Preparation And Characteristics Of The Fish Scales Gelatin

Traditional gelatin was generally extracted from skins and bones of terrestrialanimal，such as cattle，sheep and pigs．It was widely used as edible and medicinalmaterials whether people draw more and more concerns on its security because ofBSE(bovine spongiform encephalopathy)，and some Europe countries has explicitlyrestricted extractive from cattle and other terrestrial mammals used in medicine andfood． Fish scales gelatin has a higher security because of the distant relatives offresh-water fish and humans， therefore， there is no anxiety about this zoonoticdisease．Using fish scales as raw material to develop medical gelatin products andexpanding its application in food and medicine field， building process andtechnology of low pollution，low energy consumption and environment friendly toproduct fish gelatin， probing into the relationship between the preparationtechnology of fish gelatin and structure and performance of the medicinal gelatin，toprovide theoretical basis and technical support for the development of new，safe andhigh-performance medical macromolecule materials． It is of great significance todevelop the fresh-water fish resources in Hubei province， improve the resourceutilization and comprehensive economic results of fresh-water fish process，accelerate upgrade of fresh-water fish industrial technology and build the circulareconomy of efficient utilization of resources．Using HCL solution to decalcified the grass carp fish scales，pre-treating thefish scale gelatin after enzyme hydrolysis and using gelatin to make gelatin film andgelatin-chitosan blend film．In this thesis，the main research contents and results areas follows:HCl solution was used to decalcified the fish scales， the effects of theconcentration of HCl solution，soak time and solid-liquid ratio on dissolution rate ofcalcium ion in the process of pickle．The best decalcified conditions was as follows:HCl concentration was0.6mol/L，solid-liquid ratio was1:15(w/v)，pickling time was2h．To pre-treat fish scales with enzymatic hydrolysis after decalcification， theeffect of solution temperature，additive amount of enzyme and time of enzymatichydrolysis on the gelatin yield，gel strength and viscosity were studied，and theorthogonal experiment was used to optimize the enzymolysis technology． Theoptimum hydrolytic condition of Protease A for fish scales was enzyme solutionpH7.0， enzymolysis temperature30℃， the [S](substrate concentration)10%，[E]/[S](additive amount of enzyme)100u/g (dry fish scales)(0.12%(w/w) andenzymatic hydrolysis time5h．The single factor experiment was used to analyse the effect of pH，time andtemperature on the extract technology，and then orthogonal experiment was used todetermine the optimum extraction conditions of gelatin from the pre-treated fishscales by hot water．The optimum conditions was pH of5，temperature of55℃，time of6h，and solid-liquid ratio of1:10．Three indicators of fish gelatin under theexperimental conditions and freeze-drying were yield35.56%，the viscosity of6.04mPa·s，gel intensity478.58g．Physicochemical properties of grass carp fish scales gelatin were studied and itsflavor compounds， physicochemical indexes and biochemical indexes weredetermined．Results show that grass carp fish scales gelatin had a high content ofimino acids (proline and hydroxyproline)，it was21.6%，but none tryptophan．Withthe measurement result of gelatin relative molecular mass distribution by SDS-PAGEgel electrophoresis， it can be found that grass carp fish scales gelatin is mainlycomposed of α and β-component(α-chain and α-chain dimers)． Viscosity of grasscarp fish scales gelatin solution decreased gradually with the rise of temperature，itexisted good linear relation with concentration and increased with the increase ofmass concentration．The isoelectric point(PI)，the maximum wavelength absorption，gelling temperature and melting temperature of grass carp fish scales gelatin were7.6，210nm，17.7℃and27.9℃．Also its various physicochemical indexes and biochemical indexes were superior to the general medical gelatin，its fishy tastes waslight and esters，alcohols and aldehydes compounds were the main composition ofthe volatile flavor substances．Gelatin and chitosan-gelatin blend film were prepared with grass carp fishscales gelatin， the effect of content of glycerol and chitosan on the film weredetermined by measurement of their mechanical properties and moisturepermeability． Results show that grass carp fish gelatin had a good film-formingproperty，when the concentration of gelatin was8%and ratio of gelatin and glycerolwas8:1(gelatin/glycerin w/w)，gelatin film had higher tensile strength and tensilerate，also a good property to resist wet．When volume fraction of chitosan was40%，the tensile strength of the blend film was higher and the property to resist wet hadalso improved compared with the single gelatin film．...