Edible fats and oils

Standard-compliant analysis

Edible oils and fats belong to the most abundant cooking ingredients. Seldom are they consumed in their pure form. What makes their analysis special is that they are insoluble in water and that they are susceptible to degradation. With a long experience in fat and oil analysis, we offer various standard-compliant methods that include the determination of the iodine value, water content, or oxidation stability.

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Good fats, bad fats – Titration for assessing fat parameters

Olive oil

Each oil and fat has a characteristic fatty acid profile that allows conclusions as to the origin of the oil and its cardio-protective quality. So-called fat parameters such as iodine (AOAC 28.023), peroxide, and saponification value are crucial quality parameters that allow qualifying the fatty acid profile in terms of double and ester bounds.

The free fatty acid (FFA) content points to hydrolytic degradation reactions in the oil. Especially in deep fat frying, where wet foods are immersed into hot fat, water readily cleaves the ester bonds and liberates FFAs, all the more under the enzymatic action of lipase enzymes. Titration is the ideal method to accurately and precisely determine all these fat parameters.

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Laboratory automation for oils and fats

855 Robotic Titrosampler for automated total acid and total base number analysis

Assessing hydrolytic rancidity by monitoring the acid number

Base and acid numbers are crucial for classifying fats and oils as well as fat- and oil-containing products. The ongoing hydrolytic rancidity of oils and fats is a result of the water-induced cleavage of triglyceride ester bonds. Thereby, fatty acids are released; simultaneously the acid number increases.

The compact 855 Robotic TAN/TBN Analyzer is ideally suited to take over the nonaqueous TAN titration. On one hand it saves you a lot of valuable time and increases your data reproducibility, on the other hand you avoid contact with organic solvents and aggressive titrants. Last but not least, only an automated system guarantees that the electrode is always treated in the same way, which is very important if a certain conditioning procedure is required between the single measurements. Whatever your conditioning procedure is, it can easily be adapted to the Robotic Analyzer.

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Water determination according to AOAC 984.20 and ISO 8534

Standalone volumetric Karl Fischer titrator with Polytron installed for sample preparation

The water content in oil and fats largely determines quality and shelf life. The presence of water supports the cleavage of the ester bonds and releases free fatty acids.

Small amounts of water in pure fats and oils are typically below 1% and can be easily determined by coulometric Karl Fischer titration according to AOAC 954.20 and ISO 8534. For butter and margarines, which have higher water contents, the volumetric Karl Fischer method is used.


Oxidation stability – A proven method

Lipid peroxidation

Oxidation stability characterizes the resistance of oils and fats and of fat-containing foods to oxidation. While hydrolytic rancidity releases free fatty acids, oxidative rancidity produces shorter-chain fatty acids, aldehydes, or ketones. It is a standard parameter of quality control in the production of oils and fats in the food industry or for the incoming goods inspection in processing facilities. The measuring instrument, the Rancimat, is so popular that the regulatory test method is called the "Rancimat method".

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… for fats and oils

Determining the oxidation stability of butter with an Rancimat analyzer
If fats and oils are exposed to air and light for any length of time, they undergo oxidation and hydrolysis reactions. The fats and oils then develop an unpleasant taste and odor and are termed rancid. Oxidation stability is an estimate of how quickly a fat or oil will become rancid. Through the use of the 892 Professional Rancimat, it is also possible to characterize the efficacy of added antioxidants.

… for instant noodles

Determining the oxidation stability of fat in instant noodles
An example of an application for the 892 Professional Rancimat is the determination of the oxidation stability of instant noodles. The noodles are deep-fried during the manufacturing process to make preparation by the consumer faster. Due to the deep-frying step, instant noodles have a high fat content (up to 22%) and hence can become rancid after some time.

… for legumes and nuts

The microstructure of the fresh, intact nut prevents rapid oxidative spoilage. This microstructure is destroyed during the processing of nuts. As a result, fat oxidation is accelerated and the shelf life shortened. Before the oxidation stability of nuts can be determined, the fat-containing phase must be separated from the rest of the nut with petroleum ether. The isolated fat is analyzed in the 892 Professional Rancimat.

… for crackers or other baked goods

Potato chips
The Rancimat method is a simple method for determining the oxidation stability of fats contained in cereals, crackers, biscuits, and other baked goods.


Anions in mayonnaise by IC

ProfIC Vario 3 Anion
Mayonnaise can be considered as one of the most prominent oil in water emulsions. After Inline Dialysis, chloride, nitrate, phosphate, sulfate, and acetate can be determined using ion chromatography.


Salt and vinegar in mayonnaise

Monitoring vinegar and salt in mayonnaise production

Salt and vinegar content are two of the most critical parameters in the manufacture of mayonnaise. Both ingredients not only affect the shelf life but also the taste and consistency of the product.

Whereas the vinegar concentration can be determined by acid-base titration (as glacial acetic acid), the salt content is determined by titration with silver nitrate. Both applications including sample taking and preparation can be easily automated with online analyzers from Metrohm Process Analytics.

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