Production of Whole Wheat Bread with Good Loaf Volume'

Cereal Chem. 66(3):224-227 A reconstituted whole wheat bread (containing 16.3% bran plus 12.7% was included in the baking process. Addition of a high level of enzymeshorts) with a loaf volume equal to the control was obtained by allowing active soy flour eliminated the need for the no-yeast sponge stage. Certain indigenous lipoxygenase (soaking the nonflour milling fractions) or added salts and surfactants were found to improve loaf volume. In this system, lipoxygenase (enzyme-active soy flour) to oxidize the glutathione from the compressed yeast was superior to instant dry yeast for maintaining constant germ and using optimum absorption. Because lipoxygenase requires bread quality. oxygen to function and yeast consumes oxygen, a no-yeast sponge stage Demand for whole wheat bread has increased considerably in the last few years because of its better nutritional image and an increasing preference for its organoleptic characteristics (Pomeranz 1977, Rogers and Hoseney 1982). The loaf volume of whole wheat bread is substantially smaller than that expected solely from the dilution of gluten by nonflour material (Pomeranz 1977, Rogers and Hoseney 1982). This problem makes the production of whole wheat bread with the same loaf volume as white bread more expensive because of the extra flour required (Rogers and Hoseney 1982). Lai et al (1 989a,b) studied the effect of nonflour milling fractions on breadmaking. They proposed that bran binds a relatively large amount of water and changes the appearance and the handling properties of the dough. Therefore, the gluten was not properly hydrated and developed at normal absorption levels. The use of an inappropriate absorption level results in a reduction in loaf volume (Lai et al 1 989a). Lai et al (1 989b) attributed the negative effects of shorts in breadmaking to glutathione from germ and methoxylhydroquinone (MHQ) types of compounds from the other shorts fractions. They also reported methods to overcome the detrimental effects of bran, shorts, and germ on bread loaf volume. The goal of this study was to develop an optimum formula and procedure to produce whole wheat bread of good quality and volume. MATERIALS AND METHODS Flour Flour used was provided by Ross Milling Company, Wichita, KS. It contained 11.6% protein (N X 5.7) and 0.45% ash (14% moisture basis). Whole wheat flour was milled from a hard red spring wheat (17.6% protein, 14% mb). The flour was stored in a freezer at -14° C until one day before use. Vital wheat gluten was provided by Midwest Grain Products, Atchison, KS. Surfactants, Salts, and Other Chemicals Surfactants were provided by Grindsted Product Company, Industrial Airport, KS. They included sodium stearoyl lactylate (SSL), polysorbate, ethoxylated monoglyceride, succinylated monoglyceride, diacetyl tartaric acid esters of monoglycerides (DATEM), lecithin, and monoglyceride. The salts and other chemicals were reagent grade chemicals. Pup Loaf Baking The pup loaf baking formula and process was described by Finney (1984). 'Contribution no. 88-113-J, Kansas Agricultural Experiment Station, Manhattan. 2 Graduate research assistant, associate professor, and professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan 66506. -Present address: Hershey Company, Hershey, PA. 4 Present address: Entenmann's Inc., Bay Shore, NY. © 1989 American Association of Cereal Chemists, Inc. Response Surface Study A central composite rotatable design of the Box-Wilson type was used (Cochran and Cox 1957). No-Yeast Sponge Breadmaking Process Part of the formula water (which may contain a variable amount of salts) was added to the whole wheat flour or meal (containing 4% nonfat dry milk, 1% enzyme-active soy flour, 6% shortening, and 0.5% SSL; all percentages based on total amount of flour) and mixed to make a no-yeast sponge. This sponge was placed in a covered fermentation bowl and allowed to rest for 2 hr (unless specified otherwise). Yeast and the remaining ingredients (remainder of water, 6% sugar, and 1.5% salt (NaCl unless specified otherwise) were added, and the dough was mixed to optimum. The dough was fermented, punched, and baked as described by Finney (1984) except that doughs containing combinations of salts were proofed to a height equal to that of doughs containing 1.5% NaCl. Scoring Dough-Handling Properties Dough-handling properties were scored using a five-point scale. The scoring criteria were as follows: 5, good dough-handling properties (as good as white flour dough); 4, dough can be handled without difficulty when hands are lightly greased; 3, dough can be handled with slight difficulty when hands are greased; 2, dough can be handled with slight difficulty when hands are greased and slight amount of dusting flour is applied; and 1, dough is difficult to handle even when hands are greased and dusting flour is applied. RESULTS AND DISCUSSION Reconstituted Whole Wheat Breads Results from our previous studies (Lai et al 1989 a,b) suggested that the detrimental effects of bran could be overcome by using an optimum absorption and the detrimental effects of shorts could be overcome by soaking them, thus, allowing the indigenous lipoxygenase to function. A reconstituted whole wheat bread was made by adding 0.5% SSL and 29% soaked bran and shorts mixture (16.3% bran plus 12.7% shorts, based on flour weight) to 100 g of flour. The reconstituted whole wheat bread had a loaf volume equal to that of the control (100% white flour), but the loaf had a flat top and sagging sides, indicating a weak dough (Table I). Addition of a higher level of oxidant did not produce a significant improvement in grain or shape of the loaf. Vital wheat gluten (2%) was added to strengthen the flour. A reconstituted whole wheat bread with good loaf volume was obtained using this fortified flour (Table I). Shape and grain of the baked loaf were improved, but these loaves still showed signs of weakness. Lai et al (1989b) reported that a MHQ and glutathione mixture mimicked the effects of shorts and that their detrimental effects could be overcome by including enzyme-active soy flour in the baking formula and adding a no-yeast sponge step in the baking process. Reconstituted whole wheat breads were baked with a similar no-yeast sponge method (with 2 hr of resting time). The 224 CEREAL CHEMISTRY optimum resting time to produce the best loaf volume and grain (Table I) was found to be 1 hr. Determination of Optimum Absorption for Whole Wheat Bread Quality Our previous work with wheat bran (Lai et al 1989a) indicated that the best loaf volumes were obtained with the highest water level possible that did not produce an excessively sticky dough. Similar results were obtained with whole wheat flour. Effect of Neutral Salts on Whole Wheat Bread Quality Holmes and Hoseney (1987a,b) showed that certain ions affected loaf volume and changed the optimum NaCl level for breadmaking. Bran and shorts contain 14 and 17% ash, respectively, and thus, are likely to alter the optimum NaCl level normally used for white pan bread. Producing whole wheat breads containing various amounts of NaCl and combinations of sodium phosphate (dibasic) and NaCl showed that high levels of salts (2.5% NaCl or 1. 5% NaCl + 0.5% Na2HPO4) reduced yeast activity but had little effect on loaf volume. However, the added salts did significantly improve strength and handling properties of the dough. The grain and shape of the baked loaves were also substantially improved. This data suggested that, with additional proof time, the inclusion of phosphates or other salts might improve both loaf volume and grain of whole wheat bread. It appears that a whole wheat bread with good loaf volume can be produced by a no-yeast sponge process with the inclusion of an appropriate combination of certain salts. As shown above with the model whole wheat system, the inclusion of dibasic phosphate improved dough strength and loaf volume if the dough was given sufficient proof time. Replacing the 1.5% NaCl with 1.2% sodium phosphate (dibasic) or 1.4% sodium citrate improved loaf volume by about 80 cm (Table II). These findings suggested that an appropriate combination of salts could improve loaf volumes. A model describing the effects of sodium citrate and NaCl on loaf volume was obtained from response surface analysis (Fig. 1). The square of the multiple correlation coefficient (R) of this model was 0.91. According to the model, the best loaf volume can only be obtained by using an appropriate combination of sodium citrate and NaCl (Fig. 1). For this flour, the optimum combination was 1.5% NaCl and 1.4% sodium citrate. That salt combination TABLE I Effect of Rest Time on Loaf Volume of Modela Whole Wheat Bread Loaf Standard Volumeb Deviation Treatments (cm ) (cm) Control (fortified control flour)c 975 9.1 Whole wheat (soaking method) 965 14.7 Whole wheat (no yeast sponge method) 977 22.5 Whole wheat 0-min rest 933 2.9 30-min rest 982 14.3 60-min rest 990 7.1 90-min rest 982 18.9 120-min rest 981 12.6 a Model whole wheat flour is made up of 100 g of white flour, 16.3% fine bran, and 12.7% shorts. bAverages of four observations. 'All doughs contained 2% vital gluten whether made with or without bran-shorts mixture. TABLE II Effects of Salts on Loaf Volume of Whole Wheat Bread Loaf Standard Volumea Deviation Treatment (cm) (cm ) and 61 min proof time were used in the following tests, unless otherwise specified. Relation of Optimum Resting Time and Soy Flour Surface response analysis was also used to determine the effect of soy flour (source of lipoxygenase) level and rest time on loaf