Relevant for: Beverage Manufacturers
More and more beverages are sweetened with a combination of sugar and Stevia for reasons of healthy calorie reduction. DMA M and Soft Drink Analyzer M easily cope!
How much sugar is good for you?
Not only products like chocolate, ice cream, jams, and cakes contain saccharose, commonly referred to as sugar, but also many convenience foods and beverages. Soft drinks in particular represent a large source of “hidden” sugar. Nowadays consumers tend to prefer soft drinks with less sugar. Not only is calorie intake linked to obesity, it also poses health concerns that cause consumers to choose sugar-reduced drinks. Being overweight or obese is reported to lead to adverse effects on blood pressure, cholesterol , and increase the risks of coronary heart disease and type 2 diabetes mellitus. The World Health Organization (WHO) therefore recently reduced the recommended daily intake to a dose below 25 grams of sugar  which corresponds to approximately six teaspoons per day for adults, and for children only half of this amount.
Why partially replace sugar?
The problem: A regular soft drink contains 8 to 10 grams of sugar in 100 mL, so an average can might already exceed the recommended maximum daily sugar intake. The question: As the sweetening power of Stevia exceeds the sweetness of saccharose by far, the amount of sweetener in soft drinks is much lower, thus the calorie intake almost negligible. On top of that, sweeteners do not promote caries. So why not replace the entire sugar content in soft drinks with sweeteners?
The answer: It is the mouth feel and the taste that make consumers prefer sugar-sweetened beverages.
The solution: Beverages with a combination of sugar and sweetener mean less sugar while maintaining the full-bodied taste.
Will the addition of sweeteners affect the measurements with DMA M and Soft Drink Analyzer M?
A sweetener commonly used by soft drink manufacturers is the highly water soluble steviol glycoside Rebaudioside A (see Figure 1) which will subsequently be considered in more detail.
The sweetening power of this steviol glycoside, for the sake of simplicity referred to as Stevia in this report, is estimated to be at least 200 times higher than the sweetness of sugar  – another reference mentions a sweetening power of 300 to 450 . In other words, the amount of 0.01 g Stevia in 100 mL is as sweet as at least 2 grams of sugar in 100 mL or 2 °Brix.
The determination of density with the DMA M density meter and the calculation of °Brix from the measured density result is a well-established procedure among soft drink producers. If also the °Brix fresh, °Brix inverted and the degree of inversion are required, Soft Drink Analyzer M is the perfect instrument for fast and correct measurement results and reliable quality control. Will the results with DMA M and Soft Drink Analyzer M be equally correct and reliable if instead of saccharose alone a mixture of saccharose and Stevia is dissolved in the soft drink?
To shed light on this question distilled water and two different commercially available regular cola beverages were investigated at 20 °C. Repetitive determinations were performed and indicated in the respective figure. Figure 2 shows how an added 0.0978 g of Stevia to 100 mL of distilled water affects the °Brix result. From the graph it can be seen that the increased density by addition of Stevia to
100 mL of distilled water causes a rise in °Brix of 0.078. Similar amounts of Stevia added to degassed Cola 1 (0.1002 g) and Cola 2 (0.0984 g) showed an increase in °Brix of 0.078 and 0.093, respectively.
To investigate the influence of Stevia more closely, the degassed cola samples Cola 1 and Cola 2 were divided into two groups. One group was measured as such, the other one spiked with Stevia (Sigma Aldrich, Rebaudioside A ≥ 96 % (HPLC) 01432-10G). The amounts of Stevia added are summarized in Table 1.
Subsequently, both cola samples with and without added Stevia were investigated and the impact of Stevia on the °Brix results observed.
Figure 3 graphically displays the °Brix results of Cola 1 with and without Stevia.
Figure 4 graphically displays the °Brix results of Cola 2 with and without Stevia.
In order to quantify the influence of Stevia on the determination of °Brix fresh and °Brix inverted, Cola 1 was measured with Soft Drink Analyzer M. One part of a 500 mL bottle of degassed Cola 1 (compare Table 1) was measured as is. The rest was spiked with Stevia (0.0187 g Stevia in 100 mL which has a sweetening power of at least 3.7 °Brix up to 8.4 °Brix). The measurements were carried out with Soft Drink Analyzer M and an Xsample 122 sample changer. Figure 5 graphically displays the obtained results of the spiked and unspiked samples.
to Cola 1
to Cola 2
Table 1: Amounts of Stevia added to the degassed cola samples
Summary and Conclusion
As expected, the density increase caused by addition of Stevia to a regular soft drink manifests itself in a small increase of °Brix. Spiking with different amounts of Stevia was performed with degassed Cola 1 and Cola 2. Repetitive determinations were carried out (see Figure 3 and Figure 4).
The trendline connecting the results for the respective Stevia addition is linear for both cola samples. This fact indicates that the °Brix measurement with DMA M and SDA M of soft drinks containing both sugar and Stevia is accurate.
An example is presented in Figure 5: Cola 1 was spiked with a realistic amount of Stevia, corresponding to a typical amount that is expected to be found in cola beverages in today’s supermarket shelves.
Comparing the differences in °Brix actual, °Brix fresh, and °Brix inverted of spiked and unspiked Cola 1 leads to the conclusion that the added amount of Stevia that corresponds to the sweetening power of at least 3.7 °Brix up to 8.4 °Brix does not have a noticeable influence as the deviations of the spiked to unspiked results are well below the instrument’s specifications .
 Yikrazuul / Wikimedia Commons / Public Domain
 Anton Paar Instruction Manual Soft Drink Analyzer M, instrument software version: from 2.90, May 2016