostrand Reinhold, New York, USA.
2.4 We have been using a flour 'fortified' with dry gluten for breadmaking. The bread is satisfactory when made on a high-speed mixer but less so when we use a low-speed mixer. What is 'dry gluten' and can you explain why we get different results when we change mixers?
Dry gluten is obtained by washing out the starch from a wheat flour dough (McDermott, 1986). The rubbery mass left is known as gluten which is then carefully dried using controlled procedures which are designed to retain the maximum 'vitality' of the gluten, i.e. its ability to form gluten after hydration and dough mixing. Typically the protein content of the dry gluten will be in the region of 70-75% dry matter. Dry gluten absorbs about 1.5 times its own weight of water when it is used in breadmaking. The addition of dry gluten may be used to boost the level of the natural flour protein to improve the gas retention properties of the dough. It may be added to the flour in the mill or it may be added as a dry ingredient in the bakery. Dry gluten does not usually require pre-hydration before dough mixing.
The input of energy during dough mixing is an essential part of the development of a gluten structure capable of retaining gas during baking. Different mixers impart different levels of energy to the dough for a given mixing time and so are more or less effective at developing a gluten structure. High-speed mixers impart higher energy levels to the dough during mixing than low-speed mixers. This difference remains true even when the dough mixing time with low-speed mixers is lengthened. This is because the low speed of mixing results in a low rate of energy transfer.
Gluten development, as manifested by improved gas retention, is known to be linked with the rate of energy input to the dough with faster rates of energy input improving dough gas retention for many flours (Cauvain, 1998). This effect is especially true for gluten-fortified flours and it appears that mixers at low speeds are less able to make full use of dry gluten additions. However, the full reasons for the difference are not completely understood.
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