Lecture 2: Qualitative characteristics of olive oil Part II

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C. Olive oil Quality1. Olive oil composition and
quality

• 2. Quality characteristics of olive oil
• Part II

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The major fatty acids in olive oil(part I)

• Oleic Acid (C181), a monounsaturated omega-9
  fatty acid. It makes up 55 to 83 of olive oil
• Linoleic Acid (C182) , a polyunsaturated omega-6
  fatty acid that makes up about 3.5 to 21 of
  olive oil
• Palmitic Acid (C160) , a saturated fatty acid
  that makes up 7.5 to 20 of olive oil

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Oleic and other acids in olive oil (part I)

• Olive oil contains more oleic acid and less
  linoleic and linolenic acids than other vegetable
  oils

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Oleic and other acids in olive oil (part II)

• olive oil is more resistant to oxidation because
  the greater the number of double bonds in the
  fatty acid, the more unstable and easily broken
  down by heat, light, and other factors
• cooler regions (e.g. Tuscany) will yield oil with
  higher oleic acid than warmer climates

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Trans Fatty Acids

• olive oil has no trans fatty acids
• olive oil is not a trans fatty acid because it
  has not been partially hydrogenated in a factory
  to make it solid at room temperature like
  margarine has

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Percentage of Linolenic Acid allowed in Olive Oil

• with regards to polyunsaturated fatty acids
  (PUFAs), there is a wide range acceptable for
  extra virgin olive oil, however the linolenic
  acid has to be less than 0.9 per the
  International Olive Oil Council (IOOC) guidelines
• the IOOC uses the linolenic acid level to
  establish the authenticity of the olive oil

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FREE FATTY ACIDS (FFA) AND ACIDITY (part I)

• The "acidity" in olive oil is the result of the
  degree of breakdown of the triacylglycerols, due
  to a chemical reaction called hydrolysis or
  lipolysis, in which free fatty acids are formed

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FREE FATTY ACIDS (FFA) AND ACIDITY (part II)

• Factors which lead to a high free fatty acidity
  in an oil include fruit fly infestation, delays
  between harvesting and extraction (especially if
  the fruit has been bruised or damaged during
  harvesting), fungal diseases in the fruit
  (gloesporium, macrophoma, etc.), prolonged
  contact between oil and vegetation water (after
  extraction), and careless extraction methods

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FREE FATTY ACIDS (FFA) AND ACIDITY (part III)

• Storing olives in heaps or silos to encourage
  enzymatic breakdown of cell structure, and thus
  facilitate oil release is certainly not
  conducive to producing a high quality, low
  acidity oil

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Composition of fatty acids in olive oil and
effectors (part I)

• major oil fatty acids unsaturated
• oleic acid (C18 1, monounsaturated)
• saturates palmitic (C16 0), stearic (C18 0)

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Composition of fatty acids in olive oil and
effectors (part I)

• olive varietal
• soil and weather conditions
• ripening grade of olives

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Summary of 2nd Lecture

• Oleic acid
• Trans fatty acids
• Free fatty acids and acidity