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.