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    Running Head: OLIVE OIL 1

    Olive Oil: Production, Uses, and Health Benefits

    Cammane Wun, Celia Zhao, Esther Shim, Jaimee Wong, Theresa Dyane

    University of California, Davis

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    Abstract

    The origin of the olive is unknown but speculated to be from the Mediterranean coast. There

    were many different uses for olive oil besides cooking. There are approximately seven hundred

    different varieties of olives. Different varieties of olives will produce a different taste of olive

    oil. There are many factors to monitor when preparing to grow an olive tree. Optimal timing for

    harvesting is important when producing certain types of olive oil. Methods in harvesting can not

    only affect the quality of the fruit but also the cost of production of the oil. Olive oil processing

    has changed very little from its development to present day. There are four main grades of olive

    oil for consumers to choose from. The different grades affect how the oil is used. There are

    specific disposal methods of the oil because it cannot simply be thrown down the drain. Studies

    have shown that olive oil consumption can result in health benefits.

    Keywords: olives, history, harvest, process, grades, health benefits, olive oil

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    History

    The origin of the olive (Olea europaea) is unknown to man. Although many different

    people have there are many different opinions of the specific region of where it came from,

    scientists agree and have a general idea that the olive probably originated along the

    Mediterranean Coast, in what is modern day Turkey, Syria, Lebanon, Palestine, and Israel. The

    olive tree is considered to be one of the oldest trees to be cultivated, existing before the

    development of handwritten language. It was a source of capital and commodity for early

    societies in the Bronze Age (3150-1200 BCE) such as the Minoan civilization (History of the

    Olive, 1998). Additionally, many historical records documented that the olive has existed as far

    back as five thousand to six thousand years ago. It was depicted on written tablets, olive pits,

    and wood fragments in ancient tombs (Vossen, 2007a, 1093).

    There are many archaeological records of how olive oil was used throughout history.

    Before the nineteenth and twentieth centuries, the main use of olive oil was for lamp fuel. Olive

    oil also played a huge role in religious ceremonies, such as baptisms in which olive oil would be

    used as holy oil foranointing people into the church. It was also used to anoint royalty,

    specifically Greek and Jewish kings. Another use for olive oil was used to make soap, which

    was very important in consecrating the dead for many cultures. Also, fragrant olive oils were

    used as a sacrificial offering to the gods in Grecian culture in hopes of gaining favors. Not only

    was olive oil used for anointing and consecration, but it was also used by many Grecian athletes

    after a competition. Olive oil would be rubbed onto the skin of the competitor after a match and

    then scrapped off in order to get rid of the dust and sweat accumulated on the skin. To this very

    day, olive oil is still used for medicinal purposes for skin and hair care. Surprisingly, there is

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    very little record of olive oil for culinary usage during the early development and trade in the

    Mediterranean.

    The trade of olives began in the eastern Mediterranean and archeological excavations

    have shown that it was primarily introduced to the west (e.g., Greece, Egypt, and western

    Turkey). This evidence includes milling stones, decantation basins, storage vessels, frescos and

    ancient writings. More specifically, archaeologists have found ancient clay tables depicting olive

    oil trade in Crete, an early olive oil processing facility in Turkey, and clay vessel ruins used for

    storage and transport of olives found along the western coast (Vossen, 2007a, 1093).

    The increased trade of olives was correlated with the proliferation of vegetation and the

    expansion of wine grapes, date palms, and figs. During those times, olive oil was considered to

    be highly valuable, even more so than wine and other seed oils. Olive oil played a large role in

    the economy as a major product of the market which represented business and wealth. The

    largest growth of olive oil distribution occurred in the late 1700s, as societies began to move

    from rural areas to urbanized cities. Although the spread of olive oil did propagate, innovations

    for alternative sources of lamp fuel, such as gas and electricity, and also the development of

    extraction techniques of different seed oils caused the demand of olive oil to drop in the ninetieth

    and twentieth centuries (Vossen, 2007a, 1093). In the early 1800s, during the time of the

    Industrial Revolution, many innovations caused the use of olive oil for human consumption to

    rise.

    Not only did olive oil play a significant role in the economy of the early world, it was

    also distinguished and determined the social status of people as well. In ancient Greece, olive oil

    was only purchased and consumed (for cooking, lamp fuel, soap, etc.) by the rich, while the poor

    would consume mainly grains and cereals. Olive trees were considered sacred; particularly for

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    OLIVE OIL 5

    the Jewish and the Greeks where cutting an olive tree down would be punishable by death or

    exile (Dorfman, Olive Oil: A History Noble, Healthy and Slippery, 2009). Nowadays, olive oil

    is demanded by all social classes, not for social reasons, but for the health benefits that come

    with consuming it. With the developing advances in the health and food industry, olive oil

    continues to be a valuable commodity as it has been in the past, upholding its nickname as

    liquid gold (Vega, Liquid Gift of God and Earth, 2010).

    Variety of Olives

    There are many different varieties of olives, due to the cultivation and manipulation of

    the olive tree by humans, making it difficult to distinguish which variety originated from which

    species of olive. Olive varieties can be separated in categories by location of origin, strength of

    flavors (mild, medium, or strong), temperature sensitivity (hardy, sensitive, or moderate),

    ripening season (early, medium, or late), and type of fertilization (Vossen, Oil Olive Varieties).

    An important part of choosing an olive variety is the fatty acid composition of the fruit. Fatty

    acids influence the quality of the olive oil, not through actual changes in flavor, but by affecting

    how it feels in the mouth when being tasted as well as the ratio of saturated versus unsaturated

    fatty acids (Vossen, Variety and Maturity). The composition and amount of polyphenols and

    aromatic compounds also differs between the varieties of olives. According to Paul Vossen

    (Oil Olive Varieties), 40% of the quality of olive oil depends on the variety of olive. Quality is

    also affected by maturity (40%), type of processing (15%), and growing conditions (5%).

    Growing

    When growing an olive tree, certain factors are put into consideration: climate, soil, and

    water. Growing the tree is the first step to having olives that can be processed into olive oil.

    Temperature and weather are important because trees can be damaged by infestation or frost

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    even if it is a mature tree. Soil and water also should be ideal because they provide nutrients for

    the trees.

    Prior to planting, the soil of the land should be tested for different chemical compounds,

    such as sodium and magnesium, and its pH. The pH of the soil should range from five to 8.5.

    Ideally, it should be adjusted to a 6.5 but this proves not to be cost effective (Vossen, 2007b, p.

    5). Phosphorous and calcium are generally added to the soil but it is not worthwhile to do so

    since these nutrients are normally in abundance. Nitrogen is almost always added after planting.

    Olive trees are drought tolerant but it requires ideal irrigation during the growing process

    to satisfy to trees needs. Waterquality is important when growing olive trees. Water should

    also be tested for pH, electro conductivity, sodium, bicarbonate, and other chemical compounds.

    An excessive amount of sodium in water will accumulate in the soil which causes penetration

    problems (Vossen, 2007b, p. 6).

    Olive trees are best grown in a subtropical climate. Temperatures too high or too cold

    can injure and damage a tree even if it is a mature tree. Freezing conditions will kill or damage

    the tree while rainfall can cause fungal or bacterial infestation. Growing a tree in a smaller area

    can be colder compared to a more open area (Ferguson, p 27).

    The trees prefer a textured soil that is sandy and clay-like. Such soils provide aeration for

    root growth, are quite permeable, and have a high water holding capacity. Olive trees are

    shallow rooted so it does not require a very deep soil to grow. Also, they tolerate soils of

    varying chemical quality. Trees are produced well on a moderately acidic or basic soil. A soil

    that is too basic or acidic should be avoided because the poor structure of the soil prevents water

    to penetrate and drain which creates a saturated soil that kills roots (Vossen, 2007b, p 5).

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    In order to produce certain types of olive oils, when and how olives are harvested are

    some of the factors that are put into consideration. Harvesting is the final step for olives before it

    gets processed to become olive oil. Therefore, it is important to determine the right time and

    quality to harvest. An olives maturation and timing can make all the difference in yield, shelf

    life, and color of the oil product. Harvesting can be done in many different ways, from hand-

    picking to machinery. The different options can affect the production cost of the olive oil.

    An olives maturation depends on the variety of olive, temperature, and irrigation. A hot

    weather can cause the fruit to ripen quicker which results in a narrow window for optimal

    picking. Cool weather can result in a green olive fruit. Some farmers are forced to pick greener

    olives to avoid frost damage or a storm. Some varieties can ripen faster than others and some

    mature later depending on irrigation. Such idea of timing makes the decision of when to pick

    complicated.

    There are three different maturity stages to olives. After an olive tree has flowered, the

    fruit starts to develop. Initially, the olives are green and hard. Gradually, they will ripen into a

    red-purple color and finally to black. These changes in appearances are due to chemical changes

    within the fruit itself.

    A green and firm olive is considered to be an immature fruit. This type of fruit will yield

    a bitter and grassy type of oil. These oils will be high in polyphenols and other flavor

    compounds. As a result, they are quite bitter and pungent and have a long shelf life due to its

    natural preservatives. The chlorophyll content is high so the oils are often green colored. It is

    more difficult to extract oil from an unripe olive because the oil contains vacuoles that are not

    easy to rupture (Ferguson, p. 161).

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    As the olive matures from green to yellow-green, it starts to soften and changes to a red-

    purple color. This stage is called veraison. The olives are still high in polyphenol content and

    start to develop some ripe fruit characteristics. Oil produced from this type of fruit has some

    bitterness and pungency. They have close to a maximum amount of oil per gram of dry weight.

    These olives are considered to produce the best quality oils (Ferguson, pg. 161).

    As the fruit matures to a black color in both the skin and flesh, the polyphenol and

    chlorophyll content declines and the carotenoid content increases. The oil produced from a later

    harvest tends to be a more golden color, less bitter and pungent, and have a short shelf life

    (Ferguson, p. 161).

    To begin harvesting, the desired oil has to be determined. Harvesting should take place

    when the majority of the fruit in the same area is at the optimal stage for the type of oil needed.

    To help make that decision, University of California researchers have generated a method to

    determine the optimal crop time with The Olive Maturity Index. The Index depends on the color

    of the flesh and skin of the olive. Olives are picked from trees of different heights to fill a large

    container estimating two to three pounds. One hundred olives are picked out at random each

    time. This step is repeated two to three times. An olive is picked from the hundred to represent

    each of the eight maturity levels. The rest of the hundred are then compared to the reference

    olives and sorted accordingly. The number of olives in each group is counted. The Olive

    Maturity Index is the sum of the number of olives in each category multiplied by the score, with

    the sum divided by one hundred (UC Extension, 2006).

    Many aspects are considered when deciding when to harvest. To determine the optimal

    harvesting time, the following should be considered:

    The olives must have the maximum weight of oil

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    The quality of oil must be optimal The fruit and tree damage must be minimal Next years crop must not be affected Cheap cost to harvest

    The moment when the olives have the maximum amount of oil of the highest quality varies

    according to environmental conditions, variety characteristics and amount of fruit per tree. This

    point is reached when there are no longer any green olives in the tree and the majority has

    changed color. Results from the past harvesting seasons show that the outside and inside color

    of the fruit is not a good indicator for optimal harvest time. It is important to point out that once

    the fruit reaches the optimal time for harvesting, the oil quantity remains constant. However, the

    loss of moisture from the fruit falsely indicates a higher amount of oil, whereas there is no

    additional oil that have accumulated in the fruit (O' Brien, 2008).

    There are many methods to harvest olives. Olives can be harvested through hand-picking

    or through machinery. The different options indicate that harvesting costs can make a difference

    in the production cost of the olive oil. Also, weather at the time of harvest is of great

    importance. Experienced farmers know when it is the optimal time before the weather gets too

    cold and wet. It is impossible to pick olives in the wind and rain because of the dangers and

    difficulties of climbing trees with ladders. Also, moisture can cause the olives to spoil in their

    crates before they are taken to the mill for pressing (Piergiorgio).

    With hand-picking, the fruit is handpicked into bags or to nets around trees and then

    collected into a crate. The fruit picked with this method shows little damage and is free from

    other matters such as leaves or soil. The main shortcoming of this method is picking the upper

    part of trees and the cost for manual labor. Hand harvesting can also be complemented with

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    semi automated machines. Using machines can speed up harvest operations but it is easier to

    damage the fruit (O' Brien, 2008).

    Another method is called trunk-shaking. Trunk shakers use vibration from where the

    machine grips the tree to the point of fruit attachment. The shaking energy delivered to the tree

    is a function of length and frequency (Vossen, 2007b, p. 138). The shaker can shake the main

    trunk or each branch separately. The fruit is then unattached and falls onto a net or collecting

    device which is part of the machine.

    Processing

    Olive Oil is produced in the mesocarp cells of the olive and stored in a specific vacuole

    known as the lipo vacuole. Unlike most oils, the separation process is easily attained through

    physical means and does not require the addition of chemical solvents such as hexane (Gunstone,

    2011, p. 243). The process of extracting oil from the olive drupes is typically a four-step process

    that involves cleaning the olives, grinding the olives into a paste, malaxing the paste, and

    separating the oil from the vegetable and solids.

    The first step of the process involves removing all unwanted attributes such as leaves,

    stems, twigs, and other debris that may have been carried in during harvesting. Olives are then

    washed to remove dirt, pesticides, rocks, and any other unwanted materials. However, washing

    is not only a step to insure the organoleptic quality of the oil, it also helps to maintain the quality

    and lifespan of the olive oil extracting equipment, which operate at high speeds (Di Giovacchino

    et al., 2002).

    Afterwards, the washed olives are ground into a paste. In doing so, the flesh cells are

    torn and oil is released from the vacuoles. The three most common machines used in

    commercial plants are stone mills, hammermills, and metal toothed grinders. Stone mills consist

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    of two to four stone wheels that roll in circles on a slab of granite to grind the olives into paste.

    This process enables the release of large oil droplets, lower levels of chlorophyll due to not

    cutting the olive skin, and a lower extraction level of phenols, which results in a less bitter oil.

    However, the equipment is bulky, hard to clean, expensive, and the process is discontinuous.

    Hammermills grind olives using a rotating chamber through centrifugal action. Therefore this

    method is continuous, and increases the throughput. In addition, the equipment is easier to clean

    and can tolerate debris better than the stone mills. A downside to the machine is that it releases

    more phenols during extraction. The least common of the three is the metal toothed grinder.

    Olives are fed to the center of the machine where they are ground by an electrically powered

    metal grinder. The process is continuous and the equipment is less expensive but the grinder is

    the least common due to its disadvantages compared to the other two machines. It can cause an

    emulsion, which would prevent the separation of the oil and water. It also extracts higher levels

    of polyphenols, may heat up the oil paste, and the machine itselfbreaks easily (Equipment

    Explained, 2012). A study by L. Di Giovacchino et al. (2002), indicates that, The different

    crushing methods may influence oil yields obtained with the centrifugation systema higher oil

    yield was obtained when a stone mill was used (p. 589). In addition, the article stated:

    The crushing method also affects the content of the volatile compounds of the

    head-space of virgin olive oiluse of granite millstones to crush olives

    subsequently processed by a three-phases centrifugal decanter helps to obtain oil

    with a higher content of total volatile compounds and of trans-2-hexenal. The

    latter is the most important volatile component of fresh oils giving rise to the

    characteristic aroma of fresh-cut grass (p. 590).

    Now the crushed olives, also known as the paste, need to malax for about 20 to 45

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    minutes to allow flocculation and coalescence of the oil droplets. Malaxers can be horizontal or

    vertical, as well as covered or open troughs with spiral mixing blades. The malaxing time is

    essential for the yield and complexity of the oil. The longer the paste is allowed to rest, the

    greater the yield and the better the flavor. Unfortunately, a longer malaxing time also results in

    more oxidation of the paste, subsequently decreasing the shelf life of the oil and increasing levels

    of peroxide and acidity. Techniques have been invented to help prevent this oxidation while

    maintaining a sufficient olive oil yield. Heat is one practice used to help decrease malaxing time.

    Heating the paste makes the oil present less viscous, making for an easier separation between oil

    and water. Unfortunately, heat also speeds the oxidation and enzymatic browning of the paste,

    which also results in a lower quality product and higher levels of peroxide and acidity. Addition

    of water to facilitate oil extraction also results in a lower quality oil due to an increase in acidity

    and a decrease in the polyphenol content. Closed troughs have the option of using inert gases or

    vacuum chambers in an attempt to reduce oxidation by simply removing oxygen from the system

    (Equipment Explained, 2012). In addition, researchers have begun experimenting with the

    concept of enzymatic aid in the oil extracting process added just prior to the malaxing of the

    paste. Enzyme complexes naturally present in the olives are generally destroyed during the

    milling process. Therefore, exogenous enzymes are added after the crushing step. They are

    highly water-soluble and are removed simply during the next centrifugation step with the

    vegetable water. The complexes used such as Cytolase 0 degrades the walls of the oil-bearing

    cells that elude crushing and also has similar effects on the colloidal components of the olives

    pastethat retain the oil droplets (Ranalli et al., 2001, p.592). Since approximately 24% of the

    oil retained in the olive is partly in the cytoplasm bound to colloids, oil yield is greatly increased

    with no detrimental effects to the final product.

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    The last necessary step in olive oil processing is separating the oil from the vegetable

    water and solids. Within the industry, this step is known as the first press or the cold press

    due to traditional methods that involved screw or lever olive presses (Extraction Process,

    2012). Presses such as the screw, lever, and hydraulic olive press were simple systems that used

    burlap mats or bags spread with olive paste. The burlap was then stacked in vertical columns

    and light pressure was applied from the top. After the first press, hot water was added to help

    facilitate the separation. However, this method was bulky, labor intensive, and resulted in lower

    quality oil. Now, the most common separation process is the three-phase centrifugal decanter,

    which extracts the oil, water, and pomace separately (Equipment Explained, 2012). Currently,

    the greatest disadvantages with the centrifugal system are the by-products and wastewater

    generated from the process known as olive-mill waste (OMW). Olives contain a plethora of

    organic compounds, many of which are beneficial and are present in extra virgin olive oil.

    However, during the production of olives much of the bioactive compounds remain with the

    vegetable solids. These include phenolic compounds, squalene and tocopherols, triterpenes,

    pectins and oligosaccharides, mannitol, and polymerin. Disposal of compounds such as these has

    become a potentially severe pollution problem (Fernandez-Bolanos et al., 2006). For each ton of

    olive oil production about 1560 kg organic pollutants (dry basis) are produced either as sludge

    (2-phase process) or as effluents and sludge (press and 3-phase process). These pollutants are

    toxic due to their phenolic compounds content (Israilides, 2006). Within the article, Israilides et

    al. propose physical, biological, and physicochemical methods of OMW treatment including

    evaporation ponds, anaerobic digestion, membranes technology and wet oxidation as well as

    many others. The main dispute with treatment methods lies in the jurisdiction governmental

    authorities, as most methods do not meet Environmental Quality Standards (Israilides, 2006).

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    Finally the oil is collected in tanks or barrels, where gravity helps with the final

    separation, and any sediment left settles to the bottom. This process is known as racking the oil

    and is the final step with the exception of an optional filtering.

    Uses

    After milling, the oils are separated into different grades. Each grade has its own unique

    use. The first grade, extra virgin olive oil is defined as having a very nice flavor and aroma, with

    its median defects equal to zero and median fruitiness greater than zero (United States

    Standards for Grades, 2010). It also contains a free fatty acid content of no more than 2.0

    grams per hundred grams, which is common in the virgin olive oils. It is usually best when it is

    left uncooked to retain the flavor, such as for salad dressing or dipping bread (Khalil 1999). It is

    also used as a standard for the other grades of olive oils. The next grade, virgin olive oil, has a

    level of defect between zero and 2.5, leading to a relatively good flavor and odor. This oil can be

    used for cooking and baking. This grade is also the best for hair and skin care. When your skin

    or scalp is dry, massaging a small amount of olive oil will increase the moisture and can also

    treat dandruff. The third grade, pure olive oil, is a combination olive oil. It does not contribute

    any taste or aroma so it should be used for large quantity cooking. It also has a smaller fatty acid

    content than the grades above it; it has no more than 1.0 gram of oleic acid per hundred grams.

    Lastly, the lowest US grade is refined olive oil. It is processed in a different way than the other

    grades and has no more than 0.3g per hundred grams of oleic acid. This grade should be used for

    deep-frying or bulk cooking because it lacks the flavor and smell of an olive oil.

    Another factor in determining which cooking oil to use is its smoke point. This is the

    point in which the oil begins to release toxins and carcinogenic smokes and is dependent on the

    breaking of bond between the glycerol and fatty acids (Katragadda 2010). There have been

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    many studies on cooking oils and their smoke point. At high temperatures, the glycerol goes

    through oxidation, forming a molecule called acrolein. Research has shown that you should use

    high smoke point oils, especially when deep-frying. It is also been shown by Caponio,

    Pasqualone, and Gomes (2002), that microwaving the oil versus traditional cooking also leads to

    a faster degradation. This is due to the fact that microwaving sends rapid heat rather than slowly

    heats the food. To test for the degradation of olive oil, a study has shown that fluorescence

    spectroscopy is a promising, rapid, and cost-effective approach (Cheikhousman, 2005). It was

    able to detect for the fatty acid content and vitamin E loss, which was is important to the quality

    and stability of olive oil. When heat was added to olive oil, the levels of both were exponentially

    depleted. However, when it is extra virgin olive oil, according to S. Casal (2010), it can be used

    for frying because of its low acidity level. Casals study showed that a good quality olive oil is

    needed for frying which also applies to frying with vegetable oil. If the oil has a high level of

    acid, it should not be used for frying because they have a lower smoke point and oxidize quickly.

    Also, as said by D. Sun (2011), frying oils cannot be reused because the longer heating time

    results in more fatty acids which lower the smoke point. To increase the smoke point, the oil can

    be refined, which decreases the impurities in the oil, decreasing the rate of oxidation.

    One of the larger factors for consumers to decide to even use olive oil at all is cost. The

    cost of olive oil doubles compared to other oils. The cost of palm oil is $1,020.54 per metric ton

    and the cost of extra virgin olive oil is $2,874.33 per metric ton in January 2012. The cost has

    now rose 1.29% to $2,911.40 per metric ton. Consumers are the ones to blame for the increase

    in prices of olive oil because of the increase in general knowledge that olive oil can be beneficial

    to heart health.

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    When decided to use olive oil, there is also proper ways to dispose of it. Like all other

    oils, it cannot be thrown down the drain. It will solidify in the pipes and cause blockage; even

    hot water and soap will not prevent a buildup. Small amounts of it can be put into the trashcan in

    unrecyclable containers. However, for larger amounts, there is a different method for disposal.

    Restaurants can either bring it to a recycling facility or have it picked up. There are many

    programs that even have drop off storage containers so there is a place to put the used oil before

    being picked up. The oil can then be recycled for different purposes. Recycled oils are in high

    demand due to the possibility of using it as an alternative source of fuel. There has even been a

    truck newly designed for drop off and pick up of new and old oil. There are different

    compartments in the truck that store old and new oil so it can help restaurants eliminate steps in

    obtaining and removing their oil (Schoenbauer, 1999). Because of this new method, there have

    been many news articles written about how thieves are targeting restaurants for their used oil.

    They are able to sell the oil for forty cents a pound on the black market, resulting to thousands of

    dollars lost by the oil disposing companies.

    Nutrition & Health Benefits

    According to the USDAs National Nutrient Database (1999), one tablespoon of olive

    contains 119 kcal. It contains 9.850g of monounsaturated fatty acids and 1.421g of

    polyunsaturated fatty acids. There is a small amount of iron and trace amounts of potassium and

    sodium. There are also a few vitamins, most noticeably vitamin E (alpha-tocopherol) and

    vitamin K (phylloquinone). It does not contain proteins or any of the amino acids that constitute

    proteins. Compared to canola oil (Nutrient data for, 2004) and soybean oil (Nutrient data

    for, 1996), olive oil has slightly less calories, less total fat, but is higher in the amount of

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    monounsaturated fatty acids. However, it contains the smallest amount of polyunsaturated fatty

    acids as well as vitamin K.

    A major factor that causes consumers to choose olive oil over other cooking oils is the

    health benefits that it provides. Bendinelli et al. (2010) conducted a study on Italian women

    which shows that consumption of olive oil greatly reduces the risk of coronary heart disease

    compared to eating a diet filled with fruits. In a hospital based study, higher olive oil

    consumption is correlated to a decrease in the possibility of a first heart attack (Fernndez-Jarne,

    et al., 2002).

    One of the reasons for its health benefits is the high amount of monounsaturated and

    polyunsaturated fatty acids compared to saturated fatty acids. By replacing only 40% of

    saturated fatty acid intake with monounsaturated fatty acids, plasma levels of low density

    lipoprotein (LDL) showed a decrease of 15% (Roche et al., 1998). The function of LDL is the

    transportation of cholesterol from the liver to the tissues (Colpo, 2005). LDL gets a reputation of

    being the bad lipoprotein because the cholesterol that it is transporting can contribute to fatty

    deposits building up on the walls of arteries. LDL levels in blood are widely used to determine

    cardiovascular health and the risk of a myocardial infarction (heart attack).

    In a study done by Pedersen, Baumstark, Marckmann, Gylling and Sandstrom (2000), a

    diet consisting of olive oil was shown to cause a considerably higher concentration of

    cholesterol, very low-density lipoprotein (VLDL), and LDL than a diet consisting of rapeseed oil

    or sunflower oil instead of having lower concentration levels, as expected. However, only male

    participants ages 20-28 years were used so the results may not be a representative for everyone.

    The study was also only carried out for three weeks, which is a relatively short period of time

    compared to how long it takes for cardiovascular disease to show up in individuals.

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    LDL can also undergo a process called oxidation. This results in oxidized LDL, which

    may be a better indicator for cardiovascular disease where a higher level of oxidized LDL

    correlates to a higher risk (Colpo, 2005). Olive oil contains biophenols that were shown to

    reduce the oxidation of LDL in vivo, thus resulting in overall lower levels of oxidized LDL

    (Giovanni et al., 1999).

    High density lipoprotein (HDL) is considered the good lipoprotein because it

    counteracts LDL. The function of HDL is the transportation of used and discarded cholesterol

    from the tissues back to the liver where it can either be recycled or excreted (Colpo, 2005).

    Compared to sunflower oil, olive oil consumption leads to slightly higher levels of HDL

    (Pedersen et al. 2000). In another study, soybean oil was found to lead to a decrease in HDL

    while olive oil helped maintain it (de Bruin, Brouwer, van Linde-Sibenius Trip, Jansen &

    Erkelens, 1993).

    After a consumer has decided to consumer olive oil, they must make a choice of which

    olive oil to purchase. According to a study in Albania, consumers preferred olive oils that were

    higher in price due to the perception that a higher price meant higher quality oil (Chan-

    Halbrendt, Zhllima, Sisior, Imami, & Leonetti, 2010). Consumers in both Albania and Greece

    preferred domestic oils due to the individual countries history in the production of olive oil.

    Expert olive oil tasters rate oils that are bitter and pungent and free of defects (Guinard &

    Delgado, 2011) as high quality. The UC Davis Olive Center found that consumers, on the other

    hand, disliked these high quality oils and preferred oils sensory defects due to oxidative

    rancidity (Guinard & Delgado, 2011). They were also more willing to buy olive oils that had a

    country-of-origin label as well as a health claim label for extra-virgin olive oil (Finardi,

    Giacomini, Menozzi & Mora, 2009).

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