碩士 / 國立中興大學 / 食品科學系 / 86 / The effects of antimicrobials such as nisin, chelators ( EDTA
and HMP ), organic acids ( acetic acid, lactic acid and
potassium sorbate ), and their combinationsystems on the growth
of E. coli O157:H7 in ground beef were investigated. In
addition, the efficacy of immobilized antimicrobials against
this gram-negativepathogen by using an edible gel, alginate, as
immobilizer was evaluated as well.Acetic acid and potassium
sorbate could inhibit the growth of E. coli O157:H7effectively
whether at 10℃ or at 30℃. Both of EDTA and HMP could only
reduce the growth rate of E. coli O157:H7 and showed no
inhibition of the growth of this pathogen.In immobilized
antimicrobial system, most of immobilized antimicrobials treated
in this study could not inhibit the growth of E. coli O157:H7
both at 10℃ and at 30℃, which may even increase the population
of the microorganism due to maintain a moister environment for
its growth, except for acetic acid. At 30℃, immobilized acetic
acid could elongate the lag phase of E. coli O157:H7 from 4
hours to 8 hours contrast to free acetic acid. The result might
be due to the alginate coating not only reduce the
volatilization rate of acetic acid but extend the contact time
of acetic acid to target microorganism.In antimicrobial
combination system, treatment with nisin and EDTA or
potassiumsorbate at 10℃ revealed a lower cumulative change of
E.coli O157:H7 comparableto that with nisin, EDTA and potassium
sorbate alone. The use of immobilization technique could
elongate the effective time of treatment with nisin and EDTA or
potassium sorbate at 10℃. The inhibitory effect of nisin and
acetic acid at 10℃,not at 30℃, could also be improved by
applying the immobilization technique.In general, effect of
antimicrobial combination system on the growth of E. coliO157:H7
in ground beef is greater than those were used alone. On the
other hands,immobilized antimicrobial combination system can
extend the shelf-life of groundbeef comparing with unimmobilized
ones.
| Identifer | oai:union.ndltd.org:TW/086NCHU1253036 |
| Date | January 1998 |
| Creators | Tsai, Hung - Chi, 柴宏琪 |
| Contributors | Tony J. Fang, 方 繼 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 125 |
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