Optimization of Coffee-Gelatin Shot Formulations Based on Physicochemical, Rheological and Sensory Properties Using Response Surface Methodology

The objective of this study was to optimize the coffee content and alcohol content of the formulations of coffee-gelatin shots based on physicochemical, rheological and sensory properties of the products. Because the coffee content and alcohol content influenced those properties of coffee-gelatin shots significantly which were related to the consumers’ acceptance. Thirteen different coffee-gelatin shots for nine formulations based on CCRD were developed and the sensory properties (overall acceptability, color, flavor and texture), L-value, pH and viscosity of coffee-gelatin shots were determined. The regression models were developed to predict the response variables as a function of independent variables. The response surface models were developed to understand the effects of independent variables on the responses. A desirability function was used to determine an optimum formulation using a numerical optimization technique. All contour plots of response surface models were superimposed to visualize an optimum region. The regression models could predict the sensory properties, L-value, pH and viscosity of coffee-gelatin shots as a function of coffee content and alcohol content with an accuracy of 77-99% depending on the properties of coffee-gelatin shots. The coffee content and alcohol content affected the sensory properties, L-value and viscosity of coffee-gelatin shots significantly (p<0.05). The optimization results obtained using numerical and graphical optimization techniques indicated that a combination of coffee (2.50 -3.00 g) and alcohol (5.25-6.75 mL) was the optimum formulation of a coffee-gelatin shots that improved the sensory properties, L-value, pH and viscosity of the coffee-gelatin shots. This optimum formulation of coffee-gelatin shots is expected to be useful for commercial manufacturing of consumers’ desired coffee-gelatin shots.