The characteristics of polysaccharide from Gracilaria chouae and its application in food packaging with carboxymethyl cellulose and lysozyme

In this study, Gracilaria chouae polysaccharide (GCP) was prepared and mixed with carboxymethylcellulose (CMC) and lysozyme to develop a novel active packaging film (named GCLF). The GCP was mainly composed of galactose (55.17%), glucose (21.87%) and galacturonic acid (6.3%), with a high molecular weight (>700 kDa). It also showed pseudoplastic behavior and high apparent viscosity at 3%, presenting potential properties for film-forming. The addition of 3% GCP could improve the film's UV-light barrier capacity by 61.05%, modulus of elasticity by 46.5% and tensile strength by 58.67%. Simultaneously the incorporation of GCP increased the film's lightness and yellowness in color. Scanning electron microscopy (SEM) indicated that the film matrixes were well entanglementing and showed a tight and continuous microstructure. Fourier transform infrared spectrometer (FT-IR) and differential scanning calorimeter (DSC) confirmed the interactions between GCP, CMC and lysozyme on film performance. The addition of 3% GCP in the GCLF could prolong the shelf life of bass (at least 3 days). Specifically, it decreased the total number of microorganisms, total volatile basic nitrogen (TVBN), and improved sensory acceptance during 6-day storage. Besides, the GCLFs did not show toxicity in vitro on ICE-6 cells. In a word, GCP could be used as a film-forming substance, increasing the film's modulus of elasticity and its preservation properties in sea bass. The study will enlarge the application of seaweed polysaccharides in food packaging.