Study On Preparation And Application Effect Of Composite Film Containing Antagonistic Bacteria

The strategy of using antagonistic bacteria to control pathogenic bacteria is one of the main development directions of biological control,but the biocontrol effectiveness of antagonistic bacteria is often affected by environmental water and nutrition conditions.Therefore,finding a suitable way to maintain the activity of antagonistic cells is the key to give full play to the antibacterial performance,so as to solve the limitations of yeast production and application.Fruit and vegetable packaging materials should not only have the characteristics of good barrier and good resistance to external forces,but also conform to the pursuit of green and pollution-free concept,so the preparation of composite film using antagonism and natural biological materials can become a good application prospect of fresh preservation materials.This paper by laboratory screening to save one of grape spore mould has inhibitory effect on the film pellicle pichia as object,with gelatin and trehalose as film base material,composite membrane preparation containing bacteria to inhibit bacteria,by single factor and response surface experiment to optimize the best film formula,and compared with based composite membrane performance,finally apply it to the preservation of tomato fruit.The main results are as follows:(1)Through single factor and response surface experiments combined with mathematical regression model analysis,the optimal film-forming conditions of basic composite membrane are determined as follows:The actual water vapor transmission coefficient of the basic composite membrane was 0.4021±0.1109g*mm/(m~2*KPa*24h)when the gelatine concentration was 9.5%,the glycerin concentration was 1.5%and the trehalose content was 31%,which showed no significant difference from the predicted value.The prediction model fitted well with the actual situation.(2)The morphological and antibacterial properties of pichia membranifaciens were not affected by basal membrane solution,but there was no significant difference in the inhibitory effect of pellicle membrane solution and aqueous solution with the same concentration of pellicle on pathogenic bacteria(P>0.05).Compared with the basic composite film,the addition of antagonistic bacteria had no significant effect on the thickness and water content of the composite film(P>0.05),but the water vapor transmission coefficient,hygroscopicity and elongation at break of the composite film containing antagonistic bacteria were significantly decreased(P<0.05),and the tensile strength of the composite film containing antagonistic bacteria was significantly increased.The composite film containing antagonistic bacteria had excellent properties.(3)The surface of the composite film was smooth and flat without obvious change after adding antagonistic bacteria.The addition of pichia membranifaciens did not damage the chemical functional groups of the gelatin-trehalose composite membrane,and the film had good encapsulation effect on the antagonistic bacteria.In vitro experiments showed that the composite membrane containing antagonistic bacteria had a strong inhibitory effect on the growth of Botrytis cinerea,the growth inhibition rate was as high as 72.41%,and there was no significant difference compared with the positive control group.(4)The survival rate of antagonistic bacteria was more than 50%when the composite film containing antagonistic bacteria was stored in the shelf for 30 days.Compared with the conventional PE film and blank group,the incidence rate and the diameter of disease spots of tomato fruits tightly wrapped with antagonistic bacteria were significantly reduced under the condition of injury inoculation,and the hardness and weight loss rate of fruits inoculated without injury were effectively delayed.Titratable acid and vitamin C(Vc)content of the containing composite film bag,the inhibitory action was to reduce the fruit body activity of polyphenol oxidase(PPO),peroxidase(POD)and catalase(CAT)and phenylalanine ammonia enzyme(PAL)activity,slow down the speed of the fruit by oxidation,enhance the resistance of pathogenic bacteria,Can maintain good fruit quality.