Study On The Preparation Of Antibacterial And Antioxidant Locust Bean Gum-based Film And The Preservation Of Coated Fruit

With the improvement of people’s living standards,the quality and freshness of fruits have attracted widespread attention from the society.It is significant to choose an efficient and engrysaving fruit preservation technology to ensure the freshness of fruits and reduce economic losses.Fruit coating preservation technology has become a research hotpot at present,which is simple,green,environmentally friendly and cheap.In this study,four kinds of films with antibacterial and anti-ultraviolet properties were prepared,which based on locust bean gum(LBG)by adding carboxycellulose nanocrystal as the reinforcing agent.Bayberry tannin(BT)and acorn tannin(AT)are natural organic antibacterials and antioxidants,and two shapes of Zn O which were built by the growth of spindle-like and sheet-like microparticles are inorganic antibacterials.The effects of the type and addition of tannin and the shape and addition of Zn O on the micromorphology,mechanical properties,barrier properties and antibacterial properties of the films were investigated.Finally,multifunctional LBG/C-CNC/Ⅱ-Zn O/BT coatings were prepared for fruit coating preservation.In order to improve the mechanical and water vapor properties of pure LBG film,C-CNC was added as an enhancer.After 1% C-CNC was added,the surfaces of the films became smoother and more compact,and the tensile strength,water vapor and oxygen barrier properties of the films were significantly enhanced.The application of LBG+1.0C-CNC in strawberry coating preservation can effectively reduce the weight loss of strawberry.BT and AT were added to LBG+1.0C-CNC in order to endow the coatings antibacterial,antioxidant and anti-ultraviolet properties.The introduction of BT and AT made the surface of the film rougher,but both significantly enhanced the antibacterial,antioxidant and antiultraviolet properties of the films.Among them,the UV shielding effect of films with AT was better,which may be related to the formation of conjugated system inside the molecule.However,when the addition of AT exceeded 3%,the color of the films had seriously affected the appearance color of strawberries.The films with BT had better antibacterial properties,and its optimal addition would not affect the consumers to observe the appearance color of strawberries.The film with 3% BT(LCBT-3)was applied to strawberry coating preservation,which can effectively reduce the loss of weight,soluble solid,hardness,titrable acid and Vc content of strawberries.Tannin is a natural compound with defects of short useful life,low bactericidal rate and poor heat resistance.Therefore,stable inorganic antibacterial Ⅰ-Zn O and Ⅱ-Zn O were added to LBG+1.0C-CNC.The addition of Zn O endowing the film UV shielding ability and antibacterial properties,and the coatings were closely connected to the surface of fruit.Among them,the flower-like Ⅱ-Zn O cluster can provide more action sites,so it can enhance the mechanical and barrier properties of the films better.The application of the coating with 5% Ⅱ-Zn O(LCZⅡ-5)in strawberries preservation can effectively delay their appearance,prolong their shelf life and reduce their nutrients loss.In order to prepare multifunctional fruit coatings,BT was added to LCZⅡ-5 to obtain a more stable coating with stronger antibacterial,UV shielding and antioxidant properties.Moreover,the addition of BT further enhanced the mechanical and barrier properties of the films.The application of LCZⅡ-5 containing 3%BT(LCZT3)in bananas coating preservation can effectively delay their browning,prolong their shelf life and reduce their nutrients loss.In this study,a multifunctional fruit coating was finally obtained,and the prepared LCZT3 coating has great potential in fruit preservation.