Stability and release of model aroma compounds.

Abstract

Overall, this thesis has two parts: The first evaluated the use of complex coacervation for aroma encapsulation to control aroma release. The second part focused on improving the storage stability of encapsulated aroma compounds by different techniques.

In part 1 coacervate capsules were formed using gelatin and gum acacia as wall materials and either a liquid or solid core (aroma compounds). A brief storage study compared the oxidation barrier properties of coacervate capsules and spray dried powder. No significant oxidation of limonene was detected in coacervate capsules after 25 days, whereas significant oxidation was found in spray dried powder.

Then the effect of coacervate capsule properties on volatile release (measured using proton transfer reaction MS) was studied. No significant effect of glutaraldehyde cross-linking or wall:core ratio on aroma release was found. Comparing aroma release data from coacervates to their release from a spray dried material, no significant difference in release pattern could be found. However, testing temperature, aroma volatility and hydrophobicity were found to be significant but not predictive factors.

In the second part of this thesis, the storage stability (12 weeks at 30 °C) of volatiles was found to be significantly decreased by the presence of oxygen and the type of matrix in which compounds are diluted (water or various edible oils). Medium chain triglycerides, sunflower oil and soy bean oil were evaluated as the edible oils. Water was found to have a highly significant detrimental effect on volatile stability compared to the oils. The type of oil matrix was also found to significantly affect storage stability. No correlation could be detected between the oxidation level of the oil and the oxidation pattern of the volatiles.