In-mouth aroma release may be affected by structure: Study

The new study from scientists at INRA, AgroParisTech, and the University of Burgundy, investigated the role of both texture and eating technique (melting or chewing) on the dynamics of aroma release in a candy model.

The authors found the structure of the candies – modified by the amount of gelatine in the products – influenced aroma release by not only modifying interactions between aroma molecules and product constituents, but also by affecting oral behaviour.

“A better understanding of the possible relationships between sensory perception and the physicochemical properties of foods has long been an objective to allow better control of the organoleptic properties of food,”​ said the authors, led by Isabelle Déléris, from INRA, France.

“These findings demonstrate the large contribution of product structure [to aroma release profiles]… Candy structure influence aroma release by modifying not only interactions between aroma molecules and product constituents, but also by affecting oral behaviour,” ​they said.

Aroma profile​

The role that food structure and texture can have on aroma release has been widely studied in various types of real and model foods.

The authors said the aroma release effects of a products structure result from a combination of physicochemical (such as entrapment of aroma compounds in the product structure) and physiological phenomena (such as the way a structure behaves in the mouth).

They said that in many cases, increasing a products viscosity or firmness results in decreasing aroma release and perception, though they noted some contradictory results have been reported.

Numerous studies have addressed the relationship between in vivo ​aroma release and aroma perception, “however, as far as we are aware, the dynamics of perception have not been considered,”​ explained Déléris and colleagues.

The researchers therefore evaluated the consequences of product structure – in the case of candies – on the dynamics of in vivo ​aroma release, in an attempt to identify the sensory perception.

“We exploited instrumental and sensory methods in parallel as part of an original approach to describe aroma release and perception and to identify the relationships between these two phenomena,”​ explained the researchers.

Study details​

Four candies with different structures, based on different gelatine contents, were prepared. All candies had similar ingredient compositions but differed in structure – from liquid (without gelatine) to elastic gels that contained up to 15 per cent gelatine.

Concentrations of the other ingredients were the same in all four preparations (glucose syrup: 25 per cent; saccharose: 25 per cent; citric acid: 1 per cent; red dye: 0.25 per cent), and all products were flavoured with the same amount (0.4 per cent) of a concentrated aroma solution containing ethyl hexanoate, diacetyl, (Z)-hex-3-en-1-ol and gamma-Decalactone.

Déléris and her co workers reported that before in vivo testing, gelatine content had no significant effect on the aroma release, partition or diffusion of the aroma compounds.

However, they said that in vivo​ testing showed that the highest release for all aroma compounds was with a 2 per cent gelatine formulation.

The authors said the initial aroma release rate seemed to be affected by gelatine content, with the amount initially released decreasing as the gelatine content increase. But, they noted that the amounts released did not correlate directly with the initial aroma compound concentration in the products. Therefore, they explained, “in vivo release was presumably determined by interactions between physicochemical and physiological phenomena … by interaction between the product properties and oral behaviour.”​

Aroma release was found to be more intense for products with intermediate gelatine contents (between 2 and 5 per cent gelatine), though the authors reported that in-mouth residence times of these products were shorter than for the product with 15 per cent gelatine. They explained that this was probably because the aroma compounds were “more easily and more rapidly released from these less strong gels.”​

They noted that higher gelatine contents may have resulted in a longer product melting time, which may be attributed to delaying aroma compound release, leading to longer in mouth ‘residence times’ – which is largely governed by product texture.

Source: Food Chemistry​
Published online ahead of print, doi: 10.1016/j.foodchem.2011.02.028​
“The dynamics of aroma release during the consumption of candies of different structures, and relationship with temporal perception”​
Authors: I. Déléris, A. Saint-Eve, F. Dakowski, E. Sémon, J.L. Le Quéré, H. Guillemin, I. Souchon