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EISSN: 2313-3724, Print ISSN: 2313-626X

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 Volume 7, Issue 8 (August 2020), Pages: 11-16


 Original Research Paper

 Title: Initial enumeration and viability of probiotic strains in commercial yogurt products under refrigerated conditions

 Author(s): Awfa Y. Alazzeh 1, *, Rafat Zrieq 2, Firas S. Azzeh 3, Majdi M. Smadi 1, Shadi Sulaiman 4, Samir Qiblawi 5


 1Department of Clinical Nutrition, College of Applied Medical Sciences, University of Ha'il, Ha'il, Saudi Arabia
 2Department of Public Health, College of Public Health and Health Informatics, University of Ha'il, Ha'il, Saudi Arabia
 3Department of Clinical Nutrition, College of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
 4Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, University of Ha'il, Ha'il, Saudi Arabia
 5Department of Histopathology, College of Medicine, University of Ha'il, Ha'il, Saudi Arabia

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 * Corresponding Author. 

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Yogurt is one of the main food products that contain probiotic bacteria. Probiotic bacteria should be of not less than log 8 Colony-forming unit per ml (CFU/ml) in yogurt products to be effective as probiotic product. The objectives of this study were to investigate the initial enumeration and the viability of probiotic bacteria in the yogurt marketed in Saudi Arabia under refrigerated storage conditions. Twenty yogurt samples were collected and stored in 4oC, and then enumeration was conducted using the specific growth agar for the probiotic bacteria. In addition, pH measurements and water holding capacity were conducted. The results of this study showed that the initial enumeration of both S. thermophilus and Lactobacillus delbrueckii spp. Bulgaricus was higher than log 8 CFU/ml in all the commercial products studied. However, the initial enumeration of bifidobacteria was considerably low (0.8-4.5 log CFU/ml) in all the commercial products studied. Viability of both S. thermophilus and Lactobacillus delbrueckii spp in all commercial products slightly decreased during the 4-week refrigeration period. However, the viability of bifidobacteria in the commercial products was slightly decreased up to 3 weeks of recreation. In week 4, the viability of bifidobacteria in all the commercial products studied was drastically decreased. Different techniques should be adopted to improve the initial enumeration of bifidobacteria in commercial yogurt products and to improve its viability during storage conditions. 

 © 2020 The Authors. Published by IASE.

 This is an open access article under the CC BY-NC-ND license (

 Keywords: Yogurt, Enumeration, Viability, Probiotics, Refrigerated conditions

 Article History: Received 28 January 2020, Received in revised form 25 April 2020, Accepted 28 April 2020


The authors thank the technical team at the Faculty of Applied Medical Sciences at University of Ha’il. This project was funded by the Deanship of Scientific Research, University of Ha'il, project no. 0150439.

 Compliance with ethical standards

 Conflict of interest: The authors declare that they have no conflict of interest.


 Alazzeh AY, Zrieq R, and Azzeh FS et al. (2020). Initial enumeration and viability of probiotic strains in commercial yogurt products under refrigerated conditions. International Journal of Advanced and Applied Sciences, 7(8): 11-16

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 Table 1


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