Effect of α-tocopherol on oxidative stability of oil during spray drying and storage of dried emulsions

• Initiation of oil oxidation but no degradation of α-tocopherol observed during spray drying
• Addition of α-tocopherol does not prevent PUFA oxidation during spray drying and storage.
• Encapsulation of PUFAs in maltodextrin particles provides partial protection during aging.
• Negative effect of oxygen permeability and hollow structure of particles on oil protection

Lipophilic compounds such as polyunsaturated fatty acids (PUFAs) and antioxidants can be encapsulated by spray drying in order to protect and prolong their functionalities and get new handling properties. The aim of this work was to study the effect of both the spray drying stage and storage (60 °C — 50% RH) on the oxidation of lipophilic compounds encapsulated in spray dried oil-in-water emulsions (10% w/w oil in dry matter) using maltodextrin as matrix and Tween® 20 as emulsifier. Emulsions were prepared with oil containing or not containing α-tocopherol (482 ppm in oil) in order to also demonstrate the influence of the antioxidant.Results showed that there is a beginning of oxidation during spray drying, evidenced by a slight increase of markers of rancidity, i.e. conjugated dienes and volatile organic compounds. During storage, the oxidative degradation of PUFAs and α-tocopherol started quickly under the conditions of aging. This was shown to be due to the negative effect of the process and to the porosity of the solid matrix to oxygen, associated with the hollow structure of the particles. An inhibitory action of maltodextrin on α-tocopherol was also hypothesized, but it has to be confirmed.

Evolution of α-tocopherol, and conjugated diene (SA value) contents in agitated bulk oil, encapsulated oil in dry emulsion P1 and oil dispersed on MD particles (similar S/V) during 15 days of aging (60 °C — 50% RH) showing the fast consumption of antioxidant when in contact with maltodextrin leading to a lack of oil protection against oxidation in dry emulsion.Figure optionsDownload as PowerPoint slide