Citric acid crosslinked soluble soybean polysaccharide films for active food packaging applications

In this work, a nontoxic crosslinking agent, citric acid (CA), was used to crosslink glycerol-plasticized SSPS films via a heat activated reaction. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results confirmed the occurrence of esterification reaction between CA and SSPS. Microstructure of the CAcrosslinked SSPS films were characterized by scanning electron microscopy, atomic force microscopy and Xray diffraction. The water resistance, mechanical, UV-barrier, water vapor barrier, antioxidant and thermal properties of SSPS films were enhanced by CA crosslinking. The SSPS film crosslinked with 5 % CA exhibited a maximum tensile strength of 6.5 MPa and a minimum water solubility of 34.3 %. The CA-crosslinked SSPS film also presented superior antibacterial properties against Gram-positive and Gram-negative bacteria. Application test results showed that the CA-crosslinked SSPS film can effectively delay the oxidative deterioration of lard during storage, suggesting that the developed CA-crosslinked SSPS film could be a promising candidate for active food packaging.