"Due to its dimensions and adhesive properties, we argue that loaded yeasts have a longer residence time in mouth than conventional spray dry powders that ensure long lasting of encapsulated flavour," said lead researcher Gregory Dardelle from the Swiss-based company.
Using yeast as an encapsulation vehicle is not new, and yeast capsules have attracted interest from the food industry since the encapsulation of flavour in empty yeast cells has been reported to be thermally stable at temperatures up to 240 degrees Celsius, said the researchers.
The new study, published in the journal Food Hyrdrocolloids, expands on this by using a passive loading technique for flavours and then testing them in model noodle preparations.
Dardelle and his colleagues report that encapsulation of the flavours using the passive loading technique, achieved by infusion, depended on the nature of the flavour, with incorporation limited to hydrophobic (water repulsive) flavours.
Using limonene as a model hydrophobic flavour, the researchers looked at the release of the encapsulated flavour from the yeast cells in water, in oil, or in water and then oil media.
"Interestingly, the release of flavour from loaded yeasts does not occur in pure fat," said Dardelle. "Water is necessary to open the external shell structure and induce diffusion of the encapsulated flavour toward the outside medium of the yeasts."
"These results, combined with the thermo-stability of the yeast shell and the biology of the mouth, confer to the system the ultimate properties needed for an encapsulation carrier to survive high hydrophobic and thermal treatments before delivering in mouth," he said.
The researchers then looked at the potential of the yeast capsules loaded with beef and garlic flavours in both battered and instant noodle products, compared to samples prepared using spray dry powder flavours at an identical cost in use basis, which were subsequently tested by a panel of 30 untrained consumers.
While the beef flavour appreciation was identical between the loaded and spray dry powder samples, the smell, impact after the first chew, and lasting flavour were reported to be enhanced.
Similar positive results were also reported for the garlic flavoured products.
"For garlic flavour in instant noodles, taste smell and authenticity are better preserved than using conventional encapsulation products," reported the researchers.
"The integrity of the flavour is not affected when encapsulation in yeasts is considered," they wrote. "Looking at specific attributes, like boost effect, or long lasting, yeast sample clearly outperforms the conventional spray dry powder in an equal cost in use basis."
Microcapsules are tiny particles that contain an active agent or core material surrounded by a shell or coating, and are now increasingly being used in food ingredients preparation. The technology can be used to deliver a host of ingredients - flavours, oils, peptides, amino acids, enzymes, acidulants, colours and sweeteners - in a range of food formulations, from functional foods to ice cream.
The technology is attracted growing interest because it can also decrease costs for food makers, particularly those using sensitive ingredients like probiotics, and by reducing the need for preservatives.
Source: Food Hydrocolloids
Published on-line ahead of print; doi: 10.1016/j.foodhyd.2006.12.013 "Flavour-encapsulation and flavour-release performances of a commercial yeast-based delivery system" Authors: G. Dardelle, V. Normand, M. Steenhoudt, P-E. Bouquerand, M. Chevalier, P. Baumgartner