Protection of antioxidant components and production of a natural food colourant powder from Ardisia compressa juice

Ardisia compressa Kunth fruit juice is rich in bioactive compounds with proven health benefits and a characteristic intense purple colour. In this investigation the effect of the wall material (using soy protein isolate (SPI) and whey protein isolate (WPI)) and type of microencapsulation (spray drying (SD) and freeze-drying techniques (FD)) on the physicochemical properties, antioxidant properties and stability in different conditions storage of the microcapsules of the juice of Ardisia compressa Kunth was evaluated. The results obtained showed that the powders developed by FD and SD exhibited differences in colour parameters, as well as physicochemical and antioxidant properties. SPI and WPI powders obtained by FD exhibited higher retention of colour, polyphenols and antioxidant activity after the drying process and during storage. Stability tests revealed that the samples obtained presented first-order degradation of polyphenols and zero-order degradation of colour, and the conditions of greatest stability were found at low water activities (0.1-0.3) at a temperature of 25 degrees C. The micro capsules exhibited variable morphology depending on the production technique. In conclusion, freeze-drying, using WPI and SPI as wall material, improve stability to colour, polyphenols and antioxidant activity to microcapsules produced with Ardisia compressa juice, demonstrating potential for application as a natural colourant or functional additive.