Influences of freeze- and spray-drying vs. encapsulation with soy and whey proteins on gastrointestinal stability and antioxidant activity of Mediterranean aromatic herbs

The aim of the present research was to study the chemical profile of volatile and non-volatile compounds in freeze- and spray-dried oregano, thyme, sage, and rosemary as well as to study the gastrointestinal stability and the biological activity of the samples after encapsulation using two proteins (soy and whey). Chemical analysis was performed by HS-SPME/GC-MS and HPLC-PDA techniques. The antioxidant activity (FRAP, DPPH and ORAC assays) and HPLC-PDA analyses were performed before and after simulated two-phase digestion process (gastric and duodenal) using human gastrointestinal enzymes. The effect of protein carriers was depended on the plant matrix and the class of compound. Soy protein is useful for the protection of thymol and carvacrol content in thyme and the increase of the antioxidant activity of sage. Whey protein is useful for flavanols stability in all studied herbs before and after the duodenal digestive phase.

Automated summary

This research aimed to analyze the chemical profile of compounds in oregano, thyme, sage, and rosemary, as well as the gastrointestinal stability and biological activity after encapsulation with soy and whey proteins. The study found that soy protein can protect thymol and carvacrol content in thyme and enhance the antioxidant activity of sage, while whey protein can improve the stability of flavanols in all herbs studied.