The effect of freeze‐drying, pasteurisation and high‐intensity ultrasound on gastrointestinal stability and antioxidant activity of blueberry phenolics

The use of freeze‐drying and high‐intensity ultrasound can ensure better gastrointestinal stability and higher antioxidant activity of blueberry phenolics. Summary The influence of freeze‐drying, pasteurisation and high‐intensity ultrasound on gastrointestinal stability and antioxidant activity of cultivated blueberry phenolics was investigated. Quantitative and qualitative analyses were done before and after a two‐phase in vitro digestion by human digestive enzymes. Antioxidant capacity of blueberry phenolics before and after simulated digestion was evaluated using DPPH and the FRAP assays. After the simulated gastric digestion phase, high stability of phenolics was determined, especially after freeze‐drying. During the simulated duodenal digestion, the most affected compounds were anthocyanins. The average loss of quercetin derivatives was 60%, while in all ultrasound‐treated samples, a 3‐fold increase in the concentration of phenolic acids was observed. The highest antioxidant activity after in vitro gastric and duodenal digestion was determined in a freeze‐dried sample. The results after in vitro digestion demonstrated that the use of freeze‐drying and high‐intensity ultrasound can ensure better gastrointestinal stability and higher antioxidant activity of blueberry phenolics.