Sensory and Rheological Properties of Fortified Coconut Milk Based Chocolate Drink as Influenced by Cocoa Powder and Sugar Levels

Abstract

Purpose: This study investigated the sensory and rheological properties of fortified drinks made from coconut milk, cocoa powder and sugar. Methodology: Drinks samples were formulated with different concentration of coconut milk, cocoa powder and sugar levels. Samples incudes: K1 (Coconut milk 100 %), K2 (Coconut milk 99.8 % cocoa powder 0.2 %), K3 (Coconut milk 99.6 %, cocoa powder 0.4%), K4 (Coconut milk 98 %, sugar 2%), K5 (Coconut milk 97.8 %, cocoa powder 0.2%, sugar 2%), K6 ( Coconut milk 97.6 %, cocoa powder 0.4%, sugar 2%), K7 (Coconut milk 96 %, sugar 4%), K8 (Coconut milk 95.8 %, cocoa powder 0.2%, sugar 4%), K9 (Coconut milk 95.6 %, cocoa powder 0.4%, sugar 4%). The samples were produced and subjected to sensory and rheological study using standard methods. Results: Sensory evaluation; appearance from 8.13(K9) to 7.00 (K2), Aroma from 7.93 (K9) to 6.53 (K1), Mouth feel from 7.83 (K8) to 6.63 (K1) and 6.63 (K3), Taste from 7.90(K9) to 6.27 (K1) and General Acceptability from 8.30 (K9) to 6.40 (K3). The rheological parameters using the power law; consistency index (m) 0.003 to 0.19 (Nsn/m2), flow behavior index (n) n<1 for all drink samples. For the Arrhenius model, µo (frequency factor) ranged from 1.9 x10 -5 to 5.1 x 10 -8.  Ea (activation energy) ranged from 15.55 to 30.70 KJ/mol.  The r squared for both power law model and Arrhenius model, ranges from 0.825 to 0.99 that is approximately 1.  Cocoa powder and sugar levels improved sensory profile. The flow behavior indices (n) of drinks were all less than 1(n < 1) this implies pseudoplastic flow behavior for drinks samples.