A recent study published in the journal Sensors explores the use of electrochemical sensors for real-time food analysis, offering a fast and reliable method adaptable to food production environments.
Study: On-Line Monitoring of Vitamin C in Fruit Juice in Processing Plants by Electrochemical Sensor Based on PEDOT-Modified Electrodes: A Feasibility Study. Image Credit: Tatjana Baibakova/Shutterstock.com
Background
Vitamin C is a crucial water-soluble vitamin known for its antioxidant properties and role in essential biochemical processes like collagen synthesis and neurotransmitter production. It is found abundantly in fruits, especially citrus varieties, but its degradation during food processing poses a challenge to maintaining quality and nutritional value.
Conventional methods for detecting ascorbic acid in juices highlight its sensitivity to heat, pH changes, and oxidation, underscoring the need for improved processing techniques to preserve this vital nutrient.
While various approaches have been explored to enhance Vitamin C retention, many rely on expensive laboratory procedures that are not practical for large-scale food production.
This study introduces a voltammetric sensor based on poly(3,4-ethylenedioxythiophene) (PEDOT) modified with gold nanoparticles (GNP) to enable direct, on-line monitoring of Vitamin C in fruit juices. By addressing the limitations of existing food analysis techniques, this sensor offers a practical solution for real-time quality control during processing.
The Study
For this study, the researchers developed a voltammetric sensor using screen-printed carbon electrodes (SPCEs), which were modified through electrodeposition of gold nanoparticles, followed by PEDOT electropolymerization. This design enhances sensitivity and selectivity while remaining cost-effective and scalable for commercial use. The sensor underwent rigorous testing to evaluate repeatability, detection limits, and recovery rates.
To assess its performance, the sensor was tested across various concentrations of ascorbic acid, with a focus on minimizing interference from common fruit juice components like citric acid. Selectivity was measured by comparing the sensor's response to ascorbic acid in the presence of varying citric acid levels. Additionally, the sensor's stability was examined by storing it under ambient conditions to determine its effective shelf life.
A factorial design was also used to analyze the impact of heat treatment on ascorbic acid levels, helping researchers understand how different temperatures and exposure times affect Vitamin C degradation. These insights provide valuable data on the sensor's real-world application in food processing environments.
Results and Discussion
The electrochemical sensor demonstrated strong performance in terms of repeatability, with intra-sensor relative standard deviation (RSD) values below 5 % and inter-sensor RSD values below 10 % in standard solutions. The detection limit was determined to be 0.7 mg/L, with a quantification limit of 2.1 mg/L. When tested on commercial orange juice samples, the sensor achieved a recovery rate of 94 ± 1 %, reinforcing its reliability in practical applications.
Selectivity tests confirmed that citric acid—an expected interferent—did not affect ascorbic acid measurements, ensuring the sensor’s robustness in complex food matrices. Stability tests indicated that the sensor remained effective for at least two months under ambient storage conditions.
Investigating the effects of heat treatment on Vitamin C levels revealed notable degradation at higher temperatures and extended exposure times. Specifically, at 90 °C for 45 minutes, a sharp decline in ascorbic acid concentration was observed, demonstrating the sensor’s ability to track nutritional changes during thermal processing. These findings highlight its potential as a valuable tool for real-time monitoring, enabling adjustments to food processing conditions that help preserve nutrient content.
Conclusion
This research presents a novel electrochemical sensor for on-line Vitamin C monitoring in fruit juices, offering a practical alternative to traditional food analysis methods. The sensor meets key industry requirements for real-time monitoring, demonstrating excellent sensitivity, selectivity, and stability.
By closing the gap in current food analysis techniques, this innovation can support the food industry in preserving essential nutrients during processing. Integrating such advanced monitoring tools into production environments can lead to improved quality control and product integrity, ultimately benefiting both consumers and manufacturers.
The successful adoption of this technology could enhance decision-making in food production, ensuring better nutrient retention and higher-quality products on the market.
Journal Reference
Giliberti C., Malavasi M., et al. (2025). On-Line Monitoring of Vitamin C in Fruit Juice in Processing Plants by Electrochemical Sensor Based on PEDOT-Modified Electrodes: A Feasibility Study. Sensors 25(5):1385. DOI: 10.3390/s25051385, https://www.mdpi.com/1424-8220/25/5/1385