BLEACHING EARTHS

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Recommended values for neutralised oil

Recommended values for bleached oil Recommended values for degummed oil

Moreover, it is very stable at elevated temperatures (for example, when deep frying) and it is a good source of energy.

Chemical properties

Coconut oil is solid below room temperature and liquid above it, with a melting point range of 23.8-28.3ºC.

It has a low iodine value, high saponification value and high saturated fatty acid content, and mostly consists of short chain fatty acids.

As a result, coconut oil is highly resistant to oxidation and is commonly used in applications where a long shelf life is desired. Its low viscosity imparts a less greasy mouthfeel when compared to other edible oils.

All natural fats contain fatty acid glycerides (see Table 1, left) as well as minor quantities of other substances. The saponified content of coconut oil mostly consists of sterols while the unsaponifiable component includes a small number of tocopherols and phytosterols.

Production process

The quality of refined coconut oil is subject to the quality of the copra used in oil extraction, while the quality of the copra is mostly dependent on its production process and the maturity of the coconut meat.

Copra is made by first removing the husk from the coconut, breaking the shell, and then dehydrating the meat by sundrying, oven-drying or direct smoking.

The drying process greatly influences the quality of the oil. For example, when the meat is smoked directly using fuel, the shell may be contaminated by polycyclic aromatic hydrocarbons (PAHs), leading to a lower quality crude oil.

After dehydration, the copra undergoes solvent extraction or mechanical pressing to obtain unrefined (crude) oil which is then refined using a chemical or physical process to remove impurities (see Figure 1, left).

This is to ensure that the oil meets recommended standards (see Figure 2, left).

Refined coconut oil specifications

Generally, food specifications are defined by national standards and industry requirements. There are specific criteria for edible oils and oleochemicals.

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Specifications for refined coconut oil follow the internationally recognised Codex Alimentarius standard (see Table 2, following page).

Besides Codex specifications, there are additional regulations applied by authorities, such as the EU, regarding