Cross‐Batch Contamination in a Continuous Horizontal Decanter Centrifuge during Virgin Olive Oil Production

Abstract

Cross-batch contamination in a decanter centrifuge during virgin olive oil production cannot be avoided using current technology. The extent of this contamination is investigated using industrial-scale tests, by measuring the volatile profile and color on three consecutive oil batches, collected at the decanter outlet at different extraction times. The extent of contamination varied, pointing out qualitative consequences, as defective molecules are found. The latter are often active at low concentrations, and the measured cross-batch contamination can lead both to the downgrading of large batches of virgin olive oils and to the adulteration of monovarietal and certified productions. An innovative method, based on the direct determination of the color (L and a* coordinates) of oil at the outlet of the decanter is able to identify the same compositional change point indicated by gas chromatography, and could be successfully used to mitigate the effects of cross-batch contamination. Practical applications: An in-line colorimetric system can be implemented at the decanter outlet to detect the point of change between different olive batches. Otherwise, the virgin olive oil exiting from the decanter at the beginning of one batch can be collected separately in order to avoid the contamination due to the previous batch.

HS-SPME-GC-MS and Chemometrics for the Quality Control and Clustering of Monovarietal Extra Virgin Olive Oil: A 3-Year Study on Terpenes and Pentene Dimers of Italian Cultivars

“…Although the model might provide overoptimistic results due to the low number of samples for cluster 4 as explained above, this result, obtained with oils from an olive oil production year different from those of the oils used for building the model, was considered satisfactory for two further reasons: (i) the model showed to be reliable also over the olive oil production years and (ii) monovarietal EVOOs may sometimes suffer from the so-called "cross-batch contamination" phenomenon, whereby some degree of mixing during oil extraction from two consecutive batches of olives can occur using the current extraction systems. 49 The latter phenomenon may be particularly important when a batch of monovarietal olives is processed for producing monovarietal EVOOs immediately after processing a batch of olives of a different cultivar (including blends of different cultivars), but the satisfactory results of the model developed suggest that the extent of this phenomenon in the real production scenario is not so high.…”