• 作者： 蘇遠志
• 作者服務機構： 國立臺灣大學
• 中文摘要： 一、使用麩皮培養Mucor pusillus NTU-357 與 Mucor mucedo NTU-363 兩菌株，所得之 酵素抽取液經硫銨、丙酮、gel filtration、anion exchange chromatography 精製結果， NTU-357菌株之酵素比活性提高31.4倍，活性收率為33.40％；NTU-363 菌株提高66.5倍，活 性收率為20.25％。兩種精製酵素以 disc electrophoresis 分析結果證明均為 homogeneous.二、NTU-357 及 NTU-363 兩菌株之精製酵素和犢牛凝乳酵素，經測定理化學性質之結果如下： （1）最適作用溫度：NTU-357 及 NTU-363 兩菌株均為55℃，犢牛凝乳酵素為45℃。 （2）最適作用pH值：三種酵素在 pH 5.0～7.0 之間，其酵素活性均隨 pH 值之降低而增強。 （3）對熱之穩定性：在 60℃ 下放置20分鐘，NTU-357 菌株之酵素活性完全消失，惟NTU- 363菌株之酵素活性降低43％，犢牛凝乳酵素活性降低63％。 （4）對pH 之穩定性：NTU-357 菌株、NTU-363 菌株及犢牛凝乳酵素各在pH 4.0～6.5， pH 5.0～6.5 及 pH 4.5～7.0 範圍內甚為穩定。 （5）蛋白質水解活性：活性之強弱依序為 NTU-357 菌株酵素、NTU-363 菌株酵素、犢牛凝 乳酵素。 （6）金屬離子之影響：Ca 對酵素活性有極強之促進作用，尤以對 NTU-357 菌株酵素之 影響最大。Mg 亦發現有促進作用，但 Ni 對酵素活性卻有抑制作用。 （7）還原劑、thiol poison 及 chelating compound 之影響：此三類化合物之濃度在10 M 和10 M下，對三種酵素之活性皆無影響。 （8）毒性之檢定：作黃麴毒素之檢定結果均未發現其存在。三、使用NTU-357，NTU-363 兩菌株之粗酵素及犢牛凝乳酵素分別製造 Gouda type cheese 和 Cottage cheese並加以比較，其結果如下： （1）三種酵素製成之 Gouda type cheese，在製品收量、組織上及熟成過程大致相同，熟成 三個月之成品經風味試驗結果，使用 NTU-357 菌株之酵素者有強烈之苦味，而以NTU- 363 菌株之酵素與犢牛凝乳酵素製造之乾酪相較並無差異。 （2）三種酵素製成之 Cottage cheese，在外觀、組織和風味上頗為一致。惟製品之收量以 NTU-357 及 NTU-363 兩菌株之酵素製造者稍低。 （3）綜合觀之，以 NTU-363 菌株之酵素製成之乾酪優於 NTU-357，而 NTU-363 菌株之 酵素則可完全取代犢牛凝乳酵素。
• 英文摘要： 1. The enzyme extracts, produced by strains Mucor pusillus NTU-357 and Mucor mucedo NTU-363 which were cultivated in wheat-bran medium, were purified by ammonium sulfate, acetone, gel filtration and anion exchange chromatography. The results indicated that the specific activity of the enzymes from strains NTU-357 and NTU-363 increased 31.4 and 66.5 fold than those in their enzyme extracts and their yields were 33.4％ and 20.5％ respectively. And both of purified enzymes were testified to be homogeneous by using the disc electropho- resis analysis.2. The properties of the purified enzymes from strains NTU-357 and NTU-363 (MR-NTU-357, MR-NTU-363) were investigated. The results were as follows: (1) Optimum temperature: Optimum temperature for milk-clotting activity of MR-NTU-357 and MR-NTU-363 were found to be 55℃, while that of calf rennet (CR) was 45℃. (2) Optimum pH: When the enzymes were kept at pH 5.0 to 7.0, their activities were in increase with the decrease of pH. (3) Thermostability: When the enzymes were incubated at 60℃ for 20 min. the clotting activity of MR-NTU-357 was inactivated, while MR-NTU-363 and CR were lost 42％ and 63％ of their clotting activities respectively. (4) pH-stability: The clotting activities of MR-NTU-357, MR-NTU-363 and CR were stable at pH 4.0 to 6.5, 5.0 to 6.5 and 4.5 to 7.0 scparately. (5) Proteolytic activity: The enzymes tested for proteolytic activity on casein showed the following order of strength: MR-NTU-357＞MR-NTU 363＞CR. (6) Effect of metal ions: The clotting activity of enzymes used was activated by the addition of Ca and Mg , especially MR-NTU-357 was, but they were inhibited by Ni . (7) Effect of reducing agents, thiol poison and chelating compound: No effect of aboved compounds at concentrations of 10- and 10- M on clotting activity was found. (8) Assay for toxin: No aflatoxin was detected in both of MR.3. CR, crude MR-NTU-357 and MR-NTU-363 were used for the manufacture of Gouda and Cottage cheeses. The results were as follows: (1) The yield, body texture and the extent of ripening of Gouda type cheese made with both of MR (MR-cheese) were almost the same as those of CR- cheese (cheese made with CR). But, the strong bitter flavor was detected in MR-NTU-357 cheese ripened for 3 months, and the flavor of MR-NTU-363 and CR cheeses showed no difference. (2) The appearance, body texture and flavor of Cottage cheese made with both of MR and CR were almost alike. (3) In a word, the cheese made with MR-NTU-363 was better than with MR- NTU-357, and MR-NTU-363 was presumed that could substitute CR for cheese-making without changing conventional manufacturing process.
• 中文關鍵字： --
• 英文關鍵字： --