Compression Molded Soy Protein Films with Exopolysaccharides Produced by Cider Lactic Acid Bacteria

Abstract

settings Open AccessArticle Compression Molded Soy Protein Films with Exopolysaccharides Produced by Cider Lactic Acid Bacteria by Jone Uranga 1, Mª Goretti Llamas 2, Ziortza Agirrezabala 2, María Teresa Dueñas 2 [OrcID] , Oier Etxebeste 2 [OrcID] , Pedro Guerrero 1,* [OrcID] and Koro de la Caba 1,* [OrcID] 1 BIOMAT Research Group, University of the Basque Country (UPV/EHU), Escuela de Ingeniería de Gipuzkoa, Plaza de Europa 1, 20018 Donostia-San Sebastián, Spain 2 GLYCOBAL Research Group, Facultad de Química, University of the Basque Country (UPV/EHU), Paseo Manuel de Lardizabal 3, 20018 Donostia-San Sebastián, Spain * Authors to whom correspondence should be addressed. Polymers 2020, 12(9), 2106; https://doi.org/10.3390/polym12092106 Received: 21 August 2020 / Revised: 12 September 2020 / Accepted: 14 September 2020 / Published: 16 September 2020 (This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021)) Download PDF Browse Figures Abstract Two exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) strains, Liquorilactobacillus (L.) sp CUPV281 and Liquorilactobacillus (L.) mali CUPV271, were isolated from Spanish apple must. Each of the strains produced a dextran, with different branching degrees, to be incorporated into soy protein isolate (SPI) film-forming formulations. Films were prepared by compression molding, a more rapid processing method than solution casting and, thus, with a greater potential for scaling-up production. Thermal analysis showed that SPI and EPS start the degradation process at temperatures above 190 °C, confirming that the compression temperature selected (120 °C) was well below the corresponding degradation temperatures. Resulting films were transparent and homogeneous, as shown by UV-Vis spectroscopy and SEM, indicating the good compatibility between SPI and EPS. Furthermore, FTIR analysis showed that the interactions between SPI and EPS were physical interactions, probably by hydrogen bonding among the polar groups of SPI and EPS. Regarding antifungal/fungistatic activity, LAB strains used in this study showed an inhibitory effect on germination of fungal spores.