Study On Gelatin Preparation From Chicken Skin And The Gelatin Character

Collage exists mainly in the skin, the bone, the cartilage, the tooth, the muscle, the ligament and the blood vessel of the animals, and it is the most content protein which accouts for 25%-30% of the protein gross weight According to the distributing, collage is commonly classified three kinds: skin collage, bone collage and the tooth collage. Collage is the macromolecule, and the molecule weight are 300 thousand approximately.Gelatin is a kind of hydrophilic pastern matter translated from the collage. The side radicals on the surface of collage will combine water with the hydrogen bond, then expand. When heap up the expanded collage to above 50"C, it will hydrolyze , and turn into water-dissovle gelatin which can be used in food, medicine, sensitive matter, chemical industry, printing, drying and other areas widely.This research item prepare a new kind of gelatin adopted the acid technics using the chicken skin which are provided by Fujian Shengnong Industry Ltd., discuss the infections on the gain rate, the viscosity, the gel intension, the transparency, the color and luster, so as to make certain the optimization conditions and some important physics and chemistry characters are measurated in order to make good use of the abandon chicken skin.The acid technics for preparation gelatin from chicken skin as followed: pick out the fresh freezing chicken skin, cut into slice, dip into given concentration hydrochloric acid, then hydraulic degrease after several replace the same concentration hydrochloric acid, add some water to distill the gelatin with water-bath, filtrate the gel and remove the grease in it, finally, concentrate and evaporation the water to gain the finished-product gelatin.The former disposal experiment indicates: the expand rate achieves 42%, at the same time the chicken skin can keep the freshness and protect the protein in itThis paper discuss the affection that the distill conditions on the viscosity, the color and luster, the transparency and the dissolve capability. Commonly, many characteristic qualities of gelatin will descend with the distill temperature ascends and the durative time prolongs. Experiments indicate: the qualities declines are unobvious or the declines are slow with the distill temperature below 70 C and the durative time are less than 4h, but when the temperature exceeds 75 C and the time prolongs more than 5h, the quality changes are obvious, such as, the viscosity decline in great extent, the color turn into yellow and dark, many small suspend appear, which leads to the transparency becomes bad.Moreover, the dry temperature also effect the gelatin qualities: the viscosity descends unobvious while the dry temperature ascend, but the viscosity will sharply descend for the dry temperature exceeds 70 C, when the temperature ascends from 70 C to 105 C, the viscosity will descends from 550s to 428s with the thickness 1.5%. At the same time, the dry temperature also effect the gelatin dissolve time and the solidification point: when the dry temperature below 90 C, the temperature hardly effects the dissolve tune and the solidification, whereas the dissolve time will prolong greatly (from 20min to 38min with the thickness 2.0%), and the solidificationpoint also ascends (from 26 C to30 C).With experiment, the paper make certain the optimize of the distill condition as followed: pH4.7-5.0, the distill temperature 60 C, the distill time 3.0h. With this condition, the gain rate high relatively, and the gelatin white and transparent (the absorbency is 0.167, 0.374 with the wavelength 450nm,630nm and the thickness 1.5%), the bloom value attains 258g and the viscosity attains 450s (the thickness is 1.5%).The SDS-PAGE electrophoresis and the EEF methods are applied in this paper to analyse the protein molecular weight and the IP of the chicken skin gelatin. Research indicates: two kinds of protein compose the gelatin protein, and their molecular weight are 30,000 and 26,000, the IP are 8.7 and 8.9 differently.In this paper, we prepare gelatin using the abandoned chick...