Thursday, 16 October 2014 11:56

How do Olives grow?

How do Olives grow?

  • Latin Name:

    Olea europaea

  • Growth:

    USDA Hardiness Zones 9 - 11

    Click here to view the USDA Hardiness Zone Map

    Olive trees are shallow-rooted evergreens with lifespans that extend many hundreds of years. Olive trees are alternate-bearing. The fruit is borne on wood that grew on the tree the previous year.  


    For instance, if the tree bears a heavy load of fruit one year, it lacks the resources to produce much wood (shoot growth) that year, and therefore will produce a light load of fruit in the following year. In lieu of fruit, the tree will produce excess shoot growth during the year of light olive growth and will once again bear a heavy load of fruit the following year. This alternating pattern may be managed through diligent pruning and by taking care to supply the tree with adequate resources when it is supporting a large olive crop.


  • Propagation:

    The two most common ways to propagate olive trees are by seeds and by cutting. Both methods yield a transplantable tree within one year, however, olive trees that are propagated by cutting mature more quickly and bear a closer resemblance to the parent tree in terms of fruit production and growth habit.


  • Harvest:

    Olives are harvested at different stages of ripeness depending on taste desired:   Green-ripe, turning color, and naturally black-ripe. Green-ripe olives, which release a creamy white juice when squeezed, are harvested when they are an even colored shade of yellow-green. If they are allowed to ripen further on the tree, green-ripe olives begin to turn  a reddish-brown color and enter their turning color phase. At the naturally black-ripe phase, when the olives are dark purple or black, they are fully ripe and release a reddish-black liquid when squeezed. Olives reach the naturally black-ripe phase approximately 3 to 4 months after the green-ripe stage.



    Traditional methods of harvesting olives include combing the ripe fruit from the tree and into nets, or by hand-picking the fruits.  Commercial growers use mechanical pickers to harvest their large crops of olives.





  • Storage:

    Green-ripe olives store better than naturally black-ripe olives, which need to be processed within a few days after picking. For best quality, olives are stored in well-ventilated crates at 41 to 50 degrees Fahrenheit. Extended exposure to lower temperatures causes injury to the olives,  such as internal or skin browning.


    Olives are cured by a variety of methods to remove their bitterness. The most common curing processes use water, brine, dry salt or lye treatments to leach the bitter-tasting, water-soluble compound, oleuropein, from the olive flesh.


    To water-cure olives, olives are individually cracked or cut so the oleuropein leaches out more easily, and olives are soaked in water that is changed daily over at least a week (depending on desired bitterness). After the olives are cured, they are placed in finishing brine (a vinegar and salt solution) to flavor. Water-cured olives have a more bitter flavor than olives cured with brine, dry salt or lye, because water-curing removes less oleuropein than the other methods.


  • History:

    Fossilized olaea pollen has been found in Mediterranean regions such as Macedonia, Greece, indicating that the genus is native to the Mediterranean. It is also possible that olives originated in northern Africa and arrived in the Mediterranean basin via trade with Egyptians.


    Throughout civilizations across the world, the olive branch has been used as a symbol of peace, abundance, wisdom, purity, power and glory for thousands of years.


    The olive tree is among the oldest cultivated trees in the world, with a history that pre-dates written language. Ancient evidence of olive tree cultivation has been discovered in Crete, Palestine and Syria, dating back 6,000 years. The first documented commercial cultivation of olive trees dates back to 3,000 BCE, in Crete, where  crops are thought to have been the source of the Minoan civilization’s wealth. In Egypt, olive branches dating back to 1,300 BCE were discovered in the tomb of  the pharaoh, Tutankhamun - King Tut.


    Olive oil was used to anoint the heads of royalty in ancient Greece and was burned in sacred lamps in temples during religious ceremonies. Ancient Greeks also applied olive oil to their hair and skin for good health. During the original Olympic Games, olive oil burned the “eternal flame” and winning athletes were crowned with olive tree branches. References to olive trees are abundant across the canon of Greek mythology, and ancient Athenian coinage bears the image of an olive branch. The ancient Romans also held the olive in high dietary regard.


    Olives were also important in ancient Israeli and Hebrew cuisine and culture, and appear multiple times in the New Testament. In Islamic culture, too, the olive tree is mentioned several times in the Quran as a sacred tree and precious fruit. Olives are consumed in place of dates (when not available) during Ramadan fasting.


    The olive tree arrived in the Americas by way of Spanish colonists who brought seeds to present-day Peru and Chile.  South America’s dry Pacific coast is very similar to the growing conditions in the Mediterranean and the new crop did well there. In the 18th century, the Spanish planted the first olive trees in present-day California. By the 1860s, olive tree cultivation had became a very successful commercial crop there. Most olive trees grown in the United States are still grown in California.


    As of the 21st century, there are an estimated 865+ million olive trees in the world. In 2011, there were 9.6 million hectacres planted with olive trees, making them the most extensively cultivated crop in the world after coconut and palm trees.



  • Top Producers:

    The ten biggest olive-producing countries, according to Food and Agriculture Organization, are all located in the Mediterranean, and account for 95% of the world’s olives.


    Spain, Italy, Greece, Turkey, and Morocco are the top five producers of olives (FOASTAT, 2011).

  • Varieties:


  • Products:

    Products - How are olives used?

    90% of all olives harvested are used to make olive oil, while approximately 10% are used to make table olives (green-ripe, turned, and black or ripe olives that have been cured and fermented). The culinary uses for olive oil and table olives are myriad.

    The olive tree itself is also used for its fine wood and olive leaf.


    How is olive oil made?


    Olive oil is made from pressing whole olives to obtain their fat.


    Traditionally, olives were shaken or beaten from trees, but they are a soft fruit that is easily bruised and needs to be treated delicately. Once bruising occurs, the olive’s benefcial oils immediately begin to degrade, and any damage to the fruit can trigger oxidation and fermentation, which degrades the flavor of the olive oil. Today, most premium olive oil producers ensure that their olives are hand-picked to produce the best quality olive oils.

    Once olives have been picked, cleaned and washed, they are ready to undergo the process of pressing. Traditionally, olive oil was pressed using large stone wheels, but most modern processors are stainless steel rollers. Pressing grinds olives into a paste. Water is then added to the paste through a process called malaxation, which allows the oil molecules to clump together.


    Following malaxation, the mixture is stirred for 20 to 40 minutes. The longer the mixture is stirred, the more time the oil has to absorb flavors from the olive paste. However, longer mixing times allow more oxidation to occur, producing free radicals that degrade the oil quality. Cold-pressed olive oil comes from a modern mixing process that utilizes closed mixing chambers filled with a harmless gas that prevents oxidation, improving the overall quality and yield.

    After being mixed, the paste is sent through a centrifuge that extracts the oil, separating it from the remaining paste. This solid, remaining paste is called the pomace. Some manufacturers use steam, hexane or solvents to extract the remaining, low-quality oil, which is labeled as pomace oil.


    Refined vs. Unrefined Olive Oil:


    Refined olive oil: Refining olive oil is a process that uses solvents and high heat to neutralize the taste of olive oil. This process is used with low-quality olives and olives that have been damaged or oxidized through the mass production process. Due to its chemical neutralization and poor flavor, refined olive oil may be blended from a variety of sources. It is labeled as “pure olive oil” or simply “olive oil” in stores. Approximately 30% of the olive oil on the modern market is refined or combined with refined oil.


    Virgin and Extra-virgin olive oil:  Unrefined olive oil or “virgin” or “extra virgin” olive oil does not undergo chemical refinement. Unrefined olive oil is made from olives that are in good condition and have not had their taste altered by oxidation or other contamination. “Extra virgin” olive oils are the highest quality, maintaining the true flavor of the olive, as well as the highest nutrient content.

  • Top Health Benefits:

    Olives have been lauded for their health benefits since the days of ancient civilizations.  Today, cardiologists suggest that two tablespoons of extra virgin olive oil a day help keep the doctor away. Here’s a look at what one of the world’s oldest cultivated fruits has to offer:

    Olives contain dozens of health-protective phytonutrients, and the many preparation methods to make the bitter fruit palatable actually enhance its anti-inflammatory and antioxidant nutrient levels.

    Hydroxytyrosol is a phytonutrient primarily found in olives that recent medical science has hailed as the “superstar of antioxidants” due to its ORAC (Oxygen Radical Absorbance Capacity) value of 68,576--the highest level ever recorded in natural antioxidants. Its ability to absorb cell-damaging free radicals is 15 times greater than antioxidants found in green tea.


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