Bread baking tests

An obvious use of bake testing is to compare the performance of two different batches of flour. In this exercise it is suggested that the control batch is a bread flour while the test should be a non-bread-making soft flour such as an English plain flour. 

Bread is a major wheat-derived food product consumed in the United States. We tested the bioavailability to rats of monoferric phytate either with bread or baked in bread. Either the monoferric phytate or reference iron compound, ferrous ammonium sulfate, was baked in bread at three concentrations of iron. 

Figure 4. Bioavailability of monoferric phytate baked into bread. Rats were the test species and change in hemoglobin concentration during a 2-week repletion period was bioassay criterion.

Approximately 70f of the monoferric phytate baked into bread could be recovered in extracts of the bread. He have not tested the bioavailability or the chemical form of iron when an iron salt and sodium phytate are baked into bread as was done by McCance et al. (3). If an insoluble ferric phytate of any ion composition was formed, we would expect the iron to be poorly bioavailable. Hussain and Patwardhan (22) did not specify whether they added sodium phytate to the food during preparation or administered it orally when young men ate the meals in their study using a vegetarian menu. They found decreased iron balance when the percentage of phytate phosphorus to total phosphorus was increased from 8 to 40 by addition of sodium phytate. 

An example is illustrated in Figure 11.3 (cf. Figure 7.10 in Chapter 7) for the effect of varying the natural lipid level of a wheat flour on bread loaf volume in an optimized lean formula baking test. The behavior is unusual. The nonstarch flour lipid has been solvent-extracted using chloroform and added back incrementally to the defatted flour. Small additions of lipid decrease loaf volume imtil a minimum is reached at a lipid... 

FIGURE 15.11 (Continued) Sequential steps followed to perform the 100 g flour straight dough baking test, (h) Determination of bread height, (i) Determination of bread volume by rapeseed displacement, (j) Evaluation of crumb texture. 

Test baking is one answer to this problem some flour samples that had a good measured composition produce a poor loaf of bread. There are also samples that do not have very promising measured properties... 

Triticale flour has been extensively tested in Poland, a country where rye bread is traditional. The best results were obtained by using 90% triticale flour with 10% rye flour. The rye flour was made into a flour brew for 24 hours at 28-29°C. Half the triticale flour was made into a sour dough for 3 hours at 32°C followed by mixing with the rest of the ingredients plus 1.5% of salt on the flour weight. The bread was then scaled and proved for 30 min at 32°C followed by baking at 235-245°C. 

Microscopic Examination —This serves to show if a bread is made from wheaten flour alone or if it contains also extraneous flours. The test is made on the crumb, parts which are less well baked being chosen or, if possible, lumps or nodules of dough such as are often present. The fragments taken are made into a paste with water and the microscopic examination then made. A convenient method, which gives excellent results, is as follows ... 

The ash determined in the above manner furnishes One of the best criteria for deciding what quality of flour has been used in making the bread. If mineral substances or even so-called baking powder were added to the flour, the ash would show an increase in this case, tests 14 and 15 are applied. 

From PER and net protein ratio (NPR) tests, Palamidis and Markakis (12) later also found that the PER of bread mix (ingredients) or bread mix with 4% nonfat dry milk (NFDM) were 0.75 or 1.17, as compared to 0.46 or 0.75 for their corresponding breads, respectively. The findings also clearly show that baking can damage the nutritive quality of bread protein significantly and that fortification of NFDM can raise the PER of bread mix and wheat (white) bread. 

Experiment 125. — Test the following for starch by grinding a small portion of each with water in a mortar, and then adding a few drops of the extract to an exceedingly dilute solution of iodine a) wheat flour, (f) oatmeal, (c) potato, d) rice, e) beans, (/) bread, g) cracker, (//) pepper, (/) baking powder. 

Test diets were formulated by substituting bread for a portion of the glucose monohydrate in the basal iron bioassay diet (see ref. 10 or 11 for details of semipurified diet). Comparable dietary iron concentrations were attained with the same amount of bread in each diet. In addition to diets that contained bread with the iron compound baked in, each compound was added to diets that contained equal amounts of unenriched bread. The bioassay results are shown in Figure 4. The comparison diet (RBV = 100) contained ferrous ammonium sulfate with unenriched bread. There were no differences in the RBV s (calculated by slope ratio) of... 

Zeleny, Y. 1947. A simple sedimentation test for estimating the bread-baking and gluten qualities of wheat flour. Cereal Chem. 24, 465 475. 

The conventional test for the purity of flour, with respect to bran contamination, is ash content. Ash is defined as the oxidized residue remaining after flour is incinerated at high temperatures. Because the ash content of bran (up to 8%) is considerably higher than that of the endosperm (0.3%), the ash content of flour is a sensitive index of bran contamination. High ash content of white flour adversely affects both its baking performance and the crumb color of bread baked from it. Therefore, flour specifications usually aim for the minimum ash content. 

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