Influence of HTST extrusion cooking process parameters on the stability of anthocyanins, procyanidins and hydroxycinnamic acids as the main bioactive chokeberry polyphenols

- Starch based products with high amounts of chokeberry polyphenols were produced by extrusion processing.
- Improved anthocyanin retention was achieved by increasing water content.
- Anthocyanin glycoside retention is depending on SME and temperature exposure.
- Procyanidins and hydroxycinnamic contents were not affected by extrusion processing.

Chokeberry polyphenols could be used to design functional snacks and breakfast cereals. High-temperature, short-time extrusion processing is a unique technique to design such cereal based products. However, the intense amount of thermomechanical energy, which is necessary to generate crispy structures, can lead to losses of those bioactives. In order to gather information about the retention of chokeberry polyphenols in extrusion processing, the influence of process parameters, e.g. screw speed (300 and 500 1/min), barrel temperature (100 and 140 °C) and water content (15 and 22 g/100 g, wet basis), on changes of anthocyanins, procyanidins, and hydroxycinnamic acids was investigated using a model based on maize starch.At the range investigated, changing screw speed, water content, and barrel temperature had no significant (P < 0.05) influence on the retention of procyanidins and hydroxycinnamic acids. Higher screw speed increased the specific mechanical energy, the melt temperature and resulted in the loss of anthocyanins. The retention decreased linearly with the melt temperature. A higher retention was analysed by increased water content. The highest retention (about 60%) of cyanidin glycosides in this study was achieved at the highest water content (22 g/100 g, wb), irrespective of the barrel temperature and the screw speed.