Evaluation of legume cooking characteristics using a rapid screening method

Abstract

Consumer preferences for legume cooking properties should be considered at an earlier stage in the breeding process. Hence, we developed an effective, low-cost method to analyze the cooking quality attributes of cowpeas. The objective was to develop a rapid screening method to evaluate the cooking quality attributes of cowpeas (Vigna unguiculata) and compare the results with currently used methods. Soaked samples (five grams) were boiled for 27 min, and seeds and their broth were separated into dishes with covers. Samples were subjectively rated on a 1-5 scale for cooked doneness, tactile texture, aroma intensity, and opacity of the broth. Water absorption, seed splitting, and soluble solid loss were also determined. The samples were evaluated in batches of 25 and replicated three times. Cooking properties showed significant correlations with each other, but did not correlate with raw seed size and color. The method is important because consumer acceptability largely depends on cooking quality in addition to seed appearance. Many properties like cooked doneness and tactile texture were significantly affected by genetics and environment. Compression force determined with a Texture Analyzer (TA) significantly correlated with doneness and tactile texture ratings at -0.67 and -0.69, respectively (P < 0.01). Cooking times from the Mattson bean cooker (MBC) were significantly correlated with doneness and tactile texture at -0.63 and -0.65, respectively (P < 0.05). The Texture Analyzer and MBC confirmed the subjective ratings of cooked doneness and tactile texture. A procedure to determine solid losses using a refractometer, instead of the time-consuming oven-drying method, saved time and has significant promise for use in simple evaluations. The rapid cooking method required 2 hr on the first day and 5 hr on the second day to evaluate 25 samples. The method is efficient, repeatable and uses inexpensive materials compared to the TA and MBC. It also provides descriptive information, and differentiates legume cultivars based on cooking properties. This method is a useful tool in the breeding program for selecting and advancing promising lines. Food processors may also use this method for a quick evaluation to check if their legumes meet required specifications for processing.