Bioimpedance Spectroscopy Emerges as a New Tool for Produce Quality Assessment

A recent study published in the journal Foods suggests that bioimpedance spectroscopy (BIS) could offer a reliable, non-invasive way to assess the freshness of fruits and vegetables, potentially transforming quality control practices in the food industry (1). This study, led by Ilona Karpiel at the Krakow Institute of Technology, demonstrates how electrical measurements can track physicochemical changes during ripening and storage without damaging the produce.

Traditionally, assessing the freshness of fruits and vegetables relies on visual inspection, texture analysis, or destructive chemical testing (2). While effective, these approaches can be subjective, time-consuming, or unsuitable for continuous monitoring (2).

In this study, the research team investigated using BIS as an objective alternative, using electrical impedance, its components, and phase angle as indicators of internal structural and compositional changes associated with ripening (1).

What was the experimental procedure?

For their experiment, the research team examined five products—three vegetables (potato, pumpkin, and red pepper) and two fruits (apples and bananas). Over a period of nine days, the researchers conducted spectral measurements across a broad frequency range from 50 Hz to 1 MHz (1). This wide spectrum allowed the researchers to capture subtle changes in tissue properties linked to water content, cell membrane integrity, and overall structure.

What did the results show?

As the ripening of the fruits and vegetables progressed, researchers observed changes in impedance and phase angle. The results saw a consistent decrease in impedance and an increase in the phase angle. These observations were consistent with normal physiochemical process, such as cell wall degradation and moisture redistribution, that occur as fruits and vegetables age (1). Importantly, statistically significant changes were observed for pumpkin and potato, with p-values below 0.05, providing strong evidence that BIS measurements can reliably track freshness in certain produce types (1).

The researchers also found BIS was sensitive to structural characteristics. Thick-skinned vegetables like pumpkin and potato, which are often difficult to evaluate visually, showed clear and measurable electrical changes during ripening. This finding underscores the potential of BIS to detect internal quality shifts that are not apparent from surface appearance alone (1).

What were the limitations of the study?

There were several limitations in this study. First, red pepper was excluded from the final statistical analysis because of structural instability and challenges with electrode placement. This issue points to a broader technical challenge in BIS applications, which is to ensure consistent and reproducible measurements across foods with diverse shapes, sizes, and surface properties (1). The authors noted that electrode configuration and placement play a critical role, particularly when comparing products with different geometries (1).

What do the results of this study mean for future research projects?

The results of this study indicate that a primary focus of future research projects should be on expanding the applicability of BIS across a wider range of produce. One way researchers can help advance this research area is by developing more flexible electrode systems and automated calibration methods (1). The integration of artificial intelligence (AI) and machine learning (ML), which is a burgeoning area in spectroscopy, can potentially help in this area by automating data interpretation and enhancing predictive accuracy.

Improving data interpretation and predictive accuracy remains the two most important aspects that will determine whether BIS and other methods could enable real-time freshness monitoring on automated production lines. The best-case scenario is that with these improvements made, BIS and other methods can be scalable, cost-effective solutions for food quality control.

While the immediate focus is on food quality assessment, the interdisciplinary implications are notable. By bridging food science, bioengineering, and data analytics, BIS has the potential to contribute not only to improved nutrition and reduced food waste, but also to applications in healthcare and public health.

References

1. Kluza, M.; Karpiel, I.; Duch, K.; et al. An Assessment of the Freshness of Fruits and Vegetables Through the Utilization of Bioimpedance Spectroscopy (BIS)—A Preliminary Study. Foods 2025, 14 (6), 947. DOI: 10.3390/foods14060947
2. Song, K.; Yu, D.; Yang, D. Study of Nondestructive Testing of Nanguo Pear Quality Using Vis-NIR Spectroscopy. Spectroscopy 2022, 37 (6), 26–32. DOI: 10.56530/spectroscopy.rc4873o1