The preparation and human taste detection of low degree of polymerization glucose oligomers

There is growing evidence that humans and other animals can taste certain starch hydrolysis products, namely, maltooligosaccharides (MOS), and that their detection is independent of the known sweet receptor, T1R2 T1R3. The overall goal of this study was to further investigate the taste perception of low degree-of-polymerization (DP) MOS in humans. However, research in this area is limited, presumably due to a lack of MOS with specific, narrow DP profiles that are safe for human testing. In order to achieve the overall goal, a method was first developed to prepare specific groups of food-grade MOS (DP 3, 3-4, 5-6, and 6-7) by fractionating commercial mixtures of glucose oligomers and polymers. Psychophysical testing using the four prepared MOS stimuli in addition to glucose (DP 1) and maltose (DP 2) at the same concentration showed that all six stimuli were detected with similar discriminability in normal tasting conditions. In order to assess the potential role of T1R2 T1R3 in MOS taste detection, the stimuli were additionally prepared with lactisole, a sweet inhibitor. All stimuli in both lactisole treatments were prepared with acarbose to prevent oral digestion of glucosidic bonds by salivary α-amylase. Here, it was found that subjects could not detect DP 1, 2, or 3, but could still detect the MOS mixtures (DP 3-4, 5-6, and 6-7). Together, these results support the presence of a MOS taste perception mechanism independent of the T1R2 T1R3 taste receptor, and suggest it is stimulated by MOS greater than three units. After completing psychophysical testing, modifications to the MOS fractionation protocol were found to allow isolated MOS products from DP 3 to 7 to be collected. A second study thus presents the method to obtain these isolated products in a food-safe quality. Differential solubility using aqueous ethanol is first used to obtain a refined MOS preparation, which can then be further refined using column chromatography. A cellulose-based column in conjunction with aqueous ethanol mobile phases is used to separate the MOS preparation into linear, isolated MOS DP 3 to 7 in high purity. This fractionation method will not only be of high relevance to researchers interested in studying the physiological impacts of MOS consumption in humans, but will also be useful to future studies involving human taste perception of these saccharides.Keywords: isolation, column chromatography, glucose oligomers, carbohydrate taste, maltooligosaccharides, differential solubility, degree of polymerization, starch hydrolysis product

Regional Differences in Taste Responsiveness: Effect of Stimulus and Tasting Mode

Previous studies have shown that there are differences in taste responses between various regions of the tongue. Most of those studies used a controlled "passive" tasting mode due to the nature of investigation. However, food is rarely tasted in a passive manner. In addition, recent studies have suggested that humans can taste maltooligosaccharides (MOS) and that the gustatory detection of MOS is independent of the known sweet receptor. It is unknown whether regional differences in responsiveness to MOS exist. This study was set up to revisit previous work by investigating the effects of tasting mode ("passive" vs. "active") on regional differences in taste responsiveness to sucrose, monopotassium glutamate (MPG), and quinine, while also investigating potential regional differences in responsiveness to MOS. The stimuli were applied to 1 of 4 target areas, the left and right sides of the front and back of the tongue, using cotton-tipped swabs. In the passive tasting condition, the front of the tongue was found to be more responsive to both sucrose and MOS, but no regional differences were seen for quinine and MPG. In contrast, in the active tasting condition, the back of the tongue was found to be more responsive to quinine and MPG, but no differences were found for sucrose or MOS. These findings indicate that there are regional differences in taste responsiveness between the front and back of the tongue and that regional responsiveness is dependent on stimulus and tasting mode

Cephalic phase insulin release : the role of oral glucose detection and its measurement in humans

Sensory stimulation from food-related cues elicits a number of rapid physiologic responses that prepare the gastrointestinal tract for efficient nutrient utilization and help minimize perturbations to metabolic homeostasis. Cephalic phase insulin release (CPIR) is one such response that specifically promotes glucose homeostasis by limiting the rise in blood sugar after a meal. While the exact mechanisms responsible for eliciting CPIR have not been defined, stimulation of the gustatory (taste) system, especially with glucose-containing carbohydrates, appears to be particularly effective for inducing the response. However, it is unclear if this is due to the system detecting glucose itself, or to the conscious perception of taste cues associated with carbohydrates (i.e., sweet and starchy). Understanding the specific mechanisms by which gustatory carbohydrate sensing stimulates this response will be a fundamental step in CPIR research: it will allow for more focused investigations into the physiological and clinical implications of CPIR and, in parallel, will be integral for defining the properties required for foods and therapeutic agents designed to promote CPIR in an effort to support human health. The overall goal of this work was to achieve a better understanding of how carbohydrates stimulate CPIR in humans by investigating factors related to the oral detection of glucose and glucose-based saccharides

Human taste detection of glucose oligomers with low degree of polymerization

<div><p>Studies have reported that some animals, including humans, can taste mixtures of glucose oligomers (i.e., maltooligosaccharides, MOS) and that their detection is independent of the known T1R2/T1R3 sweet taste receptor. In an effort to understand potential mechanisms underlying the taste perception of glucose oligomers in humans, this study was designed to investigate: 1) the variability of taste sensitivity to MOS with low degree-of-polymerization (DP), and 2) the potential role of hT1R2/T1R3 in the MOS taste detection. To address these objectives, a series of food grade, narrow-DP-range MOS were first prepared (DP 3, 3–4, 5–6, and 6–7) by fractionating disperse saccharide mixtures. Subjects were then asked to discriminate these MOS stimuli as well as glucose (DP 1) and maltose (DP 2) from blanks after the stimuli were swabbed on the tongue. All stimuli were presented at 75 mM with and without a sweet taste inhibitor (lactisole). An α-glucosidase inhibitor (acarbose) was added to all test stimuli to prevent oral digestion of glucose oligomers. Results showed that all six stimuli were detected with similar discriminability in normal tasting conditions. When the sweet receptor was inhibited, DP 1, 2, and 3 were not discriminated from blanks. In contrast, three higher-DP paired MOS stimuli (DP 3–4, 5–6, and 6–7) were discriminated from blanks at a similar degree. Overall, these results support the presence of a sweet-independent taste perception mechanism that is stimulated by MOS greater than three units.</p></div

Representative chromatograms from HPLC-ELSD depicting saccharide character of the four samples (A, DP 3; B, DP 3–4, C: DP 5–6, and D: DP 6–7) produced through column chromatography.

<p>Representative chromatograms from HPLC-ELSD depicting saccharide character of the four samples (A, DP 3; B, DP 3–4, C: DP 5–6, and D: DP 6–7) produced through column chromatography.</p

Proportion correct^a and discriminability (<i>d’</i> value)^b of target stimuli in the absence and presence of lactisole.

<p>Proportion correct^a and discriminability (<i>d’</i> value)^b of target stimuli in the absence and presence of lactisole.</p

Chemical characterization of four MOS samples prepared for psychophysical testing.

<p>Chemical characterization of four MOS samples prepared for psychophysical testing.</p