Lipids and phenols in table olives

The olive fruit is essentially constituted by the epicarp, or skin, mesocarp, or pulp, and the endocarp, or stone, and the latter includes the seed. Table olives (also called eating olives) are prepared from healthy, specifically cultivated, olive varieties picked at the right maturation stage and whose quality, after appropriate processing, corresponds to that of an edible well preserved product. The most important industrial preparations of table olives are the Spanish (or Sevillian) for green olives, the Californian for oxidised black olives, and the Greek for naturally black olives. In the Spanish and Californian procedures, olives are treated with a diluted aqueous NaOH solution, that brings about several changes in the susceptible classes of compounds in the fruit. Note, however, that the composition of the triglycerides remain unaffected by these procedures. After the treatment the olives are rinsed to remove the alkali, and the fruit is then left to ferment in brine for several months. The production of naturally black olives in brine, according to the Greek traditional method, is a simple, natural process which does not use chemicals. The main phenols in the olive are oleuropein, hydroxytyrosol (β(3-4-dihydroxyphenyl)ethanol), tyrosol (β(4-hydroxyphenyl) ethanol) and verbascoside; the major polycyclic triterpenes are the oleanolic and maslinic acids. The NaOH treatment hydrolysed oleuropein into β(3-4-dihydroxyphenyl) ethanol, oleoside 11-methylester and oleoside. These last glucosides and the oleuropein itself, in acidic medium, yielded glucose and a number of compounds called, collectively, oleuropein aglycones. During the fermentation process phenols diffuse from the pulp into the brine. Also, even during the alkaline treatment, there is the rapid diffusion of the pentacyclic oleanolic and maslinic acids salts into the brine.