Optimal sensory evaluation protocol to model concentration–response curve of sweeteners

The objective of this study was to develop an optimal sensory evaluation protocol to model the concentration–response (C–R) curve of various sweeteners in skimmed milk system. C–R curve was modeled for xylose, tagatose, erythritol, sucralose, and stevia. Five concentrations of each sweetener corresponding to the sweetness of 1%, 2%, 3.5%, 5%, and 7% sucrose were calculated by the sweetness potency value obtained from a previous study. Three types of sensory evaluation method were compared for their accuracy in modeling the C–R curve. Traditional method measured the sweetness intensities of 5 concentration levels of a specific sweetener in one test set (eg. xylose 1.6%, 3.2%, 5.6%, 7.9%, 11.1%). Hetero sample-equi concentration method measured the sweetness of 6 types of sweeteners having similar sweetness intensity level in one test set (eg. set 1: sucrose 1%, xylose 1.6%, tagatose 1.2%, erythritol 1.7%, sucralose 0.002%, stevia 0.04%; set 2: sucrose 2%, xylose 3.2%, tagatose 2.4%, erythritol 3.3%, sucralose 0.004%, stevia 0.08%, etc.). Sucrose-sweetener combined method measured the sweetness of 5 levels of specific sweetener as well as the 5 levels of sucrose in one test set. All samples were evaluated by 10 trained panelists. Reference standards for sweetness intensities were provided in all methods. To identify the most accurate sensory evaluation protocol, the concentrations of each sweetener corresponding to the sweetness levels of 1.5% and 4.5% sucrose were interpolated from the C–R curve modeled for each sweetener measured by the 3 methods. The actual sweetness intensities of the interpolated concentrations of each sweetener were validated with the sweetness intensities of 1.5% and 4.5% sucrose levels. The result showed that the sucrose-sweetener combined method was the most accurate protocol. Traditional method tended to overestimate the sweetness potency value of sweeteners in low concentration range whereas hetero sample-equi concentration method tended to underestimate the value. Another significant finding was that the sweetness potency value of each sweetener changed as the concentration changed.