Survival of <i>Escherichia Coli</i> O157:H7 During Storage of Yogurt at Different Temperatures

Bachrouri, M.; Quinto, E. J.; Mora, Mabel

doi:10.1111/j.1365-2621.2002.tb08743.x

Cited by 34 publications

(33 citation statements)

References 22 publications

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“…Our results are in accordance with those observed by Kasımoglu and Akgün (19) and Bachrouri et al (5) , who reported counts of E. coli O157:H7 increased about 1 log CFU mL -1 from initial inoculum during fermentation process. In the same context, Osaili et al (18) reported a large increase of E. coli O157:H7 count of 3.05 log CFU mL -1 during the fermentation process.…”

Section: Resultssupporting

confidence: 93%

“…Some researchers have studied the survival of E. coli O157:H7 in food systems, especially yogurt, and they have related the survival of the cells during fermentation process (5,18) . Our results suggested E. coli O157:H7 was able to grow despite the acidic environment developed and the bacterial competition.…”

Section: Resultsmentioning

confidence: 99%

“…Although yogurt is considered safe due to low acidity, some authors have reported E. coli O157:H7 survival during the storage period (5,6) . It has been shown that E coli O157:H7 cells have an effective mechanism to resist to extreme acid stress situations, and its resistance depends on the interaction with environmental compounds (7) .…”

Section: Introductionmentioning

confidence: 99%

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Escherichia coli O157:H7 SURVIVAL IN TRADITIONAL AND LOW LACTOSE YOGURT DURING FERMENTATION AND COOLING PERIODS

et al. 2017

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The purpose of this study was to evaluate the behavior of E. coli O157:H7 during lactose hydrolysis and fermentation of traditional and low lactose yogurt. It also aimed to verify E. coli O157:H7 survival after 12 h of storage at 4 °C ±1 °C. Two different types of yogurts were prepared, two with whole milk and two with pre-hydrolyzed whole milk; in both groups one yogurt was inoculated with E. coli O157:H7 and the other one was not inoculated. The survival of E. coli and pH of yogurt were determined during fermentation and after 12-h refrigeration. The results showed that E. coli O157:H7 was able to grow during the fermentation period (from 4.34 log CFU.mL -1 to 6.13 log CFU.mL -1 in traditional yogurt and 4.34 log CFU.mL -1 to 6.16 log CFU.mL -1 in low lactose yogurt). The samples with E. coli O157:H7 showed gas formation and syneresis. Thus, E. coli O157:H7 was able to survive and grow during fermentation of traditional and low lactose yogurts affecting the manufacture technology. Moreover, milk contamination by E. coli before LAB addition reduces the growth of L. bulgaricus and S. thermophilus especially when associated with reduction of lactose content Keywords: β-galactosidase; EHEC; fermented milk; lactic acid bacteria; lactose hydrolysis. ResumoObjetivou-se no presente estudo avaliar o comportamento da E. coli O157:H7 durante o processo de hidrólise da lactose e fermentação de iogurte tradicional e com teor reduzido de lactose. Além disso, objetivou-se verificar a viabilidade da E. coli O157:H7 e a viabilidade das bactérias ácido láticas após 12 h de estocagem a 4 °C ±1 °C. Dois diferentes tipos de iogurte com amostras controle e amostras inoculadas foram preparados, sendo dois com leite integral e dois com leite integral pré-hidrolisado; em ambos os grupos um foi inoculado com E. coli O157:H7 e um não foi inoculado. A 2 Cienc. anim. bras., Goiânia, v.18, 1-9, e-39554, 2017Escherichia coli O157:H7 survival in traditional and low lactose yogurt during fermentation sobrevivência da E. coli e o pH dos iogurtes foram determinados durante a fermentação e após 12h de refrigeração. A partir dos resultados observou-se que a E. coli O157:H7 foi capaz de se multiplicar ou manter-se viável durante a fermentação (4,34 UFC.mL -1 para 6,13 UFC.mL -1 no iogurte tradicional e 4,34 UFC.mL -1 para 6,16 log UFC.mL -1 em iogurte com lactose reduzida). Nas amostras inoculadas com E. coli O157:H7 houve formação de gás e sinérese. Dessa forma, concluiu-se que a E. coli O157:H7 foi capaz de sobreviver e de se multiplicar durante a fermentação afetando a tecnologia de fabricação. Além disso, a contaminação do leite antes da adição das BAL reduziu o crescimento de L. bulgaricus e S. thermophilus, especialmente quando associado à redução da lactose. Palavras-chave: β-galactosidase; bactérias ácido láticas; EHEC; hidrólise da lactose; leite fermentado.

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

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Escherichia coli O157:H7 SURVIVAL IN TRADITIONAL AND LOW LACTOSE YOGURT DURING FERMENTATION AND COOLING PERIODS

et al. 2017

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“…Bachrouri et al (2002) observed that E. coli O157:H7 counts decreased by only 0.8 log 10 cfu/g in yoghurt stored at 4 C for 72 h, while in yoghurt stored at 22 C, they could not detect any bacteria after 16 h of challenge. Since commercial Amasi was refrigerated at 7 C for 24 h, survival of E. coli O157:H7 could have been enhanced by low temperature, compared to that in traditional Amasi, which was kept at ambient temperature throughout the 3-days of challenge.…”

Section: Enumeration and Characterization Of Microorganisms In Traditmentioning

confidence: 94%

Adaptation of Escherichia coli O157:H7 to acid in traditional and commercial goat milk amasi

Dlamini

Buys

2009

Food Microbiology

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a b s t r a c tAcid resistance of Escherichia coli O157:H7 strains UT 10 and UT 15 were determined in traditional Amasi fermented for 3 days at ambient temperature (ca 30 C) and commercial Amasi fermented at 30 C for 24 h and stored at 7 C for 2 days. Escherichia coli O157:H7 counts in commercial Amasi were detected at 2.7 log 10 cfu/ml after 3 days while those in traditional Amasi could not be detected after the same period. There was no significant difference (p # 0.05) in the survival of acid adapted (AA) and non-adapted (NA) E. coli O157:H7 in traditional Amasi, while in commercial Amasi, the NA strain survived significantly (p # 0.05) better than its AA counterpart. Regardless of prior adaptation to acid, E. coli O157:H7 can survive during fermentation and storage of fermented goat milk Amasi. Also, the fermentation time, pH and storage temperature affects the survival of E. coli O157:H7 in the fermented milk.

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“…Akdemir-Evrendilek 22 noticed that E. coli O157:H7 in the plain yoghurt, yoghurt drink and fresh-salted yoghurt inoculated with 10 6 -10 7 cfu/mL E. coli O157:H7, survived for 45 days at 4 and 22ºC. Bachrouri et al 34 studied the behavior of E. coli O157:H7 strains during the storage of plain live yoghurt at 4ºC. The researchers reported that E. coli O157:H7 counts decreased from 4.4 log cfu/g to 3.6 log cfu/g after 72 h and was not detected after 312 h. In these samples the pH values ranged from 3.94 to 4.11 during the storage.…”

Section: Discussionmentioning

confidence: 99%

İki Farklı pH Değerine Kadar İnkübe Edilen ve 4oC’de Depolanan Yoğurtlarda E. coli O157:H7’nin Canlı Kalma Durumu

Arican¹,

Andiç²

2009

Kafkas Univ Vet Fak Derg

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SummaryIn the present study the survival of Escherichia coli O157:H7 in yoghurt produced at two different initial pH levels was investigated. Samples were contaminated with two different doses of E. coli O157:H7 (10 3 cfu/mL and 10 5 cfu/mL). Yoghurt samples were taken from incubation at pH 4.0 and 4.6. Incubated samples were stored at 4 o C for 14 days. In the samples, viable counts of E. coli O157:H7, pH and titratable acidity were determined on day 0 and the 1 th and 14 th days of storage. E. coli O157:H7 survived in yoghurt produced at pH 4.0 and 4.6 in the both contamination level. The survival of E. coli O157:H7 was significantly lower at pH 4.00 than at pH 4.60 (P<0.001) and at 10 3 cfu/mL than at 10 5 cfu/mL contamination level (P<0.001).

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Survival of Escherichia Coli O157:H7 During Storage of Yogurt at Different Temperatures

Cited by 34 publications

References 22 publications

Escherichia coli O157:H7 SURVIVAL IN TRADITIONAL AND LOW LACTOSE YOGURT DURING FERMENTATION AND COOLING PERIODS

Escherichia coli O157:H7 SURVIVAL IN TRADITIONAL AND LOW LACTOSE YOGURT DURING FERMENTATION AND COOLING PERIODS

Adaptation of Escherichia coli O157:H7 to acid in traditional and commercial goat milk amasi

İki Farklı pH Değerine Kadar İnkübe Edilen ve 4oC’de Depolanan Yoğurtlarda E. coli O157:H7’nin Canlı Kalma Durumu

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