【作者】 郭善广；

【导师】 赵谋明；

【作者基本信息】 华南理工大学 ， 食品科学， 2007， 博士

【摘要】 我国是肉类生产大国,肉制品加工副产物血液产量丰富,仅猪血一项年产量就达130万吨以上。畜禽血液营养丰富,其中大部分为血红蛋白存在于红血球中,占血液总蛋白质含量的70～80%,而且血红蛋白中还含有丰富的血红素铁。由于其口感、色泽的原因只有少部分被人们直接食用,其他大部分被用作动物饲料。即使是用作饲料,也仍然存在着难以消化吸收、生物利用率低的重要问题。本文以血红蛋白为原料,研究蛋白酶水解血红蛋白的优化条件及内在规律,进行血红蛋白酶解液的脱色及血红素提取,评价酶解产物及脱色产物的风味、探讨二者的抗氧化活性,以期为血红蛋白的酶解、酶解液脱色、血红素提取和酶解产物利用提供理论依据和技术支撑。成分分析结果表明猪血红细胞(血红蛋白)是一种高蛋白、低脂肪、低热量原料,非常适合作为水解底物。单一酶水解血红蛋白蛋白质回收率(PR)较低。冷冻、超声和均质溶血使酶解过程的PR增加5-7%。Pancreatin与Protamex (PP)、Pancreatin与Flavourzyme (PF)组成的两种组合酶水解血红蛋白的PR达95%左右,而且产物没有苦味。两种组合酶对底物中优先作用疏水性氨基酸,降低了酶解产物产生苦味的可能。酶解产物的Q值与风味评价结果吻合,可用于指导生产实践。组合酶水解体系在水解时可能会发生一些产物之间的聚合反应,导致PR有所降低。吸附助剂对色素的有一定的亲和能力,但不是脱色的关键因素。pH对两种组合酶水解液的脱色效果影响显著。色素自身的絮凝和沉降作用在脱色过程中起主导作用。色素因疏水相互作用产生笼形水合物并形成较大粒径的水合物晶体,可离心除去。脱色可降低肽的疏水性、改善水解产物的风味。酶解和脱色均可提高血红蛋白的营养价值。冷冻结晶可以富集、浓缩血红素。PF和PP两种组合酶的血红蛋白酶解液及其脱色酶解液均具有DPPH自由基清除能力、还原力和铁离子螯合能力,前者酶解产物的活性高于后者。水解度与抗氧化活性的相关性比较差。脱色可明显降低抗氧化活性。PF水解产物的铜离子螯合能力弱于PP水解产物,脱色可以提高产物的铜离子螯合能力。PF和PP酶解产物及其脱色产物可以抑制亚油酸氧化体系中的过氧化作用,而且具有一定的量效关系。脱色降低酶解产物的抗脂质过氧化能力。PF脱色血红蛋白酶解产物能够抑制广式腊肠中的脂质过氧化反应,但无明显剂量效应。浓度为4%的PF脱色血红蛋白酶解液可抑制腊肠酸价升高。喷雾干燥产物抑制酸价升高的能力与抑制脂肪氧化的能力均强于酶解液,可能是在加工过程中产生了具有抗氧化性质的新物质。PF和PP两种组合酶的脱色血红蛋白酶解液的平均疏水性有所下降,PF和PP的脱色产物的抗氧化性随着其平均疏水性的下降而降低。肽的分子量与其抗氧化性之间无相关性,主要应取决于其氨基酸组成和三维构象,疏水性氨基酸较之亲水性氨基酸在构成和维持肽的立体构象的作用可能会更强一些,因此疏水性氨基酸对肽的抗氧化性影响会更大一些。血红蛋白酶解产物分离出的三种肽类的活性具有差异,其中碱性肽的活性最强,酸性肽次之,中性肽最弱。更多还原

【Abstract】 China is a big meat process country and has an abundant byproduct blood in which only porcine blood can generate 1.3 million tons annually. Animal blood is richly containing hemoglobin in the blood cells which represents 70-80% of the protein content of blood and also includes contains hematin. However, due to the taste and the color only a little blood was consumed directly by people and the other larger amounts was used as feedstuff. Further more, blood is still can not be digested and absorbed easily for the problem of low bioavailability. This work used hemoglobin as resources, researching optimal conditions and some intrinsic mechanisms of enzymatic hydrolysis of hemoglobin, decoloring the hydrolysate and extracting hematin, valuing the flavor and antioxidant activity of the hydrolysate and the decolorized for supporting the theory and technology of enzymic hydrolysis of hemoglobin, decolorization, extraction of hematin, and utilization of the product.The composition of porcine hemoglobin showed it had high content of protein, low content of fat and low calorie. Therefore, porcine hemoglobin was a good substrate for hydrolysis. Hemoglobin was hydrolyzed by one protease just obtaining relatively low protein regovery (PR). Freeze, ultrasonic and homogenization can hemolyze blood cells and increase PR of hydrolysis for 5-7%. Both of the enzyme admixtures, Pancreatin and Protamex (PP) as well as Pancreatin and Flavourzyme (PF), hydrolyzed hemoglobin got high PR about 95%. And moreover, the hydrolysates had no bitter taste. The both of the enzyme admixtures had specificity for terminal a variety of hydrophobic amino acids and thus reduced the bitter taste of the product. The Q value of the hydrolysate was in agreement with the results of taste, so the Q rule can be direct the practice. During hydrolysis of hemoglobin by the both enzyme admixtures, the product aggregated leading to decrease PR.Though adsorbent can adsorb pigment it was not critical factor for decoloring. pH significantly influence the result of decolorization. Pigments flocculated and precipitated between themselves during process leading to decolorization. Pigment formed clathrate hydrates for the sake of hydrophobic interaction and further aggregated to bigger clathrate hydrates which can be removed by centrifuge. Decolorization reduced the hydrophobicity of peptides and improved the flavor of product. Hydrolysis and decolorization can promote the nutritional value of hemoglobin. Freeze can enrich and concentrate hematin.The hydrolysate and its decolorized of PF and PP had DPPH radical scavenging activity, reducing power and ferrous ion chelating activity, and the activity of the former hydrolysate was stronger than that of the latter. No relativity between the degree of hydrolysis and the above mentioned antioxidant activity which can be depressed by decolorization. In contrast, copper ion chelating activity, which can be improved by decolorization, of the hydrolysate of PF was weaker that of PP.The hydrolysate and its decolorized of PF and PP restrained lipid peroxidation in the linoleic acid system, and the antioxidant activity, which was also can be depressed by decolorization, was increased with increasing concentration of the products. The decolorized of PF inhibited lipid peroxidation in Chinese Cantonese sausage, but the activity had no relation to the concentration. At higher concentration of 4%, the decolorized of PF decreased the acid value of Chinese Cantonese sausage. The activity of inhibiting lipid peroxidation and decreasing acid value of powder of spray-dried was stronger than that of liquid hydrolysate possibly due to generated new material possessing antioxidant activity.The average hydrophobicity of hydrolysate coming from PF and PP was reduced after decolorization, and the antioxidant activity of the both decolorized decreased with decreasing the hydrophobicity. No relativity was found between antioxidant activity and molecular weight of peptides; the antioxidant activity of peptide should mainly determined by amino acid composition and cube configuration. The effect of hydrophobic amino acid on constituting and maintaining the cube configuration was more important than that of hydrophilic amino acid, and so the hydrophobic amino acid influenced deeper the antioxidant activity of peptide than hydrophilic amino acid. Three categories peptides separated from hydrolysate of hemoglobin had different antioxidant activity, among which, the antioxidant activity of basic peptide was strongest, acidic peptide took second place and the neutral was weakest.更多还原