Flour characteristics

The quality of flour used ia the production of yeast-raised products depends on several factors, including the quality and characteristics of the wheat variety, the environmental conditions under which the wheat was grown, the skill of the miller in separating the endosperm of the wheat kernel from the germ and bran, and the proper treatment of the flour in the mill. 

When such contaminated flour enters trade channels, either as such or in the form of prepared products, the finding of hair fragments is highly significant. Whether they may have come from the flour or have originated in a bakery or factory does not lessen their repugnance to the consumer. Recovered hairs are identified by means of their several characteristics. Some of the more salient are conspicuous intemodes and compound medulla of rat hairs, inconspicuous intemodes and smooth continuous medulla of cat hair, and differences discernible after treatment with 10% sodium hydroxide and after treatment with hypochlorite. 

Coextrusion is the process of extruding two or more materials simultaneously or in tandem. It allows a combination of an ingredient such as wheat flour, which is inexpensive and easily enriched with vitamins and minerals, with dairy protein, which provides functionality and texture. For example, an early coextrusion of wheat flour and rennet casein was performed by van de Voort et al. (1984), who obtained products with varying characteristics depending on process parameters. 

Another product, defatted com germ flour was coextruded at 150 or 170 °C with 5% milk protein to produce a puffed nutrient snack (Peri et al., 1983). The addition of fhe milk profein af fhe lower temperature improved the organoleptic characteristics of fhe exfrudafes but adversely affected the product expansion and consistency of fhe samples at the higher temperature. 

Singh, R. K., Nielsen, S. S., Chambers, J. V., Martinez-Serna, M., and Villota, R. (1991). Selected characteristics of extruded blends of milk protein raffinate or nonfat dry milk with com flour. /. Food Process. Preserv. 15, 285-302. 

Experienced Extensograph users learn the characteristic shapes of the extensogram typical for flour suitable for particular uses (Figures 9-11). Bread flours need both resistance and some extensibility while in biscuit flours a low resistance and a high extensibility are needed. 

This method is used in several countries, including France and the USA. The characteristic difference with other methods is that a portion of the flour, e.g. a third, is fermented with the water the yeast and any added sugars. 

Measured quantities of the pre-ferment are mixed with flour. The dough is then subjected to the combination of intense mixing and the action of the oxidising agent. It is then extruded and cut into loaf sized portions, proved and baked. Bread made by the Do-Maker process has a very even crumb texture, which is characteristic of the process. 

Successful performance of legume flours as food ingredients depends upon the functional characteristics and sensory qualities they impart to the end product. 

Flours made from field peas by wet or dry milling, or air classification, possess distinctive sensory, functional and nutritional characteristics. 

Compositional differences in the pea seeds influence the quality of the end products. Pea flours have been used for protein enrichment of a number of cereal-based products however, undesirable sensory characteristics may limit their use, in spite of improved functional effects in food systems. The production of volatile compounds during cooking and baking of foods with pea supplementation affects their acceptability. Enzyme systems active in unheated pea flours may contribute to their functional properties, but adversely affect the sensory quality of the food. 

When the pea flour was heated, the flavor was considerably improved. Cooked yellow pea flour-fortified noodles were comparable to the control with respect to sensory characteristics and yield. 

Field Pea Flours in Bread Products. Legume flours, particularly soy, have long been incorporated into wheat-based products, both for their functional effects and for protein fortification. In general, increasing the levels of legume flours results in decreased loaf volume, lower crumb grain quality, and adverse flavor characteristics in the baked bread (Table III). 

Raidl and Klein (43) substituted 5, 10, and 15% field pea flour in chemically leavened quick bread. The viscosity of the pea flour batters was significantly lower than either the wheat control or soy containing batters. The starch composition of the pea flour and lower water absorption properties of the protein could have affected the viscosity. Volumes of pea flour loaves were lower than the control and soy loaves. Most of the sensory characteristics of the field pea loaves were similar to those of the control quick breads. However, all flavor scores were significantly lower for pea flour products, since they had a recognizably beany or off-flavor. 

Flavor is one of the major characteristics that restricts the use of legume flours and proteins in foods. Processing of soybeans, peas and other legumes often results in a wide variety of volatile compounds that contribute flavor notes, such as grassy, beany and rancid flavors. Many of the objectionable flavors come from oxidative deterioration of the unsaturated lipids. The lipoxygenase-catalyzed conversion of unsaturated fatty acids to hydroperoxides, followed by their degradation to volatile and non-volatile compounds, has been identified as one of the important sources of flavor and aroma components of fruits and vegetables. An enzyme-active system, such as raw pea flour, may have most of the necessary enzymes to produce short chain carbonyl compounds. 

Whole oilseeds and legumes and their derivatives (defatted flours, and protein concentrates and isolates) are used in traditional foods as sources of protein and for their texture-modifying functions. This article reviews, on a comparative basis, processes for preparation of vegetable food proteins, compositions and characteristics of the resulting food ingredients, and their functionalities and uses in traditional foods. 

The maximum amounts of vegetable food protein flours that can be substituted in bread without affecting loaf volume and texture are 5-10% (depending upon the source), and 18-20% can be substituted in cookies without affecting spread and surface characteristics (26). The quantity of vegetable protein flour that can be accommodated in bread can be increased substantially by pre-toasting and by the use of approximately 1.5% sodium stearoyl 2-lactylate (28) and other emulsifiers. 

Chin-chin is crisp, slightly sweet, golden brown knots of pastry. These deep fat fried cakes are made in different shapes and styles. Chin-chin is often flavored with vanilla extract, nutmeg, caraway seed, orange or lemon rind. The African panel preferred the chin-chin with no substitution for all characteristics except appearance. The non-African panel preferred chin-chin without any substitutions for all characteristics. The soybean flour was the most desirable substitution at 30% of the all purpose flour. 

African panel preferred the puff-puff containing 30% defatted cottonseed. The non-African panel preferred the puff-puff containing the all purpose flour for all characteristics except the absence of greasiness. 

Cottonseed, peanut, sesame seed, and soybean flours, when used as supplements, add to the quality of the protein. The improvement of protein quality was due to the flours compensating for limiting amino acids. Supplementation using various flours improved total protein, amino acid content and some physical characteristics in akamu, yeast bread and sugar cookies. 

When structured soy protein fiber was added to fermented salami at 15 or 30% levels, trained sensory panels found the flavor to be undesirable, whereas a 116-member untrained panel found the product containing 30% soy flour to be undesirable in flavor, tenderness and overall desirability (26). The flavor of beef patties containing 20% soy protein flour or concentrate was rated about equal to all beef patties by a 52-member panel, whereas patties containing 30% were scored lower by the panel (6). Berry et al. (7) found the characteristic "soy-like" flavor to be more... 

Characteristically, legume seeds are rich in protein and contain intermediate to high levels of lysine and threonine which are important in balancing the deficiencies of these essential amino acids in cereal diets. Certain legume proteins, such as soybean, also exhibit strong functional properties, especially water solubility, water and fat binding and emulsification. Thus soybean flours, protein concentrates and isolates have been used widely as nutritional supplements and functional ingredients in foods. 

Functional property tests were conducted in duplicate. AACC (21) methods were used for the determination of water hydration capacity (Method 88-04) and nitrogen solubility index (NSI) (Method 46-23). Oil absorption capacity was measured by the procedures of Lin et al. (22) and oil emulsification by a modification (22) of the Inklaar and Fortuin (23) method. Pasting characteristics of 12.0% (w/v, db) slurries of the flours and processed products were determined on a Brabender Visco/Amylograph (Method 22-10). The slurries were heated from 30 to 95°C before cooling to 50°C to obtain the cold paste viscosity value. Gelation experiments were conducted by heating 15% (w/v db) slurries in sealed stainless steel containers to 90°C for 45 min in a water bath C3). 

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