Study On The Preparation Of Konjac Glucomannan/Alginate Sodium Blend Films And Its Application In Fresh-keeping Of Large Yellow Croaker

In recent years,along with synthetic plastic safety and decreasing of non-renewable resources(oil),looking for a new material that not only has excellent properties of plastic but also is easy to be biodegradable and do not threaten people healthy has been the focus of food science researchers for a long time.Polysaccharide,as following the protein,nucleic acid,is another natural macromolecular compound with a variety of functional activity and its preparation of membrane which is easily biodegradable and excellent characteristic,is a good substitute of plastic packaging,and has been gradually become a hot topic for researcher.In this paper,Konjac glucomannan(KGM)was selected as the main raw materials,and blended with Alginate Sodium(AGS)to prepare edible film.The ratio of AGS/KGM,CaCl2 concentration,and glycerin content were selected as variable factors,and the tensile strength,breaking elongation and water vapor transmittance of the blend membrane were considered as index evaluation of the quality of edible film.The response surface was used to optimize preparation technology of KGM/AGS and determine the best condition of KGM/AGS blend membrane.Moreover,the influence of the KGM/AGS edible film on the quality of large yellow croaker in low temperature was also investigated.The main conclusions are as follows:(1)In this paper,KGM and AGS were selected as two main raw materials to prepare edible film.The ratio of AGS/KGM,CaCl2 concentration,and glycerin content were selected as variable factors,and the tensile strength,breaking elongation and water vapor transmittance of the blend membrane were considered as index evaluation of the quality of edible film.The response surface was used to optimize preparation technology of KGM/AGS and the best condition of KGM/AGS blend membrane was determined as:The ratio of KGM:AGS=8.6:10,CaCl2 concentration=2.09%,and glycerin content=0.15%.The water vapor transmittance,tensile strength and breaking elongation and of the blend membrane that obtained by actual test were 0.108%,18.44Mpa and 15.66%,respectively.(2)In order to verify the performance of the KGM/AGS blend membrane,KGM/AGS blend film was used to coating preservation of large yellow croaker,and compared with untreated group,polyethylene film preservation.Results showed that the total microbial colony,TVB-N value,pH value,TBARS value,drip loss of KGM/AGS blend membrane coating ice fresh large yellow croaker during storage were less than polyethylene group and blank group.Besides ice fresh large yellow croaker treated with KGM/AGS blend membrane can effectively slow down the change of hardness during storage.It indicated that blend membrane can inhibit the decrease of nutrition element of large yellow croaker during storage.Meanwhile,the fish protein components of large yellow croaker is relatively complex and the main components are myosin and actin from SDS-PAGE analysis.Little change of different protein component of yellow croaker after treated with various preservation techniques needed further research.The effect of KGM/AGS coating preservation is better than the plastic fresh-keeping film which is a kind of potential ideal replacement for the plastic fresh-keeping film material and it has a promising application and broad prospect in food preservation industry.