Preparation Of Pectin/Cellulose Based Antimicrobial Films And Investigation Of Antimicrobial Release

Antimicrobial bio-based film, as one of the most promising concepts of active packaging, has been great increasing attracted by the food and packaging industry. It not only can provide active protection to food products by releasing antimicrobial agents onto food surface to prevent the product deterioration, extend the shelf life, but also can reduce the consumption of traditional plastic packaging and alleviate the damage to the ecological environment. The release ability of antimicrobial agents in packaging materials influences the shelf life of food. The reasonable relese of antimicrobial agent can be achieved by adjusting the release of antimicrobial agent.In this study, a packaging system based on polysaccharoses (low methoxy pectin/carboxymethyl cellulose (LMP/CMC)) was developped to investigate the packaging performance of composite films. The release profiles of potassium sorbate (PS) from LMP/CMC films into lipophicity food simulants were investigated. The influencing mechanism of CMC content, concentrations of CaCl2 and MMT on PS release was investigated. The changes of DP and KF.P in the relationship of CMC content, concentrations of CaCl2 and MMT were analysed. Linear equations were obtained between release parameters (DP or K,P) and tempearature, CMC content and concentrations of MMT, respectively. Based on Fickian diffusion model, a release prediction model of PS was established. The real food was used to investigate the release of PS.(1) The preparation and performance evaluation of composite films.LMP/CMC films were prepared by casting. MMT was incorporated into film materials. The results showed that the addition of CMC resulted into increased color and transparency and improved the tensile strength of composite films. The incorporation of MMT improved the TS of composite films, resulted in lower water vapor permeability and water content of composite films. An excess in MMT content was a cause of poor particle distribution, resulting in poor TS and water barrier property.(2) The release profiles and mechanism of PS from antimicrobial films into food simulants. The release profile of PS incorporated in LMP/CMC copmosite films into fatty foods (95% ethanol and isooctane) was investigated from 4 to 60C. It was evidence that the higher the temperature, the faster is the PS release. The release rate of PS into isooctane was lower than that of PS into 95% ethanol. The effects of different contents of CMC, different concentrations of MMT, CaCl2 and PS on the release of PS into 95% ethanol and 50% ethanol were determined at 4C? The results show that the differences of swelling ratios between 95% ethanol and 50% ethanol result into the different release profiles of PS. The release of PS was delayed with the content of CMC decreased and the concentrations of CaCl2 and MMT increased. In 95% ethanol, the swelling behavior of antimicrobial films was no significantly changed. The increasing content of CMC increased the moisture content of films and further accelerated the release of PS. The increasing concentrations of CaCl2 reinforced density of film materials and further delayed the release of PS. The increasing concentrations of MMT retained more PS in film materials and further reduced the release of PS. In 50% ethanol, the swelling behavior of antimicrobial films was significantly changed. The increasing content of CMC increased the swelling rate of films and further accelerated PS release. The increasing concentrations of CaCl2 reinforced molecular interaction of film materials, decreased the swelling rate of films and further delayed the PS release. The increasing concentrations of MMT decreased the swelling rate of film materials and further delayed the PS release.(3) The investigation of key parameters (DP or KF,P) of PS release from LCP filmsThe release data for PS from LCP films into food simulants were further analysed in terms of a Fickian diffusion model.The changes of DP and KF,P in the relationship of CMC content, concentrations of CaCl2 and MMT were analysed. Power law model was used to analyze the release mechanism of PS in 95% ethanol and 50% ethanol. The results show that DP and KF,P of PS could be described by Arrhenius equation. Fickian difussion model was able to be used to simulate the diffusion process of PS from films with different contents of CMC, concentrations of CaCl2 and MMT (1,2%) into 95% ethanol. The release process of PS from films with high MMT content was co-dominanted by First order kinetics and Fickian difussion model. DP and KF,P of PS was significant decreased by decreasing the content of CMC, and increasing the concentrations of CaCl2, and MMT. A linear relationship was obtained between Dp (KF,P) and the CMC ratio (CaCl2 content). Fickian difussion model was used to simulate the diffusion process of PS from films into 50% ethanol. The decreasing of CMC content and the increasing of concentrations of CaCl2 and MMT resulted in the decreasing of DP. A linear relationship was also obtained between DP and the content of CMC and CaCl2. The estimated n-values demonstrated that Fickian diffusion was the predominant mechanism of the short-term release of PS in 95% ethanol. Non-Fickian diffusion was found in 50% ethanol.(4) Stablishment and prediction of release model of PS from LCP antimicrobial films.Relation equations were obtained between release parameters (DP and KF,P) and the content of CMC and tempearature, respectively. Based on Fickian diffusion model, a release prediction model of PS was established taking into the content of CMC and tempearature. The prediction results show that the proposed model can effectively predict the release of PS from LCP film into food simulant. Olive oil was choosed as real food (fatty food) to investigate the release of PS in LCP films.The results also show that the proposed model can effectively predict the release behavior of PS into real food.