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71768

GROWTH, SURVIVAL AND ADAPTATION OF Shigella flexneri UNDER ACIDIC CONDITIONS RELEVANT TO THOSE APPLIED DURING DAIRY PROCESSING

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Last updated: 22 Jan 2023

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Abstract

Shigella flexneri is an important fooborne pathogen that has been associated with dairy products. This study aimed to assess the growth, survival and adaptation of S. flexneri under acidic conditions relevant to those adopted in dairy processing. S. flexneri could grow at mildly acidic pH values of 6.0 and 5.0 adjusted by HCl, lactic acid, or acetic acid, but at slower growth rates, compared to unacidified conditions of pH 7.3. Lower pH values ranging from 3.0 to 4.5 caused declines in the initial numbers of S. flexneri, but the pathogen could survive exposure to pH 4.0 and 3.5 for variable times depending on the acidifying agent. The order of sensitivity of S. flexneri to acids at those lower pH values were acetic acid > lactic acid > HCl. The survival of S. flexneri under the acidic conditions of yoghurt prepared from full fat (6%) and half fat (3%) buffalo's milk was also studied. The viable numbers of S. flexneri were generally higher in full fat yoghurt than half fat yoghurt on milk coagulation and during the cold storage of yoghurt. S. flexneri could survive for at least 14 days in full fat yoghurt, compared with 7 days in half fat yoghurt. This could be attributed to a potential protective effect of fat. S. flexneri exhibited an ability to adapt to acidic conditions, since its previous exposure to pH 5.5 increased its tolerance to pH 3.5. The pattern of acid tolerance in pH 3.5 by acid-adapted cells of S. flexneri depended upon the adaptation time that ranged from 30 min to 120 min.

DOI

10.21608/jfds.2013.71768

Keywords

Shigella flexneri, Milk, low pH, lactic acid, acetic acid, yoghurt, acid adaptation

Authors

First Name

M.

Last Name

Mahana

MiddleName

Y.

Affiliation

Dairy Dept., Fac. of Agric., Mansoura University,

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Orcid

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First Name

W.

Last Name

El-Sharoud

MiddleName

M.

Affiliation

Dairy Dept., Fac. of Agric., Mansoura University,

Email

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City

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Orcid

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First Name

Marwa

Last Name

El-Nabawy

MiddleName

E.

Affiliation

Dairy Dept., Fac. of Agric., Mansoura University,

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Orcid

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Volume

4

Article Issue

3

Related Issue

10810

Issue Date

2013-03-01

Receive Date

2020-02-18

Publish Date

2013-03-01

Page Start

87

Page End

99

Print ISSN

2090-3650

Online ISSN

2090-3731

Link

https://jfds.journals.ekb.eg/article_71768.html

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https://jfds.journals.ekb.eg/service?article_code=71768

Order

6

Type

Original Article

Type Code

886

Publication Type

Journal

Publication Title

Journal of Food and Dairy Sciences

Publication Link

https://jfds.journals.ekb.eg/

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Article

Created At

22 Jan 2023