Influence of Picual Olive Ripening on Virgin Olive Oil Alteration and Stability during Potato Frying

Abstract

Ripening modifies oil attributes and composition. However, the influence of olive ripening on virgin olive oil (VOO) thermal oxidative stability on food-frying has not been studied yet. Oils from Picual olives of low (VOO1), medium (VOO2), and high (VOO3) ripeness were obtained, and their thermal oxidative stability during 40 potato-fryings was tested. Unused VOO1 showed higher antioxidant content and oxidative stability than VOO2 and VOO3. Polar compounds (PC), oligomers, and altered fatty acid methyl esters (polar-FAME) increased, whereas linoleic acid, polyphenols, and tocopherols decreased in the three VOOs through frying. The alteration was lower in VOO1, followed by VOO2 (0.105, 0.117, and 0.042 g/100 g oil less of PC, oligomers and polar-FAME per frying, respectively, in VOO1 than in VOO3). In conclusion, VOO obtained from low-ripeness Picual olives should be preferred when frying fresh-potatoes due to its higher thermal and oxidative stability, permitting a higher number of potato-frying uses.

Frying performance of two virgin oils from <em>Cornicabra</em> olives with different ripeness indices

“…These values were relatively lower compared to those reported for other olive varieties, e.g. Picual, harvested at the same season period (Olivero-David et al, 2014).…”

“…The fatty acid composition covered the expected normal range for Cornicabra virgin oils, i.e. high levels of oleic acid and low levels of linoleic and stearic acids (Salvador et al, 2001a;b). This differs from VOOs obtained from other varieties (Olivero-David et al, 2014;Sánchez-Casas et al, 2003).…”

“…low, medium and high, the oil obtained from olives with low index was significantly more stable in the discontinuous frying of potatoes (Olivero-David et al, 2014). This did not differ substantially in the fatty acid composition, but presented higher amounts of total polyphenols and tocopherols, which gave rise to a higher oxidative stability as measured by the Rancimat test.…”

“…The absolute amount of individual FAME was calculated by multiplying the percentage area of each fatty acid methyl ester by the amount of the unaltered FAME fraction expressed as parts per unit giving equivalent results to those obtained using an internal standard (Olivero-David et al, 2014).…”

“…Cornicabra and Picual are known to be two Spanish olive varieties whose virgin oils normally present elevated stability to oxidative degradation (Salvador et al, 2001a). As it seems to be for Picual virgin oils, it would be of great industrial interest to get to know whether the oils of Cornicabra variety also present better frying performance when they come from olives with low ripeness indices (Olivero-David et al, 2014).…”