Chemistry Of Olive Oil
Chemical analysis is the only certain fact that shows the quality of the extra virgin olive oil you buy. There are few important things you need to know about olive oil, take a moment and read below.
Free Fatty Acids (FFA)
- Determination - Free Fatty Acids are formed due to breakdown of the triacylglycerols in oils during extraction. Fatty acids are "free" when the are no longer bound to any other molecules.
- Indicators - An elevated level of FFA can indicate poor quality or mishandled fruit, too much time between harvesting and extraction, poor storage and/or high temperature during extraction.
Units: % as oleic acid - IOC limit ≤ 0.8
- Determination - The major fatty acid in olive oil triacylglycerols is Oleic acid making up 55 to 85% of olive oil
- Indicators - The higher the oleic acid monounsaturated fat content translates to increased durability and shelf-life.
Units: % as oleic acid - IOC limit ≥55
- Determination - Peroxides are primary oxidation products that are formed when oils are exposed to oxygen causing defective flavors and odors
- Indicators - Primary measurement of rancidity in oil. Higher peroxide levels indicate oxidized and/or poor quality oil & give an idea of the freshness & storage conditions.
Units: mEQ O2/kg oil - IOC limit≤20
- Determination - UV spectrophotometric determination Secondary measurement of rancidity in oil. Elevated levels of UV absorption indicate oxidized and/or poor quality oil, possible refining and/or adulteration with refined oil.
- Indicators - Secondary measurement of rancidity in oil. Elevated levels of UV absorption indicate oxidized and/or poor quality oil, possible refining and/or adulteration with refined oil.
Units: K1%/1cm - IOC limits K232 ≤2.5, K270≤0.22, DeltaK≤0.01
- Determination - Phenols are healthful anti-oxidant substances in olive oil which aid in slowing down the natural oxidative processes.
- Indicators - Phenolic content decreases over time and is an indicator of freshness, with higher amounts improving shelf-life and oxidative stability.
Units: ppm - OC limits N/A
- Determination - Fresh olive oil has a much higher proportion of 1,2-diacylglycerols to Total diacylglycerols while olive oil extracted from poor quality fruits and refined oils have a higher level of 1,3-diacylglycerols
- Indicators - The ratio of 1,2-diacylglycerols to the Total diacylglycerols are a useful indicator of fruit quality and acts as a snapshot of olive oil freshness. Low values can also indicate oxidized oil & sensory defects.
Units: %Total 1,2-diacylglycerols - AOA limit≥35
- Determination - Upon thermal degradation of olive oil, chlorophyll pigments break down to pheophytins and then to pyropheophytins
- Indicators - The ratio of pyropheophytins to the total pheophytins is useful for distinguishing fresh olive oil from soft column refined, deodorized, or backblended oils.
Units: %Total Pheophytins - AOA limit≤17
*IOC= International Olive Council, AOA= Australian Olive Association