Manufacture of fermented olives

There are three main styles or types of table olives, based on their method of production (Figure 7-7). Spanish-style (or green Spanish-style) olives are treated with sodium hydroxide (lye) and fermented. Greek-style or naturally-black, ripe-style olives are not treated with lye, but are fermented. The fermentation for both types is mediated by the natural microflora, much like that for other fermented vegetables (discussed below).The third type of olive is the ripe black- or green-style. They are lye-treated, but are not fermented.They may also undergo

Box 7-5. Olives and the Mediterranean Diet

The Mediterranean diet has long been promoted as a model for healthy eating (Willet et al., 1995). This diet takes its name from the foods normally consumed by Greek, Italian, Spanish, and other populations that reside around the Mediterranean Sea. The diet advocates high consumption of fruits and vegetables, grains and pasta, legumes, olive oil, and fish; moderate intake of wine and dairy products; and low intake of meat products. The epidemiological association of this diet with reduced risks of cancer and heart disease and total mortality is highly significant (Keys, 1995 and Trichopoulou et al., 2003).

Perhaps the most prominent foods associated with the Mediterranean diet, and among those thought to be responsible for many of the health benefits, are olives and olive oil. Studies on olive and olive oil components indicate that the phenolic fraction is particularly important (Visioli et al., 2002).As previously noted, phenolic compounds confer bitterness to olives (e.g., oleuropein) and are involved in color development, and some have antimicrobial activity. It now appears that some of these same phenolic compounds also have pharmacological activity and may be responsible, in part, for the health-promoting properties of the Mediterranean diet (D'Angelo et al.,2001).

The main biological activities associated with oleuropein, hydroxytyrosol, tryosal, verbasco-side, and other phenolic compounds found in olives and olive oil are related to their antioxidant properties (Soler-Rivas et al., 2000). They have been found to inhibit low-density lipoprotein (LDL) oxidation and accumulation of oxidized end products. Oxidation of lipoprotein and other lipids is considered to be an important step in initiating coronary heart disease. Other cardioac-tive effects associated with these phenols include anti-arrhythmic and cardioprotective activities. Olive phenols also protect human cells against oxidative stress and injury. In addition, oxidative damage to DNA may be prevented by the free radical scavenging activity of olive phenols.

As noted earlier, most table olives are treated with lye as part of the de-bittering process (the exception being Greek-style, naturally black olives).Although this process hydrolyzes much of the bitter oleuropein, olives still contain appreciable amounts of the hydrolysis products,

Box 7—5. Olives and the Mediterranean Diet (Continued)

elenoic acid glucoside and hydroxytyrosol, as well as other so-called biophenols. One recent study (Romero et al., 2004), for example, reported total polyphenol concentrations of 2.4 to 11.0 mM in juice from Spanish- and Greek-style olives. Some of the Spanish-style olives contained up to 1 g per kg or 0.1%,which is even more than that found in virgin olive oil.The presence of these compounds is now considered so important to human health that researchers in Greece have encouraged the table olive industry to consider modifying processing conditions to increase polyphenol concentrations (Blekas et al., 2002).

References

Blekas, G., C.Vassilakis, C. Harizanis, M.Tsimidou, and D.G. Boskou. 2002. Biophenols in table olives.J.Agric.

Food Chem. 50:3688-3692. D'Angelo, S., C. Manna,V. Migliardi, O. Mazzoni, P. Morrica, G. Capasso, G. Pontoni, I? Galletti, and V. Zappia. 2001. Pharmacokinetics and metabolism of hydroxytyrosol, a natural antioxidant from olive oil. Drug Metab. Dispos. 29:1492-1498. Keys,A. 1995. Mediterranean diet and public health: personal reflections.Am.J.Clin. Nutr. 61:1321S-1323S. Romero, C., M. Brenes, K.Yousfi, P. Garcia,A. Garcia, and A. Garrido. 2004. Effect of cultivar and processing method on the contents of polyphenols in table olives.J.Agri. Food Chem. 52:479-484. Soler-Rivas, C., J.C. Espin, and H.J. Wichers. 2000. Oleuropein and related compounds. J. Sci. Food Agric. 80:1013-1023.

Trichopoulou,A.,T. Costacou, C. Bamia, and D.Trichopoulos. 2003 Adherence to a Mediterranean diet and survival in a Greek population. N.E.J. Med. 348:2599-2608. Visioli, F.,A. Poli, and C. Galli. 2002.Antioxidant and other biological activities of phenols from olives and olive oil. Med. Res. Rev. 22:65-75. Willett, W.C., F. Sacks, A. Trichopoulou, G. Drescher, A. Ferro-Luzzi, E. Helsing, and D. Trichopoulos. 1995. Mediterranean diet pyramid: a cultural model for healthy eating.Am. J. Clin. Nutr. 61 (Suppl. 6): 1402S-1406S.

a special aeration treatment that promotes oxidation of pigments and conversion of a green color to black. This is the type referred to as California-style olives.

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