Cereal Chem. 74(2):129-134Breads baked from wheat flours (protein contents 14.1-16.5% at 14.0% mb) that were pretreated with 2-3 mL of gaseous acetic acid per kg of wheat flour, showed maximum bread height and specific volume (cm 3 /g). Flour-water suspension and the crumb pH values were gradually decreased with increased amounts of acetic acid. Gas generation and dough expansion tests with bread dough showed that the addition of the same amount of acetic acid, which achieved maximum specific volume, also showed the highest rate of gas generation and dough expansion.However, increasing acetic acid decreased these values. Scanning electron microscope (Cryo-SEM) observation showed that the bread dough made from the same acetic acid-treated flour indicated continuum and no cracks in the dough matrix. Evaluation of mixograms showed the decrease of mixing stability with increased acetic acid levels. Viscosity and water binding capacity of flour-water suspensions were sharply increased by the addition of acetic acid at pH 5.0-3.5.

Breadmaking was performed with cellulose-blended wheat flour. Cellulose granules (7 types) of various sizes (diameter) were prepared by kneading. With increase of the blend percent of the cellulose samples from 10% to 20%, breadmaking properties such as bread height and specific volume (SV) gradually decreased in every sample; however, the decreasing levels of the properties in 7 types of various sizes varied. The decrease of bread height and SV was associated with the size of the cellulose granule. It was observed at both 10% and 20% blends that the same bread height and SV as for bread baked with only wheat flour could be obtained when the diameter of cellulose granule was above 154 mum in cellulose/wheat flour breadmaking, while they gradually decreased with granules below 154 mum. When the largest cellulose granules were mechanically ground to make smaller ones, the bread height and SV decreased with increasing grinding time. It was ascertained that the size of the cellulose granule was important for breadmaking properties. Cellulose-blended wheat flour was subjected to mixograph tests. When cellulose granules above 154-mum dia were blended with wheat flour, the profile of the mixogram was almost the same as that for wheat flour; that is, the profile had a short mixing requirement and showed a viscous gluten matrix. However, when cellulose granules below 81-mum dia were blended, a different curve showing a nonviscous dough due to breakdown of the gluten protein was observed, as ascertained by microscopy. Farmograph test showed that the amount of the released gas from cellulose-blended bread dough increased with decrease of the size of the cellulose granule due to breakdown of the gluten protein.

Wheat starch granules were obtained from soft wheat flour by acetic acid fractionation (pH 3.5), and the starch was stained by reaction with Remazolbrilliant blue (RBB) dye. RBB‐stained starch was extracted with 1% sodium dodecyl sulfate (SDS) and 1% 2‐mercaptoethanol (ME) for 14.5 hr at room temperature. This extraction step was repeated five times (extracts 1–5). SDS‐ME extracts were subjected to size‐exclusion column chromatography, and comparisons of their profiles for specific absorbance at 650 nm (A650) and carbohydrates were made. After high molecular weight (HMW) carbohydrates on the starch granule surface were extracted, HMW carbohydrates inside the granule appeared to be extracted. Finally, low molecular weight (LMW) carbohydrates near the granule surface were extracted. Phase‐contrast light microscopy of the treated starch granules showed that all granules became transparent. Two different interior structures were observed. Scanning electron microscopy indicated that the granule was split into two parts at the equatorial groove. The interior of the granule showed two different areas: a central hole area and the surrounding stratified area. Extraction beyond five times with the same solvent dissolved the weak part of the granule structure and left two types of skeletal structures. The appearance of the skeletal structure of the granule surface was different from the appearance of interior structures.

Amylose contents in 39 strains of rice starch, including waxy starch, low amylose containing starch, and non‐waxy starch, were measured. Seguchi et al. [1] reported that waxy wheat starch exhibits a ghost appearance by staining and swelling with 25% KI/10%I2 solution at 25 °C. We subjected the 39 rice strains to staining in the same manner. We found that the relative ghost area (%) in a rice starch, which is a measure of granule swelling in 25%KI/10%I2 solution, , is related to its amylose content (r = ‐0.78). As the relative ghost area (%) of the rice starch increased rapidly when the amylose content decreased below 5%, we concluded that at least 5% of amylose is required to maintain the structure of rice starch granules. Furthermore, the red‐brown central region in ghostly appearing granules decreases with amylose level and the surrounding light brown region increases. When the starch does not contain amylose, the ghost is entirely light brown. The decrease in the area of the red‐brown central region with decreasing amylose content suggests that amylose is concentrated in the red‐brown central region of the ghost.

Cereal Chem. 75(1):37-42Wheat flours were stored at room temperature (15-25°C), 40, 60, 80, and 100°C for various times. The baking performance of these flours was then evaluated in terms of the springiness of pancakes (recovery from crushing). Baking performance improved with increased storage time at each temperature. Brabender Amylograph tests of the flours indicated that the onset temperature in viscosity decreased with increased storage time at each temperature. When the flours were fractionated by acetic Publication no. C-1998-0105-06R.

Maitake mushroom powder drastically decreased dough strength in Brabender farinography and was also effective in deteriorating bread-making properties (bread height and specific volume). These effects of maitake on farinograph values and bread-making properties were lost by boiling maitake/water suspensions or by adding EDTA, suggesting that the deteriorative effects by maitake may be caused by a metal protease. Flour dough that contained maitake was treated with 1% sodium dodecyl sulfate (SDS), and extracted proteins were subjected to SE-HPLC and SDS-PAGE. The range of high-molecular-weight (HMW) protein in those profiles gradually decreased with an increase of maitake, and HMW protein/total protein correlated well with bread height but did not have a clear effect on specific volume.

A soft wheat flour, Tokutakaragasa (protein 9.69 %), was dry-heated at 120℃ for 10, 20, 30, 60, and 120 minutes, and baked into Kasutera cakes (Japanese sponge cakes). The volume of Kasutera cake increased with duration of dry heating. Also, the stability of foam in Kasutera cake batter increased with the dry-heating time of wheat flour. The mixograph profile of dry-heated wheat flour also suggests the hydrophobicity of wheat flour. Thus, the results suggest that the hydrophobicity of the dry-heated wheat flour could stabilize the foam in Kasutera cake batter and contribute to increasing Kasutera cake volume.

Wheat starch granules were separated from waxy wheat flour by the acetic acid (pH 3.5) fractionation technique. Waxy wheat starch samples were stained red‐brown using KI/I2 solution. Subsequently, the concentration of the KI/I2 solution was increased to >2.5% KI and 1.0% I2. Then the appearance of the waxy wheat starch granules quickly became ghostlike. The internal structure of the ghost could be observed. This structure consisted of two parts with different colors: a red‐brown central part and a slightly pinkish surrounding part. Sonication of the ghost at 20 kHz for 20 sec separated the central part from the surrounding part. Each of the separated parts were subjected to gel‐filtration chromatography, and their chromatography profiles indicated only amylopectin and no amylose. The central and surrounding parts had molecular weights of 54.3 × 105 and 23.8 × 106 from Berry plots, respectively.