Preparation And Functional Evaluation Of Edible Films Based On Active Components Of Hops

Public awareness of food safety is continuously enhancing with the improvement of economic level,and also focusing on the food preservation technology.However,the traditional plastic film can not meet the safety and health needs,and the edible film has received attention owing to its excellent property.In this paper,preparation of gelatin and/or chitosan edible coating liquid and edible film with hop extract,?-acid or ?-acid as antibacterial agents,and determining the optimal addition ratio of various additives in different coating.The edible films were prepared and its performance was evaluated.The release of the antibacterial agents in different food simulants of gelatin-chitosan was studied.The effects of gelatin ? chitosan coating solution containing hop extract on fresh strawberry were investigated.The main results of research were as follows:1.In gelatin and chitosan edible coating,the concentration of hop extract and ?-acid was 0.15%,and the concentration of ?-acid was 0.20%;the gelatin films exhibited lower mechanical properties.The chitosan films showed a higher swelling.Adding the bacteriostatic agents into the edible films can enhance the mechanical properties,bacteriostatic agents has no significant effect on the thickness,water content and solubility of edible films.In addition,the edible films exhibited great antibacterial properties.2.In the gelatin-chitosan composite edible coating,the concentration of the hop extract and the ?-acid was 0.15%,and the concentration of the ?-acid was 0.20%;the mixing of gelatin and the chitosan can improve the properties of edible films;the addition of bacteriostatic agents can increase the tensile strength of the edible film,and the hop extract has the biggest influence on the mechanical properties of the film.The addition of bacteriostatic agents has no significant effect on the thickness,water content and solubility of the edible film.The edible film containg bacteriostatic agents have great antioxidant and bacteriostatic activity,especially against Gram-positive bacteria.It is indicated that an edible film containing hop extract,?-acid or ?-acid can be used as a packaging material to slow food bacterial growth and lipid oxidation.3.The release behavior of antibacterial agents in gelatin-chitosan edible films into ethanol aqueous 10%,50% and 95%(v/v)were studied.In different food simulating liquids,the release of the bacteriostatic agents slowed down and releases less with the water content of the food simulating liquid increases.At different release temperatures,with the temperature raising the release of the bacteriostatic agents were faster and release increasing.It was found that the release behavior of the antibacterial agents in the food simulant at 4,25,30 ? temperature was in good agreement with the Peleg model.4.Fresh strawberries were preserved by gelatin?chitosan coating containing hop extract,and the trend of various indexes of strawberry during storage is investigated.The results showed that compared with the control group,the edible coatings can effectively reduce the weight loss rate of strawberry,slow down the decrease of VC content,polyphenols,total sugar,reducing sugar and titratable acid content in strawberry.Avoid the loss of nutrients and extend the shelf life.