Flavour release study as a way to explain xanthan–galactomannan interactions

In spite of numerous studies and abundant literature, xanthan(X)/galactomannan(GM) interactions still remain controversial while such mixtures have been intensively employed for a long time. The present work aims to bring new highlights on the nature of the interactions involved between both polysaccharides through an original approach: the behaviour of small volatile solutes in water-based X/GM solutions and mixtures.To this aim, a study of limonene release from X/guar (X/G) and X/carob (X/C) water-based mixed solutions has been investigated in the dilute and semi-dilute polymer concentration regimes. The aroma compound release from both matrices was compared together with the rheological properties of the solutions.When considering the limonene release as a function of the concentration regime, a dramatic decrease of the limonene release was observed for the X/C mixtures in the neighbourhood and above the critical overlap concentration C*. This result combined with kinetic experiments allowed to state the occurrence of specific interactions between limonene and polymeric junction zones formed in the X/C matrices. The apolar nature of the aroma compounds used allows to consider the nature by itself of the interactions responsible for volatile retention to be hydrophobic.A different mechanism for synergistic interactions between X and G was observed. The synergy appears quite lower than X/C mixtures and can be explained by phase separation occurring in the X/G mixture, favoured by ordered conformation of X.