Taste perception of oligosaccharides derived from pullulan.

Recent studies indicate that humans can taste starch hydrolysis products (i.e. maltooligosaccharides; MOS). However, the structural specificity of oligosaccharides that elicit such perception is not known. This study investigated taste perception of pullulan-derived oligosaccharides (PDOS) that are structurally similar to MOS, but differ in that every third glycosidic linkage in PDOS is α-1,6, rather than α-1,4. Three food-grade PDOS stimuli were produced by limited-enzyme hydrolysis of pullulan. The resulting products were stimuli with degree of polymerization (DP) of 3, 6, and 9. Subjects discriminated all 3 stimuli from blanks at a significant level (P < 0.00001) in the absence of lactisole, a sweet taste inhibitor. In the presence of lactisole, the subjects could not detect DP 3 at a significant level (P > 0.05), but were able to detect DP 6 and 9 (P < 0.005), although the degree of detectability dropped significantly (P < 0.05). In a follow-up qualitative study, subjects made the target stimuli and glucose into 2 groups (glucose/DP 3 vs. DP 6/DP 9) and characterized both groups as mostly "sweet" with having different sweetness intensity. With lactisole, they described glucose and DP 3 as "taste like blank" (lactisole water) and found it challenging to describe DP 6 and 9 stimuli due to their subtle nature. These results suggest that taste perception of PDOS primarily depends on the sweet taste receptor, although they may elicit other sensory attributes; this is strikingly different from the reported taste of MOS. The potential impact of structural configuration on taste perception is further discussed.

Sodium, but not potassium, blocks bitterness in simple model chicken broths.

Potassium chloride (KCl) has proven useful as a salty taste replacer to help reduce dietary sodium. But unlike sodium, which in simple aqueous solutions blocks the perception of bitterness of selected compounds, KCl does not blocker bitterness. We tested the ability of potassium to block bitterness in a more complex translational system by presenting model chicken broths to healthy adults. Broths were presented in three added salt conditions: (1) no added salt, (2) salted with sodium chloride (NaCl), or (3) salted with KCl. To create a model bitter off-taste, four concentrations of l-tryptophan (l-tryp, present in chicken meat) were added to each broth. In Experiment 1, the base broth consisted of chicken flavor only. In Experiment 2, the base broth was more complex, containing savory (umami) ingredients. In both experiments, subjects rated broths with either added NaCl or KCl as saltier than unsalted broths. Only NaCl, however, suppressed bitterness (by about 30%, across a wide range of l-tryp concentrations). Accordingly, when complex foods have sodium reduced and potassium increased to balance salty taste, the bitterness reducing properties of sodium will need to be replaced independently, since potassium does not share this effect.