Eur Food Res Technol (2001) 213:38–42 DOI 10.1007/s002170100325 Abstract Effects of different amounts of gluten, fat, emulsifier, and dextrose on the quality of breads baked in the microwave oven were investigated. Response sur- face methodology was used to optimize the formulation of microwave baked breads. Firmness, specific volume, and weight loss of the breads were determined. Breads formulated with low gluten flour were softer and had higher volume. Volume of these breads can be compara- ble with the volume of conventionally baked breads. For breads formulated with flour containing low gluten, the increase in fat and emulsifier contents decreased the firmness and increased the specific volume of breads. Fat, emulsifier, and dextrose contents were found to be the significant factors to reduce the weight loss of micro- wave baked breads. Keywords Bread · Microwave baking · Optimization · Response surface methodology Introduction Bread baking is a complex process in which both physi- cal and biochemical reactions are included. The increase in fuel prices and the desire to achieve more efficient heat transfer have created the idea of using microwaves in the baking of breads [1]. However, the mechanism and the speed of microwave heating are major problems in the formulation of microwave baked products. The physi- cochemical changes and interactions of the major ingre- dients which would normally occur over a lengthy bak- ing period in a conventional system can not always be completed during short baking period of a microwave system [2]. Moreover, each component in the formula- tion of a bakery specifically interacts with microwave energy [3]. Additional product development is necessary in order to form microwave baked systems that will have the same volume, texture, and eating quality as those as- sociated with conventionally prepared ones. When conventional formulations of bread were baked in the microwave oven, unacceptable textures were ob- tained [4, 5]. The exterior parts are tough and the interior parts are firm and difficult to chew [6]. Toughness is re- lated to gluten while firmness is related to the large di- ameter, reswollen starch granules. Microwave baked products with acceptable texture can be achieved by ma- nipulating the gluten protein network, the size and the swelling of starch granules, and the moisture level. The firmness problem of bread interior can be reduced by using fat and emulsifiers which can delay the gelatiniza- tion. The gelatinization of starch is known to affect the volume of breads. If starch gelatinizes too fast or slow, low volumes of breads are obtained [1]. Reducing the water activity of dough by salts or dextrose helps to ob- tain a more uniform texture in microwave baked breads [6]. There is limited information in literature related to the optimization of microwave baked breads. When the yeast level and proofing time were increased the ham- burger buns browned in a conventional oven prior to baking in a microwave oven were equal in quality with conventionally baked buns [7]. The main objective of the study is to find an optimum formulation for microwave baked breads by considering the effects of different amounts of gluten, fat, emulsifier, and dextrose. Materials and methods Preparation of bread. A hamburger bread recipe containing 100% flour, 8% sugar, 64% water, 6% nonfat dry milk, 2.25% salt, and 3% compressed yeast (all percentages were given in flour weight basis) was used in the experiments. Fat (vegetable margarine) (8, 12, 16%), emulsifier (1, 2, 3%), and dextrose (1, 3, 5%) were add- ed to the recipe as independent variables according to experimen- tal design. As an emulsifier Purawave (Puratos, Belgium), which is composed of lecithin, soy protein, mono-di glycerides, and veg- etable gums, was used. In order to observe the effects of gluten on microwave baked breads, two different flour types were used. Type A flour contains 8.7% protein, 12.6% moisture, and 0.7% O. Ozmutlu · G. Sumnu ( ✉ ) · S. Sahin Middle East Technical University, Food Engineering Department, 06531, Ankara, Turkey e-mail: gulum@metu.edu.tr ORIGINAL PAPER O. Ozmutlu · Gülüm Sumnu · S. Sahin Effects of different formulations on the quality of microwave baked breads Received: 17 November 2000 / Revised version: 31 January 2001 / Published online: 19 April 2001 © Springer-Verlag 2001