Effect of cold storage and controlled atmosphere on fruit and oil quality of ‘Paranzana’ olives

Objective of the work was to verify the effect of cold storage and controlled atmosphere on long term storage of olives in relation to quality of the fruit and of the extracted oil. ‘Peranzana’ olives with about 50% of the skin turned black, were stored in air at ambient temperature (approximately 15 to 20 °C), air at 5 °C, and 3% O2 in nitrogen at 5 °C, in two replicates for treatment. Initially, and after 7, 17, 25 and 31 days samples were taken, and oil extracted with a laboratory scale milling plant. Before milling, respiration rate, firmness, color, and weight loss, were determined on drupes from every replicate. On oil samples the following quality attributes were measured: acidity, peroxide value, coefficients of specific extinction at 232 and 270 nm, oil stability (Rancimat test), and total phenolics. Olive quality was strongly affected by temperature; olives stored in air at room temperature showed an higher metabolic activity as indicated by respiration rate, percentage of color development, higher weight loss and lower firmness, than olives stored at 5 °C (both in air and low oxygen). In addition olives stored at room temperature were affected by decay, starting from 17 days of storage, while no decay was observed during the whole duration of the storage at 5 °C. Temperature also affected olive oil quality, while little differences were observed between air and low oxygen conditions at 5 °C. Acidity, peroxide value and specific extinction coefficients in the oil obtained from olives stored in air at room temperature, were significantly higher than in the oil obtained from olives stored at 5 °C (both in air and low oxygen). Results showed a good potential of refrigeration for application in the olive oil industry, in order to preserve quality of the product and to lengthen the processing season. Keywords. Olea europea L., olive oil