Correlation between rheological properties and limonene release in pectin gels using an electronic nose

MARÍA EUGENIA MONGE; R. MARTÍN NEGRI; DANIELA GIACOMAZZA; DONATELLA BULONE

Palermo, Italia

Congreso; XVIII Congresso Nazionale della Societá Italiana di Biofísica Pura e Applicata (SIBPA); 2006

Societá Italiana di Biofísica Pura e Appli

Pectin gels were used as matrices for encapsulation of limonene with addition of a non ionic detergent, Tween 80, necessary for its encapsulation. The effect of polysaccharide concentration on gelation kinetics was studied by rheological measurements, determining for each case, the gelation time. The effects of the flavour and the detergent on the gelation kinetics were also studied for each pectin concentration. Samples with different composition were analyzed in order to differentiate the effects of the polymer concentration from the effect of the gels’ components on the gelation kinetics. Previous results show how the matrix properties are affected by the presence of encapsulated compounds to be released [1], [2]. The effect of the structural properties of the matrix on the released flavour was analyzed. The release of encapsulated limonene from cured gels towards the headspace was monitored using an electronic nose developed at the University of Buenos Aires. This device is able to detect the gels headspace with an array of non specific SnO2 sensors, obtaining fingerprints of the aroma released. The analysis of limonene release from gels with different pectin concentrations was performed using Principal Component Analysis. The intensity of flavour release was found to decrease with increasing polymer concentration. A direct relation was observed between the increased solid like character of the gel matrix and the decreased intensity of flavour release. Results showed that although the presence of limonene and Tween 80 increases the initial rate of network formation, no significant differences in the gel final structure are observed. The comparison between mechanical properties of gels with and without flavour suggests that the release modulation is mainly due to interaction of the pectin chains with detergent and flavour instead of a significant difference induced by their presence in the gel structure.  Experiments with optical microscopy of the gels surfaces also suggest that the different possibility of interaction between flavour and detergent with pectin chains according to the polysaccharide concentration.