Characterization of agar/soy protein biocomposite films: Effect of agar on the extruded pellets and compression moulded films

Published Date
Carbohydrate Polymers
20 October 2016, Vol.151:408–416, doi:10.1016/j.carbpol.2016.05.089

• Author 

• T. Garrido
• A. Etxabide
• P. Guerrero
• K. de la Caba ^,

• BIOMAT Research Group, University of the Basque Country (UPV/EHU), Escuela de Ingeniería de Gipuzkoa, Plaza de Europa 1, 20018 Donostia-San Sebastián, Spain

Received 7 March 2016. Revised 20 May 2016. Accepted 24 May 2016. Available online 25 May 2016. 

Highlights

• •
  Transparent films were successfully obtained by extrusion and compression moulding.
• •
  Agar caused conformational changes in protein due to agar-protein interactions.
• •
  Film solubility decreased while water uptake increased by the incorporation of agar.

Abstract

Agar/soy protein biocomposite films were successfully processed by extrusion and compression moulding, obtaining transparent and homogeneous films. The conformational changes occurred during the extrusion process and the effect of agar on the final properties were analyzed. As shown by differential scanning calorimetry (DSC) and specific mechanical energy (SME) values, during the extrusion process protein denatured and unfolded protein chains could interact with agar. These interactions were analyzed by Fourier transform infrared spectroscopy (FTIR) and the secondary structure was determined from the amide I band. Those interactions were supported by the decrease of film solubility. Furthermore, the good compatibility between agar and soy protein was confirmed by the images from scanning electron microscopy (SEM).

Keywords

Agar

Soy protein

Extrusion

Compression

Biocomposite films

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• ⁎ 
  Corresponding author.

© 2016 Elsevier Ltd. All rights reserved.

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