Edible oil & oilseed tests & pricing

Test

Purpose

Free Fatty Acids

Free Fatty Acid (FFA) content (expressed as % FFA as oleic acid) is an important parameter in classification of olive oil. This test identifies oil quality, condition of the fruit prior to harvesting, the quality of fruit processing and the storage conditions of the oil. Fruit damaged prior to harvest, by pests or disease, or fruit being stored for extended periods prior to processing will result in higher levels of FFA.  Australian and IOC standards indicate the FFA content should be below 0.8% for an oil to be classified as EVOO.

Peroxide Value

Peroxide Value (PV) is the primary measurement of oxidation in oil and gives an indication of the oils’ freshness and storage conditions. The PV test measures intermediate oxidation products which lead to formation of volatile compounds responsible for deterioration of oil flavours, which ultimately cause sensory defects such as rancidity. The PV of olive oil can increase from exposure to oxygen and/ or light, particularly at elevated temperatures. To ensure PV’s are kept as low as possible, oil should be stored in cool, inert vessels, i.e. stainless steel or glass, away from light. Displacement of oxygen in containers with an inert gas, such as nitrogen, also helps to stop oxidation of the oil. Australian and IOC standards indicate the peroxide value should be below 20mEq oxygen/kg oil for an oil to be classified as EVOO.

UV Absorbance

UV Absorbance (UV) measures changes in structure of fatty acids, which occurs due to ageing, heating or refining of oil. This test may be used to indicate an olive oil is relatively fresh and is not adulterated with refined oil. Measurements are made in the UV region of the spectrum, specifically at 232, 264, 268 and 272nm. This information is then used to determine Delta K, K₂₃₂ and K₂₆₈ (K₂₆₈ sometimes reported as K₂₇₀, based on solvent used for the test). Increased values of K₂₃₂ and K₂₆₈ in olive oil usually indicates the presence of refined oils. Australian and IOC standards indicate K₂₃₂ should be below 2.50, K₂₆₈ should be below 0.22 and Delta K should be +/-0.01 for an olive oil to be classified as EVOO. Values outside these limits indicate advanced oxidation or adulteration.

Polyphenols

Polyphenols (PP) are a group of compounds which are present in olive oil, acting as antioxidants to increase the shelf life of the oil while also contributing to the sensory characteristics of the oil, especially bitterness and pungency. The amount of PP present in olive oil is determined by olive variety, fruit maturity (decreases as the fruit ripens), harvest time, processing technology, grove management and climate. Storage conditions of the oil can also affect the amount and type of PP present. There are no set limits for PP in the Australian or IOC standards. Australian oils generally have a PP content between 50 and 400 mg/kg oil. Robust oils tend to have a higher content of PP, while medium and mild oils have lower PP contents.

Organoleptic Classification (Sensory)

A panel of tasters trained to IOC standards assess the positive and negative attributes of olive oil to determine the quality and classification of the oil. Positive attributes assessed include fruit, bitterness and pungency. Negative attributes indicate a defect in the oil including rancidity, fusty/muddy, musty, winey and frostbitten. Defects are often due to errors along the production line from poor fruit quality and environmental conditions to issues during processing and storage. Olive oils can be classified as Extra Virgin, Virgin, Ordinary and Lampante depending on the Australian or IOC Standard guidelines. By both standards, to be classified as EVOO, olive oils must have the presence of a fruity characteristic and an absence of any sensory defects. To be certified as EVOO in Australia, olive oils must comply with both sensory and chemistry (FFA, PV & UV) standards.

Induction Time

Induction Time (Rancimat) measures the relative stability of an oil against oxidation and is an indication of the shelf-life of the oil. Air is bubbled through the oil sample at an elevated temperature of 110⁰C and a 20 L/h air flow. As the oil degrades there is a sudden change in conductivity, measured as Induction Time. The length of time it takes for the oil to respond indicates the stability of the oil against oxidation.

Pyropheophytin a

Pyropheophtins (PPP) are by products of chlorophyll formed when the pigment structures change as a result of heating or ageing. This test identifies fresh oil from oil that has been in long term storage or which has been heated in a refining process. The Australian standard indicates an olive oil should have a PPP value below 17% to be classified as EVOO. There is no set limit for PPP in the IOC standard.

1,2 Diacylglycerols

This test is used to detect old or damaged oil and complements the PPP test. The content of 1,2- Diacylglycerols (DAGs) can be used as a quality criterion for EVOO. The fresher the oil the higher the % level of DAGs. The Australian standard indicates an olive oil should have a DAGs value greater then 35% to be classified as EVOO. The DAGs value will decrease 20 to 25% every year even under correct storage conditions.

Fatty Acid Composition

Fatty Acid Composition (FAC) is an important measure of the quality of an oil as the proportions of individual fatty acids determine the physical properties and nutritional value of the oil. The profile indicates proportions of saturated, monounsaturated and polyunsaturated fatty acids expressed as a %.

Trans Fatty Acids

Trans Fatty Acid Composition (Trans) is an important measure of oil quality in regards to the health effects in our diets. Trans fatty acids are formed during high temperature refining or during hydrogenation of oils.

α-Tocopherols

Tocopherols are fat soluble antioxidants valued for their ability to inhibit oxidation in food. Vitamin E (α-Tocopherol) is an important dietary nutrient for humans only synthesised by plants. The tocopherol content increases food storage levels by protecting food lipids from auto-oxidation.

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