Effects of heat treatment and additives on the anthocyanin content in blackcurrants and its relation to colour and texture

Over the last decade there has been a growing interest in the potential health benefits from eating a diet rich in fruit and berries containing large amounts flavonoids. Among these the anthocyanins have been given a lot of attention and studies indicate that they might help prevent tumour growth and urinary tract infections to mention a few of the potential benefits. In studies on model systems, anthocyanins have been proven to be degraded by heat, oxygen access, pH increases and addition of sugar. In this study the focus has been shifted to the effects of heat and other common processing parameters on anthocyanins in a blackcurrant mash, which is more resembling to real products. Anthocyanins were extracted from blackcurrants by using acidified methanol solution. UV-spectrophotometry was used to measure the anthocyanin concentrations. The effect on colour and texture was also investigated by colourimetry with a hand held coulormeter and shear rate ramp tests with a rheometer respectively. The results indicate that it is possible to predict anthocyanin degradation in blackcurrant mash induced by heating with a simple exponential decay model. Additionally it was concluded that the pH level is a major factor influencing the degradation speed. Furthermore, an increase in the glucose and ascorbic acid content decrease and increase the anthocyanin degradation respectively. It was also concluded that the colour is affected by the anthocyanin degradation but no clear correlation was found. Eventually no correlation between anthocyanin content and texture was found