Optimization of coconut milk formulation containing gum tragacanth using response surface method

Coconut is a good source of bioactive compounds due to the presence of tocopherols and phytosterols, which are increasingly used to enrich various food products. The use of coconut powder in the formulation of flavored milk with regard to its phytosterol compounds can increase the nutritional value of milk and its organoleptic acceptability among consumers. However, one of the major challenges in the flavored milk industry is their physical instability, which can be effective in using hydrocolloids at the appropriate concentration. Therefore, the aim of this study was to determine the optimal formulation of coconut milk containing tragacanthin gum (solution of tragacanth) to achieve a product with Desirable quality characteristics. For this purpose, the response surface method with the central composite investigated the effect of tragacanthin gum on 5 levels (0, 0.075, 0.15, 0.225 and 0.3%) and coconut powder on 5 levels (2, 3.5, 5, 6/5 and 8%) on the physical, chemical and sensory properties of coconut milk was used. Statistical results showed that increasing coconut powder and tragacanthin gum in coconut milk formulation significantly decreased pH and increased acidity (p<0.05). According to the results of the viscosity test, the viscosity increased as the formulation of tragacanthin and coconut powder increased (p<0.05). Results show an increase of sedimentation amount once the coconut powder increased. While by increasing the gum tragacanthin concentration, there was a twofold effect in sedimentation amount and in average level of gum, the minimum amount of sediment was observed. Also, the sensory evaluation of coconut milk samples indicated that the highest sensory acceptability was for samples containing intermediate amounts of coconut powder. But tragacanthin gum only influenced the flavor and consistency of parameters. Finally, the sample consisted of 4.28% coconut powder and 0.15% tragacanthin gum as optimum sample with desirable physical, chemical and sensory properties.