Electronic Tongue Analysis of Major and Minor Steviol Glycosides and Their Application in Foods
Type of DegreeMaster's Thesis
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The electronic tongue (E-tongue) is a taste-sensing analytical device that simulates the human tongue. It has been predominantly adopted in food industries as a tool for taste evaluation. Significantly, some products causing carry-over effects to human panels due to strong aftertastes, such as stevia, would need an analytical approach like E-tongue to assess tastes, especially for analysis of large numbers of samples. Stevia, a natural sweetener, contains major and minor steviol glycosides with different taste characteristics. Rebaudioside (Reb) A, the major steviol glycoside, is the most widely used in the food industry, but it provides a bitter aftertaste. Minor steviol glycosides (i.e., Reb D and M) display a similar taste profile to sugar with a significantly less bitter aftertaste, but their contents in the leaves are low. Therefore, this study examined the potential of E-tongue to find an optimal ratio between major and minor steviol glycosides to resolve both the bitter taste of Reb A and low concentrations of Reb D and M. This study verified a protocol for the E-tongue analysis with the most updated sensors for stevia samples. Also, it was found that some of the mixtures between Reb A and Reb M showed comparable taste profiles to a single steviol glycoside, Reb M. However, human panel data would be needed to confirm the findings. The second study evaluated sensory characteristics of Reb A, D, and M in ice cream using regular ice cream consumers (n=92) as minor steviol glycosides have been little studied for food applications. The results confirmed that these minor steviol glycosides might resolve the bitter aftertaste often associated with Reb A in food applications, and they might be able to act as sole sweeteners without affecting sensory qualities.