DEVELOPMENT AND CHARACTERIZATION OF EXTRUDATES FROM NIGERIAN PIGEON PEA: ROLE OF PRE-TREATMENT

Abstract

Consumption of pigeon pea, a drought tolerant legume with adequate nutritional composition has been limited due the prolonged time required during cooking. With high production capacity, the transformation of this crop into a ready to eat extruded snacks would increase its consumption while strengthening Nigerian food processing industries. Through this research driven innovation, a long shelf life extruded snacks from 100% whole pigeon pea (a legume) were developed following the use of native and pre-treated seeds as extrusion feed materials.  The pre-treatment involved a short time hydrothermal treatment at 90 0C and alkaline treatment with 0.5% sodium bicarbonate which targeted hydration of starch and cell wall degradation. The extruded snacks were produced at a high temperature of 140 0C and short time (22 seconds) using co-rotating twin screw extruder which extrusion conditions influenced the quality characteristics of the expanded snacks. The sectional expansion index (SEI) significantly (P<0.05) increased from 1.09 in NNPHME (extrudate from high (22%) moisture native pigeon pea) to 3.42 in BBE (extrudate from dry (11% moisture content) milled alkaline treated pigeon pea) while the bulk density (BD) decreased mostly in BBE. The peak viscosity ranged from 168 cP in NNPHME to 1661 cP in BBHME (extrudate from wet (22% moisture content) milled alkaline treated pigeon pea). The cold water viscosity, an indication of  starch gelatinised during extrusion increased greatly to 849.33 cP in BBE compared to 36.66 cP in native non-extruded pigeon pea. Hence, the expansion, textural and pasting properties of extrudates from treated feeds was improved compared to extrudates from non-treated feeds. Considering the good quality attributes of some of the extruded snacks such as expansion ratio, bulk density, textural characteristics and long shelf-life, it would be recommended as fast-moving consumer goods to industrialists