Scientists make nano-organogels for food
convert sugars in the presence of olive oil to form 'nano
organogels' - potentially leading to novel delivery systems for
food preservatives, flavours, and bioactive functional ingredients.
The science behind the gels entailed using the enzyme lipase B from Candida antarctica (CALB) to form esters of trehalose, a sugar found naturally in mushrooms, honey, lobster and shrimp. The trehalose diesters then self-assemble into 3-D fibres measuring between 10 and 50 nanometers in diameter.
As the fibres entangle, a large amount of solvent gets packed together, trapping some 10,000 molecules.
"The organogels reported may find potential applications in the food and cosmetics industries in which trehalose if already used routinely," wrote the researchers in the journal Angewandte Chemie (doi: 10.1002/anie.200600989).
"In particular, the ability of the longer-chain trehalose diesters to gel olive oil attests to its potential use as a food or cosmetic additive that can be prepared by using food-approved enzymatic synthesis approaches," they said.
Professor Jonathan Dordick and co-workers from Rensselaer Polytechnic Institute in New York, tested the trehalose esters in a variety of organic solvents including acetonitrile, acetone, isopropanol, ethyl acetate, as well as in olive oil.
From a food industry perspective, the most interesting solvent was the use of olive oil in gel formation. And Dordick and his colleagues found that longer ester-chain trehalose derivatives could form gels in olive oil with relatively low minimum gelation concentrations.
Disintegration of the gels could occur, said the researchers, by re-exposure to lipase, an enzyme that is naturally present in the human intestine.
This research opens up the possibility that essential oils, preservatives, and nutraceuticals could be encompassed in the trehalose nano-gels, with release dependent on re-exposure to the enzyme.
The researchers did try other sugars, including sucrose, maltose and lactose, but gels were only formed in the presence of trehalose.
"We are using the building blocks provided by nature to create new nanomaterials that are completely reversible and environmentally benign," said Professor Dordick.
"The importance of this finding is the ability to use the same naturally occurring enzyme both to create chemically functional organogels and to reverse the process and break down these gels into their biologically compatible building blocks."
The research was funded by the National Science Foundation-funded Nanoscale Science and Engineering Center (NSEC) at Rensselaer, the Center for Directed Assembly of Nanostructures.
