Effects of Fermentation and Steaming on the Proximate and Antinutritional Properties of Pigeon Pea Seed Flour

Abstract

Pigeon pea is one of the underutilized legumes despite its high nutritional quality. The effect of fermentation and steaming on the quality attributes of commonly consumed legumes have been established but not fully on pigeon pea. This study therefore investigated the effects of fermentation and steaming on the quality properties of pigeon pea flour with the aim of optimizing these processing conditions. Response Surface Methodology (RSM) based on 3-level full factorial of the Random sample design was selected to optimize the effects of fermentation and steaming on the quality parameters of pigeon pea flour resulting from the experimental runs. The quality parameters of the treated pigeon pea flour: proximate (protein, ash, moisture, crude fibre, fat, carbohydrate) and antinutritional factors (Tannin, phytate, trypsin inhibitor and saponin) were determined to see the effects of fermentation and steaming using standard laboratory procedures. Numerical optimization technique was used to obtain the optimum processing conditions for the treated sample. Data were analyzed by ANOVA analysis. The values for moisture content, protein content, fat content, fiber content, ash content, and Nitrogen Free Extract of fermented pigeon pea flour ranged between 10.07 – 14.11%, 23.53-26.51%, 0.86 – 2.89%, 0.97 – 1.34%, 3.35 – 4.43%, and 51.39 – 58.04%, respectively. The result of the anti-nutritional properties of the samples showed fermented pigeon pea with the range of 51.95 – 93.96 mg/100g, 4.62 – 6.13 mg/100g, 86.72 – 275.21mg/100g and 2.18 - 4.32 % respectively. Result obtained from the steamed pigeon pea showed the lowest tannin (31.93 mg/100g) and phytate (4.59 mg/100g) contents were observed in samples steamed at 97.5oC for 30 and 20 minutes, respectively. The lowest tannin (65.89 mg/100g) and highest phytate (6.12 mg/100g) contents also were observed in samples roasted at 140oC for 10 minutes, respectively. The anti-nutritional levels of the pigeon pea flour were reduced as shown from the results, which indicated that pigeon pea flour could be utilized effectively for the production of complementary, confectionary foods or supplemented in legume-cereal based diets.