Pea flours

Figure 3. Representative sugar cookies prepared from defatted peanut, soybean, and field pea flours at 0, 10, 20, and 30% wheat flour replacement levels. Reproduced with permission from Ref. 3. Copyright 1978, American Association of Cereal Chemists.

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. 

KLEIN AND RAIDL Field-Pea Flours as Protein Supplements... 

The protein efficiency ratio (PER) of field pea flours is considerably less than that of casein (1.46 vs. 2.50), and somewhat less than that of soy flour (1.81). However, composites of wheat flour and pea or rice and pea (50% of the protein from each source) had PER s of 2 or more (22). Thus, supplementation of cereals with pea flour results in improvement of protein quality. 

The predominant polysaccharide in dehulled field pea flour is starch (49.7-59.8%) and the major soluble sugars are a-galactosides (4.78%) and sucrose (1.85-2.2%) (8,23,24). Verbascose is the major a-galactoside present in field pea flour (23,24). The a-galactosides are the main contributors to the flatulence caused by ingestion of legume flours. 

Protein content of field peas is negatively correlated with lipid, cell wall material (CWM), sugar, and ash content and positively correlated with starch separation efficiency and protein separation efficiency in air classification of pea flour. The lower separation efficiency of low protein peas may be due to their high lipid and CWM content which makes disintegration of seeds and separation into protein and starch particles by pin milling difficult. It is suggested that peas with a specific protein content should be used in order to control the protein and starch fraction contents (18). 

Field Pea Flours in Pasta. Incorporation of non-wheat flours into noodles improves the protein content and quality, but may have an adverse effect on the flavor and texture of the pasta. Hannigan (38) reported that 10% substitution of wheat flour with pea or soy flour resulted in satisfactory quality of Japanese Udon noodles. 

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. 

Nielsen et al. (39) used pea flour and pea protein concentrate, both cooked and raw, in noodles and spaghetti. The pasta was made from composite flours prepared by blending 33% pea flour with 67% wheat flour or 20% pea concentrate with 80% wheat flour. Protein content of the fortified noodles was approximately one-third higher than the wheat flour noodles. Addition of pea flour reduced the cooking time, but resulted in a softer product and lower yield than the wheat pastas. Precooking the pea flour improved flavor and decreased noodle dough stickiness, but the texture and yield of the cooked pasta was still less than that of wheat products. 

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). 

Results have varied with respect to the amount of field pea flour that can be incorporated into a yeast bread before an unacceptable product is produced. Tripathi and Dat (40) made breads containing 3, 10 and 13% field pea flour and found breads made with more than 5% pea flour were not acceptable. Loaf volume decreased as the percent substitution increased. At the 5% level, color, flavor and taste of the breads were rated as excellent, but at the 10 and 15% levels, there was a bitter taste. 

Yeast bread (40) 5, 10, 15% pea flour Decreased volume Acceptable sensory quality at 5% Bitter taste at 10 and 15%... 

Yeast bread (37) 5-20% raw or cooked pea flour Decreased volume Bleaching effect with raw pea flour Lower acceptability above 15%... 

Yeast bread (42) 2.5-10% pea flour No volume change Acceptable, beany at 10%... 

Biscuits (44) 8% pea flour Aroma and flavor decreased Doughy texture... 

Repetsky and Klein (42) found that pea flour significantly affected the texture, color and flavor of yeast breads. At... 

The baking studies with yeast breads indicate that levels of substitution of up to 15% pea flour or concentrate for wheat flour result in breads that are generally acceptable, but are readily distinguishable from, and less preferred to, wheat controls. 

Although the use of a cooked or heated pea flour or concentrate improves flavor, the functionality of the product in bread is adversely affected. 

Field Pea Flour in Other Baked Products. When McWatters (44) substituted 8% field pea flour and 4.6% field pea concentrate for milk protein (6%) in baking powder biscuits, sensory attributes, crumb color, and density of the resulting biscuits were adversely affected. No modifications were made in recipe formulation when pea products were incorporated. The doughs were slightly less sticky than control biscuits that contained whole milk. This might be due to lack of lactose or to the different water absorption properties of pea protein or starch. Panelists described the aroma and flavor of these biscuits as harsh, beany and strong. Steam heating the field pea flour improved the sensory evaluation scores, but they were never equivalent to those for the controls. 

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. 

Unheated pea flours are also effective in bleaching and improvement of doughs (37,31). Mixing times are shorter with pea-wheat flour combinations, and mixing tolerance is increased. 

The levels of pea flour that are most effective for dough improvement are usually less than 5%, and 0.75 to 3% has been recommended. At higher levels, undesirable dough behavior occurs, as well as flavor deterioration. 

Pea Flour and Pea Protein Concentrates," PFPS Bulletin No. 1, Prairie Regional Laboratory, National Research Council and College of Home Economics, University of Saskatchewan,... 

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