Degree of free fatty acid saturation influences chocolate rejection in human assessors

In foods, free fatty acids (FFAs) traditionally have been viewed as contributing an odor, yet evidence has accumulated that FFAs also contribute a unique taste ("oleogustus"). However, minimal work has been conducted using actual foods to test the contribution of FFA to taste preferences. Here, we investigate flavor, taste, and aroma contributions of added FFA in chocolate, as some commercial manufacturers already use lipolysis of triglycerides to generate unique profiles. We hypothesized that small added concentrations of FFAs would increase preferences for chocolate, whereas higher added concentrations would decrease preferences. We also hypothesized a saturated fatty acid (stearic C18) would have a lesser effect than a monounsaturated (oleic C18:1), which would have a lesser effect than a polyunsaturated (linoleic C18:2) fatty acid. For each, paired preference tests were conducted for 10 concentrations (0.04% to 2.25%) of added FFAs compared with the control chocolate without added FFAs. Stearic acid was tested for flavor (tasting and nares open), whereas the unsaturated fatty acids were tested for both aroma (orthonasal only and no tasting) and taste (tasting with nares blocked to eliminate retronasal odor). We found no preference for any added FFA chocolate; however, rejection was observed independently for both taste and aroma of unsaturated fatty acids, with linoleic acid reaching rejection at lower concentrations than oleic acid. These data indicate that degree of unsaturation influences rejection of both FFA aroma and taste in chocolate. Thus, alterations of FFA profiles in foods should be approached cautiously to avoid shifting concentrations of unsaturated fatty acids to hedonically unacceptable levels.