Optimization of blending ratios of jam from swazi indigenous fruits tincozi (syzygium cordatum), tineyi (phyllogeiton zeyheri) and umfomfo (cephalanthus natalensis oliv.) using mixture design

Abstract

This research was conducted to study effect of blending ratios on the physicochemical and sensory attributes and to optimize the blending proportions of jam made by blending three indigenous fruits: Tincozi (syzygium cordatum), Tineyi (phyllogeiton zeyheri) and Umfomfo (cephalanthus natalensis oliv.). An augmented simplex lattice mixture design was used where a total of seven formulations were generated using Design Expert software. The results indicated that the blending ratio affected the sensory attributes and the physico-chemical properties significantly (p < 0.05). Except for flavor, pH and water activity which were described by special cubic model, a quadratic Scheffer's model adequately (R2 = 0.84–0.99) described the relationship between blend proportions and the quality attributes. A graphical optimization indicated that the optimal ranges of the proportions for the three fruits for an acceptable product were 7–32%, 7.5–32% and 9 − 15%, for Tineyi, Tincoz andUmfomfo, respectively. The numerical optimization showed the optimal combination for an acceptable quality to be 20%, 18% and 12% for Tineyi, Tincoz and Umfomfo, respectively which had an overall desirability value of 0.914. Based on the results of the study the three fruits could be blended to produce jam of an acceptable quality.