Optimization of Cocoa liquor, Allanblackia floribunda fat and African elemi oil blend for formulation of chocolate based on physicochemical properties

Abstract

The objective of this study was to optimize the physicochemical properties cocoa liquor, Allanblackia floribunda fat and African elemi oil blend for developing dark chocolate using RSM combining with I-optimal Design to replace chocolate from cocoa butter and partially hydrogenated vegetable oils to increase nutritional health benefits. Sixty percentage (60%) dark chocolate formulations based on complete randomized I-optimal Design was developed and physicochemical properties (moisture, melting point, hardness, viscosity, free fatty acid and peroxide value) of the blends were evaluated as responses. Regression models, response surface models, numerical optimization based on desirability function to determine an optimum formulation, contour plots of response surface models to visualize an optimum region were developed. Results of the physicochemical properties of individual oils showed melting point, viscosity, peroxide value, free fatty acid and iodine value of 35.5 ?, 37 ? and 30.68 ?, 0.40 Cst, 0.41 Cst and 0.36 Cst, 0.70, 0.81 and 1.13 meq/kg oil, 0.40%, 0.51% and 0.57%, 37.4, 39.04 and 76.78 g/100, respectively, for cocoa liquor, Allanblackia floribunda and African elemi oil. The regression models were able to predict the physicochemical properties of the dark chocolate as a function of factors with an accuracy of 86-99% depending on the responses. The optimum condition selected after numerical optimization revealed that the mixture of cocoa liquor (61.1%), Allanblackia floribunda (35%) and African elemi (38%) with desirability index of 0.705 was the optimum formulation which improved the dark chocolate. Physicochemical properties of the formulated dark chocolate showed moisture content of 1.18%, melting pt (35.5?), hardness (15.9 Nmm2) viscosity (3.54 Cst), FFA (0.08 %) and PV (1.28 meq/kg) whereas the control sample recorded 1.12%, 36.55?, 16.16 Nmm2, 2.95 Cst, 0.06 %, and 1.05 meg/kg for moisture content, meltin

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