Sucrose release from agar gels and sensory perceived sweetness

• Gels of varying concentrations of agar and sucrose were prepared.
• Sweetness of the gels was evaluated by a time–intensity method.
• The maximum intensity reached a plateau for high sucrose gels.
• High agar gels showed high modulus and fracture stress but low sweetness.
• Gel strength also delayed the time at which maximum sweetness was perceived.

Sweetness resulting from sucrose released from agar gels of varying concentrations of agar (0.5, 1.0, and 1.5% w/w) and sucrose (10%–50% w/w) was evaluated. The intensity of sweetness as perceived by subjects was investigated during consumption of the gels. A time–intensity method was applied: the maximum intensity and area under the time–intensity curve were higher in gels with lower concentrations of agar as expected from previous studies. The intensity of sweetness as estimated by the area under the time–intensity curve increased with sucrose concentration, but the maximum intensity tended to reach a plateau above a certain sucrose concentration. The manifestation of the maximum sweetness was delayed with increasing concentrations of sucrose and agar. The total duration of the perception of sweetness was longer in gels with higher sucrose concentrations but did not depend on the concentration of agar in the range examined. Instrumental characterization of these gels was also conducted. Young's modulus, fracture stress, fracture strain, and energy obtained from a conventional uniaxial compression test of sample gels increased with sucrose concentration and the modulus, stress, and energy were higher in gels with higher agar concentration. Although mechanical characteristics such as Young's modulus, fracture stress, strain, and energy, increased with increasing sucrose concentration, the sweetness intensity tended to a plateau; therefore, physiological and psychological factors experienced during oral processing should be taken into account to understand the perceived sweetness intensity.

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