Check oxidation in fats&oils by testing p-Anisidine Value

Are you looking for a rapid and reliable way to verify the goodness and the real oxidation stage of the fats and oils you are selling, buying or processing? Here is the solution called p-Anisidine Value analysis.

The p-Anisidine Value analysis (AV) deals with fats and oils and with the oxidation processes occurring in them, the undesirable series of chemical reactions involving oxygen that degrades their quality.

Oxidation generates a sequence of breakdown products, starting with primary oxidation products (peroxide value, dienes, free fatty acids) then secondary products (carbonyls, aldehydes, trienes) and then tertiary products.

Here below you can find 4 different applications of the AV’s determination in food analysis, represented by some matrices on which the analysis can be significantly performed.

Palm oil

Food industries generally need to control the quality of the palm oil they use in the food processing to avoid the presence of a bad smell or rancid flavor in the final product. It allows also to check and control the freshness and the quality standards of the oil, especially in relation to its shelf-life.

Other vegetable oils (rapeseed oil, soybean oil, sunflower oil)

Many industries use vegetable oils for food processing. They can be used as a first matter as well, being submitted to different kind of processes like refining or frying that alter the origin state of the oil. In this case the p-Anisidine Value analysis allows to control the oil state and changes in time, always referred to oxidation reactions.

Fish oil

It has many manufacturing uses: food, cosmetics, nutraceutical, and others. In this cases checking the quality of the fish oil bought or directly used in the working process can be very significant.

Lanoline

One of the latest request our R&D laboratory received concerned the need to analyze p-Anisidine value in Lanoline, a waxy substance used in the beauty and cosmetic industry.

All of these matrices oxidize very fast in comparing to other kind of fats and oils. In fact they contain a large number of polyunsaturated fatty acids, having reactive double bonds between their carbon atoms that facilitate the chemical reactions involving oxygen. The data about this microscopic condition (given by the p-Anisidine Value parameter) can absolutely help in showing the whole oxidation story of the matrix. Indeed that is very important in the case of oils or fat very rancid but presenting reduced Peroxide Value. P-Anisidine Value analysis allows to control the quality, the smell and the state of conservation of the matter detecting the deeper stages of the oxidation.

The lower the p-Anisidine Value, the better the quality of fats and oils analyzed. Depending on the market the values required vary: for fish oils the p-Anisidine value must be lower than 30, in other sectors is instead required less than 10 AV.

The chemical analysis method for p-Anisidine Value determines the amount of aldehydes (principally 2-alkenals and 2,4-dienals) in animal and vegetable oils and fats by reaction of these compounds with the p-Anisidine. This reaction highlights the concentration of the quantity of aldehydes and ketons, giving the dimension of the secondary oxidation of the fat matrices.

The official method (AOCS Official Method Cd 18-90), a spectrophotometric analysis method measuring the absorbance at 350 nm, requires the use of two different reagents, more than 10 minutes time testing, the handling of toxic and possibly carcinogenic chemicals (Isooctane, Acetic Acid, p-Anisidine), laboratory’s facilities (a fume hood, a spectrophotometer, laboratory glassware) and specialized personnel.

The CDR FoodLab® analysis method as well is a photometric method: it allows the reading at 366 nm (p-Anisidine’s molecular wave length and absorbance of light) and uses the p-Anisidine as a reagent. It traces the procedure of the official method but it has the following advantages:

• 2 minutes time testing
• carcinogen or dangerous substances handling not involved
• chemical laboratories or facilities and specialized operators not needed
• analysis procedure simple and rapid
• reliability of the results, expressed as AnV as the AOCS reference method convention

See how you can performe the p-Anisidine test with the CDR FoodLab® system.

In the analysis p-Anisidine (4-methoxyaniline) is therefore used as a reagent to point out the secondary stage of the oxidation: it is one of the three possible isomers of the Anisidine or methoxyaniline. The other two isomers are o-Anisidine (2-methoxyaniline) and m-Anisidine (3-methoxyaniline).

p-Anisidine Value actually measures the secondary oxidation products like aldehydes, carbonyls, trienes, ketons. Together with a test like Peroxide Value it can really give a deep information about the state of an animal or vegetable oil and fat.