CEM and Fatty Acid Quantification - Making Healthy Eating Options Easier

It’s not just this time of the year that people start thinking about their diet, we are all now much more interested in eating and drinking sensibly and healthily. Of particular concern is the amount and type of fat that we consume and, to assist us, since December 2014, in Europe, regulations have required food producers to show the saturated, monounsaturated and polyunsaturated fat, as well as cholesterol content, of their foods.

One main class of fatty acids, which have been shown to have particular health benefits, are the Omega-3 fatty acids. Fish oils are a particularly rich source of these polyunsaturated fatty acids and have been shown to have cardioprotective actions, help maintain brain function and even assist in getting the waist size down by affecting fat cell composition. There is little doubt then that better food labelling can only help us make better choices in what we eat.

The quantification of fatty acids in foods is not a particularly straightforward task though. The most common method involves the initial preparation of fatty acid methyl esters (FAME’s) and their subsequent separation and quantification using gas chromatography. The FAME’s are usually prepared by saponifying esterified fatty acids to free fatty acids and then re-esterifying them to form methyl esters.

The saponification process involves heating the food under examination in the presence of a strong alkali (e.g. potassium hydroxide) with the following esterification promoted by a catalyst such as boron triflouride. Such catalysts may be harmful, are closely regulated and can have a limited shelf life when methylated as well as potentially producing artefacts. The methyl esters are then extracted with an organic solvent for gas chromatography.

The process of fatty acid quantification, as can be seen from the above, can be quite involved, with a number of different steps, lengthy (up to 24 hours) and uses dangerous catalysts and solvents. Anything that can be done to speed up the process, make it easier and less dangerous, can therefore be seen as an aid both to manufacturers and to consumers interested in healthy living.

A method for the rapid, high through-put, preparation of FAME’s using microwave technology, which does not involve potentially harmful catalysts, has been developed by CEM in conjunction with University College Dublin, can therefore be seen as great boon to the whole food industry. Although specialised equipment is required, great advantages are offered in terms of time saved, reproducibility, throughput and safety.

CEM have a reputation for the innovative use of microwaves in laboratory investigation, producing many ‘greener’ protocols and saving time, labour and money. Although the application of microwaves for FAME preparation in biodiesel production has stimulated a lot of interest, their use in the analysis of fatty acids, despite an initial publication in 1998, has not been pursued.

Concerns about the loss of volatile components may have contributed to this reticence, but given recent successes in illustrating how well microwave energy can drive reactions, even in the absence of a catalyst, microwave assistance, for FAME preparation and fatty acid quantification, was overdue for further investigation.

Using CEM’s MARS 6 Microwave Reaction System a protocol was developed for the preparation of FAME’s and samples of meat products, olive oils and peanut butter, dairy products and prepared ready meals were run. These were then analysed by gas chromatography and results compared with those found using a conventional FAME production method and the same gas chromatographic procedure.

CEM’s MARS 6 System is easy to operate and can process up to 40 samples simultaneously. The three part vessels feature self-regulating pressure control, which require no tools to assemble, and the protocol developed for FAME preparation on the MARS 6 takes only an hour to completion.

The subsequent fatty acid profiles for microwave assisted and conventionally prepared FAME were qualitatively and quantitatively similar over the full range of food products.

The recovery (and reproducibility) of both microwave and conventionally derivatized FAME’s was acceptable and of a similar order. However, using the MARS 6, in comparison to conventionally preparation, FAME preparation was simple, less labour intensive and did not require the use of toxic (and expensive) catalysts that also have the potential for artefact production.

In this health conscious era, to have better labelling of foodstuffs using techniques that are in themselves, healthier, less expensive and ‘greener’, seems to make perfect sense.

Date added: 2016-01-22 13:26:11