Effect of Olive Fruits Storage in Sea Water on Oil Quality
Olivera Koprivnjak*1, G. Procida2, Đ. Benčić3 and T. Zelinotti4
1Institute of Agriculture and Tourism, C. Hugues 8, HR-52440 Poreč, Croatia.
2Dipartimento di Economia e Merceologia delle Risorse Naturali e della Produzione, via Valerio 6, I-34127 Trieste, Italy.
3Faculty of Agriculture, Department of Pomology, Svetošimunska 25, HR-10000 Zagreb, Croatia.
4Dipartimento Dogane – Direzione Centrale A.M.L.C., via M. Carucci 71, I-00143 Roma, Italy.
Article history:
Received January 28, 1999
Accepted June 14, 1999
Key words:
olive fruits storage, sea water, virgin olive oil, quality
Summary:
Lengthy and/or unsuitable storage of olive fruits can significantly decrease the quality of virgin olive oil. Dipping in sea water is a traditional and still very frequent method of preserving olives in Croatia. Changes in standard olive oil quality indicators during storage of olive fruits (cultivar »Bjelica«) have been studied in comparison with storing in brine (4 % solution of natrium chloride), drinking water and in wooden boxes in the open air. The samples of oil were obtained by processing olives in the pilot plant composed of a hammer crusher and a press with steel nets. During the 30 days of storage in aqueous media, there was a slight increase in the content of free fatty acids, while in the samples stored in the open air, the increase was significantly higher. The peroxide values and absorbance coefficient at 232 nm were decreasing during storage in aqueous media while absorbance coefficient at 270 nm remained constant. With dipping olives in brine and sea water the desired fragrant characteristics of oil disappeared after 10 days, while in samples exposed to the air they were noticeable even after 30 days of storage. For oils obtained from olives kept in brine and sea water undesired taste and smell of brine were characteristic. Overall quality index decreased in all of the studied methods of storage and no significant differences have been observed between them. The most evident difference between storage methods was exerted trought the fraction of total chlorophylls. In aqueous media it increased by about 8 times, while in the open air it decreased by about 1.5 times in regard to reference sample. The results lead to the conclusion that storing olives in aqueous media does not change significantly basic physicochemical quality indicators but reduces oil quality primarily due to undesired changes of sensory characteristics.
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