Just Noticeable Difference in Sweetness Perception in Iced Coffee Beverages

open_access
Open Access
Author:
Czyszczon, Kacie
Area of Honors:
Food Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
John Hayes, Thesis Supervisor
Fede Harte, Thesis Honors Advisor
Keywords:
Food Science
Sensory Science
Sweetness
Just Noticeable Difference
Weber Ratio
Psychophysics
Sugar-sweetened beverages
Sucrose
Iced Coffee
Coffee
Abstract:
Iced coffee is a growing beverage category. However, sugar-sweetened beverage consumption contributes to obesity and other related diseases. This study aimed to determine the just noticeable difference (JND) and Weber Ratios for sucrose in iced coffee beverages to quantify how much sugar—and consequently, calories—can be reduced without compromising consumer acceptability. Additionally, a secondary goal was to evaluate the degree of liking of iced coffee at varying sugar levels. A sensory test was conducted with two phases: (1) a series of 2-Alternative Forced Choice (2-AFC) tests to determine the JND and Weber Ratio, and (2) hedonic ratings to assess consumer liking. In the 2-AFC tests, we used iced coffee with five decreasing sucrose concentrations (10.5%, 9.5%, 8.5%, 7.5%, and 6.5% w/w), paired with a 11.5% reference. Participants were instructed to choose the sweeter sample. In the hedonic test, participants were asked to rate their overall liking of three iced coffee samples (6.5%, 9.0%, and 11.5% w/w) on a standard 9-point hedonic scale. Results indicate the JND of sweetness for sucrose in iced coffee occurs approximately at 10% w/w relative to a starting concentration of 11.5% w/w – that is, a drop of ~1.5 percentage points. This reduction corresponds to a relatively small reduction of energy (28 kcal) from sugar, assuming a 16 fluid ounce bottle (473.147 mL), which may be too small for meaningful health outcomes. However, findings suggest that larger sugar reductions—though noticeable—may still be acceptable to consumers. Future research should explore other iced coffee flavors such as caramel or mocha and assess the JND of non-nutritive sweeteners to inform sugar reduction strategies in the beverage industry.