Ingredient levels optimization and nutritional evaluation of a low-calorie blackberry (Rubus irasuensis Liebm.) jelly

Response surface methodology (Box-Behnken design) was applied to assess and model effects of 3 factors, sweetener, low methoxyl pectin, and calcium content (each at 3 levels), on the overall acceptability of a blackberry (Rubus irasuensis Liebm.) jelly, as determined by 100 consumers. Jelly was produced using clarified juice, obtained from a cross-flow microfiltration process. Results showed that the model fit was significant, and there was satisfactory correlation between actual and fitted values (R-2 = 0.925 and adjusted R-2 = 0.791). The model presented no significant lack of fit (P = 0.096). Sweetener level had a significant effect on overall acceptability (P <= 0.05), but low methoxyl pectin and calcium levels did not. The statistical model was further used to optimize the factor levels for highest acceptability, in order to obtain a jelly that provided less than 8 calories per serving, making it possible to label the product as "low calorie". The product is a good alternative for consumers who wish to diminish sucrose intake.