Open Access

ARTICLE

Soy Protein Isolate Film by Incorporating Mandelic Acid as Well as Through Fermentation Mediated by Bacillus Subtilis

by Rakesh Kumar¹, Priya Rani¹, K. Dinesh Kumar²

1 Department of Biotechnology, Central University of South Bihar, Gaya-824236, India.
2 Department of Materials Science & Engineering, Indian Institute of Technology, Patna 801106, India.

* Corresponding Author. Rakesh Kumar. Email: ; .

Journal of Renewable Materials 2019, 7(2), 103-115. https://doi.org/10.32604/jrm.2019.00027

Abstract

Soy protein isolate (SPI) biopolymeric films were prepared by adding different contents of mandelic acid (1 to 5% wrt SPI) to glycerol plasticized SPI by solution casting method. Also, SPI was fermented by Bacillus subtilis to get fermented SPI films by solution casting. Molecular mass determination of mandelic acid incorporated and fermented SPI films was carried out by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Mandelic acid incorporated and fermented SPI films were characterized by Fourier-transform infrared spectroscopy (FT-IR), dynamic mechanical analysis (DMA), tensile strength, water uptake and optical transmittance studies. Results indicated that incorporation of mandelic acid in SPI resulted in high tensile strength (8.03 MPa) and high α-relaxation (Tα) as well as low water uptake. On the other hand, films cannot be prepared from fermented SPI with SPI contents of 8% and 12%. However, film from fermented SPI with 16% SPI content could be prepared but it exhibited low tensile strength (3.18 MPa) and low Tα as well as high water uptake. The resulting mandelic acid incorporated SPI films were also subjected to antimicrobial studies. At all the concentration of mandelic acid, we can easily observe the antimicrobial effect in mandelic acid incorporated SPI films unlike fermented SPI films. This work will be helpful in fabricating antimicrobial SPI film from renewable resources.

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