As sketched in Phase II of Figure 2 above, computer-generated alternatives and their realization should evolve in successive cycles where results from experimental tests are fed back to problem formulation (3), in the form of updated models and heuristics. When several alternative formulations are required, a rank of feasible solutions with increasing values of the objective f may be generated through integer cuts.30 In any case, successive cycles should desirably result in an optimal alternative, which meets all product specifications and integrate the consumer assessment. Most heuristic rules have a linear formulation, however, property and process functions are likely to be non-linear, so problems in the form of (3) will be MINLP problems, as it is illustrated in the case study.
In summary, a general methodological approach is presented here for the design of formulated products, in which a fuzzy measure analysis for the consumer assessment, along with heuristics and property models incorporation for the product realization phase, are used to guide the selection of formulations that solve the original design problem, using the reformulations of cosmetic emulsions as case studies.