The Production and Human Taste Detection of Glucose Polymers with Distinct Chain Length Ranges

Graduation date: 2016A majority of human caloric intake is in the form of complex carbohydrates, which have been assumed to be tasteless. However, there is considerable evidence from rat and human studies to support the existence of a secondary carbohydrate taste receptor that detects glucose polymers. Psychophysical studies in our lab suggest that humans can taste maltodextrins and cooked starch after active tasting and thus support the presence of the postulated complex carbohydrate taste receptor. However, maltodextrins contain simple sugars (i.e., glucose and maltose) that activate the known sweet taste receptor, which is confounding when investigating the perception of glucose polymers. This thesis had two objectives: to produce three glucose polymer stimuli devoid of simple sugars with distinct chain length ranges and to evaluate the human taste detection of the stimuli. We developed an economical highly-modifiable methodology to produce large quantities of three compositionally distinct glucose polymer stimuli (i.e., Samples 1-3) from a corn syrup solid (CSS) starch hydrolysis product (CSS DE20). Ethanol-water differential solubility was used to remove simple sugars and to narrow the glucose polymer chain length ranges before rotary evaporation and freeze-drying. Determined by HPLC analysis, the average percent composition of Samples 1-3 were DP3-DP8, DP9+: 26.4 ± 1.5%, 73.6 ± 1.5%; 75.5 ± 1.8%, 24.5 ± 1.8%; and 0%, 100%. The average percent yield of Samples 1-3 were: 51.20 ± 1.33%, 8.04 ± 0.37%, and 25.98 ± 2.07%, respectively. To achieve the second thesis objective, the taste detection of Samples 1-3 at 6 and 8% (w/v) was evaluated using triangle tests without and with acarbose, an α-amylase inhibitor. Based on the findings of Sclafani et al. (1987), it was hypothesized that humans can detect the glucose polymer stimuli based on their proportion of short chain glucose polymers; the relative taste detection of the test stimuli would be Sample 2 (75% DP3-8) > Sample 1 (25% DP3-8) > Sample 3 (0% DP3-8). It was hypothesized that as glucose polymer stimuli concentration increased there would be an increase in the degree of taste detection. It was hypothesized that the presence of acarbose would alter the degree of taste detection if the hydrolysis of the glucose polymer stimuli was significant. According to the calculated d’ values, subjects were able to significantly discriminate Sample 1 and Sample 2 against water, but were unable to detect Sample 3. There was a significantly higher discrimination of Sample 2 at 8% (w/v) compared to 6% (w/v). However, the discrimination of Samples 1 and 3 were not different across concentrations, possibly due to a trivial increase in the number of detectable molecules from 6 to 8% (w/v). In addition, the presence of acarbose did not elicit any significant difference in the discrimination of Samples 1-3 against water. This result implies that salivary α-amylase did not play a significant role in the glucose polymer stimuli detection likely due to an insignificant alteration of the stimuli saccharide profile. Overall, this research produced three glucose polymer stimuli devoid of simple sugars with distinct chain length ranges and supports the existence of a postulated complex carbohydrate receptor in humans that can detect short chain glucose polymers