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A primary study on texture
modification and proteolysis of mao-tofu during fermentation
Xinhuai Zhao* and Xiaoting
Zheng
Key Lab of
Dairy Science, Ministry of Education, Northeast Agricultural
University, Harbin 150030, PR China.
*Corresponding author. E-mail:
zhaoxh@mail.neau.edu.cn. Tel: 86 451 55191813. Fax: 86
451 55190340.
Accepted
17 December, 2008 |
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A strain of Mucor was isolated from mao-tofu, a local
fermented soybean product in central China, and used in this
study to evaluate its role on texture modification and
proteolysis of mao-tofu. Texture and microstructure of mao-tofu
was monitored by texture analyzer and scanning electron
microscopy (SEM). Proteolysis occurred during
fermentation was evaluated by SDS-PAGE and chemical
analysis. Results from Texture Profile Analysis showed that
adhesiveness of mao-tofu had an increase trend while
hardness, cohesiveness and springiness had a decrease trend
as fermentation progressed. SEM analysis showed that the
microstructure of mao-tofu was modified from a typical
network structure to a more homogeneous structure. SDS-PAGE
profiles indicated that cleavage of native soybean proteins
occurred during fermentation and that molecular weights of
most peptides were less than 20 kDa. The contents of
water-soluble protein, total free amino groups and
water-soluble free amino groups in mao-tofu fermented for 6
days were increased from 0.33%, 47.3 mmol/100 g and 120.7
mmol/100 g to 5.46%, 158.2 mmol/100 g protein and 338.2 mmol
/100 g protein, respectively. All these results indicated
that the texture or microstructure of mao-tofu was greatly
modified as the results of soybean protein degradation
during fermentation.
Key
words:
Mucor sp., mao-tofu, fermentation, texture, proteolysis. |
