| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 85 === This study was conducted to investigate the growth of Bifidobacterium
spp., and changes of the composition in soymilk during the fermentation
process.Results indicate that the growth behavior of Bifidobacteria in
soymilk varied with different species. Supplementation of carbon or
nitrogen sources into soymilk promotes growth of Bifidobacteria strains
differently. Addition of glucose, lactose, bifitose stimulated the
growth of B. infantis ATCC 14633. On the other hand, the highest maximum
population of B. longum B6 was found to reach its maximum after 48 hour
of cultivation in soymilk added with lactose or galactose. Meanwhile,
addition of peptone, tryptone, casitone, casein enzymatic hydrolysate or
yeast extract to soymilk enable B. infantis ATCC 14633 to reach its
growth maximum in a shorter cultivation time of 24 hour. Besides, B.
longum B6 grows relatively well, determined after 24 hour of cultivation,
in soymilk added with yeast extract or malt extrat than that in control.
It was also found that the growth of Bifidobacterium spp. tested in
soymilk uncouples to its acid production. Acid production of
Bifidobacteria mainly concentrated in stationary phase of its growth.
Increased contents of crude protein and the titrable acidity in soymilk
after 48 hour of fermentation with Bifidobacterium spp. were noted.
Besides, amount of free amino acids also increased in the fermented
soymilk, indicating that test organisms are capable of hydrolysing
protein. Meanwhile, contents of thiamin and riboflavin increased while
niacin decreased in soymilk fermented with either B. infantis ATCC 14633
or B. longum B6.
The ratio of acetic to lactic acid content in soymilk reached
approximately 1.5 after 48 hour of fermentation. Contents of stachyose,
raffinose decreased while contents of monosaccharide such as fructose,
glucose and galactose, increased slightly in the fermented soymilks.
B. infantis ATCC 14633 and B. longum B6 showed a significant difference
in their viability in fermented soymilks during the storage period.
Holding at 5℃or 25℃, viable cells of B. longum B6 reduced more than
those of B. infantis ATCC 14633. However, less population reduction of
test organisms was noted at 5℃than at 25℃. After 10 day storage at
5℃, the population of B. infantis ATCC 14633 and B. longum B6 was
reduced about 0.44 log CFU/ml and 3.18 log CFU/ml, respectively.
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