Sensory evaluation of a milk formulation supplemented with n3 polyunsaturated fatty acids and soluble fibres

The hypocholesterolemic effect of some polyunsaturated fatty acids and soluble fibres has been demonstrated mostly in epidemiological studies. Two types of fatty acids (eicosapentaenoic-EPA 20:5n-3 and docosahexaenoic-DHA 22:6n-3) and soluble fibres (oat flour and guar gum), were mixed in different proportions and used in a milk formulation according to a factorial design (32) with a repetition in the central point. The 10 assays were submitted to a sensory test, using a structured hedonic scale applied to heart surgery patients (n=240), in order to evaluate the general acceptability of each mixture. Some of these (n=137) answered a questionnaire, which was used to identify the target public for this product, using multivariate analysis and the correspondence technique. Response surface methodology (RSM) was used to model the polynomial quadratic regression which predicts the “sensory acceptability (y)” as a function of variation from selected factors: x1=(n3 polyunsaturated fatty acids or n3PUFA)g/kcal and x2=(soluble fibres or SF)g/kcal. The concentrations used in the mixtures were: 0.1–0.8 and 0.1–0.3 g/100 kcal, respectively. The coefficient of determination (R2) was 95.76%, indicating the good fit of the model to the experimental data. The high level of n3PUFA and SF significantly decreased the sensory quality of the product, limiting the maximum expression of the functional properties of these two factors. The contour plots obtained from the quadratic model permitted determination of the acceptability of the milk formulation, which was estimated in each possible combination of n3PUFA acid and SF. These procedures were essential for developing a good product with functional properties for human consumption.