A Study On The Effect Of Gelatin Chitosan Film On Preservation With Bacteriostats And Antioxidants

On account of the high protein content, the Penaeus vannamei is easy to be invaded by b acteria in the process of fishing, transportation, processing and storage, and along with the eff ect of endogenous enzymes such as polyphenol oxidase, the Penaeus vannamei is susceptible t o decay..In order to reduce the loss of aquatic products in processing, storage and transportatio n, natural antibacterial agent and antioxidant were added into edible preservative film to exten d the storage duration of fresh shrimp and provide a convenient and efficient method for stora ge. The main research contents and conclusions of this paper were as follows:(1)sFour kinds of highly effective antibacterial agents were selected: tea polyphenol, nisi n, lysozyme, and clove oil. The inhibitory effect of them to two different bacteria(Staphyloco ccus aureus G+, Aeromonas hydrophila G-) were synthetically compared by plate colony count ing method, and results showed that the inhibitory effect of these four kinds of antimicrobial a gents against Staphylococcus aureus ranked as follows: Nisin> clove oil > tea polyphenols > l ysozyme; the inhibitory effect of these four kinds of antimicrobial agents against Aeromonas hydrophila ranked as follows: clove oil > tea polyphenols > lysozyme >Nisin..As the spoilage bacteria in Penaeus vannamei are mostly gram-negative bacterium(G-), 0.06% clove oil show ed a strong inhibitory effect, followed by 0.07% tea polyphenols. Finally, the antibacterial ag ent added to the membrane was determined to be clove oil with a concentration of 0.06%.(2)aFour kinds of high efficient antioxidants were selected: tea polyphenols, ascorbic aci d, and sodium erythorbate and phytic acid..The antioxidant capacity was determined by the m ethod of scavenging hydroxyl radical, and the effect ranked as follows: sodium erythorbate > VC> phytic acid> tea polyphenols. After comprehensive comparison, 0.60% of sodium erythor bate showed the strongest antioxidant effect. Ultimately sodium erythorbate were determined to be added to the film as the optimum antioxidant with a concentration of 0.60%. As a result, 55.62% of hydroxyl radical was removed.(3)aBoth gelatin chitosan film contains 0.06% clove oil and 0.60% of sodium erythorbate and gelatin chitosan film without clove oil and sodium erythorbatewere coated on the surface of the shrimp. The shrimp were stored at 4 degrees centigrade in refrigerationand the total number of colonies, TVB-N, pH value, TBA value and sensory evaluation were analysed and comparedand the conclusion was drawed as: film coating could effectively inhibit the spoilage of shrimp, while adding 0.06% clove oil and 0.60% sodium erythorbate showed better effect and the shelf life could be extended for two more days.