Technological Aspects of Anthocyanin Utilisation in Functional Foods
Plant phenolics, such as anthocyanins, are increasingly gaining in importance for use in functional foods because of their bioactivity. Bilberries (Vaccinium myrtillus) are known to contain high amounts of anthocyanins whose strong antioxidative potential
is related to numerous health effects. The low molecular hydrophilic anthocyanins show highest stability inside their natural environment and in their flavylium-form at very acidic environment (pH < 3). At elevated pH-conditions as prevalent in most foods they degrade quickly (Cabrita et al, 2000). After oral administration anthocyanins are rapidly metabolised and resorbed. At the same time they are characterised by a low bioavailability and recovery rate (Clifford, 2000). Regarding this basic conditions the encapsulation of anthocyanins appears expedient in two aspects. On the one hand encapsulation stabilises sensitive anthocyanins and allows food application in form of microcapsules. On the other hand, the quick intestinal metabolisation of anthocyanins and their low bioavailability indicate the need for increasing the resistance towards environmental conditions in the gut. Whey proteins are widely used in food industry and are capable of building up a thermally induced gel matrix at strong acidic conditions (Liu et al, 1994). The insolubility of the gel network in aqueous environment makes them a suitable matrix material for (micro-) encapsulation. Thus, one objective of this research was to investigate the use of acidic whey protein gels for encapsulation of bilberry extract (BBE) by evaluating stability of differently encapsulated anthocyanins. Targeted release of encapsulated anthocyanins in the gut requires prevention of predestination release in the stomach. For this reason a further objective was the investigation of shellac as enteric coating for the whey protein hydrogel based encapsulation system.