Research On Preparation And Physicochemical Properties Of Vegetable Carbon Black-gelatin Edible Films

The reinforcement of gelatin edible film has always attracted a great attention in the field of edible packaging.In this paper,the edible films were prepared by gelatin and edible vegetable carbon blacks were added in order to improve the mechanical properties and barrier property of gelatin films,and endow it the new UV resistance and anti-photooxidation performance for its extension of the market application.Two commonly used particle sizes(nano,100-200 nm;micron,1-2 ?m)of vegetable carbon black were added into 40 g/kg gelatin solutions with four concentrations(0%,1%,5%,10%,based on gelatin)to prepare new vegetable carbon black-gelatin composite edible films.The effects of vegetable carbon blacks on the internal structures and physicochemical properties of gelatin films were investigated.And the mechanism of reinforcing the gelatin film by vegetable carbon black was discussed.The results of the particle size distribution of film-forming solutions showed that the binding between vegetable carbon black and gelatin chains reduced the particle size of the film-forming solution.And the larger micron vegetable carbon black had a great influence on the network structure of the film.The FTIR analysis showed that the binding between the vegetable carbon black and gelatin chains was mainly physical binding.The DSC analysis showed that the binding of vegetable carbon black particles and gelatin chains increased the density of the network structure in the film,improving the heat resistance of the gelatin film.From SEM images,the results showed that the vegetable carbon black made internal structure of the composite films become compact,and the degree of compactness of the film increased with the increase of the vegetable carbon black concentration.And at 10%concentration,the vegetable carbon black particles produced obvious agglomeration in the film.From the 5%-concentration SEM images,the filament structure was observed in the cross section of composite film.This structure might be related to the improvement of mechanical properties.Determination results of film performance showed that the vegetable carbon black could effectively improve the tensile strength(TS)of gelatin film.When the concentration was increased to 5%,the tensile strength of the film was the highest.5%of nano vegetable carbon black increased the TS of gelatin film by more than 30%.By the analysis of internal structure,we inferred that the gelatin chains might twine around the surface protrusions of vegetable carbon black to reinforce gelatin film.But the vegetable carbon black reduced the elongation at break(EAB)of gelatin film.In addition,the addition of two particle sizes of vegetable carbon black could effectively improve the barrier properties of gelatin films,including water barrier properties and oxygen barrier properties,especially for the nano vegetable carbon black.The 5%nano vegetable carbon black improved the water barrier properties of gelatin film by more than one time.Importantly,the addition of vegetable carbon black increased the UV aging resistance of the gelatin film.Meanwhile,the strong UV absorption capacity of nano vegetable carbon black benefited the anti-photooxidation performance of composite films.In conclusion,with these improved properties,the vegetable carbon black-gelatin composite edible film may have great market potential in edible packaging field,especially for the anti-photooxidation property.