Effect of storage on the original pigment profile of spanish virgin olive oil

Abstract

The present study was carried out on 12 virgin olive oils to determine whether one year's storage under mild conditions of 15°C and darkness affected the initial pigment composition of recently extracted virgin olive oil. Although the total pigment content remained constant, the individual contribution of each pigment changed. The acid compounds liberated from the fruits during the oil extraction process promote the beginning of chlorophyll pheophytinization and the isomerization of the 5,6-epoxide groups of the minor xanthophylls. During the first 3 mon of storage, there was a generalized increase in pheophytinization that was different for each oil (P < 0.01, Duncan test) but was not correlated with the free acidity measured in them. At the same time, isomerized xanthophylls and allomerized pheophytins increased slightly. Following this stage, pyropheophytin a (a pigment not present in the initial oils), was detected; its concentration increased during storage. There were no significant differences in the final percentages of pyropheophytin a among the 12 oils, and the concentration of this new compound represented around 3% of the chlorophyll fraction. The pheophytin a/pyropheophytin a ratio always exceeded 20. All these small pigment transformations were signs that the oil had been stored. The content and class of pigments present in virgin olive oil are authentic indicators of its history prior to marketing.

Chlorophylls and Carotenoids in Food Products from Olive Tree

“…Pyphy a PP) content is a highly variable parameter that depends not only on the operating conditions time and temperature) but also on the initial amount of pheophytin a P) in the starting oil. This compound is the precursor pigment for PP and is associated with variety and ripening degree [100]. However, when the PP content is expressed as percentage PPP), with respect to the sum of PP+P, the parameter shows a considerably lower variation margin.…”

“…Moreover, three ratios have been proposed to determine the authenticity and correct processing of Spanish VOOs [28,99]. The genuine pigment proile of the fresh VOO is modiied also during its storage, and it is therefore a good indicator of the suitability of the conditions employed in the preservation of the product [100].…”

“…Lutein is susceptible to esteriication with faty acids on the two hydroxyl groups of its structure this process, however, does not occur in the olive fruit see Section 2.2) despite its high content in faty acids as the fruit has a typical noncarotenogenic metabolism, and lutein and xanthophylls remain unesteriied. Thus, the presence of esteriied lutein in VOO is indicative of the addition of the colorant E-161b.The qualitative pigment proile of genuine VOO is afected by the small degree of degradation of the oil that can take place during its storage, even under appropriate storage conditions in darkness and at a controlled temperature [100,102]. In general, all the degradation reactions that began during the oil extraction progress during its storage the carotenoid pigment fraction is afected by geometric isomerization Z/E isomerizations) 5,6-epoxide is transformed to 5,8-furanoid xanthophylls degradation of pigments gives colorless products.…”

“…In oils stored at controlled temperatures of 15°C, less than 3% of PPP are formed after a year [100], whereas at an average annual temperature of 22°C, the compound can reach values of 7 14% [102]. Therefore, the PPP parameter has been suggested as a chemical marker for monitoring the degradation of VOO [89,100,103].Traditionally, the presence of pyropheophytins in foods of plant origin has been associated with heat treatments of cooking or conservation [104], and in this sense, their presence in VOOs is related with deodorato or deodorized olive oils [105,106]. PP becomes the major chlorophyllic derivative in olive oil that has been thermally treated by deodorization to eliminate organoleptic defects, and its percentage content can reach values of 60% and above.…”

A study of the differences between trade standards inside and outside Europe

“…The high volatility of acetone suggests making the injection in the HPLC instrument as rapid as possible. The alternative is a method (Gallardo-Guerrero et al, 2005) that gives information on individual pigments but it is tedious for the rapid control demanded by the olive oil sector.…”