| As part of the national"double carbon"policy to address environmental issues stemming from petroleum-based products,natural polymers have emerged as a promising alternative in the fields of food biology and medicine due to their biodegradability and biocompatibility.Chitosan,the only alkaline polysaccharide found in nature,is widely available and possesses a range of biological activities.Similarly,gelatin,a hydrolyzed form of animal collagen,exhibits protein-like physical and chemical properties without causing immune stress,making it an attractive natural polymer.This paper explores the potential application of polymer composites in food packaging and drug delivery using chitosan and gelatin as raw materials.Firstly,a film material with an indicating function was prepared by incorporating raspberry anthocyanin（RA）and curcumin（Cur）into a matrix of chitosan,gelatin,and starch.The physical and chemical properties of the film were investigated,as well as its suitability for food packaging.Secondly,the sustained-release behavior of Cur as a drug carrier was studied by loading it into a matrix of chitosan and gelatin,cross-linked with citric acid.The main research contents and results of this paper are outlined below:（1）A packaging film material with indicator functionality（CSG）was constructed using chitosan,gelatin,and starch as substrates,with the addition of RA and Cur.The research results showed that when the concentrations of RA and Cur were 0.7%and 0.3%,respectively,the tensile strength of the film material increased from 6 Mpa（CSG）to 17 Mpa(CSG-RA/Cur73),and the elongation at break increased from 55%to 61%.At the same time,the corresponding antioxidant activity increased from 20%（CSG）to 80%(CSG-RA,CSG-RA/Cur82,CSG-RA/Cur73).In a fresh chicken preservation experiment,films containing RA and Cur showed that compared with the blank group（17 mg/100g）,the TVB-N value of the composite film group was<15 mg/100g after 48 hours,which met the fresh chicken standard.The total number of bacteria detected after 48 hours was lower in the film containing the natural indicator compared to the blank group（6.76 log CFU/g）and the CSG group（3.3 log CFU/g）,with a TVC value<2.9 log CFU/g,indicating significant antibacterial activity.In the fresh color display experiment,theΔE value of CSG-RA/Cur73 was the highest at 43.58 after 48 hours,which was higher than theΔE values of CSG-RA,CSG-Cur,and CSG-RA/Cur82（39.41,35.79,25.47,respectively）,demonstrating superior indicator performance.Therefore,the addition of natural indicators not only effectively improved the mechanical properties of the film material but also provided antibacterial and indicator functionalities,making the composite film material more promising for food packaging applications.（2）The drug release behavior of a composite material based on chitosan and gelatin as substrates,crosslinked with citric acid（CA）as a crosslinking agent,and loaded with hydrophobic bioactive molecule Cur was investigated in simulated physiological environments such as oral cavity,gastric fluid,intestinal fluid,and PBS 7.4.The antioxidant activity,antibacterial activity,biocompatibility,and degradation behavior were also studied.Results showed that the material had better sustained release behavior when the concentration of CA was 0.4%,and the swelling index was 539 g/g,he swelling equilibrium time was 40 min.The release efficiency of Cur was highest in simulated intestinal fluid,with a release percentage of approximately 42%.The ABTS radical scavenging rate was generally above 70%,and the inhibition rates against Escherichia coli and Staphylococcus aureus were over 90%.The biocompatibility of the gels with CA concentrations of 0.6%,0.8%,and 1.0%reached 50%,indicating the tremendous potential of chitosan/gelatin gels crosslinked with CA for delivering hydrophobic molecules such as Cur.The results presented above highlight the numerous advantages of chitosan and gelatin’s biocompatibility,demonstrating their exceptional properties as natural materials.These materials have significant applications in food packaging and drug delivery,and hold valuable academic and practical potential.Overall,the findings underscore the importance of these natural materials in various fields and suggest promising opportunities for further research and development. |
