Seasonal dynamics of oil accumulation and fatty acid composition in olive varieties in northwestern Argentina.

RONDANINI, D. P.; CASTRO, D. N.; SEARLES, P.S; ROUSSEAUX, M. C.

Simposio; VIIth International Symposium on Olive Growing; 2012

In warm valley of NW Argentina, oil content at harvest in some varieties is low and fatty acid composition frequently is not within the standard ranges indicated by the IOOC. The most common defects are low oleic, high palmitic, and high linoleic acid contents. In order the understand the factors involved, we analyzed oil accumulation and its fatty acid composition for six olive varieties growing in the three main production valleys of La Rioja, NW Argentina. These valleys are Capital (400 masl), Aimogasta (800 masl) and Chilecito (900 masl). A bi-linear model was fitted to each variety for both oil accumulation and oleic content as a function of thermal time. Differences in duration and rate of oil accumulation were observed between varieties and locations. However, final oil content was better explained by accumulation rate than duration. Moreover, oil accumulation rate showed a modest negative linear relationship with average maximum daily temperature. Four contrasting patterns of oleic acid dynamics during ripening were observed: (1) a brief plateau followed by an early, sharp linear decrease (Arauco and Arbequina); (2) a long plateau followed by a late linear decrease of moderate slope (Barnea and Manzanilla); (3) a brief plateau followed by a slow linear decrease (Frantoio); and (4) no decrease (Coratina). Three novel contrasting patterns of increase (Arbequina and Arauco), slight decrease (Barnea, Manzanilla and Frantoio) and strong reduction (Coratina) of palmitic acid have been also identified. Average minimum daily temperature during the oil synthesis period (ranging 16-21ºC) was negatively related to final oleic acid content. These findings provide a physiological description of how low oil content and fatty acid composition are reached in olive oils of different varieties growing in NW Argentina.