Process and Kinetic Models of Hydrochloric Acid -Extracted Collagen from Bighead Carp Scale

Fish scale contains rich collagen. Collagen is an important material which is widely used in many kind of industries. Extracting collagen from fish scale not only reduces the pollution but also obtains new raw material of commercial collagen. In this paper, single factor test method was firstly used to investigate the effects of liquid/solid ratio, concentration of hydrochloric acid, extraction time and extraction temperature on collagen extraction yield from bighead carp scale and their optimal values were determined. Based on which, the response surface method was used to establish the process and kinetic models for the collagen extraction process. The results show that the two models in the form of multiple regression are basically identical with the actual values and can be used to predict the collagen extraction yield and collagen extraction velocity under different operation conditions, and to adjust the operation parameters for obtaining the expected collagen extraction velocity with high collagen extraction yield in order to realize the ideal utilization efficiency and production intensity of the collagen in fish scale. Introduction Fish scale is a kind of waste produced in fish processing. Fish scale contains reach collagen which is an important biological, food and cosmetic material and can be widely used in pharmaceutical, food and cosmetics industries because of its excellent biocompatibility, low antigenicity, immunogenicity, and good function of auxiliary cell regeneration. To extract collagen from fish scale can not only reduce biological pollution but also obtain potential new collagen resources in the world. Recently, fish collagen has attracted many scholars and researchers to engage into this research area. Most of the published articles focused on the isolation and characterizations of collagen from the scales of different kind of fishes[1-2]. The process model reflects the relations between collagen extraction yield (as target) and main operation parameters(as influence factors). The kinetic model reflects the relations between collagen extraction velocity (as target) and main operation parameters(as influence factors). These two models can predict and adjust the technical parameters to achieve the expected collagen extraction yield and collagen extraction velocity under different operation conditions, which is conductive to realizing idea utilization of fish scale and collagen production intensity. In this paper, single factor test and response surface test methods were used to establish the process and kinetic models for the collagen extraction from bighead fish scale and the significance of the models and model terms were analyzed and validated with the actual values. Experimental Materials and chemicals. The scale of bighead carp was collected from the local market in Nanchang, Jiangxi, China. L-hydroxyproline (BR) was obtained from Sinopharm Chemical Reagent Co.,Ltd.(Shanghai,China). The other chemicals used in the experiment were chemical pure and made in China. 5th International Conference on Information Engineering for Mechanics and Materials (ICIMM 2015) © 2015. The authors Published by Atlantis Press 476 Decalcification of fish scale. The scales were leached in a 0.5 mol/L HCl solution with oscillation for 57 min and then soaked for 10 h in a 0.5 mol/L Na2CO3 solution with constant stirring. After that the decalcified fish scales were repeatedly rinsed with water. Extraction of collagen. a) Single factor test. a.1 g fish scale, firstly accurately weighed and decalcified, was added 15 distilled water and certain amount of 0.5 mol/L hydrochloric acid solution and the effect of extraction time(6,12, 24, 36,48 h) on collagen extraction yield was investigated at 28 . b.1 g fish scale, firstly accurately °C weighed and decalcified, was added 15 mL distilled water and certain amount of hydrochloric acid solution with different concentrations and the effect of hydrochloric acid concentration (0.25, 0.5, 0.75,1.00,1.25 mol/L) on collagen extraction yield was investigated at 28 . c.1 g fish scale, firstly °C accurately weighed and decalcified, was soaked in certain amount of 0.5 mol/L hydrochloric acid solution and the effect of the added amount of distilled water (5,10, 15, 20, 25 mL) on collagen extraction yield was investigated at 28 . d. 1 g fish scale, firstly accurately weighed and °C decalcified, was added 15 mL distilled water and a certain amount of 0.5 mol/L hydrochloric acidsolution and the effect of temperature(10, 20, 28, 30, 40 )on collagen extraction yield was °C investigated. The results show the optimal technical parameters are determined to be: liquid/solid ratio 15 mL/g, hydrochloric acid concentration 0.5 mol/L (the collagen will be greatly lost when hydrochloric acid concentration is over 0.5 mol/L), extraction time 24 h and extraction temperature 28 (the collagen will be easily denatured when temperature is higher than 28 ). °C °C b) Response surface test Based on the results obtained by single factor test, the optimal parameters were taken as the investigation factors and collagen extraction yield and collagen extraction velocity were taken as the double targets. The design of four factors with three levels was listed in Table 1. Table 1 Design of four factors/three levels for response surface test Factor level code -1.00 0.00 1.00 Ratio of liquid/solid, mL/g X1 10 15 20 Concentration of hydrochloric acid, mol/L X2 0.25 0.50 0.75 Extraction time, h X3 12 24 36 Extraction temperature, °C X4 20 28 36 Measurement of collagen extraction yield and velocity. The collagen extraction yield (%) is defined as the ratio of hydroxyproline content in extraction solution (w2, mg/g) to total hydroxyproline content in raw fish scale (w1, mg/g). The standard curve of hydroxyproline was drawn and its regression equation was obtained as y= 0.10946x-0.00639 ( R=0.9982), where y is the absorbance and x is the mass concentration of hydroxyproline, μg/mL. The collagen extraction velocity is defined as mass of extracted collagen per unit volume and per unit time, mg/(L·h), Results and discussions. According to the design in Table 1,29 sets of test (including 5 sets of central group tests) were separately conducted when the extraction yield and extraction velocity were taken as double targets and the results were listed in Table 2.