Quality Control of Extra Virgin Olive Oil Using CDR OxiTester Systems: The Valdelsa 2025 Case Study

The 2025 olive oil harvest in Tuscany provides an interesting case study for understanding how agronomic variability, climatic conditions, and process control can directly influence the chemical and sensory profile of extra virgin olive oil.

An in-depth study published by Olivo e Olio analyzed the 2025 production of a small olive-growing operation in the Valdelsa region of Tuscany. The study took into account agronomic observations, harvesting practices, extraction technology, chemical analyses, and sensory evaluations, with the aim of describing the final quality of the oil produced during a hot and complex season.

The study utilized the CDR MiniFood Olive rapid analysis system for olive oil quality control, a compact analyzer used for testing both at the mill and in the laboratory.

This instrument is now discontinued and has been replaced by the CDR OxiTester Jr, a more technologically advanced analysis system capable of determining acidity, peroxides, and polyphenols.

This case highlights a fundamental point for mills and producers: when the quality of extra virgin olive oil depends on rapid decisions, analytical testing must be conducted close to the production process.

The olive grove described in the study is located in the Valdelsa area, in the heart of Tuscany. It comprises about 200 trees and features a multi-varietal structure typical of traditional Tuscan olive cultivation.

The main cultivars are Frantoio, Leccino, and Moraiolo, which together account for about 85% of the grove. These are complemented by lesser-known local cultivars, such as Rossellino, Maremmano, Leccio del Corno, Pendolino, and Morcaio.

This varietal diversity contributes to the olive grove’s resilience and the complexity of the final oil. At the same time, it introduces natural variability in ripening times, phenolic content, and sensory profile.

The 2025 season was particularly challenging. High temperatures, drought conditions, and a significant infestation of the olive fruit fly, Bactrocera oleae, required careful agronomic management. The producer adopted integrated pest management practices, including regular monitoring and the use of attractant traps, with the goal of limiting damage and reducing the need for insecticide treatments.

The olives were harvested primarily by hand, with mechanical assistance limited to the highest parts of the canopy. This approach helped preserve the integrity of the drupes and allowed for a more selective harvest.

After harvesting, the olives were taken to the mill, where they were washed, destemmed, and processed quickly. According to the study, pressing took place within 72 hours of harvesting, a critical factor in limiting fermentation and preserving the oil’s quality.

The extraction process included hammer crushing, controlled kneading, and centrifugal separation. The kneading temperature was maintained below 27 °C, in line with cold-pressing criteria. The extraction system was also designed to limit exposure to oxygen and promote the preservation of volatile and phenolic compounds.

These process choices were reflected in the analytical data, particularly in the low and stable acidity values.

The study used two complementary analytical approaches.

The first sample, from olives pressed on October 28, 2025, was analyzed directly at the mill using the CDR MiniFood Olive. This immediate analysis provided a real-time indication of the oil’s quality right after extraction.

Two other samples, taken on November 4 and November 10, 2025, were subsequently analyzed at the CDR laboratory using the CDR OxiTester. This allowed for a more controlled evaluation of the oil and the determination of polyphenols, an important parameter for interpreting the product’s antioxidant potential and sensory profile.

The analytical parameters considered in the study were:

Acidity (FFA), expressed as a percentage of oleic acid

Peroxide value, expressed in meq_O₂/kg

Polyphenols, expressed in mg/kg

The results showed a consistent quality profile.

To contextualize these results within the broader framework of the 2025 olive oil season, the CDR “Francesco Bonicolini” Chemical Laboratory collected and analyzed various samples of Tuscan olive oil, evaluating parameters such as acidity, peroxide value, and biophenols. This in-depth analysis allows for a comparison of the data from the Valdelsa case study with the overall trends of the season and with the main agronomic and production challenges recorded in Tuscany. [Read the article ...]

Acidity levels were very consistent across all samples, remaining around 0.30%. This indicates good olive integrity, proper post-harvest handling, and the absence of significant fermentation prior to milling.

The peroxide values were also consistent with a well-managed extra virgin olive oil. Sample A showed the lowest value, consistent with the analysis performed immediately after extraction. Samples B and C showed slightly higher values, likely due to the time elapsed between extraction and laboratory analysis, the natural progression of primary oxidation, and the varying stages of olive ripeness.

The polyphenol content, ranging from 269 to 317 mg/kg, was described as average for a Tuscan extra virgin olive oil. This result appears consistent with the climatic conditions of the 2025 season, which was hotter and drier than the previous year. The more advanced stage of ripeness of the Frantoio cultivar olives may also have contributed to a lower phenolic profile compared to more favorable vintages.

From a sensory perspective, the oil was described as clean, balanced, and mature, with medium-intensity bitterness and pungency. These observations are consistent with the analytical data, although this is a qualitative assessment and not an official panel test.

This case study demonstrates how chemical analysis can help producers understand the effects of climate, agronomic management, and the extraction process on the final quality of extra virgin olive oil.

In a challenging growing season, analytical data provide objective information to support production decisions and quality classification.Acidity helps assess the integrity of the olives and the conditions under which the raw material was handled. The peroxide value provides indications of primary oxidation. Polyphenols help assess the oil’s antioxidant potential, its likely stability over time, and its sensory profile.

The study also confirms the importance of conducting analyses on the production line. Immediate testing at the mill allows for quality verification during or immediately after extraction, while laboratory analysis enables a more comprehensive evaluation of different batches and production dates.

The case study on the 2025 harvest in Valdelsa demonstrates how rapid chemical analysis can provide a more precise understanding of the quality of extra virgin olive oil, especially during seasons characterized by climatic stress and pest pressure.

Despite the challenges of the 2025 harvest season, the oils analyzed showed low acidity, moderate peroxide values, and a phenolic profile consistent with seasonal trends. These results confirm the value of an integrated approach that combines careful agronomic management, controlled extraction, and analytical monitoring.

For mills and producers, this type of monitoring can transform chemical analysis from a simple final check into an active tool for process and quality management.

In the conclusions of the article published in *Olio e Olivo*, the author, Riccardo Meucci of the National Institute of Optics of the CNR in Florence, thanks Gabriele Casini of CDR S.r.l. for the support provided in conducting the analyses using CDR OxiTester instrumentation and for verifying the reliability of the measurements.

This acknowledgment confirms the importance of technical and application support in the proper execution of analyses, especially when chemical data are used to interpret oil quality in relation to agronomic, technological, and seasonal factors.

To learn more about the production context, the conditions of the 2025 growing season, and the quality results described in the study, please refer to the full article published in *Olivo e Olio*.