Diversity in NaCl tolerance of Lactococcus lactis strains from dl-starter cultures for production of semi-hard cheeses

Kristensen, Lise Søndergaard; Siegumfeldt, Henrik; Larsen, Niels‐Erik; Jespersen, Lene

doi:10.1016/j.idairyj.2020.104673

Cited by 6 publications

(4 citation statements)

References 21 publications

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“…The knowledge about sodium chloride tolerance of an L. lactis isolate allows a rational selection and control of starter cultures in the manufacture of dairy products, especially cheese, with different levels of salt. Thus, incorporation of strains more sensitive to salt in initial cultures would potentially increase autolysis and the release of intracellular enzymes, neutralizing with sensory defects, such as bitterness, often described in low-salt cheeses (Kristensen et al 2020).…”

Section: Resultsmentioning

confidence: 99%

Probiotic Characterization And Safety Assessment of Lactococcus Lactis Subsp. Lactis R7 Isolated From Ricotta Cheese

Cunha

Uecker

Jaskulski

et al. 2021

Preprint

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The aim of this study was to identify and characterize in vitro Lactococcus lactis R7 isolated from commercial ricotta cheese. The results from phenotypic characterization demonstrated that L. lactis R7 had growth potential in a wide temperature range (15 °C and 45 °C), ability to tolerate high osmotic concentrations (sodium chloride 4.0 %), ability to growth in acidic and alkaline condition (pH 2.0 and 9.6), and ability to sugar fermentation (glucose, maltose and ribose). The findings confirm that L. lactis R7 belong to the genus Lactococcus. The results from molecular identification by 16S RNA identified the isolate as Lactococcus lactis subsp. lactis R7. The phenotypic characteristics combined with the molecular identification, indicate that the isolate R7 belongs to the lactis subspecies. The isolate L. lactis R7 was tolerant to acidity and bile salts. In the intestinal tract, cell concentrations were higher than 7.98 log CFU.mL-1 in the presence and absence of bile salts. L. lactis R7 showed antioxidant and inhibitory capacity for lipid peroxidation. It also demonstrated capacity for self-aggregation (25.8%), coaggregation (18.3%) and hydrophobicity (11.1%). The antagonist activity of the isolate was greater against Staphylococcus aureus (12.2 mm), when compared to Escherichia coli (11.1 mm) and Salmonella enteritidis (9.5 mm). In the MTT assays, L. lactis R7 did not show cytotoxicity to VERO cells at the evaluated concentrations. In conclusion, L. lactis R7 isolated from ricotta cheese presented probiotic characteristics and compatible safety aspects for use as a food technology culture.

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Section: Resultsmentioning

confidence: 99%

Probiotic Characterization And Safety Assessment of Lactococcus Lactis Subsp. Lactis R7 Isolated From Ricotta Cheese

Cunha

Uecker

Jaskulski

et al. 2021

Preprint

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“…It is likely that the salt reduction applied was not sufficiently contrasted; salt levels can affect both bacterial growth and metabolic activities in a strain-dependent manner, as previously illustrated on L. lactis , and P. freudenreichii in Swiss-type cheeses. , …”

Section: Discussionmentioning

confidence: 99%

“…Therefore, under the conditions of the present study, the reduction in salt did not modify the profile of aroma compounds. It is likely that the salt reduction applied was not sufficiently contrasted; salt levels can affect both bacterial growth and metabolic activities in a strain-dependent manner, as previously illustrated on L. lactis 45,46 and P. freudenreichii in Swiss-type cheeses. 47,48 4.3.2.…”

mentioning

confidence: 99%

Fine-Tuning of Process Parameters Modulates Specific Metabolic Bacterial Activities and Aroma Compound Production in Semi-Hard Cheese

Cao

Aubert

Maillard

et al. 2021

J. Agric. Food Chem.

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The formation of cheese flavor mainly results from the production of volatile compounds by microorganisms. We investigated how fine-tuning cheese-making process parameters changed the cheese volatilome in a semi-hard cheese inoculated with Lactococcus (L.) lactis, Lactiplantibacillus (L.) plantarum, and Propionibacterium (P.) freudenreichii. A standard (Std) cheese was compared with three variants of technological itineraries: a shorter salting time (7 h vs 10 h, Salt7h), a shorter stirring time (15 min vs 30 min, Stir15min), or a higher ripening temperature (16 °C vs 13 °C, Rip16°C). Bacterial counts were similar in the four cheese types, except for a 1.4 log 10 reduction of L. lactis counts in Rip16°C cheeses after 7 weeks of ripening. Compared to Std, Stir15min and Rip16°C increased propionibacterial activity, causing higher concentrations of acetic, succinic, and propanoic acids and lower levels of lactic acid. Rip16°C accelerated secondary proteolysis and volatile production. We thus demonstrated that fine-tuning process parameters could modulate the cheese volatilome by influencing specific bacterial metabolisms.

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“…The salt tolerance of lactococcal isolates from a commercial DL-culture used for Danbo cheese manufacture was examined at 3.4%, 8.0%, and 15% salt by Kristensen et al (2020). Viability generally decreased with increasing salt level and was reflected by flow cytometry profiles of viable cells.…”

Section: Starter Permeabilization During Cheese Ripeningmentioning

confidence: 99%

Invited review: Starter lactic acid bacteria survival in cheese: New perspectives on cheese microbiology

Wilkinson

LaPointe

2020

Journal of Dairy Science

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The importance of starter cultures to cheese manufacture and ripening is well known. Starters are inoculated into cheese milk at a level of ~10 6 cfu/mL either from a bulk culture or using commercial direct-to-vat cultures. Before ripening, starters grow in the milk to reach populations of 10 7 to 10 9 cfu/g of curd depending on processing variables such as cook temperature, inclusion of washing steps, degree of partitioning with curds and whey, and importantly salt addition rate. Inherent strain-related properties also determine final populations in the curd following manufacture and include temperature sensitivity, salt sensitivity, presence of prophage, autolytic and permeabilization properties (which are influenced by processing steps), presence and type of cell envelope proteinase, and metabolic activity. Ripening of important industrial cheese varieties such as Cheddar, Dutch, Swiss, and Italian-type cheese varieties is characterized by extended storage under temperature-controlled conditions enabling characteristic flavor and texture development to occur. Over ripening, microbiological, biochemical and enzymatic changes occur with a decline in starter viability, release of intracellular enzymes, hydrolysis of proteins, carbohydrates and lipids, and formation of a range of volatile and nonvolatile flavor components. Recent reports suggest that starter strains may be present during the later stages of ripening and therefore their potential role needs to be reconsidered. This review will focus on our current understanding of starter viability and vitality during cheese ripening and will also review the area of starter permeabilization, autolysis, and enzyme release.

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Diversity in NaCl tolerance of Lactococcus lactis strains from dl-starter cultures for production of semi-hard cheeses

Cited by 6 publications

References 21 publications

Probiotic Characterization And Safety Assessment of Lactococcus Lactis Subsp. Lactis R7 Isolated From Ricotta Cheese

Probiotic Characterization And Safety Assessment of Lactococcus Lactis Subsp. Lactis R7 Isolated From Ricotta Cheese

Fine-Tuning of Process Parameters Modulates Specific Metabolic Bacterial Activities and Aroma Compound Production in Semi-Hard Cheese

Invited review: Starter lactic acid bacteria survival in cheese: New perspectives on cheese microbiology

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