Effect of mono or co-culture of EPS-producing Streptococcus thermophilus strains on the formation of acid milk gel and the appearance of texture defects

Nguyen, An Thi-Binh; Picart-Palmade, Laëtitia; Nigen, Michaël; Jimenez, Luciana; Ait-Abderahim, Hassina; Marchesseau, Sylvie

doi:10.1016/j.idairyj.2019.06.007

Cited by 8 publications

(1 citation statement)

References 28 publications

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“…One disadvantage of these methods is that they can only be applied to investigate bacterial monocultures. In industrial applications, commercial starter cultures for yogurt fermentation usually consist of several strains of S. thermophilus , which are chosen for their specific properties such as fast acidification, texture-promoting capacity, and phage resistance ability ( Mostafaie et al, 2018 ; Nguyen et al, 2019 ). Although the phenotypic characterization of S. thermophilus strains would be an extensive and time-consuming task, this method is reliable and repeatable and can reflect the symbiotic characteristics of different strains.…”

Section: Introductionmentioning

confidence: 99%

Milk fermentation by monocultures or co-cultures of Streptococcus thermophilus strains

Han

Wu²,

Guo³

et al. 2022

Front. Bioeng. Biotechnol.

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Direct vat-set starter cultures are the key ingredient for the production of fermented dairy products. The characteristics of the strains used for fermentation determine the fermentation time, texture and flavor of the fermented milk products. In this study, a large-scale analysis of the acid production rate, texture, carbon source utilization characteristics of Streptococcus thermophilus strains was conducted. All 100 S. thermophilus strains were divided into six groups according to the acid production rate and into two groups according to the consistency texture. A universal medium, basing on the carbon sources metabolic properties were optimized (0.5% lactose and 3.5% glucose), to culture all of the tested strains. Among them 40 strains were used to test pH-controlled conditions using this universal culture medium. After 5–7 h of fermentation, the optical density (OD) values of all fermented products exceeded 10, suggesting the potential for high-density cultivation of S. thermophilus. Although the OD could be further increased by adding more glucose, this may have hindered subsequent lyophilization because of high residual lactic acid in the fermented product. Next, the application of Streptococcus thermophilus strains in fermented milk was studied. Monocultures and co-cultures of strains were evaluated and compared. The results revealed the existence of symbiotic or competitive relationships between different S. thermophilus strains. Based on the findings, the mixing ratio of three symbiotic S. thermophilus strains was optimized. A co-culture of these three strains yielded fermented milk with high viscosity, low post-acidification, good sensory properties and processability.

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Section: Introductionmentioning

confidence: 99%