An Introduction to the Use of Fully Automated, High-Speed ​​Polarimeters in the Food and Sugar Industries

Carbohydrates generally exhibit optical activity. A polarimeter is a traditional piece of testing equipment in the sugar industry and is also widely used across the broader food sector—including in the production of seasonings, beverages, and confectionery—for measuring sugar content and screening the quality of raw materials. The DS-P900T series of fully automatic, high-speed polarimeters from CHNSpec (CaiPu Technology) features a dedicated sugar-measurement mode. It also supports the determination of optical rotation and concentration, making it suitable for a variety of samples encountered in sugar refineries, food processing quality control departments, and food testing laboratories.

Throughout the sugar production chain—from raw materials like sugarcane and sugar beets to intermediate products such as syrup, and finally to finished white or brown sugar—sugar content analysis is essential. The instrument’s sugar-measurement mode provides results in the International Sugar Scale (°Z), with a range of ±259°Z, aligning with standard testing practices in the sugar industry. Samples taken from the production line can be analyzed rapidly in the laboratory, providing data to guide adjustments to the production process. Because syrups can have high concentrations and some crude syrups are dark in color with poor light transmission, the instrument’s minimum transmittance specification becomes critical; high-end models are capable of handling even these dark, low-transmittance syrup samples.

In the food processing industry, products such as confectionery, candied fruits, sugar-sweetened beverages, and honey require the analysis of sugar-related parameters. In the production of monosodium glutamate (MSG), the optical activity of sodium glutamate allows for the determination of its concentration via polarimetry—a standard industry practice. Some extracts used as food ingredients are dark in color and possess complex matrices, requiring the instrument to have a high sensitivity for detecting weak light signals. For many small and medium-sized food enterprises, where testing is primarily focused on screening and most samples are clear and transparent, entry-level models are sufficient for routine sugar content and optical rotation measurements.

Food samples vary significantly in their physical state: some are clear, transparent solutions, while others—often obtained through extraction—are colored. Furthermore, temperature can affect the solubility of certain samples; a drop in temperature may cause sugar to crystallize, altering the state of the solution. For such temperature-sensitive samples, temperature control is necessary. Mid-range and high-end models equipped with temperature-control modules can maintain a stable temperature during testing, preventing crystallization from interfering with the results. In scenarios involving batch sample testing, quality control (QC) departments in food processing plants often handle multiple batches daily. The instrument completes six replicate measurements in an average of 26 seconds, allowing for the assessment of result stability for a single sample. The system can store up to 1,500 measurement methods, enabling the pre-saving of specific testing parameters for various food samples; these can be instantly retrieved when switching between samples, thereby streamlining operational workflows. A 10.1-inch touchscreen ensures ease of use, allowing frontline QC personnel to become proficient after only brief training.

Regarding data management, small-to-medium-sized food plants typically only require the ability to save and print test reports. The entry-level model meets these daily needs by supporting data export via USB and report printing through a WiFi-connected printer. For large-scale food enterprises that have implemented a digital Laboratory Information Management System (LIMS), all three hardware versions offer seamless LIMS integration. If an enterprise maintains a rigorous data audit and traceability protocol, the mid-range model is the ideal choice, as it includes features such as hierarchical user management and electronic signatures.

During actual testing, food samples often feature complex matrices; some may contain suspended impurities that scatter light and interfere with the optical rotation signal. Consequently, samples must undergo proper preparation—such as filtration to remove suspended particles—to ensure that only a clear, clarified liquid enters the polarimeter tube. Regular zero-point calibration and automated multi-point calibration are essential to ensure the instrument remains in optimal working condition.

In the food and sugar industries, the core requirements for using a polarimeter fall into two categories: the rapid screening of parameters such as sugar content (Brix), and the precise analysis of samples that are dark-colored or temperature-sensitive. Depending on factors such as sample color, the need for temperature control, and specific data management requirements, laboratories can select the appropriate version of the fully automatic, high-speed polarimeter to ensure quality control for both food raw materials and finished products.