Effect of saponins on the foam/flow properties of paste and physical characteristics of akara made from decorticated black‐eyed cowpeas

Akara, a deep‐fat‐fried cowpea paste product, is a popular snack food in West Africa. Foaming capacity of the cowpea paste is important for achieving a spongy light‐textured fried product. The effect of two saponins, Yucca and Quillaja, on the foaming capacity of cowpea paste was investigated. Results showed that an increase in the amount of saponin added (1, 2, 4%) resulted in a decrease in specific gravity and apparent viscosity of the cowpea paste. Addition of saponin also significantly reduced the firmness and increased the cohesiveness of the akara compared with the control. Akara made using the Quillaja saponin was less firm and more cohesive than akara made using the Yucca saponin. An increase in the amount of saponin added to the cowpea paste resulted in a darker (lower L*) and browner colour of akara. However, akara containing 1% Yucca saponin had similar colour attributes to the control but was less firm and more cohesive. Copyright © 2005 Society of Chemical Industry     

Improving the nutritional quality and maintaining consumption quality of akara using curdlan and composite flour

Soybean flour and curdlan were incorporated into cowpea flour to determine their effect on lowering the fat content and on the physical properties of akara. At 20% substitution, soybean flour lowered the fat content of akara by 7.7% and increased the protein content by 28.7% without significantly affecting the firmness or the colour of akara. Addition of 1% curdlan decreased the fat content by 32.2% but significantly increased the firmness of akara and produced a darker‐coloured product. The paste moisture content of akara containing 20% soybean flour and 1% curdlan was modified to obtain product characteristics comparable with the control (100% cowpea flour) while maintaining a lower fat content. Optimum results were obtained for paste with 63% moisture content. Firmness of this modified product was similar to the control and the fat content was lower (17%) compared with the control (26%).     

Sensory properties of akara (fried cowpea paste) prepared from paste stored at low storage temperatures

Akara (fried cowpea paste) a popular West African cowpea (Visna unguiculata) product was prepared from cowpea paste stored under refrigeration (4‐6°C) and freezer (‐18°C) temperatures for 10 and 24 days respectively. Blanched and unblanched paste were stored. Akara from freshly prepared paste was used as control. The sensory properties investigated were colour, taste, texture and aroma. Akara from various paste samples; refrigerator stored paste (RSP) freezer stored paste (FSP) and fresh paste (FP) were rated for the various attributes and the degree of difference from the control by a trained panel. Sensory attributes of RSP akara were majorly rated between good and fair in the first 3 days. Attributes were rated between fair and bad by the 6^th and 10^th days of storage and were significantly different from FP akara. Sensory attributes of FSP akara were rated between good and fair until the 17^th day of storage. Blanching proved beneficial as a pre‐storage treatment for the preservation of akara texture in the first 3 days for RSP and for 24 days for FSP. The results showed that the properties of cowpea paste which influence texture and overall sensory quality of akara, were better preserved in frozen storage. The implications of the results on the feasibility of bulk production and storage of cowpea paste for retail as a frozen ingredient are discussed.     

Particle-size Distribution of Cowpea Flours Affects Quality of Akara (Fried Cowpea Paste)

ABSTRACT: Matching of particle-size distribution and further blending of cowpea paste made from dry milled seeds were used as tools for producing akara of comparable quality to the traditional West African wet-milled product. All blended samples showed a reduction in viscosity after whipping ranging from 48.2% to 54.2%. HM-1.73 (Hammer mill with 1.73-mm screen) produced the least number (11) of akara balls per batch with highest per ball weight (20.93 g). Akara fat content varied from 14.7% to 33.1%. Akara made from HM-2.54 (hammer mill with 2.54-mm screen) contained 21.1% fat and was acceptable to consumers.     

Influence of cowpea (Vigna unguiculata L Walp) variety on protein quality and sensory properties of akara,a popular West African cowpea‐based food

The influence of newly developed cowpea varieties (IT81D‐699, IT82E‐18, IT84S‐2246‐4 and TV_x3236) on the proximate composition, protein quality and sensory properties of akara, a popular West African cowpea‐based food, was investigated and the results obtained were compared with those for akara prepared from a local blackeye cowpea variety. Protein quality was evaluated using weanling albino rats fed diets which were formulated to supply 10% protein using defatted akara samples, with casein as a control. Akara samples prepared from IT81D‐699 and TV_x3236 had crude protein contents, texture and overall acceptability comparable to those of akara prepared from the blackeye variety. Also, akara diets formulated using IT81D‐699 and TV_x3236 showed significantly (p < 0.05) higher values for weight gain, protein efficiency ratio, net protein ratio and true digestibility than diets formulated with IT82E‐18, IT84S‐2246‐4 and blackeye, suggesting an improvement in the nutritional quality of akara produced using these (IT8ID‐699 and TV_x3236) newly developed cowpea varieties. Copyright © 2004 Society of Chemical Industry     

Effect of Hydration of Cowpea Meal on Physical and Sensory Attributes of a Traditional West African Food

Effects of water level (56, 58 and 60%) and hydration time (0, 30, and 60 min) on apparent viscosity of cowpea paste and physical-sensory attributes of akara, a finished food made from paste, were determined. Water level had a greater effect than hydration time on paste viscosity and on crude fat content, shear force, lightness (L), and saturation index (ΔE) of akara. Apparent viscosity of cowpea paste was the only parameter significantly affected by the interaction of water level and hydration time. Overall, the 60% water level produced paste with flow properties and akara with physical characteristics most like the traditional product. Sensory attributes of mealased products were acceptable.     

QUALITY AND CONSUMER ACCEPTANCE OF AKARA (FRIED COWPEA PASTE) PROCESSED FROM WET- AND DRY-MILLED COWPEA (VIGNA UNGUICULATA) MEAL WITH SPECIFIED PARTICLE SIZE DISTRIBUTION

Direct quality indicators of cowpea paste and akara produced from traditionally wet‐milled peas, and hammer‐milled (dry‐milled) and freeze‐dried (wet‐milled) meals were examined in this study. Both meal samples studied were formulated to consist of 65% medium‐sized particles and 35% large particles by weight. Particle volume mean diameters (µm) of the three paste samples were not significantly different from one another at the various stages during akara production. Scanning electron micrographs of akara crumb were converted to threshold images and analyzed. There was no significant difference in the amount of air found in the akara samples. Akara produced from both meals was found acceptable by sensory panelists with no significant difference in any of the attributes or overall liking among the three samples.     

Foam-mat drying of cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis>) using glyceryl monostearate and egg albumin as foaming agents

Foam-mat drying of cowpea using glyceryl monostearate (GMS) and egg albumin (EG) as foaming agents was investigated. GMS and EG were incorporated into cowpea paste (22%, 25% and 28% total solids) at 2.5, 5.0, 7.5, 10.0, 12.5 and 15% (w/w), and whipped for 3, 6, 9, 12, 15, 18 and 21 min, maintaining 15, 25 and 35 °C foaming temperatures. Foam density was measured and expressed in g/cm³. Cowpea foams were dried at 60 °C (Twb, wet bulb temperature 35 °C) for 48 min. Sensory attributes of akara produced from fresh and reconstituted pastes were evaluated.Generally, foam density decreased with increased concentrations of GMS and EG in cowpea paste. Foam density decreased with decrease in total solids of cowpea paste. Minimum foam densities were obtained in cowpea foams with GMS and EG after 9 and 21 min of whipping, respectively. EG-stabilized foams were unstable for drying. Sensory evaluation showed no significant difference (P>0.05, 0.01) in the quality attributes of akara produced from fresh and reconstituted GMS-stabilized cowpea powders.     

Effects of Pre-decortication Drying Treatment on the Microstructure of Cowpea Products

A pretreatment process developed to prepare cowpeas for mechanical decortication by dry abrasion involves wetting, equilibrating, and drying. Drying temperatures of 50°C, 70°C, 90°C, 110°C, and 130^°C affected the microstructure of cowpea seeds, meal and akara (fried cowpea paste). Severe heat treatment damaged the middle lamella of cotyledon cells, changed the birefringence property of starch granules, reduced the amount of air incorporated in whipped paste and produced akara with a nonuniform, dense structure.     

EFFECT OF FROZEN STORAGE ON THE QUALITY OF AKARA, FRIED COWPEA (VIGNA UNGUICULATA) PASTE

Akara, a fried food of West African origin, is made from whipped cowpea paste flavored with fresh onion, fresh hot or bell pepper, and salt. Akara has potential for U.S. markets as a fully cooked, frozen, reheatable product. Akara was stored at ?18°C for 9 months and compared to freshly prepared akara in selected quality characteristics. Frozen, thawed akara had a higher moisture and lower crude fat content, required significantly less force to shear, and had a lighter, less intense color than freshly prepared product. Frozen/thawed/reheated akara received lower senson scores for color, moistness and flavor than the fresh product. Analysis of headspace volatiles of freshly prepared akara and akara frozen 3, 6 and 9 months resulted in fifteen peaks. Two peaks were significantly affected by frozen storage.     

EFFECT OF PROCESSING VARIABLES OF COWPEA (VIGNA UNGUICULATA) MEAL ON THE FUNCTIONAL PROPERTIES OF COWPEA PASTE AND QUALITY OF AKARA (FRIED COWPEA PASTE)

The importance of particle size distribution in conjunction with milling method (dry‐milled hammer‐milled meal [HM] or wet‐milled freeze‐dried meal [FD]) on the functionality of cowpea paste and textural characteristics of akara produced from dry meal was investigated. All meal samples contained a minimum of 65% by weight medium‐sized particles and different combinations of large and fine particles to compose the balance. With the exception of the pastes made from meal consisting of 35% fine particles, all pastes had good foaming ability and handling characteristics. However, akara made from the HM and FD blends with 35% large particles had hardness values not significantly different from the traditionally prepared (wet‐milled) akara (5.317, 4.048 and 5.341 N, respectively), indicating that the meal blends had the potential to produce akara acceptable to consumers.     

EDIBLE COATINGS FOR REDUCING OIL UPTAKE IN PRODUCTION OF AKARA (DEEP-FAT FRYING OF COWPEA PASTE)

Recent trends in food processing have emphasized the development and improvement of reduced fat foods. The objective of this study was to evaluate the effectiveness of edible coatings formulated from hydroxypropyl methylcellulose, methylcellulose, corn zein, and amylose in restricting oil absorption during deep-fat frying of akara, a traditional West African food made from whipped cowpea paste. Effectiveness of two methods of coating application (spraying and dipping) were examined. Portioned balls of akara paste were partially-fried in peanut oil for 100 s at 193C. Coatings were applied, dried, and the product was frozen at -18C. After thawing, samples were finish fried at 166C to an internal temperature of 70C. Total moisture content of all coated samples was significantly higher than the control. Coated akara absorbed significantly less oil than the control for both sprayed and dipped applications. For both applications, the coated samples appeared to be soggy and less brown when compared to the control samples.     

Fat reduction affects quality of akara (fried cowpea paste)

Akara, a fried finger food made from cowpeas (Vigna unguiculata), is popular in West Africa and has been shown to be acceptable to American consumers. Akara is, however, a high‐fat food (about 31%, dry wt basis). We determined the effects of incorporating two modifiers, high amylose cornstarch or extruded cowpea flour, on akara fat content and consumer acceptability. The modifiers were used at the 10% level. Akara fat content was reduced by 26.1% with cornstarch and by 36.8% with extruded cowpea flour. There were no significant differences in sensory ratings among samples, and all samples received acceptable ratings (6 = like slightly) for overall liking.     

Effect of milling and preparation method on the physical properties and quality of moin-moin (steamed paste)

ABSTRACT:  Moin-moin is steamed cowpea paste native to Nigeria. This product is classified as a protein/starch gel with the dominate portion of the gel network consisting of cowpea starch. Moin-moin was prepared from starting materials (cowpea meal and cowpea flour) and compared to moin-moin prepared from dry, whole, undecorticated cowpea seeds. Texture profile measurements showed that moin-moin made from cowpea flour (small particle size) formed a firmer structure when compared to moin-moin made from either cowpea meal or whole, dry cowpea seeds. Starting materials with smaller particle sizes and longer cooking times produced stickier moin-moin. The cowpea solids to water ratio was shown to affect the firmness of moin-moin, where a 3.75:1 ratio of solids to water produced a firmer product than other concentrations. Generally, color was unaffected across treatment regimens as identified by an expert sensory panel, although instrumental color measurements showed significant differences for hue angle and chroma. This study demonstrated that the particle size of this food ingredient contributes significantly to its functionality in food formulations.     

Protein Nutritional Quality of Traditional and Novel Cowpea Products Measured by In Vivo and In Vitro Methods

Effect of processing on nutritional quality of cowpea meal protein was determined by in vivo and in vitro methods. Uncooked meal and meal which had been extruded at various temperatures and moistures; slurried, steamed, and drum-dried (SDP); and hydrated to a paste and deep-fat fried (akara) were studied. PER values of extrudates (1.81–1.97), and akara (1.89) were higher than those of raw meal (1.44) or steamed, drum-dried paste (1.63). The saturation kinetics model showed similar trends but differences were not significant. In vitro digestibility was highest for extrudates (83–85%), intermediate for akara and SDP (82.8%, 81.2%), and lowest (77.8%) for raw meal. C-PER/DC-PER gave differing and contradictory results.     

Effect of Holding Time on the Functionality of Cowpea Paste and Quality of Akara

Whipped cowpea pastes were held at room temperature (20°C) for 0, 30, 60, 120, and 240 min before preparation of akara (fried cowpea paste). Apparent viscosity of whipped paste was measured at different shear rates (0.17, 0.34, 0.85, 1.70, 3.40, 6.80, and 17.00 sec^?1). At any given shear rate, paste became more viscous with increasing holding time. Akara became darker and less yellow in color as paste holding time increased. Akara made from paste held 120 min or longer had an unacceptably dense, firm texture.     

EVALUATION OF THE SENSORY QUALITY OF AKARA (FRIED COWPEA PASTE) BY TEENAGE CONSUMERS

Cowpeas (Vigna unguiculata) are a nutritious legume, but their consumption in the U.S. is limited by the lack of convenience and innovative forms of use. Akara is a popular West African food made from deep-fat fried cowpea paste and has potential for extending the use of dry cowpeas in U.S. markets. Acceptance tests involving 122 Georgia teenagers were conducted to assess their response to akara. Akara made from decorticated seeds was more acceptable than akara made from nondecorticated seeds. Akara was most acceptable to males, blacks, and to those who had completed nine or more grades in school. The product was more likely to be consumed at a restaurant or cafeteria than at home or at a fast food establishment. These findings indicate that akara has potential for success in the fried food market and could be targeted toward certain segments of the teenage population.     

PHYSICAL AND SENSORY CHARACTERISTICS OF FRIED COWPEA (VIGNA UNGUICULATA L. WALP) PASTE FORMULATED WITH SOY FLOUR AND EDIBLE COATINGS

Akara, a popular West African fried food made from dry cowpeas, contains about 31% fat on a dry weight basis. Previous work in our laboratory showed that akara made from a 94% cowpea flour/6% soy flour blend plus edible coatings absorbed 26% less oil during frying than akara made from 100% cowpea. The objective of the present study was to determine the quality and acceptance of modified akara, either freshly fried (one‐stage) or partially fried/frozen/thawed/finish‐fried (two‐stage) as would be employed in the home or a foodservice setting. Soy‐substituted akara was firmer than freshly fried, 100% cowpea (control) akara. Methylcellulose‐coated akara was significantly different in total color from the control. Consumer acceptance studies indicated that, compared with two‐stage fried/100% cowpea akara, the two‐stage fried/6% soy formulation had similar hedonic ratings for flavor, texture, oiliness and overall acceptance. Sensory evaluation also indicated that two‐stage fried/6% soy akara with edible coatings was considered unacceptable (ratings < 5.0).     

Effect of Pre-decortication Drying Treatment on the Textural Quality of Cowpea Products: Seeds and Akara

This study describes the influence of a pre-decortication drying treatment on the textural quality of cowpea seeds and akara (fried cowpea paste). Heat-treated seeds were more brittle than the unheated control, but there were no significant differences in seed brittleness among drying temperatures. Akara from the 110°C treatment was less cohesive and required more energy per unit mass to shear and compress than the other samples. Overall, the 50°. 70° and 90°C treatments produced akara that compared favorably in textural quality to the control. Objective textural parameters obtained from either TPA or the Kramer cell method correlated well with sensory measures of texture.     

Effect of milling method on selected physical and functional properties of cowpea (Vigna unguiculata) paste

Particle size distribution (PSD) of cowpea meal is an important determinant of paste functionality and end product quality. Samples from various mills and screen sizes were used to determine PSD, water‐holding capacity (WHC) and swelling capacity (SWC). Hammer mill (1.73 mm screen) meal had a geometric mean diameter (d_gw) of 221 microns, whereas PM‐360 [plate mill with one complete turn (360°) of clearance] meal had a d_gw of 1559 microns. All other milling processes resulted in meal with an intermediate particle size. To reduce the particle size of cowpea pastes, cowpea meals were hydrated to pre‐determined moisture contents, held for 15 min, and then blended in a blender before whipping. Blending increased the WHC and SWC of all samples.