ENCAPSULATION OF BIOACTIVE RICH EXTRACT FROM GRAPE BY-PRODUCT USING SPRAY DRYING TECHNIQUE

Grape pomace, which is the main by-product of vinification industry, is frequently discarded due to its lack of use. This material is an attractive source of bioactive compounds and its valorisation is encouraged. In this sense, the aim of this work was to evaluate the performance of different extraction methods on recovering bioactive compounds from grape pomace, and to encapsulate such compounds using spray drying technique. Bioactive rich extracts from grape pomace were obtained by conventional extraction method (C), ultrasound assisted method (U), and pressurized liquid extraction (LP) using ethanol 40% (v/v) as extraction media. All the extracts were evaluated according to the total phenolic compounds and anthocyanins content. Then, the extract which presented the highest content of bioactive compounds was selected and encapsulated by spray drying technique, using maltodextrin as wall material. The encapsulation process was evaluated according to the process yield, and the obtained microparticles were characterized regarding to the retention of phenolic compounds, size distribution, morphology, and Fourier transform infrared spectroscopy. Among the extraction techniques evaluated, LP was the one that promoted the obtention of extracts with the highest amount of phenolic compounds (92.1 ± 1.2 mg AG/g pomace), contrasting to the other techniques applied (C: 27.1 ± 4.3 mg AG/g pomace and U: 34.9 ± 1.4 mg AG/g pomace). On the other hand, the extracts obtained by C and U presented similar anthocyanins content (5.7 ± 0.1 and 5.2 ± 0.7 mg/g pomace, respectively), while extracts from LP had the smallest one (2.0 ± 0.4 mg/g pomace). Even thought, the extracts from LP were the one selected to the encapsulation procedure, due to their expressive amount of phenolic compounds. The proposed encapsulation procedure presented 47.4% process yield, generating particles of 7.72 ± 0.94 µm mean diameter. Overall, particles presented a spherical morphology with some rugosity on the surface, which is characteristic for particles produced by spray drying technique. In general, the infrared spectra of particles presented similar peaks to the spectra of maltodextrin, and no new peaks were detected. This indicates that the particle’s surface was mainly composed by maltodextrin, which surrounded phenolic compounds from grape pomace during the encapsulation procedure. Our findings demonstrated that LP is an efficient technique to recover important bioactive compounds from grape pomace. Besides being able to remove high content of phenolic compounds from grape pomace, LP requires less time and energy than the other extraction methods evaluated. Also, the encapsulation by spray drying was useful to protect these valuable compounds inside the maltodextrin matrix. Thus, both techniques combined presented to be a good alternative for valorising grape by-products.