Study On The Extracting Craft Of Gelatin From Tilapia Fishskin And Fish Scale

In recent years the tilapia is the main economic fish species which is cultured in China.In 2004,our country,s tilapia yields reached 899,000 tons,and its process has developed quickly.The export of our country,s tilapia reached 107,000 tons in 2005. According to the estimation,the fishskin and fish scale reached about 20,000 tons which are from the offals of tilapia,s process.Because these fishskin and fish scale contain abundant collagen,they are a kind of low price and valuable material which can be used to produce high-quality gelatin.Gelatin is the production of collagen by moderate degradation and denatur alization.The major extracting craft includes preceding process,bleaching and ext racting the gelatin with water-bath.This research study used the fishskin and fis h scale of tilapia as the raw material.after preparing experiment,respectively pe rformed orthogonal test with alkaline,acid,acid and saline,saline and alkaline,enz yme.By direct-viewing analysising and Overall balancing with orthogonal test,th e gain rate,viscosity and the bloom value of gelatin were mensurated to respe ctively obtain five optimal preceding process of fishskin and fish scale.Five kin d of preceding process of fishskin and fish scale under the single optimum co ndition were analyzed and compared to obtain the respective optimal craft.Then the optimal craft of fishskin bleaching was obtained through orthogonal test.Fi nally,the pH single factor experiment,temperature and time combinative optim ization experiment were performed to obtain the optimal craft of extracting gel atin from fishskin and fish scale.The results are as follows:The best extracting craft with tilapia fishskin is as following:preceding process for fishskin adopts enzyme,concentration 0.2%compound enzyme solution,the original pH value is 3.5,reactive temperature 40℃and time 1h.The bleaching craft uses potassium permanganate-oxalic acid combination method,by oxidation bleaching carrying on 3h with 6%potassium permanganate solution and later deoxidization bleaching carrying on 45 minutes with 1.5%oxalic acid solution,afterward clean fishskin to pH5-6 or so.The original pH value of extracting gelatin is about 5-6.The extracting gelatin is divided 3 times to carry on,the temperature 60℃→65℃→70℃,every heating time 2h,filtrate,unite percolate,concentrate and dry.In the optimal condition the gelatin gain rate could reach 22.25%,viscosity could reach 5.17 mPa.s,the bloom value could reach 271 Bloom g and diaphaneity could reach 100mm.The best extracting craft with tilapia fish scale is as following:preceding process for fish scale adopts enzyme,concentration 0.2%compound enzyme solution,the original pH value is 3.5,reactive temperature 35℃and time 1h.Clean fish scale to pH5-6 or so after soakaging 4h with 2%hydrochloric acid.The extracting gelatin is divided 3 times to carry on,heat 3h at 65℃,heat 3.5h at 70℃and heat 3.5h at 75℃,filtrate,unite percolate,concentrate and dry.In the optimal condition the gelatin gain rate could reach 13.23%,viscosity could reach 8.07mPa.s,the bloom value could reach 324.5Bloom g and diaphaneity could reach 345mm.In addition this study mensurated the physical and chemical properties of gelatin from fishskin and fish scale.The items all reached the standard for Chinese edible gelatin GB 6783—94.