Development of protein mixtures and evaluation of their sensory properties using the statistical response surface methodology

The Statistical Response Surface Methodology method was used to find the right proportion of three protein substrates as an alternative to whole milk in a powder formulation for the preparation of a chocolate-flavoured milk drink regularly consumed in institutional programmes. Starting with a nutritionally standardised commercial product, parts of the whole milk solids were replaced with a mixture containing soy protein isolates, hydrolysed gelatine and wheat gluten. According to an experimental design of the simplex-centroid type, the contribution of each ingredient to the total protein content of the mixture was subjected to sensory analysis by the 'scale difference from control' method. A quadratic polynomial model. was fitted for prediction as it fitted into the experimental data. The proportion of the three protein substrates was suggested by graphical presentation of the contours. The mixture was then applied to the formulation of the milk drink and subjected to a sensory analysis. The final product presented a centesimal composition similar to that of the commercial product at a lower cost and a degree of acceptability that did not differ from the control (P < 0.01). The results demonstrated the importance of the Response Surface Methodology as an indispensable technique for the development of products.