Preparation,characterization And Application Of Konjac Glucomannan/pullulan Active Blend Films

Fruits and vegetables are prone to decay during storage,while traditional packaging has no activity and is difficult to degrade.Therefore,some packaging materials which easy to degrade,edible,and good for the preservation of fruits and vegetables has become a research highlight.Konjac glucomannan(KGM)and pullulan(PUL)have excellent film-forming properties,non-toxic and easy degradation,and has a broad application prospect in food packaging.In addition,in previous study also found that when the ratio of KGM to PUL was2:1,and the total concentration was 1%(w/v),the film forming and the preservation effect of strawberry was better.However,KGM and PUL composite film also have some limitations,such as hydrophilicity,poor mechanical properties and low antioxidant and antibacterial activity.Based on this,in order to improve these properties of KGM and PUL composite film and broaden its application in perishable fruits and vegetables,some active substances were added to the KGM/PUL composite film,and the effects of different treatment methods on the film properties were also discussed.The main research in this paper is as follows:(1)Active films were prepared by blending Konjac glucomannan/Pullulan/Microcrystalline cellulose and Tea polyphenols.The effect of different content of MCC(0%～20%),and different treatment methods of film-preparing process,including ultrasonic or magnetic stirring on rheological properties,physicochemical,morphological characteristics,antioxidant and antibacterial were explored.Results suggested that ultrasound lowered the viscosity of film-solution,while adding MCC increased the water vapor permeability(WVP)and haze degree of films.Incorporating of optimal content of MCC(10%～15%),and treated by ultrasound could further increased the tensile strength(TS),U-10%film showed the highest TS(117.61 MPa),ultrasound could make the evenly disperses MCC in film-matrix by SEM.Additionally,films with TP presented excellent antioxidant activities and antibacterial activities against S.aureus and E.coli.Finally,the active films effectively preserved of Agaricus bisporus.Overall,the active films have potential applications in food packaging.(2)The various ratio of hydroxypropyl-β-cyclodextrin(HPCD)to lecithin(LEC)was 0:1,0.5:1,1:1,1.5:1 and 2:1(w/w)co-stabilized cinnamon essential oil(CEO)nanoemulsions were prepared.These nanoemulsions were successfully incorporated in the konjac glucomannan/pullulan polysaccharides-based film matrix.The composition of nanoemulsions and the effect of various nanoemulsions on rheological,mechanical,Water vapor permeability,optical,color,morphology properties,and CEO retention rate of the composite films were characterized.The results demonstrated that HPCD and LEC nanoemulsions had small particle size under 120 nm and high stability,the incorporation of nanoemulsions reduced the viscosity of film-solution,transmittance,Water vapor permeability and mechanical properties of films,but the HPCD: LEC is 1:1 w/w of nanoemulsions could restored the mechanical properties of the films.Otherwise,1:1 w/w of nanoemulsion film also exhibited a more compact and uniform structure,Furthermore,2:1 w/w of nanoemulsion films had oxidant and better antibacterial activities against E.coli and S.aureus.The nanoemulsion films utilized in this study also prolonged the shelf life of exceed 4 days of sweet cherries while maintaining their commercial value.