Descriptive sensory analysis of instant porridge from stored wholegrain and decorticated pearl millet flour cooked, stabilized and improved by using a low-cost extruder.

Pearl millet flour, particularly wholegrain flour, is highly susceptible to development of rancid aromas and flavors during storage. Grain decortication and extrusion cooking using a friction-heated single-screw extruder were investigated as potential flour stabilization processes. Raw and extruded wholegrain and decorticated grain pearl millet flours were stored at ambient (25°C) and elevated (40°C) temperatures for 6 months. A trained descriptive sensory panel developed a lexicon of 44 attributes to profile the aroma, flavor, and texture of porridges prepared from the flours. Grain decortication alone did not show an effect on the aroma and flavor profile of porridge. Extrusion cooking of both wholegrain and decorticated flours increased cereal-like aromas (branny, canned sweetcorn, sweet, and wheaty) and flavor (starchy), as well as stiffness and cohesiveness of the porridges. The porridges from the extruded pearl millet flours stored for up to 6 months at ambient and elevated temperatures did not show any indications of rancidity. In contrast, rancidity-associated aromas (chemical, painty, and soapy) and flavor (chemical) increased in porridges from the raw flours stored for 4 weeks and longer. These results indicate that grain decortication did not sufficiently reduce fat content to prevent oxidation, while extrusion cooking stabilized the pearl millet flours. In addition, intensified "cereal-like" aromas and flavors were probably due to Maillard reactions occurring during extrusion cooking. Resulting aroma compounds could have been immobilized in the extruded matrix and not released during flour storage. The application of extrusion cooking with a simple friction-heated single-screw extruder is a viable process for both precooking and extending the shelf life of pearl millet flours. PRACTICAL APPLICATION: This study demonstrates the potential of extrusion cooking to precook wholegrain pearl millet while preventing fat rancidity in wholegrain pearl millet flour, thereby improving the sensory quality and stability of pearl millet food products. The extensive sensory characterization of pearl millet porridge-type foods can serve as a guidance tool for development, improvement, and quality control of pearl millet foods. Furthermore, it establishes the efficacy of simple friction-heated, single-screw extruders for commercial manufacture of ready-to-eat wholegrain pearl millet food products by small and medium scale entrepreneurs.

Relating sensory profiles of canned amaranth (Amaranthus cruentus), cleome (Cleome gynandra), cowpea (Vigna unguiculata) and Swiss chard (Beta vulgaris) leaves to consumer acceptance.

BACKGROUND: The younger generation of South Africans generally do not consume traditional meals prepared using African green leafy vegetables, primarily because they are regarded as bitter, "poverty" foods. Canning of these vegetables could create value-added products that can be sold in the commercial market. Descriptive sensory evaluation and consumer acceptance testing with young females were used to assess the potential of such products. RESULTS: The sensory attributes of amaranth, cleome and cowpea leaves canned in brine and in a cream sauce were described using 21 attributes grouped by aroma, taste, texture/mouthfeel and aftertaste. Amaranth and Swiss chard products were described as sweet with a popcorn-like aroma. Cleome products were described as bitter, sour, pungent, chemical-tasting, astringent, sandy with a metallic mouthfeel and strong aftertaste. Cowpea products were described as having woody and tobacco aromas as well as a chewy and cohesive texture. Among the products canned with a cream sauce, young female consumers preferred amaranth and Swiss chard; cowpea was less liked, while cleome was least liked. CONCLUSIONS: Canned amaranth leaves have potential as a commercial product that may be well liked by young consumers. The cowpea leaves product has consumer potential, but the formulation needs revision, while canned cleome leaves need further research work. © 2017 Society of Chemical Industry.