Microencapsulation of extracted bioactive compounds from brewer's spent grain to enrich fish-burgers

- The potential re-use of brewer's spent grain has been proposed.
- A microencapsulation process of extracts from brewer's spent grain is optimized.
- The effects of two spray-dried operating parameters were studied.
- The microencapsulated extract was used to enrich fish-burger.
- Fish-burger with good sensory evaluation and high antioxidant properties was realized.

In this work bioactive compounds (polyphenols and flavonoids) were extracted by supercritical CO2 from brewers's spent grain (BSG). The extract was microencapsulated to mask its unpleasant and bitter taste and tested on fish-burger formulation. The extraction process was carried out at 40 °C and 35 MPa of pressure whereas the microencapsulation was performed by means of a spray-drying, using Capsul® as wall material and modifying inlet temperature (90-120-150 °C) and ratio between extract and carrier (1:2; 1:4; 1:6; 1:8). A sensory evaluation of fish-burgers prepared with different bioactive powders of BSG was carried out to establish the best combination of operating parameters. The sample with 5% microencapsulated BSG extract and Capsul® solution in ratio equal to 1:2 at 150 °C was chosen as the best compromise between chemical properties of active powder and sensory evaluation of fish sample. Finally, the antioxidant properties of fish burger with microencapsulated BSG extract were compared to the control. Results confirmed the potential use of BSG as food ingredient because fish-burgers were found richer in polyphenols (30%) and flavonoids (50%) and with a better antioxidant activity than the control sample.

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