ANTHOCYANINS-RICH MICROCAPSULES EXTRACTED FROM BLACKBERRY POMACE USING A GREEN TECHNOLOGY

Blackberry (Rubus fruticosus) pomace has been recognized as a rich source of anthocyanins. In this context, the objective of this study was to evaluate, through experimental design, the best conditions for anthocyanins extraction from blackberry pomace by using an ultrasonic bath, afterward to produce microcapsules by spray drying technique (evaluating by ATR-FTIR). A factorial experimental design was used in the extraction step, including: extraction time (X1=15 or 45 minutes) and ultrasound (40 kHz frequency) absence or presence (X2=0 or 100%), with temperature fixed in 60°C, and anthocyanin content was used as response. Maltodextrin (DE 10) was used as an encapsulating agent, in a ratio of 1: 1 (w/w), in the microencapsulation process. Response surface for anthocyanins extraction showed that high extractive values were obtained in a region at 45 minutes and ultrasound presence. ANOVA effect estimates showed ultrasound presence (X2) and the interaction between time and ultrasound (X1X2) were significant (p<0.05) for anthocyanins analyses. The encapsulating agent protected anthocyanins during the drying process, presenting the same values of anthocyanins (≈2.50 µg cyanidin-3-glucoside/mg product), since the microcapsule present only 50% of the extract. In the ATR-FTIR spectra of extract and microcapsule was observed peaks between 1718 cm-1 and 1731 cm-1, which could be assigned to stretching vibrations of the aromatic ring, typical for anthocyanins. The microcapsule presented an absorption peak between 929 cm-1 and 931 cm-1 attributed to C-O stretching of C-O-C groups in the anhydroglucose ring from maltodextrin. The Gaussian deconvolution presented peak area 27.91% higher than pomace, while microcapsule presented peak area 47.70% lower than extract, as expected, which may be related with the maltodextrin a ratio 1:1 (w/w) used to microencapsulation. Thus, the ultrasound-assisted extraction was efficient to improve anthocyanins recovery. Moreover, their encapsulation proved feasible for technological application as a functional ingredient.