雞肝水解物之製備與抗氧化功效評估

隨著畜產品之開發越來越多元化，如能針對雞肝之特性加以開發利用，則可增加相關產業之收益，亦可提高其附加價值。欲開發雞肝之利用價值，本試驗中利用酵素水解，將雞肝酵素水解為雞肝水解物(chicken-liver hydrolysates, CLH)，進行成分分析、體外抗氧化能力與體內抗氧化功效之評估。體外試驗結果中發現：由alcalase、papain與pepsin水解雞肝試驗中，以pepsin水解產物之DPPH自由基清除能力最佳，因而選擇pepsin作為後續水解雞肝之用；接著藉由製成率、蛋白質與胜肽含量變化、成本效益、及體外抗氧化試驗，篩選出酵素受質比1:400水解2小時，作為水解雞肝之最適條件。CLH之成分變化分析結果中發現，雞肝經酵素水解後，胜肽片段皆小於10 KDa，而胺基酸組成中以天門冬胺酸與麩胺酸此兩種酸性胺基酸含量最高；而CLH中含有抗氧化金屬離子成分錳、硒，而有害重金屬離子，鎘、汞、錫、砷等含量皆遠遠低於國家標準。接續評估CLH之體內抗氧化功效，實驗中將利用D-半乳糖誘導體內氧化壓力上升之C57BL/6小鼠作為此次試驗之動物模型；確立D-半乳糖動物模型試驗中，選定以1.2 g D-半乳糖/ kg BW作為最適誘導劑量。體內抗氧化功效評估試驗中，D-半乳糖處理之小鼠同時補充低劑量(50 mg/kg BW)與高劑量(250 mg/kg BW)之CLH，經由分析小鼠體內氧化壓力與抗氧化酵素活性結果中發現，D-半乳糖處理組之體內氧化壓力顯著高於控制組(P<0.05)，而體內抗氧化酵素活性也顯著低於控制組(P<0.05)；補充CLH之組別，可顯著改善D-半乳糖誘導下氧化壓力上升與抗氧化酵素活性下降之現象(P<0.05)。綜觀上述可知，CLH具有良好之體外與體內抗氧化能力。

關鍵字

雞肝；抗氧化；半乳糖

並列摘要

To enhance the value of chicken livers, this study was to develop antioxidative chicken-liver hydrolysates (CLHs) via an enzymatic hydrolysis. According to the in vitro results, the CLHs produced by pepsin showed the best (P<0.05) DPPH scavenging ability than those produced by alcalase and papain. Furthermore, the optimal hydrolyzing conditions were chosen as the enzyme to substrate ratio, 1:400 and 2hours based on yield, protein and peptide contents, costs, and in vitro antioxidative tests of CLHs. An SDS-PAGE analysis indicated that molecular weights of peptides in final manufactured CLHs were lower than 10KDa. Besides, CLHs were rich of acidic amino acids, i.e. aspartic acid (Asp) and glutamic acid (Glu), and also contained both manganese (Mn) and selenium (Se) which are essential cofactors of antioxidative enzymes, superoxide dismutase and glutathione peroxidase, respectively. The contents of heavy metal ions. i.e. cadmium (Cd), mercury (Hg), tin (Sn) and arsenic (As) in CLHs did not exceed the regulatory levels of Taiwan Food and Drug Administration (TFDA) as well. To evaluate the in vivo antioxidative effects of CLHs, the oxidative animal model was successfully established by 1.2g D-galactose (DG)/kg BW in male 12-week-old C57BL/6 mice. After 6 weeks of experimental period, DG increased (P<0.05) TBARS values and decreased (P<0.05) GSH and TEAC levels in serum and organs compared to non-DG treatments. However, those antioxidative values were improved (P<0.05) by CLH cotreatments. In conclusion, our manufactured CLHs showed antioxidative abilities which may result from its peptide structures, acidic amino acids, and antioxidative minerals. We hope that this study not only diversifies animal byproducts to increase the byproduct’s value but also offers consumer another choice of healthy ingredients from animals.