Stability of anthocyanins in high pressure homogenisation

Foods containing anthocyanins have shown significant health benefits in various studies. However, outside of their natural environment they are extremely unstable. Encapsulating them in aqueous emulsion droplets under adapted conditions could improve anthocyanin stability. Producing emulsion droplets, however, requires mechanical shear stresses, resulting in increased temperatures known to be critical to anthocyanin stability. Aqueous anthocyanin-rich bilberry extract solutions were therefore exposed to defined thermal, as well as combined thermal and mechanical, stresses, as typically occur during emulsification processes. At pH 3.5, anthocyanin degradation could be detected, especially for thermal stressing, showing the temperature–time–load as the main parameter. Anthocyanins were, however, found to be stable against mechanical stresses. To limit thermal degradation during emulsification, processing time at elevated temperature has to be limited. It was shown, that these conditions can be realised in a high pressure homogenisation process, followed by fast cooling in iced water.