Shelf-life evaluation of pasteurised Nocellara del Belice table olives produced by the Castelvetrano method

Introduction

Table olives produced with the Castelvetrano method undergo limited fermentation and only partial acidification, which may affect stability during storage. Green Nocellara del Belice olives are treated with dilute NaOH and salt, without extensive washing, then refrigerated in brine for at least 14 days to achieve rapid debittering while preserving their bright green colour and mild flavour. Before packaging, the brine is acidified and the product pasteurised. Under these conditions, shelf-life cannot be defined solely in microbiological terms but must also account for changes in product quality.

Methods       

Pasteurised Nocellara del Belice table olives (60–63 PU), whole or pitted, were packaged in five commercial formats — tin cans and four glass jars (314, 327, 580 and 1062 mL) — and stored at 25 °C or 45 °C for up to 180 days, with all analyses performed in triplicate. Microbiological analyses were conducted alongside measurements of pH, water activity, salinity and free acidity. Colour was assessed via CIELAB parameters and total colour difference (ΔE), and sensory properties were evaluated by a trained panel. Multivariate analysis (PCA and hierarchical clustering) was performed to explore relationships among variables.

Results and Discussion

No microbial growth was detected during storage, confirming the effectiveness of pasteurisation, although clear changes occurred in physicochemical and sensory attributes, especially at 45 °C. Crispness and flavour balance declined progressively, while colour changes were less pronounced but still temperature-dependent. Pitted olives lost quality faster than whole olives, indicating greater structural susceptibility. Multivariate analysis confirmed temperature as the primary driver of product evolution, with olive format playing a secondary role and packaging having comparatively little influence.

Conclusions

The shelf-life of pasteurised Castelvetrano table olives is thus driven primarily by quality degradation rather than microbiological instability, with temperature and product format as key factors in preserving product quality during storage.