Carbohydrate taste sensitivity testing in healthy volunteers to determine human oral carbohydrate taste function and its association with food consumption, BMI, and ad libitum consumption of carbohydrate foods

Participants will be required to attend the sensory laboratories at Deakin University on two separate occasions during which detection threshold (DT) and suprathreshold intensity (ST) for glucose (sweet) and maltodextrin (carbohydrate), hedonic ratings for glucose and maltodextrin solutions, and hedonic ratings for a range of sweet and carbohydrate prototypical foods will be determined. For DT and ST measures, participants will be tasting a total of 16 solution samples (8 glucose samples, 8 maltodextrin samples; 25mL each sample), with concentrations ranging from 0.11-6.31% w/v. For hedonic ratings for glucose and maltodextrin, participants will be tasting a total of 16 solution samples (16 glucose samples, 16 maltodextrin samples; 25mL each sample), with concentrations ranging from 0.11-6.31% w/v. Examples of foods that participants will taste includes fairy floss, honey, kidney beans, rice cakes, white rice, white bread, chocolate sauce, dried apples, raisins, pasta, tomato sauce, and pretzels. They will be served in a 30mL medicine cup. Each participant will test both sweet and carbohydrate solutions/foods. During these sessions, participants will also consume two different iso-caloric preload milkshakes (glucose, maltodextrin). Participants were randomly assigned to the sequence of sweet and complex carbohydrate milkshakes using a web-based program (http://randomizer.org) (i.e., either consuming a sweet milkshake in the first visit or complex carbohydrate milkshake). Demographic information will be collected, including sex, age, and height and weight measurements. BMI (kg/m2) will be calculated from the height and weight measurements. Participants will also be asked to complete a Food Frequency Questionnaire (FFQ) and a Likes and Dislikes Questionnaire online within 1 week of sensory testing. Psychophysics tasks (DT, ST), as well as hedonic ratings for a range of sweet and carbohydrate solutions will be conducted in computerised, partitioned sensory booths in the Centre for Advanced Sensory Science using Compusense Five Software Version 5.2 (Compusense Inc., Ontario, Canada). To measure hedonic ratings for a range of sweet and carbohydrate foods, participants will be asked to collect food samples from a counter in the Deakin University’s Teaching Food Laboratory. They will then be asked to taste and rate their liking of the foods on their individual workbenches. Filtered deionised water will be used as an oral rinsing agent. Participants will be instructed to rinse their mouths with filtered deionised water for five seconds before beginning each task and between each sample set. To eliminate any visual or olfactory input, all testing sessions will be conducted under red lighting, and participants will be asked to wear nose clips during testing (except hedonic ratings). All solutions were served at room temperature, with a three-digit code allocated to each sample. Participants will be asked to abstain from eating and drinking (except room temperature water) for two hour prior to each session. Each session will last about 2 hours, and participants will be given breaks between tasks (around 15 minutes). The sweet (glucose) and carbohydrate (maltodextrin) milkshakes (per 100g) will consist of: 8.8% glucose/maltodextrin (The Melbourne Food Depot, Melbourne, Australia; Star-Dri 5, Tate & Lyle Ingredients Americas, USA), 63.7% long-life skim milk (99.9% fat free; Devondale Murray Goulburn, Melbourne, Australia), 26.5% light thickened cream (~18% fat; Bulla, Derrimut, Australia), and 1.0% imitation vanilla essence (Queen Fine Foods, Alderley, Australia). All milkshakes will be prepared fresh on the day of testing and stored refrigerated (+/- 3 degree celsius) using plastic food storage containers. Visit one will include collection of demographic data, DT and ST measurements for glucose and maltodextrin solutions, hedonic ratings for sweet foods, and milkshake ad libitum measurements for either one of the milkshakes. Visit two will include hedonic ratings for sweet and carbohydrate solutions, hedonic ratings for carbohydrate foods, and milkshake ad libitum measurements for either one of the milkshakes. There is a one week washout period between both visits. For clarity, 'sweet' foods denotes sweet tasting foods, whereas 'carbohydrate' foods denotes non-sweet carbohydrate foods (e.g., dietary starches).