Analytical methods for steviol glycosides in stevia sweeteners

101 Toxic Food Ingredients

101 Toxic Food Ingredients

Get Instant Access

According to the Voluntary Specifications of Non-chemically Synthesized Food Additives (Second Edition 1993), the quantitative analysis oftotal steviol glycosides in stevia extracts is performed using high-performance liquid chromatography (HPLC) on an NH2 column (normal-phase mode), in the following manner. About 60 to 120 mg of the sample is accurately weighed and dissolved in 80% (v/v) acetonitrile to make 100ml of a test solution. About 50 mg each of stevioside and rebaudioside A, dried previously for 2 hours at 105 °C are accurately weighed, and the standard solutions of both compounds are prepared in the same fashion as the test solution. The test and standard solutions are injected into an HPLC apparatus under the following conditions:

Pipette For Lab The Old Type

Figure 9.2 HPLC elution profiles of 'stevia extract' (1) and 'sugar-transferred stevia extract' after treatment with /»-amylase (2).

Figure 9.2 HPLC elution profiles of 'stevia extract' (1) and 'sugar-transferred stevia extract' after treatment with /»-amylase (2).

detector: ultraviolet spectrometer (wavelength 210 nm);

packing material: NH2 (aminopropyl)-modified silica or polymer gel;

column: A stainless column of 3.9—4.6 mm diameter and 15—30 cm length;

column temperature: 40 °C;

Mobile phase: acetonitrile-water (80:20);

flow rate: retention time of stevioside is adjusted to about 10 minutes; injection volume: 10—20 ^L.

Peak areas of stevioside, rebaudioside A, rebaudioside C and dulcoside A in the chromatogram of the test solution and those of standard stevioside and rebaudioside A in chromatograms of each standard solution are measured, and quantities of the four sweet principles of S. rebaudiana leaves are calculated as follows:

Where,WS: Weight (mg) of stevioside standard; WR: Weight (mg) of rebaudioside A standard; WT: Weight (mg) ofthe test sample; TS: Peak area ofstevioside in the test sample chromatogram; TD: Peak area of dulcoside A in the test sample chromatogram; TRA: Peak area of rebaudioside A in the test sample chromatogram; TRC: Peak area of rebaudioside A in the test sample chromatogram; SS: Peak area of stevioside in the standard chromatogram; SR: Peak area of rebaudioside A in the standard chromatogram.The total amount ofsteviol glycosides is presented by the sum of the quantities of the above four principles.

In the Voluntary Specifications of Non-chemically Synthesized Food Additives (Second Edition 1993), 'sugar-transferred stevia extract' (enzymatically modified stevia) is registered by levels ofboth the total steviol glycosides and the unglucosylated steviol glycosides.The total steviol glycosides are calculated by the sum of the quantities of isosteviol and sugars in the acid hydrolysate of the steviol glycosides, while the quantity of unglucosylated steviol glycosides in this product is determined by using about 1.5 g of a test sample on an HPLC column according to the analytical method for the 'stevia extract'.

Figure 9.2 shows HPLC patterns of 'stevia extract' and 'sugar-transferred stevia extract' after treatment with ^-amylase.

Was this article helpful?

0 0
You Are What You Eat

You Are What You Eat

Nutrition is a matter that people spend their careers learning about and requires volumes of books to explain. My objective is to instruct you how to consume a healthy nutritional diet that aids your body in burning off fat instead of storing it. You do not require overwhelming science to get this.

Get My Free Ebook


Post a comment