Dados do Trabalho

Título

SONICATION IN THE PRE-TREATMENT OF Gracilaria sp. FOR PROTEIN EXTRACTION

Introdução

The Brazilian coast has a wide variety of macroalgae, especially red algae, which have a great potential as an alternative source of protein. However, this characteristic is little explored due to the difficulty in extracting it. Therefore, the aim of this study was to evaluate the application of sonication as a pre-treatment for protein extraction from Gracilaria sp., assessing yield of protein besides emulsion and foam abilities.

Material e Métodos

After resuspending the macroalgae flour in 1% w/v water solution, sonication was applied at 255 W for 5 minutes, followed by alkaline extraction at pH 12 for 60 minutes at temperatures 25 and 80 °C (US5-25 and US5-80). The solution was centrifuged and the supernatant neutralized. Control extract without ultrasound treatment (US0-25 and US0-80) were also evaluated.

Resultados e Discussão

Higher temperature (US0-80 and US5-80) increased protein yield (20%). At 25 °C, the ultrasound pre-treatment (US5-25) resulted in lower yield (10%) in comparison with untreated samples (12% for US0-25). This indicates that the application of heating during the extraction may be more advantageous than the use of ultrasound. The emulsifying activity was highest in sample US5-25 (96 m²/g), followed by US0-80 (89 m²/g). Emulsion stability was higher for US0-25 and US5-25 (250 and 101 minutes, respectively) while US0-80 and US5-80 were lower (20 and 25 minutes). Sonication was positive for emulsifying activity at 25 °C, but high temperature caused lower stability probably due to protein denaturation. The foaming capacity increased with sonication, reaching 25% for US5-25 and 17% for US5-80, US0-25 got up to 15% and US0-80 to 8%. Foam stability after 1 hour was highest in US0-80 (94%), while the others had between 86 and 88%.

Conclusão

Therefore, the properties of the Gracilaria sp. proteins studied here are promising for application in food. However, the best way to obtain them has to be selected according to the final application purpose.