In order to extend the shelf life of food, manufacturers usually add hydrogen to natural oils. However, this process also results in the acceptance of trans fats that have harmful effects on health, such as raising harmful cholesterol levels and increasing the risk of heart disease.
In order to extend the shelf life of food, manufacturers usually add hydrogen to natural oils - a process called hydrogenation [the introduction of a hydrogen atom into a compound]. However, this process also results in the acceptance of trans fats that have harmful effects on health, such as raising harmful cholesterol levels and increasing the risk of heart disease.
Trans fats are found in vegetable oil, margarines, crackers, cookies and snacks. Worldwide health authorities recommend reducing the consumption of trans fats. Now, chemists from the University of UC Riverside in California have developed a catalyst - a substance that accelerates a chemical reaction - which allows for the reduction of oils while minimizing the amounts of trans fats obtained.
In their experiments, the researchers, led by Francisco Zaera, professor of chemistry, used platinum, a common catalyst in processes such as these. Almost eighty percent of all industrial chemical processes use catalysts. With annual global sales of approximately fifteen hundred billion dollars, catalysts contribute approximately thirty-five percent to global domestic production. They are used in the production of products, petro- and agro-chemicals, pharmaceutical products, cosmetics, food and polymers.
By controlling the structure of the platinum particles, the research group was able to produce a more selective catalyst. Catalytic selectivity refers to the ability of the catalyst to "prefer" a particular chemical reaction pathway from a wide possible selection. In this case, pickiness refers to the partial fattening of the fats without getting trans fats. The research team found that the activity of the platinum catalyst is the most selective when the particles arrange themselves in a tetrahedral array in which the various atoms are organized in a hexagonal crystal system, similar to a honeycomb. Particles with this structure enable the receipt of the cis isomer, which is harmless to health, of the hardened fat. The researchers found that other types of crystals lead to receiving trans fats.
Platinum catalysts of the type used by the team are referred to as heterogeneous because they exist in a different phase (solid) than that of the reactants (liquid or gas). Compared to homogeneous catalysts, in which the catalyst is in the same phase (liquid) as the reactants, heterogeneous catalysts have the advantages of simple preparation, convenient handling, easy separation from the reaction mixture, recycling, high stability and low cost.
However, their main disadvantage, unlike homogeneous catalysts which are molecular, lies in the fact that the use of heterogeneous catalysts requires their dispersion as tiny particles in a substrate with a high surface area in order to optimize their activity. Most often, this results in obtaining catalysts with surfaces containing non-uniform structures.
The research is also a breakthrough because it demonstrates for the first time that high selectivity can be achieved using heterogeneous catalysts such as platinum by controlling the structure of their surface.
"The more controlled the preparation of the catalysts, the easier it is to direct the catalytic selectivity of a unique chemical process," explains the researcher. "Our research shows that it is possible to prepare heterogeneous catalysts that provide increased control regarding selectivity. This opens new avenues, we hope, for chemists' ability to achieve selectivity for other reactions as well through the design of unique heterogeneous catalysts with defined structures."
"Our research shows that, thanks to new advances in nanoscience, highly selective and highly advanced heterogeneous catalysts can be produced by controlling their structure," adds the researcher. "In this aspect, our research changes the accepted concept regarding heterogeneous catalysts. These catalysts can now better compete with homogeneous catalysts, which are commonly used in industry in reactions that require extremely high selectivity such as those involved in the production of pharmaceuticals and other fine chemicals."
The research findings appeared this month in the electronic edition of the journal Nature Materials. As a continuation of the research, the group of scientists plans to find other reactions in which high selectivity is essential. The researchers also plan to improve the synthetic methods used to obtain selective catalysts.
One response
Trans fat is not healthy, but eating platinum doesn't seem very healthy to me either...