The unsaponifiable matter (unsap)

The unsaponifiable matter (unsap) content in the residual oil extracted from palm oil mill effluent (POME) typically ranges around 1.033% by weight. 

Characteristics of POME Residual Oil Unsaponifiable Matter

Percentage: ~1.033% wt/%w of the extracted residual oil.
Context: POME contains about 0.6% to 0.7% residual oil/grease, which holds minor components like carotenoids, sterols, and higher alcohols that comprise this unsaponifiable fraction. 

Unsaponifiable Matter (Unsap) Range

The normal range for unsaponifiable matter (the components like sterols, tocopherols, carotenoids, and squalene that do not turn into soap) varies depending on whether you are measuring pure oil or the residual oil extracted from wastewater: 

• Crude / Refined Palm Oil: Typically 0.2% to 1.2%. International standards (such as Codex Alimentarius and FOSFA) explicitly restrict unsaponifiable matter to a maximum of 1.0% to 1.3% by weight for genuine edible palm oil.
• Palm Oil Mill Effluent (POME) Residual Oil: Typically 0.3% to 1.1%. POME itself is a watery, acidic wastewater slurry containing about 0.5% to 2% residual oil. When that residual oil is solvent-extracted from POME, its natural unsaponifiable matter sits around 1.03%. 

What it Means if the Unsap is Above 4%

If a laboratory test returns an unsaponifiable matter value above 4%, it indicates a severe abnormality or quality defect:

1. Adulteration or Contamination with Mineral Oils: This is the most common reason for artificially high unsap levels. Because petroleum-based products (like engine lubricants, paraffin, or fuel oils) cannot be saponified by alkalis, any presence of these oils will falsely inflate the unsap percentage.
2. Severe Oil Oxidation and Degradation: Highly oxidized or poorly stored palm oil contains a high concentration of polymerized fatty acids. During testing, these polymers frequently co-extract alongside the unsaponifiable matter, artificially raising the final value.
3. Heavy Concentration of Non-Oil Organic Additives: If the sample is derived from a heavily concentrated POME sludge or pond sediment, the solvent used in the extraction test may have accidentally stripped out non-fatty organic materials (like waxes, heavy pigments, or complex cell-wall material from the palm fruit fiber) rather than pure lipids. 

If you are analyzing this for commercial or processing purposes, an unsap level above 4% means the batch fails standard industrial specifications and is unsuitable for food-grade usage or standard biodiesel feedstock without extensive pretreatment.