NIRS for the Quality Control of Non-Nutritive Sweeteners

Over the last decade, the introduction of non-nutritive sweeteners as sugar substitutes in foodstuffs has seen a sharp increase. Typically found in soft drinks and snacks, sucralose, a halogenated sucrose derivative, and Stevia, taken from the leaves of the Steviarebaudiana plant are two of the most commonly used non-nutritive sweeteners.

Sucralose and stevia are much sweeter than sugar and, as a result, are found in much lower concentrations in foodstuffs. Yet, regulations for non-nutritive sweeteners are becoming increasingly strict to ensure food safety.

There are several analytical methods that can be used to determine the different types of sweeteners found in foods, including high-performance liquid chromatography (HPLC), ion chromatography, and thin-layer chromatography.

However, these methods can be time- and labor-intensive, leading to more significant running costs. In contrast, near-infrared spectroscopy (NIRS) facilitates the simultaneous determination of different sweeteners without requiring chemicals or any sample preparation, with results achievable in under a minute.

DS2500 Liquid Analyzer

The DS2500 Liquid Analyzer delivers superior near-infrared spectroscopy that meets the demands of quality control applications in both the laboratory and on the production line. The analyzer is a dynamic solution with a proven capacity for routinely analyzing liquids in various production environments.

Robust by design, the DS2500 Liquid Analyzer is a sturdy piece of equipment making it ideal for deployment in harsh production environments as it is resistant to dust, moisture, and vibrations.

The DS2500 covers the entire spectral range from 400 to 2500 nm and produces accurate results in less than one minute. The reproducibility of the DS2500 Analyzer’s results and intuitive interface supports users in their daily routine while also addressing the rigorous demands of the pharmaceutical industry.

Regardless of the sample type and challenges that may arise, an array of custom accessories helps optimize functionality to ensure excellent results are delivered, whether analyzing coarse-grained solids such as granulates or even semi-solid samples such as creams.

The capacity of the MultiSample Cup can provide an added productivity boost when measuring solids, as it facilitates sequential automated measurements of up to nine samples simultaneously.

Experimental Equipment

Samples of both Stevia (0.5–4.5%) and sucralose (0.5–4.5%) in sucrose (95%) mixtures were prepared and subsequently analyzed to generate a prediction model for measurements and data acquisition.

The Metrohm NIRS DS2500 Solid Analyzer was used to measure the samples as shown in Figure 1. Furthermore, 15 mm disposable vials, a DS2500 holder, and a DS2500 Iris in reflection mode was used to ensure data quality. The software package Vision Air Complete was used to capture data and develop the prediction model.

Table 1. Hardware and software equipment overview. Source: Metrohm Middle East FZC

Figure 1. Metrohm NIRS DS2500 Solid Analyzer used to determine Stevia and sucralose content in sucrose mixtures. Image Credit: Metrohm Middle East FZC

Result

The Vis-NIR spectra obtained were used to generate prediction models for the different reference parameters of sucralose and Stevia in sucrose as shown in Table 2. Correlation diagrams which demonstrate the relationship between the Vis-NIR prediction and the reference values are displayed in Figures 3–5 alongside the respective figures of merit (FOM).

Figure 2. Selection of Vis-NIR spectra of Stevia and sucralose in sucrose samples which were analyzed on a DS2500 Solid Analyzer. Image Credit: Metrohm Middle East FZC

Result Sucralose Content In Sucrose

Figure 3. Correlation diagram and the respective figures of merit for the prediction of sucralose content in sucrose using a DS2500 Solid Analyzer. The lab values were determined using HPLC. Image Credit: Metrohm Middle East FZC

Source: Metrohm Middle East FZC

Result Stevia Content In Sucrose

Figure 4. Correlation diagram and the respective figures of merit for the prediction of Stevia content in sucrose using a DS2500 Solid Analyzer. The lab values were determined using HPLC. Image Credit: Metrohm Middle East FZC

Source: Metrohm Middle East FZC

Conclusion

In this article, the value and feasibility of near-infrared spectroscopy to determine concentration levels of non-nutritive sweeteners sucralose and Stevia in sucrose blends are clearly demonstrated.

Vis-NIR spectroscopy facilitates rapid and cost-effective measurements with greater accuracy, offering a viable alternative to conventional analytical methods (Table 2).

Table 2. Time to result overview for the different non-nutritive sweeteners examined in this study. Source: Metrohm Middle East FZC

This information has been sourced, reviewed and adapted from materials provided by Metrohm Middle East FZC.

For more information on this source, please visit Metrohm Middle East FZC.