Improvement of thermal stability and antioxidant activity of anthocyanins of Echium amoenum petal using maltodextrin/modified starch combination as wall material.

To protect anthocyanins of Iranian borage extract (IBE) by encapsulation, maltodextrin (MD)/modified maize starch (MMS) combinations were used at four ratios (MD/MMS: 1/0, 1/0.25, 1/0.5, 1/1, w/w%). The microencapsulated powders with different ratios of wall material presented encapsulation efficacy between 93.1 and 97.4%. FTIR confirmed the cross-linking interaction between extract and MD/MMS wall. Increased thermal stability of extract was also indicated by DSC analysis. The stability of microstructures and crude extract at two conditions (5 and 40 °C) was evaluated by UV and HPLC methods during 60 days. The results of stability showed that encapsulation by treatment 4 (MD/MMS 1:1) improved the stability of anthocyanins 43.8% compared to crude extract. Additionally, microcapsule created in this treatment provided great antioxidant stability. The release in the simulated gastrointestinal tract revealed that the anthocyanins were chiefly retained inside the microparticles in the stomach, and were released in the intestine. The results demonstrated that the microencapsulation with MD and MMS by the spray-drying method can improve the stability, antioxidant and functional characteristics of borage extract, which could be useful in the food and pharmaceutical industry.