| Summary: | 碩士 === 東海大學 === 畜產學研究所 === 85 === 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.
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