Determination of steviol glycosides in seven Stevia rebaudiana (Bertoni) extracts routinely used in the food and confectionary industry

Abstract

Stevia rebaudiana Bertoni extracts are used as natural non-nutritive sweeteners in several countries worldwide. The principal components of stevia leaf extracts are stevioside and rebaudioside A. Stevioside has about 300 times the sweetening power of sucrose, but is the main cause of the bitter aftertaste of crude stevia extracts. Rebaudioside A has greater sweetening power and a less pronounced bitter aftertaste, and so is usually the preferred component. The overall taste of the sweetener depends on the composition of the stevia extract used and the steviol glycosides present. To characterize the unique taste profile of stevia sweeteners, we analyzed stevioside, rebaudioside A, rebaudioside B and isosteviol content in seven different commercial food-grade extracts used as raw material. A sensitive method, using HPLC coupled to electrospray ionization-tandem mass spectrometry, was applied. The amount of steviol glycoside in the seven different extracts varied. As expected, rebaudioside A was the most abundant, ranging from 497 to 1,000 mg/g. One sample contained only rebaudioside A. Rebaudioside B and stevioside levels ranged from negligible to 40% of the total glycosides determined, with concentrations ranging from 2.7 to 386 mg/g of raw material. The concentration of isosteviol was below the limit of detection in all samples. These data can help in the selection of the most suitable commercial extracts for use as sweeteners in food, beverages and confectionery.