Optimization of the Chemical Interesterification of Allanblackia (Allanblackia floribunda), African Walnut (Tetracarpidium conophorum) and Fluted Pumpkin (Telfairia occidentalis) Seed Oil Blend for use in Bakery Shortening Production, a Response Surface Approach

Abstract

Abstract The objective of this work was to optimize the interesterification temperature (X1), time (X2) and catalyst concentration (X3) of Allanblackia, African walnut and fluted pumpkin seed oil blend for bakery shortening production, using a rotatable central composite design (RCCD) in response surface methodology (RSM). The extracted seed oils were interesterified using sodium methoxide as catalyst. Solid fat content, smoke point, melting point, density, viscosity, Iodine value and free fatty acid were evaluated as responses. Regression models were generated and adequacy tested with lack of fit test and coefficient of determination (R2). The results showed that interesterification temperature, interesterification time and catalyst concentration of the oil blend had significant (p˂ 0.05) effects on responses, with R2 value of 96.8, 95.3, 94.2, 90.1, 99.5, 93.2 and 75.7 % and C.V of 0.266, 0.146, 0.502, 0.499, 0.602, 0.448 and 7.830 %, respectively for solid fat content, smoke point, melting point, density, viscosity, Iodine value and free fatty acid. Model lack-of-fit in all cases were desirably not significant (p>0.05). Adequate precision values were 16.2006, 13.328, 11.758, 10.054, 46.69, 10.024 and 14.182 for solid fat content, smoke point, melting point, density, viscosity, Iodine value and free fatty acid. Predicted optimum condition and desirability index of 0.907 was obtained at 74.57 °C, 46.0 min and 0.278 % interesterification temperature, time and catalyst concentration respectively, while optimum solid fat content, smoke point, melting point, density, viscosity, Iodine value and free fatty acid were 5.15 %, 221.91 °C, 32.49 °C, 0.911, 25.06 cSt, 76.42 g/100g and 0.08 % respectively. The experimental results obtained validate the predicted model within the acceptable range of the responses. The results also suggest that the obtained model is acceptable and recommended for the optimization of interesterification temperature, time and catalyst concentration for improved bakery fat quality and consistency. Melting point and FFA of the oil blend were reduced significantly (p<0.05) after interesterification, while smoke point and Iodine value increased significantly (p<0.05).