Preparation And Properties Of New Hard Capsules By Fish Gelatin-Carboxylated Chitosan

Fish gelatin,derived from fish protein gums,including fish gelatin,collagen,etc.,is dissolved or evenly dispersed in water to form a viscous,slippery solution or gel,which is an upgraded version of gelatin.Fish gelatin is mainly extracted from fish byproducts(fish bones,fish skin,fish scales,etc.),and China is a large aquatic country with sufficient supply of fish gelatin.In addition,fish gelatin is the most promising alternative to mammalian gelatin because of its functional versatility,safety of consumption and lack of religious restrictions.However,fish gelatin have poor rheology and gelation properties,which limit their application in a wide range of fields such as food and medicine.Based on this,this thesis selects carboxylated chitosan to modify fish gelatin,firstly,to deeply investigate the mechanism of fish gelatin-carboxylated chitosan interaction;secondly,to realize the successful preparation of fish gelatin-carboxylated chitosan composite film;finally,to successfully apply to the preparation of fish gelatin-carboxylated chitosan hollow hard capsules.From theory to practice,it provides a basis for the industrial production of fish gelatin-based composite films and hard capsule in the future.(1)The effects of different carboxylated chitosan additions and environmental p H on the phase behavior of the fish gelatin-carboxylated chitosan system were investigated by turbidity,potential,spectroscopy and chromatography.The turbidity of the fish gelatin-carboxylated chitosan complex system was maximum when the carboxylated chitosan concentration was 0.2%.In addition,the higher addition of carboxylated chitosan could lead to the shift of the most attained turbidity of the composite system toward lower p H,which is due to the addition of carboxylated chitosan promoting the formation of cohesions.Zeta potential,spectroscopic and chromatographic results indicate the formation of hydrogen bonds between the two.The main driving force for the formation of complex condensates was electrostatic interaction.The agglomerates formed by fish gelatin and carboxylated chitosan showed a loose and porous shape and were amorphous in structure.(2)In order to obtain the best experimental conditions for the fish gelatincarboxylated chitosan composite film,the mechanical properties and barrier properties of the composite films were investigated by single-factor experiments,which were influenced by different ratios,glycerol addition and drying temperature.When the drying temperature was 40 ℃,fish gelatin: carboxylated chitosan=80:20,and the glycerol addition amount was 10%(w/w),the composite film had the best comprehensive performance.The compatibility of the composite membranes was studied using spectroscopy and electromagnetic wave transmission and compared with a single fish gelatin membrane and a single carboxylated chitosan membrane.The results showed that fish gelatin and carboxylated chitosan had good compatibility,and the composite films produced did not show phase separation and were amorphous in structure,which were suitable as hard capsule materials.(3)The hard capsules were prepared without changing the ratio of fish gelatin to carboxylated chitosan after adjusting the total concentration of the mixed gum solution according to the viscosity requirements for the preparation of hard capsules.The effects of temperature,drying time and different ratios on the preparation of hard capsules by fish gelatin-carboxylated chitosan were studied.The results showed that the hollow hard capsules prepared at a gel retention temperature of 60 °C,a drying time of 3 h,a glycerol addition of 30%(dry basis),and a blending concentration of 12%(w/v)(fish gelatin: carboxylated chitosan=50:50 or fish gelatin: carboxylated chitosan=40:60)had capsule wall thicknesses of 0.085 mm and 0.097 mm,dry weight loss: 12.7% and 11.8%,and brittleness all>2/50,respectively.The transparency was above 80%,which basically met the requirements of the national pharmacopoeia.The release characteristics of fish gelatin-carboxylated chitosan hard capsules were analyzed by choosing 0.1 mol/L HCl as the dissolution medium,and the prepared hollow hard capsules were compared with commercially available gelatin capsules,and it was found that the commercially available gelatin capsules were all dissolved within 10 min,while the homemade capsules were only dissolved within 20 min.According to the national pharmacopoeia standard,the homemade hollow hard capsules met the condition that all the hard capsules should be dissolved within 30 min,and the overall standard was met.