| 摘要: | 本研究旨在探討於羊乳中分別接種 Lactobacillus. bulgaricus(CCRC 14009)、Streptococcus. thermophilus (CCRC 12257)、 L. acidophilus (CCRC 10695)、 Bido-bacterium. bifidum( CCRC 11844)、B. longum(CCRC 11847) 為菌元調製成酸酪乳， 分別測定 其理化學性狀和生物學之變化並探討將來利用之可行性。試驗共分三階段 ：第一階段為不同菌元之生長試驗， 採用單一或混合菌元接種 3%(V/V) 於滅菌羊乳中，測定發酵過程中之菌數、酸度、糖類及有機酸的變化以做 為其他階段之基本發酵條件；第二階段測定菌元發酵前後膽固醇、 脂肪 酸、 葉酸及游離胺基酸之變化； 第 T 階段為接種 (S.thermophilus + L. bulgaricus、L. acidophilus + B. bifidum、L. acidophilus + B.longum) 製成羊乳酸酪乳之貯存試驗。 第一階段試驗結果顯示：接種單株菌中以L. bulgaricus於第6小時最早達 到最高菌數，混合菌元則以S. thermophilus 與L. bulgaricus混合接種 組於第6小時最早達到最高菌數，所有菌元平穩期可維持14小時左右；菌 元分解乳糖與產酸能力，單株菌元以L. bulgaricus最強(p<0.05)， 混合菌元則以S. thermophilus與L. bulgaricus組較強；L(+)型乳酸，單 株菌以L. bulgaricus 及S. thermophilus產生量最高(p<0.05)，混合菌 元則 以S. thermophilus與L. bulgaricus混合組產生量顯著較高( p<0.05)；黏度方面，混合菌元可改善單一菌元不佳之問題。 第二階段試驗結果： 脂肪酸組成方面， 所有菌元於發酵後飽和短 中鏈脂肪酸(C4~C10) 有下降的趨勢 (p>0.05)； 膽固醇方面，發酵後皆 有上升情形； 葉酸含量，除L. bulgaricus 於發酵後有下降情形外， 其 餘各組皆有增加， 其中以 S. thermophilus增加 1.75 倍為最高 (p<0.05)； 游離胺基酸的變化， S. thermophilus 及 B. bifidum於發 酵後，游離必需胺基酸皆有增加趨勢。 第三階段試驗結果： 三組接種不同混合菌元羊乳酸酪乳於貯存四週後其 菌數均尚達109 CFU/ml；貯存期間酸度有輕微上升 (p<0.05)；三組中β - 半乳糖??活性皆有隨貯存時間而下降之趨勢； 乳清析出，三組皆隨 貯存時間增加而輕微增加 (p<0.05)；但是黏度則有些許下降之趨勢；在 貯存期間，其組成分 ( 蛋白質、脂肪、灰分等 ) 皆無顯著的改變 (p>0.05)； 而在官能品評方面，則隨貯存時間之增加，其總接收性平均 皆有下降之趨勢，然而質地組織並無顯著的改變 (p>0.05)；於貯存期間 ，以 L. acidophilus 與 B.bifidum 混合組平均外觀品評值最低。 綜合上述結論， 試製羊乳酸酪乳於貯存四週後，均可維持菌數在 109 CFU/ml，符合中國國家標準對一般發酵乳的規定 (107 CFU/ml)； 而原本 羊乳中就含有較低的乳糖，製成酸酪乳後有部分被分解再加上含有大量的 乳糖分解?存在，因此有利於乳糖不耐症者食用；然羊乳酸酪乳仍具有的 特殊羊騷味，是否能廣受大眾喜愛，如何改善並研發多種適當調合口味， 以符合產品多元化的市場需求，則有待將來進一步的研究探討。
Five strains of lactic acid bacteria Lactobacillus bulgaricus (CCRC14009), Streptococcus thermophilus (CCRC 12257), L. acidophilus (CCRC 10695),B. bifidum (CCRC 11844) and B. longum (CCRC 11847) were used as startersculture on the manufacturing of goat(s yogurt. In experiment Ⅰ the grown-uptest of single or mixed starters was performed for testing of variation of thenumbers of lactic acid bacteria, TA%, carbohydrate and organic acid in theprocess of fermentation as basic condition. In exp. Ⅱ, C ange on content ofcholesterol, free fatty acid, folic acid and free amino acid by exp. Ⅰstarter used after fermentation.In exp. Ⅲ, three goat(s yogurt ( L.bulgaricus + S. thermophilus、 L. acidophilus + B. bifidum and L. acidophilus +B. longum ) was examined during processing and storaging at 4 ℃ for 4 weeks. The results were as follows： Experiment Ⅰ. 1. L. bulgaricus was the starter first reached stationary phase within sixhours. Mixed starters of S. thermophilus and L. bulgaricus (1:1), were the early reached the stationary phase within six hours. The stationary phase can keep going for about 14 hours. 2. L. bulgaricus had the strongest ability in lactose hydrolysis and lacticacid forming ( p<0.05). Mixed starters of S. thermophilus and L. bulgaricus had the strongest ability in lactose hydrolysis and lactic acid forming(p<0.05). 3. The maximum production of L(+) lactic acid is the mixture L. bulgaricus andS. thermophilus (p<0.05) at the mix ratio of 1:1, the average is 1.42 (g/dl)during the periods of fermentation. In the single starter was L. bulgaicusproducing maximum L(+) lactic acid (p<0.05). 4. The L. bulgaricus has the better perfermance of viscosity in the singlestarter treatments, and the mixed starter can improve the viscosity fermentedwith single starter. Exp. Ⅱ. 5. After fermentation, the amont of saturated short chain fatty acid (C4-C10)had decreased (p>0.05) in all starters. 6. Cholesterol content was increased after fermentation in all starters. 7. Folic acid content, except L. bulgaricus was decreased after fermentation,others were increased. 8.After fermentation, free amino acids content of S. thermophilus and B.bifidum group increased, individually, which higher than other strains. Exp.Ⅲ 9. 4 weeks of storage, the lactic acid bacteria counts of three goat(s yogurttreatments were 109 CFU/ml, there were slightly increased during storage. 10.With the increasing of storage time, the activity of β -galactosidase ofthree goat milk yogurt treatments was decreased. 11. With the increasing of storage time, the syneresis increase slightly amongthe three treatments, and the viscosity decreased slightly. 12. During storage, three goat(s yogurt were not different significantly inyogurt composition (protein, fat and ash,etc) (p>0.05). 13. In respect of organoleptic test, with the increasing of storage time, themean total acceptability decrease, but there is not different significantly intexture (p>0.05). During the storage time of goat milk yogurt, both L.acidophilus and B. bifidum had the lowest mean appearance score. In general, the lactic acid bacteria in goat yogurt decreased duringstorage. But they can still maintain above 109 CFU/ml during four weeksstorage which is reaching the Chinese National Standard about the fermentedmilk ( 107 CFU/ ml). Not only goat milk was low lactose content than cow milk, but also a great deal of lactose were hydrolyzed in the goat,s yogurt whichshould be advantagous of lactase intolerance consume it. Concering goat milkordor, which applied to developing market, many kinds of fla ored productsshould be developed to satisfy the request of the multiplicities of products. |
