Flour Extraction Rate Research Articles

Effect of Flour Extraction Rate and Baking on Thiamine and Riboflavin Content and Antioxidant Capacity of Traditional Rye Bread

The effect of rye flour extraction rates and baking on thiamine and riboflavin content, and antioxidant capacity of traditional rye bread were studied and compared with white wheat flour. The content of thiamine was higher (10.9%) in rye dough formulated with dark rye flour (F-100%; extraction rate of 100%) than in rye dough formulated with brown rye flour (F-92%; extraction rate of 92%) that was similar to dough made with wheat flour. The riboflavin content in rye dough made from flour F-100% was also higher (16%) than in dough formulated with flour F-92%, and both provided larger riboflavin content than wheat dough. Baking led to reductions in thiamine of 56% for wheat bread and of 20% for both rye breads; however, this process caused only a 10% decrease in riboflavin for wheat bread and a 30% decrease for rye breads. Trolox equivalent antioxidant capacity, peroxyl radical scavenging capacity, DPPH radical scavenging activity, and Folin-Ciocalteu reducing capacity were higher in rye than in wheat dough and bread. Baking process produced slight changes in antioxidant activity, except for Superoxide Dismutase-like activity where a sharp decrease was observed. Our findings showed that rye breads are an important source of B vitamins and rye breads formulated with dark and brown flours showed better antioxidant properties than wheat bread. Therefore, rye breads should be more widely recommended in human nutrition.

Asian noodles: History, classification, raw materials, and processing

Noodles in various contents, formulations, and shapes have been the staple foods for many Asian countries since ancient time. They can be made from wheat, rice, buckwheat, and starches derived from potato, sweet potato, and pulses. Noodles based on wheat are prepared mainly from three basic ingredients; flour, water, and salt. There exist two distinct types of wheat flour noodles based on the presence and absence of alkaline salts, regular salted noodles, and alkaline noodles. The basic process of dough mixing, sheet forming, compounding, sheeting/reduction, and cutting are essentially constant for all machine-made noodles. Noodle strands coming out of cutting rolls can be further processed to produce different types of noodles. This article analyzed all the major processes involved from raw material to finished products in relation to noodle processing properties and cooked noodle texture. Different ingredients and their functionality in noodle processing were discussed as well. Guidelines were provided to select the right ingredients to produce high quality noodle products. Processing properties, appearance, and colour of noodles are the three key criteria used to judge a process and raw material quality. High quality noodles should be bright in colour with very slow discoloration, have an adequate shelf life without visible microbiological deterioration or oxidative rancidity, and have appropriate flavour and textural characteristics which will vary according to the noodle type and region. Flour plays a key role in all aspects of noodle quality. Protein content is positively correlated with noodle firmness and sometimes negatively correlated with elasticity. Therefore, a correct range of protein content is important for textural characteristics. Adequate gluten strength and extensibility is required in all noodle flours. Noodle dough must be strong enough to withstand sheeting, but not so strong as to cause tearing or difficulty in sheet reduction. A good level of dough extensibility ensures that dough sheets do not shrink back during successive roll passes. The importance of the pasting properties of starch to the texture of cooked noodles has been well-documented. The required soft, smooth, and elastic textural properties of certain types of white salted noodles can be best obtained from wheats with high starch paste viscosity and high swelling starch properties. Alkaline noodles do not have the same requirement for high starch swelling properties. Noodles made from flour with high swelling starches have softer texture than those with low swelling starch. Noodles should be bright and slow in discoloration with time after manufacturing. For white salted noodles, a white or creamy white colour is desirable. The level of natural yellow pigment levels (xanthophylls) in flour is highly correlated with noodle colour, and this is wheat variety dependent. For yellow alkaline noodles, a bright yellow colour is required, although the preference for the degree of colour development is regionally based. Noodle darkening increases with the increases of flour extraction rate. This is due to the action of polyphenol oxidase (PPO) enzymes which are largely located in the bran layer. Low flour extraction and ash levels are preferred for the manufacture of noodles with a clean and bright appearance. A relatively fine flour particle size enables even hydration during mixing and optimum, uniform gluten development during sheeting. Increased starch damage, however, is associated with poor noodle colour and undesirable high cooking loss and excessive surface swelling.

KANE hard red spring wheat

KANE is a hard red spring wheat that meets the end-use quality and kernel visual distinguishability specifications of the Canada Western Red Spring market class. KANE was found to be adapted to the wheat-growing regions of Manitoba and eastern Saskatchewan from the data provided by the Central Bread Wheat Cooperative registration test in 2003–2005. In comparison with the check cultivars Katepwa, McKenzie, CDC Teal, AC Barrie, and Superb, the overall grain yield of KANE was similar to the high yield checks McKenzie and Superb. Compared with the highest yielding check McKenzie, KANE was 1.7 d later maturing, was 6 cm shorter, had stronger straw, and was significantly higher (1.1 kg hL-1) in test weight. KANE is resistant to the prevalent races of leaf rust and stem rust. Resistance to common bunt and loose smut was intermediate, being similar to CDC Teal and McKenzie, respectively. Resistance to fusarium head blight was similar to AC Barrie. KANE has good preharvest sprouting resistance with similar or lower sprouting scores compared to the best check in 4 out of 5 yr of testing. End-use quality tests showed that KANE had a 0.7% higher flour extraction rate than the best checks and was within the range of the checks for the other quality traits. Key words: Triticum aestivum L., cultivar description, red spring wheat, test weight, preharvest sprouting, leaf rust

Effect of bread making on formation of Maillard reaction products contributing to the overall antioxidant activity of rye bread

This paper reports the effects of flour extraction rate on antioxidant activity, early, fluorescent and coloured Maillard reaction products in rye flour, crumb, crust and bread. Extent of the reaction was determined by analyses of furosine, fluorescence compounds and browning while antioxidant properties were measured by Folin reaction, Trolox Equivalent Antioxidant Capacity (TEAC) and Oxygen Radical Antioxidant Capacity (ORAC FL) assays. Antioxidants present in rye flours and breads scavenged peroxyl and ABTS radicals and reduced Folin-Ciocalteu reagent. Data indicated that baking favoured the formation of antioxidant compounds. In controversy, milling to obtain white rye flour negatively affected bread quality.

Effect of Flour Extraction Rate on White and Red Winter Wheat Flour Compositions and Tortilla Texture

ABSTRACTWheat flours commercially produced at 74, 80, and 100% extraction rates made from hard white winter wheat (WWF) and hard red winter wheat (WRF) were used to produce tortillas at a commercial‐scale level. Flour characteristics for moisture, dry gluten, protein, ash, sedimentation volume, falling number, starch damage, and particle‐size distribution were obtained. Farinograms and alveograms were also obtained for flour‐water dough. A typical northern Mexican formula was used in the laboratory to test the tortilla‐making properties of the flours. Then commercial‐scale tortilla‐baking trials were run on each flour. The baked tortillas were stored at room and refrigeration temperatures for 0, 1, 2, and 3 days. Maximum stress and rollability were measured every day. Tortilla moisture, color, diameter, weight, and thickness were measured for each treatment. Finally, tortilla acceptability was tested by an untrained sensory panel. Analyses of variance (ANOVA) were performed on the data. WWF had higher protein content, dry gluten, sedimentation volume, and water absorption than the WRF. The WWF was the strongest flour based on farinograph development time and alveograph deformation work. It also produced the most extensible dough measured with the alveograph (P/L). Flour protein and ash contents, water absorption, and tenacity increased directly with the flour extraction rate. Both WWF and WRF performed well in commercial‐scale baking trials of tortillas. Tortillas made with both types of flours at 74 and 80% extraction rates had the best firmness and rollability. However, tortillas made with WWF 80% had the best color (highest L value). Tortillas prepared with 100% extraction rate flour were also well accepted by the sensory panel, had good textural characteristics, and became only slightly firm and slightly less rollable after three days of storage at room temperature.

Evaluation of white-grained wheat in Hungary

Most cultivated wheat varieties belong either to the redor white-grained type. Compared to red wheat varieties, white wheat has many advantages for the milling industry, such as high flour extraction rate and greater fibre content because of closer milling. Also, it has some aesthetic advantages, such as whiter flour, while the products are less raw flavoured than those made from red wheat (Chang and Chambers 1992). In addition, the bran of white grain can be considered as a useful by-product that is widely used in the snack industry. These nutritional parameters make white wheat suitable for processing in healthy food production. According to Varallyay (2006) healthy food and sustainable land management are closely related. In developed countries, white wheat has been increasingly used to make high fibre food products (Bequette and Herrman 1994). All the wheat varieties cultivated in Hungary belong to the red type. However, growing white wheat would potentially help to meet the special demand for healthy food with high fibre content and nutritional value. Besides the favourable nutritional effects mentioned above, however there are some disadvantages of growing white wheat. White genotypes are highly susceptible to preharvest sprouting (PHS) caused by rain before harvesting. This could result deterioration in quality parameters, such as falling number and bread volume (Huang and Varriano-Marston 1980, Pepo et al. 2005, Gut and Bichonski 2004). There is a positive relationship between the kernel colour and resistance to PHS (Wang et al. 1999). Red-grained genotypes are generally resistant, while white ones are susceptible to PHS. In some cases the white and red-grained cultivars can hardly be distinguished visually. Some light-red or white genotypes may show the opposite phenotypes as a consequence of various environmental stresses (McCaig et al. 1993). Thus, determining the genetically determined seed colour is of special importance, as these two types require different milling and baking techniques (Dowell 1998). To date, chemical methods have been developed for determining grain colour (De Pauw and McCaig 1988, Ram et al. 2002). The aim of this study was to evaluate the competitiveness of the white-grained Martonvasar breeding lines identified by routine grain screening during the breeding process.

Antioxidant Contents and Antioxidative Properties of Traditional Rye Breads

The purpose of this research was to find out the effect of flour extraction rate on the antioxidative properties of traditional rye bread and then to compare the bioactive compounds content and antioxidant properties of rye breads with commercial wheat roll. Four types of rye flour with different extraction rates of 100 (whole meal dark flour), 95 (brown flour), 90 (brown flour), and 70% (light flour) originated from Warko rye cultivar were used for traditional bread baking with sourdough fermentation. Four types of the respective rye breads were analyzed for their potentially beneficial components, including tocopherols and tocotrienols, total phenolics and flavonoids, reduced glutathione, and inositol hexaphosphates. Moreover, the phenolic acids profile was provided. The Trolox equivalent antioxidant capacity (TEAC) of the breads was evaluated using free radical scavenging activities of 80% methanol extracts against ABTS*+ radical cation (ABTS radical cation decolorization method) whereas radical scavenging activity (RSA) was determined against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*). The superoxide dismutase-like activity (SOD-like activity) was evaluated as free radical scavenging activities of PBS extracts against superoxide anion radicals (O2*-). The results were compared to whole meal rye bread as well as to wheat roll taken as representative example of wheat based bakery product. The studies showed that flour extraction rates strongly affected the content of bioactive compounds and antioxidative properties of traditionally baked rye breads. The incorporation of the rye flours with extraction rates from 100 down to 70% in the formulation caused decrease in tocopherol (T), tocotrienol (T3), inositol hexaphosphate (IP6), and phenolic compound (TPC) contents in rye breads. No changes in reduced glutathione (GSH) contents were noted between each type of rye bread. A significant decrease in Trolox equivalent antioxidant capacity and radical DDPH scavenging activity was also found in bread formulated on flour with an extraction rate of 70% in comparison to the breads formulated on flour with extraction rates from 100 to 90%. The highest SOD-like activity was noted for rye bread formulated on flour with an extraction rate of 70%. The four types of rye breads showed better antioxidative properties and higher antioxidant contents when compared to wheat roll with one exception made to tocopherols and tocotrienols.

Effect of reduced tillage on wheat quality traits

The effect of tillage systems (TS) on wheat quality traits including grain yield, thousand-kernels weight, hectoliter mass, flour extraction rate and flour rheological properties were evaluated. Five different TS were compared in winter wheat (Triticum aestivum L.) production on one experimental field (chernosem) located in the Baranya region, north-eastern Croatia from 1998 to 2001. Tillage systems included conventional tillage (CT), disc harrowing, fine till (DHF), soil loosening (SL) + disc harrowing (DH), disc harrowing, coarse till (DHC) and no-tillage (NT). The most stable grain yield was obtained by DHF and CT in all three experimental years. There was no striking regularity with regard to applied TS and hectoliter mass and thousand-kernels weight. The biggest difference of hectoliter mass was determined between CT and NT. TS had significant influence on the flour extraction rate in all three experimental years. The influence of TS on farinographic parameters was significant for all three experimental years for the quality number. Quality number was greater under CT than under other TS. Tillage effect on extensographic and amylographic parameters in the 3-year average did not show statistically significant differences. To sum up, since disc harrowing (DHF) and (DHC) followed by soil loosening with chisel produced equal grain yield and wheat quality parameters were slightly better than conventional tillage, these systems could be presented as an even handed replacement for ploughing.

Bioactive compounds in rye flours with different extraction rates

Rye flours with extraction rate of 100% (wholemeal flour), 95% (brown flour), 90% (brown flour) and 70% (light flour) were prepared in order to study the relation between flour extraction rates and content of bioactive compounds. The following compounds were analysed: total phenolic compounds (TPC), total flavonoids (TF), inositol hexaphosphate (IP6), reduced (GSH) and oxidized (GSSG) glutathione, tocopherols (T) and tocotrienols (T3). The reduced/oxidized glutathione status (GSH/GSSG) of the flours was examined as a potential index of flour resistance against oxidative stress. The following observations were made in relation to the flour extraction rates and bioactive compounds contents: (a) milling process caused decrease in content in TPC, TF, IP6, GSH and GSSG, T and T3, (b) the most resistant against oxidation processes were suggested a brown flours, then light and finally wholemeal flour, (c) the ratio of tocotrienols to tocopherols (T3/T) was the highest in rye flours with extraction rate of 100–90% whereas light flour was the poorest source of tocopherols and tocotrienols. The provided data support current trend to increase number of rye products from wholemeal or brown flours.

PREDICTION OF FLOUR EXTRACTION RATE IN HARD RED WINTER WHEAT USING THE SINGLE KERNEL CHARACTERIZATION†

ABSTRACT Flour extraction rate is a key determinant in milling efficiency and profitability and can be useful in projecting flour output from a mill. Wheat is generally purchased based upon a small group of traditionally measured physical characteristics. This article explores the use of the Single Kernel Characterization System (SKCS) to predict flour extraction rate. Regression analysis was performed using the SKCS parameters and test weight against flour extraction rate for over 600 observations from multiple years from the hard red winter wheat production areas of the U.S. The regression equation had an R2of 0.81. The data suggest that the SKCS 4100 and test weight can be used to predict flour extraction rate in hard red winter wheat. Using the regression equation as a tool, mill buyers may be able to make better decisions regarding their wheat purchases and prediction of flour output.

Selenium Distribution in Wheat Grain, and the Effect of Postharvest Processing on Wheat Selenium Content

Selenium (Se) is an essential micronutrient for animals and humans, and wheat is a major dietary source of this element. It is important that postharvest processing losses of grain Se are minimized. This study, using grain dissection, milling with a Quadrumat mill, and baking and toasting studies, investigated the distribution of Se and other mineral nutrients in wheat grain and the effect of postharvest processing on their retention. The dissection study, although showing Se concentration to be highest in the embryo, confirmed (along with the milling study) previous findings that Se (which occurs mostly as selenomethionine in wheat grain) and S are more evenly distributed throughout the grain when compared to other mineral nutrients, and, hence, lower proportions are removed in the milling residue. Postmilling processing did not affect Se concentration or content of wheat products in this study. No genotypic variability was observed for grain distribution of Se in the dissection and milling studies, in contrast to Cu, Fe, Mn, and Zn. This variability could be exploited in breeding for higher proportions of these nutrients in the endosperm to make white flour more nutritious. Further research could include grain dissection and milling studies using larger numbers of cultivars that have been grown together and a flour extraction rate of around 70%.

Effect of extraction rate of wheat flour on the quality of vermicelli

In order to develop newer varieties of vermicelli with improved nutritional quality, studies were carried out on the quality of vermicelli as influenced by different extraction rate of wheat flour, from 66% to 100%. Chemical and rheological studies carried out showed considerable variation among the flours. With increase in extraction rate, the water absorption of the vermicelli dough increased from 35% to 42.5%. There was no significant difference in the colour of vermicelli when extraction rate was increased from 66% to 80%. However, a further increase made the vermicelli more brownish. The cooking quality of vermicelli made from different extraction rate flour of wheat showed reductions in cooked weight from 420% to 315%, and increase in solid loss during cooking from 8% to 10.5%, with increase in extraction rate. The solid loss during cooking was reduced by the addition of 0.25% glycerol mono-stearate and 0.25% of sodium stearoyl lactylate, whereas the water uptake increased. Addition of 2% gluten strengthened the strands and reduced surface stickiness. The results show the possibility of making vermicelli from either 100% extraction rate flour or whole-wheat flour, which could be a product of better nutritional value.

Milling of Regular and Waxy Starch Hull‐less Barleys for the Production of Bran and Flour

ABSTRACTFive registered cultivars of hull‐less barley (HB) with regular or waxy starch were milled in a Quadrumat Jr. mill to obtain whole grain flour; pearled in a Satake mill (cultivar Condor only), and the pearled fractions examined by microscopy to determine true HB bran. The samples were milled after tempering and drying in a Buhler mill to obtain bran and flour yields. Flour color and composition of HB were unaltered on milling in the Quadrumat Jr. mill. Microscopic evidence showed that a 70% pearl yield was devoid of the grain's outer coverings, including the aleurone and subaleurone layers. Therefore, the balance of 30% constitutes true bran in HB. Dry milling (as‐is grain moisture) of regular starch HB in the Buhler mill gave 59% total flour and 41% bran (bran + shorts) yields, the comparative values for the waxy starch HB were 42 and 58%. On tempering HB from 9 to 16% grain moisture, the total flour yield decreased in both types of HB but to a lesser extent in the waxy starch HB due to decreases in reduction flour. On drying HB to 5 or 7% moisture, total flour yields increased due to contamination with bran and shorts. The milling study led to the conclusion that HB, at best, be dry‐milled and a bran finisher be used to obtain commercial flour extraction rates. Lower total flour yields in the waxy starch HB than in the regular starch HB milled at the same grain moisture levels seemed due to higher β‐glucan rather than grain hardness. Waxy starch HB flour had higher mixograph water absorption and water‐holding capacity than regular starch HB or soft white wheat flour milled under identical conditions. Roller‐milled HB products offer the best potential for entry into the food market.

Effect of Roller Mill Extraction Rate on the Chapatti‐Making Quality of Canadian Flours

ABSTRACTThe effect of roller mill extraction rate on the chapatti‐making potential of Canadian wheat from six different classes was assessed. Objective measurement of texture including pliability, puncturability, and tearing force, in conjunction with color, discerned significant differences due to flour extraction rate as well as wheat class. The 85% extraction yield was determined by sensory panelists to yield the best chapatti. Analyses of objective measurements, HunterLab values L*, a*, and b*, in conjunction with sensory assessments, suggested that the optimum chapatti have a brightness (L*) of 75–79, redness (a*) of 1.5–4.0, and a yellowness (b*) >17. Sensory scoring compared with objective measurement indicated that a tearing force of <4.0 kg was necessary to achieve optimum panelist evaluation of tearing and chewability. The primary reasons for a fair rating were attributable to either a too white and nonwheaty taste for the low extraction flours or, in the case of the 95% extraction material, dark chapattis with a slightly off flavor. No chapatti prepared from any of the wheat classes or varying extraction rate flours resulted in an unacceptable rating. Evidence suggests that removal of low‐extraction mill‐streams, up to 40%, from a 85% extraction yield flour did not have a detrimental effect on chapatti quality.

Relationships between biochemical and quality-related characteristics of breads, resulting from the interaction of flour, microbial starter and the type of process

The possible relationships between biochemical characteristics [total starch, sugars, low-molecular-weight dextrins (LMWD), acetic and lactic acids, soluble solids and crumb-swelling power] and characteristics related to the quality of wheat bread (volume, texture and sensory quality scores) have been investigated. Variables influencing the possible interactions occurring were the type of flour (white and whole-wheat flours), the starter microorganism (Lactobacillus brevis, L. plantarum) and the type of process used to introduce the lactobacilli inoculum (sourdough, straight). The main factor explaining variability of data was related to sensory quality attributes and physical characteristics of the breads. The second factor was related to LMWD and the third to the acidity and lactic acid content of breads. The first factor permitted separation of the bread samples into two groups on the basis of flour extraction rate, whereas LMWD allowed differentiation between white breads made with sourdough or straight processes. Cluster analysis included the level of acidity and the lactic acid content as additional factors grouping control breads (without starter) together with breads made using a straight process. The best canonical correlation was established between the physical characteristics of breads and carbohydrates, soluble solids and crumb-swelling power. The first pair of canonical variables between two sets of experimental variables showed a squared correlation coefficient of 0.986.

Influence of flour, bacterial starter and breadmaking stages on total starch, sugars and low-molecular-weight dextrins/ Influencia de la harina, del iniciador microbiano y de la etapa del proceso de panificación sobre el almidón total, azúcares y dextrinas de bajo peso molecular

Wheat flours and bacterial starters were used in sourdough and straight breadmaking processes. The effect of the processing stage on levels of starch, sugars and low-molecular-weight dextrins (LMWD) with degrees of polymerization (DP) 3-7 were studied. The breadmaking step and type of flour affected the majority of the variables. The type of microorganism influenced only sugar contents. In factor analysis, the first two factors correlated with LMWD and the third factor with starch. Sourdough and fermentation mainly influenced changes in LMWD; baking did not result in further differences. Sourdoughs and unfermented doughs had the greatest amounts of monosaccharides, whereas fermented doughs and breads had the highest levels of dextrins with DP 3-5. The type of wheat was more significant than the flour extraction rate in governing LMWD.

Effects of formulation and processing conditions on easily extractable lipid and nitrogen components of wheat sourdoughs

SummaryThe changes in free lipid (neutral lipids, glycolipids, and phospholipids) and extractable nitrogen (amino acids, peptides, and proteins) components of unyeasted and yeasted wheat sourdoughs started with Lactobacillus plantarum B‐39 were investigated in samples under different processing conditions. A central composite surface response design was used with factor analysis to investigate the effect of flour extraction rate (ash content), added water, presence or absence of yeast, and fermentation temperature on readily extractable lipid and nitrogen components. Absolute values for extractable protein and non‐protein components were highly correlated with ash content of flour (factor 1); whereas phospholipids and neutral lipids were closely connected with added water (factor 2). Sixty sourdoughs were classified into three groups: 1) high‐ash fermented sourdoughs produced high (>350 mg kg−1) total non‐protein amino nitrogen and medium (<3 mg g−1) lipid levels; mid‐ash flour doughs had lower levels of both components; 2) low‐ash fermented sourdoughs produced low (<300 mg kg−1) levels of amino acids and peptides and medium lipids levels, and 3) unfermented sourdoughs had low (<250 mg kg−1) levels of non‐protein nitrogen components and most made with lowash flour had medium lipid levels; most made with medium and high‐ash flours had high (>4 mg g−1) neutral lipid levels and were largely separated from the low‐ash group. The most promising sourdoughs for bread were those with low added water, fermented from higher ash flour with maximum levels of extractable amino acids, peptides and proteins and medium to high polar and neutral lipid levels.

Effect of processing conditions on acidification properties of wheat sour doughs

The pH, total titratable acidity (TTA) and lactic and acetic acids production have been investigated for wheat sour doughs with and without yeast addition, inoculated with two strains of Lactobacillus plantarum (B33, B39). To study the effect of flour extraction rate (0.54, 11.11 and 1.68% ash content), dough yield (DY) (160, 200 and 240 of sour dough/100 g flour), and fermentation temperature (25, 30 and 35°C) a response surface regression, factor analysis and K-means clustering analysis were used. • Results from factor analysis point out that the extraction rate of flour governs TTA and acetic acid content; this factor accounts for the 53% of variability of the data. Dough yield is highly correlated with lactic acid content, explaining 27% of the total variance. Finally, temperature explains the remaining 16% of variation, but it is not related to any analytical variable. From K-means clustering analysis, flour extraction rate of 1.68% ash content leads to the highest TTA and acetic acid values, whereas DY of 240 g sour dough/100 g flour gives the greatest lactic acid content, and DY of 160 leads to the lowest levels of TTA and organic acids .

Comparison of Polyphenol Oxidase Activities in Wheats and Flours from Australian and U.S. Cultivars

Abstract Polyphenol oxidase (PPO) activities of wheats from various classes and cultivars (grown both in the U.S.A. and in Australia), of some U.S. and Australian wheats, of wheat flours at various extraction rates and of kernels separated by size from various cultivars were measured by the oxygen electrode method. PPO activity of wheats was affected by both cultivar and growing location. Wheat flour contained on the average 3% of the PPO of the wheat grain. PPO activities of the flours increased as the flour extraction rates increased. Contrary to expectation, for a single cultivar, small kernels contained less PPO (on a weight basis and especially on a kernel basis) than did large kernels. Differences among kernels of various sizes for a single cultivar were smaller than differences in PPO among kernels of comparable sizes among various cultivars.

The effects of extraction rate and flour-sieve aperture on the properties of experimentally milled soft wheat flour

The effects of flour extraction rate and flour particle size (flour-sieve aperture) on the physical dough properties and cookie-making quality of soft wheat flour were examined during the development of a soft wheat experimental milling procedure. Soft wheats were milled to three extraction rates, and flour particle size was manipulated by changes in flour-sieve clothing. Physical dough properties, as measured by the farinograph and the alveograph, were weakly affected by milling procedure. However, cookie spread, cookie ratio and total cookie score exhibited strong negative relationships to both flour extraction rate and flour-sieve aperture. Soft wheats of different intrinsic cookie-making quality were ranked similarly by all milling procedures. Key words: Soft wheat, experimental milling, cookie-making quality, soft wheat quality screening