Olive oil has been in use since ancient times. The Ancient Greeks used to call it ‘liquid gold’; it was an essential part of their diet, athletes would rub it on their bodies, and winners of the Olympic Games would be crowned with the olive tree’s leafy branches as a sign of glory.
A Mediterranean diet, where olive oil of good quality is the main source of fat, has been associated with the prevention of chronic disease. Virgin olive oil consumption can possibly exert positive outcomes in the prevention of several pathologies like cancer, cardiovascular disease and aging by inhibiting oxidative stress. These beneficial properties are mainly attributed to its composition, a high percentage of monounsaturated acids (oleic acid) and significant amounts of minor components with strong antioxidant activity postulated to be responsible for its antithrombotic, anti-inflammatory, anticarcinogenic properties.
Phenolic compounds, α-tocopherol, triterpenes, squalene, sterols and oleocanthal are some of the most important components of olive oil. It may also help relieve itching, stings and bites, burns, ulcers, gastritis and activates the secretion of bile and pancreatic hormones that consequently lowers the incidence of gallstones.
Climate, soil, variety of trees, time of harvest and production method account for the different organoleptic characteristics and the quality and quantity of nutritious elements in olive oil. Cold press and first press of the olives, which means that olives are only once pressed without the use of heat, result in a more nutritious product. Unfortunately those methods are very rare in massive production nowadays. Early harvest olive oil, meaning that olives are harvested while not fully ripened, gives higher polyphenol and antioxidant levels in the produced oil and subsequently a longer shelf life and higher nutritional value. Hand picked olives may indicate that the oil is of better quality because olives are not over-ripened and not torn, which can cause oxidation.
Virgin olive oil is characterised by a higher oxidative stability compared to other edible oils due to the high ratio of monounsaturated/polyunsaturated fatty acids. Raw consumption is preferable but even when heated, not all beneficial compounds are destroyed. Virgin olive oil subjected to heating operation at 180ºC, simulating the ‘frying process’, retained most of its nutritional components such as phytosterols, triterpenes and squalene at levels with nutritional significance.
Additionally, olives can be used to their cores. After the initial oil extraction, they are used to make natural soaps and soap flakes that can be used as natural moisturizing soaps or as an alternative to conventional chemical detergents. According to recent experimentation, it is also possible that olive cores can be used to produce energy, which might be more environmentally friendly and cheaper than widely used fossil energy.
Classification of olive oil
The International olive oil council (IOOC) classifies olive oil as:
* Extra virgin olive oil which comes from the first pressing of the olives, contains no more than 0.8% acidity, and is judged to have a superior taste. There can be no refined oil in it.
* Virgin olive oil has acidity less than 2% and judged to have a good taste. There can be no refined oil in it.
* Refined olive oil is usually virgin olive oil that has been refined.
* Olive oil is a blend of virgin oil and refined oil, containing no more than 1.5% acidity. It commonly lacks a strong flavour.
* Olive-pomace is a blend of refined pomace olive oil and possibly some virgin oil.
* Lampante is not used for consumption but in the industrial market.
It should be stated here that the United States is not a member of IOOC and does not legally recognise its classifications.
Related references:
Escrich E, Ramirez-Tortosa M. C, Sánchez-Rovira P, Colomer R, Solanas M, Gaforio J. J. (2006) Olive oil in cancer prevention and progression. Nutr. ReV. 64, 40-52.
Allouche Y, Jimenez A, Gaforio JJ, Uceda M, Beltran G. (2007) How Heating Affects Extra Virgin Olive Oil Quality Indexes and Chemical Composition. J Agric Food Chem.
About the author Eirini Manthou is a researcher in the area of Exercise and Nutrition in Glasgow University- Scotland. www.freewebs.com/eirinimanthou
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