Xi’an Herbsine Bioengineering - Key parameters for the identifcation of saw palmetto oil

Saw palmetto oil has the unique ability to improve benign prostatic hyperplasia. Due to the shortage of raw materials and complicated processing, its price is quite high. Meanwhile, there are many poor-quality products on the market. As a complex natural product, the difference in processing methods may lead to variations in certain parameters of the product, leading to misunderstanding in identification.

From a scientific point of view, the identification of saw palmetto oil isn't complicated, but for many traders and primary users, a simple and effective identification method is far better than using complex, expensive instruments and long-term testing to get a suspected conclusion.

Based on the US Pharmacopeial Convention (USP) and European Pharmacopoeia (EP), Xi'an Herbsine Bioengineering analysed saw palmetto oil from mainstream markets and came to the conclusion that some extremely simple methods, even without professional technical means, can identify saw palmetto oil. For many traders, this is good news.

Basic identification

This is suitable for users who lack experience in experimental conditions to perform initial screening. The things they will find include an odour with a slight irritant smell and a freezing point, which sees the oil start to solidify at 10-15°C; however, freezing becomes more obvious with a smaller sample.

Advanced identification

This method, on the other hand, grants users access to technical conditions or conducting an authoritative external inspection of laboratories. With this type of identification, Herbsine found several problems with palmetto oil, including:

  • the ratio of fatty acids content using gas chromatography (GC) was either in full or partial compliance with USP standards
  • the ratio of acid value to saponification value was 55-90%
  • high-performance thin-layer chromatography (HPTLC) compared with a raw material.

Meaningless identification

With technical methods that are complex and unsuitable for use with fatty oils, this produces confusing conclusions due to infrared radiation (IR), nuclear magnetic resonance (NMR) spectroscopy and assessing colour variations.

Reaching the freezing point

The quality of saw palmetto oil taken by CO2-supercritical extraction is similar, even though the origin and appearance of saw palmetto oil are different; GC, HPTLC, IR and NMR testing can confirm this.

When the ambient temperature is lower than 15°C, saw palmetto oil begins to solidify, causing serious problems for the soft capsules manufacturers tend to use in the northern hemisphere. This means saw palmetto oil - which does not have insulation measures taken from November to March every year - will partially or completely freeze.

Even worse, some inexperienced trading companies or users consider solidified saw palmetto oil to be problematic.

The freezing point of vegetable oil is determined by the ratio of saturated fat to unsaturated fat in it. Unfortunately, saw palmetto oil contains more than 50% saturated fatty acids and has a much higher freezing point than common vegetable oils. In addition, the freezing point of oil is not a specific temperature but a range. It will begin to form a floc at a certain temperature and will not all freeze.

According to Herbsine's experience, when the temperature is below 15°C, saw palmetto oil is no longer clear and transparent. There is gradually more precipitation and the oil becomes turbid, which is called the cloud point. When the oil can't flow, it is called the pour point. Finally, the oil is completely transformed into a solid state.

When ambient temperature is lower than 15°C, saw palmetto oil will become turbid, precipitated or even freeze. As the quantity of oil packed in a 200L solution is large, the freezing process may take several days.

Saw palmetto oil that is stored in warehouses with fluctuating temperatures during the winter months needs to be paid special attention to, as sediment forms at the bottom while the upper part remains an oily liquid. In this case, saturated fatty acids with a high freezing point will precipitate, despite some of the unsaturated fatty acids still being liquid. So, the oil taken from the top does not represent the quality of the entire package and, as a result, the products fail to comply with the requirements for fatty acid content. At this time, it is necessary to increase the ambient temperature to make the oil take a liquid form before use.

Fatty acid ratio to consider for being compliant with USP and EP

Herbsine found that, with fatty acids, samples from Europe are not significantly different from others; however, the ratios of several fatty acids were not USP-compliant. The reason may be that EP only requires that saw palmetto oil contains not less than (NLT) 80% of fatty acids and NLT 23% of lauric acid. However, these products do not comply with USP.

Vegetable oil that has been preserved for a long time is slowly hydrolysed by microorganisms, enzymes and heat, resulting in free fatty acids. Therefore, the acid value can be used as an indicator of the degree of hydrolysis or rancidity of the oil during preservation. The smaller the acid value, the better the quality of the oil, leading to improved freshness and refining.

However, saw palmetto is a special plant, and its oil contains a high number of free fatty acids.

At present, USP specifies that the saponification value of saw palmetto oil should be in the range of 210-250, but the acid value has not yet been specified.

EP 9.0 states that the saponification value of saw palmetto oil should be 220-250, with the acid value being 150-220.

It is believed that the acid/saponification value be 50.5-76.5%. In the future, the ratio may be as high as 90% or more, which is also a way of identifying the authenticity of saw palmetto oil.

Additional characteristics and colour variance

Saw palmetto oil has an obvious characteristic chromatography, which can be easily distinguished from other vegetable oils through HPTLC.

The colour of saw palmetto oil from different manufacturers varies greatly. According to Herbsine's research, several factors affect the colour of the oil:

  • ??When raw materials are stocked for a long time, the colour of the extracted oil is deeper.
  • ??The seed coat of the saw palmetto berry is rich in pigment. Removing the seed coat before production helps to obtain a lighter-coloured oil.
  • ??Different supercritical-extraction technology - pressure - can also result in different colours.
  • ??After dehydration, and the depickling and refining process for supercritical-extraction oil, the company obtained a nearly colourless product.

In addition, the main components of saw palmetto oil colour include carotenoids, chlorophyll and lutein. These natural pigments are not stable. In fact, Herbsine has found that saw palmetto oil begins to fade in about 7-15 days after it is exposed to light, and the colour is stable after becoming slightly lighter.

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20201, Dongxing Bldg. No.64 Jiangong Rd. Xian, 710043
P.R. China
Tel:+86 29 82566097 Fax:+86 29 82566097-801
Contact: Xi’an Herbsine Bioengineering
URL: www.herbsino.com

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