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Studies on the Two Steps Enzymatic Hydrolysis of Pigskin Protein and Properties of Its Hydrolysate

Author: YuDongHua
Tutor: XuZhiHong
School: Huazhong Agricultural University
Course: Agricultural Products Processing and Storage
Keywords: Pigskin Enzymatic Antioxidation Processing properties Emulsifying properties High - protein emulsifying system
CLC: TS251.92
Type: Master's thesis
Year: 2011
Downloads: 83
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Abstract

Of pigskin collagen-rich, is a high quality animal protein resources. China pig producing countries, resource-rich pigskin pigskin on the use of a narrow applications, utilization is low, not high value-added products. This selection of commercially available pigskin as raw material, to get pigskin protein powder after degreasing, drying, crushing, and then step-by-step selection of alkaline protease and papain hydrolyzed the pigskin protein powder, preparation of low molecular weight pigskin polypeptide, and to determine the optimal hydrolysis process. In addition, the different molecular weight range pigskin protein peptide in vitro antioxidant effects and its processing characteristics, and focus on how to improve the emulsifying properties. This study was designed as a the pigskin polypeptide food, the antioxidant health care products and the development and utilization of new emulsifiers provide a theoretical basis, thereby enhancing the pigskin added value. The main contents and results are as follows: 1 the pigskin protein two-step enzymatic process optimization: selection of alkaline protease and papain, to the amount of enzymatic hydrolysis time, temperature, pH and enzyme test factors, respectively, to the degree of hydrolysis (DH dual enzyme step-by-step) and ammonia nitrogen concentration as an indicator optimization pigskin protein hydrolysis conditions. The results show that the temperature and the amount of enzyme addition in the first step enzymatic process has a significant effect of DH (P lt; 0.05), have a significant effect in the second-stage hydrolysis process time and temperature on the concentration of ammonia nitrogen ( P lt; 0.05). The optimal enzymatic process conditions: the first step to the added amount of alkaline protease 2100 U / g substrate, hydrolyzed under the conditions of the hydrolysis temperature of 55 ° C and a pH value of 9.5 to 3 h; second step bottom 22500U / g was papain added amount of hydrolyzed under the conditions of the hydrolysis temperature of 50 ° C and a pH value of 5.0 to 5 h. This process under the pigskin protein degree of hydrolysis and the hydrolyzate, ammonia nitrogen concentration of 16.79%, and 0.956 mg / mL. 2. Relative molecular mass distribution of the pigskin protein hydrolyzate refined its product: the anion and cation exchange resin mixed bed removal salt pigskin protein hydrolyzate peptide recovery and desalting rate indicators analyzed chromatography column temperature, elution speed, anion and cation exchange resin volume ratio on the kind of hydrolysates from the initial pH of the the pigskin protein hydrolyzate peptide recycling and desalination effect; using hollow fiber membrane desalination product classification, The three components, and compare the three components of the relative molecular mass distribution. The results show that the temperature of the column, elution speed and anion and cation exchange resin volume ratio of peptide recovery and desalting rate had a significant effect (P lt; 0.05); initial pH of the sample hydrolysates from peptide recoveries impact (P lt; 0.05), but the desalination rate differences are not significant (P gt; 0.05). Determine the best conditions for the anion and cation exchange resin mixed bed desalination: the column temperature of 15 ° C, anion and cation exchange resin volume ratio of 3:1, the sample initial pH 4.0, the flow rate of 10 BV / h, the desalination rate 71.35% polypeptide recovery rate of 96.33%. Therefore, the anion and cation exchange resin mixed bed is a pigskin protein hydrolyzate effective desalination method. The relative molecular mass of the two components and refined products desalted through film classification mainly below 6000 Da, and mainly in the form of small molecule peptide. 3. Objects outside the the different components pigskin protease solution Antioxidant Study: Comparison of the three components of desalination, membrane grading scavenging, ABTS radicals, the ability of anti-superoxide anion and different processing conditions processing of ABTS radical scavenging rate: To investigate the relationship between the three components of the amino acid composition and in vitro antioxidant effect. The results showed that (1) pigskin protein hydrolyzate different components of the in vitro antioxidant role, size and its relative molecular mass size distribution of the different components of anti-oxidation, there is a close relationship between the amino acid composition. Component 1,2,3 Hydroxyl Radical Scavenging turn increases and significant difference between (P lt; 0.05): the ability to turn anti-superoxide anion component 2 gt; component 3 gt; component 1 significant difference between (P lt; 0.05); component between 2 and 3 to remove the ability of ABTS radical difference not statistically significant (P gt; 0.05), but they are significantly higher than the component (P lt; 0.05). (2) pigskin Hydrolysates of each component in the process of its antioxidant role affected in varying degrees. Wherein component 2 Clear the ABTS radical capacity by temperature, pH, storage time, and the addition amount of the divalent ions, the influence of differences of the saccharide added amount was significantly (P lt; 0.05): component 1 by pH, storage time, a divalent The ion concentration significant difference (P lt; 0.05); component 3 by pH, storing the time of impact difference was significant (P lt; 0.05). Three component 3 in the process to maintain a good anti-oxidation activity. 4. The pigskin different components of the protein hydrolyzate processing properties of: comparing the pigskin protease solution before and after solubility and oil absorption, as well as of hydrolysates from the three-component water absorption, emulsification, emulsion stability, surface hydrophobicity analysis solubility, the relationship between the surface-hydrophobic and emulsifying. The results showed that, the pigskin protease solution before and after, solubility, oil absorption change significantly (P lt; 0.05) better than pigskin protein hydrolysates solubility and oil absorption. The different molecular weight component of the pigskin Hydrolysates exhibit good absorbent, among Comparative worst absorbent component 1, component 3 is preferably, component 2 centered. Emulsifying properties of different components hydrolysates by the pH, protein concentration, the amount of oil, ionic strength, and other factors, the emulsifying properties of the components 2 and 3 wherein the ratio of component 1 is good, and the difference was significant (P LT; 0.05). Surface hydrophobicity index of the size of the different components as component 2 GT; component 3 GT; component 1, and among them the presence of a significant difference (P LT; 0.05). One of the protein surface hydrophobicity may be an important factor to affect its emulsifying properties 5 pigskin Hydrolysates of a different component of protein emulsified system Properties: A Comparative Study of the the protein emulsified viscosity of the system prepared by the components 1,2,3 elastic modulus and microscopic morphology. The results show that the three protein emulsifying system exhibit pseudoplastic nature of the fluid, the shear-thinning; stirred at low speed, the three protein emulsifying system of the elastic modulus influenced by the angular frequency changes significantly as the frequency increases. increases dramatically. Further, three manifested variation like: When the angular frequency of 1.8 to 100 rad / s when the angular frequency in the 0.1 to 1.5 rad / s, G \G 'is greater than G \Microscopy revealed that the component 2 and the component 3 to form a more uniform, fine emulsifying system component of an emulsifying system formed of relatively coarse, which is likely related to the size of the emulsifying ability of each component itself.

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