Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 342173
Title Behaviour of Staphylococcus aureus during sufu production at laboratory scale
Author(s) Han, B.; Sesenna, B.; Beumer, R.R.; Nout, M.J.R.
Source Food Control 16 (2005)3. - ISSN 0956-7135 - p. 243 - 247.
Department(s) Food Microbiology Laboratory
Publication type Refereed Article in a scientific journal
Publication year 2005
Keyword(s) fermented soybean food - quality
Abstract Sufu is a Chinese soybean cheese, obtained by fungal fermentation of soybean curd (tofu) with Actinomucor elegans to yield pehtze, followed by enzymatic maturation in brine solution containing 12-16%, (w/w) of NaCl for 2-6 months. After equilibration, the final product, sufu, usually contains half of the NaCl concentration of the brine used. We studied the behaviour (survival, growth, formation of enterotoxins) of several strains of Staphylococcus aureus in a laboratory- sea le simulation of the production of sufu. Of 15 S. aureus strains tested, strains No. 1, 3, 4, 5, 8, 9, and 10 showed good growth in sterile Brain Heart Infusion broth with high (6-12%, w/w) NaCl concentration, demonstrating their halotolerance. S. aureus growth was not negatively influenced by A. elegans, and no interaction between the mould and the bacterial strains was observed during pehtze preparation. S. aureus strains No. 3 and 5 were selected for maturation experiments because they grew up to 8.9-9.5 log cfu/g and they produced their typical enterotoxin in all substrates tested. With the objective of creating a worst-case scenario, halotolerant enterotoxin producing S. aureus strains were inoculated at several stages of the sufu model system. Levels of 6% and 12% of NaCl in the brine solution were still too low to inhibit their growth and enterotoxin production. Even 18% of NaCl in the brine solution could not inhibit their growth, but enterotoxin production was prevented. Brine solution with 24% of NaCl inhibited growth as well as enterotoxin production. In conclusion, a salt concentration of 9%, in the final product will be a minimum safeguard against S. aureus enterotoxin formation. (C) 2004 Elsevier Ltd. All rights reserved.
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