Influence of starter cultures on the proteolysis of Teleme cheese made from different types of milk

Pappa, Eleni C.; Kandarakis, I.; Zerfiridis, Gregory K.; Anifantakis, E.; Sotirakoglou, Κyriaki

doi:10.1051/lait:2006010

Cited by 25 publications

(14 citation statements)

References 39 publications

(57 reference statements)

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“…relies on the metabolic activities of bacterial colonies, leading to the formation of flavors and textures of cheese (11,25). So far, ripening has always been described with average processes on the cheese scale with destructive techniques like grinding (5,12,23) or slicing (10), and microgradients of nutrients and metabolites are thus assumed to occur between colonies in the cheese matrix. Ripening process kinetics should then depend not only on the activities of colonies but also on the spatial organization of colonies inside the matrix.…”

mentioning

confidence: 99%

Spatial Distribution of Bacterial Colonies in a Model Cheese

Jeanson

Chadœuf

Madec

et al. 2011

Appl Environ Microbiol

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In most ripened cheeses, bacteria are responsible for the ripening process. Immobilized in the cheese matrix, they grow as colonies. Therefore, their distribution as well as the distance between them are of major importance for ripening steps since metabolites diffuse within the cheese matrix. No data are available to date about the spatial distribution of bacterial colonies in cheese. This is the first study to model the distribution of bacterial colonies in a food-type matrix using nondestructive techniques. We compared (i) the mean theoretical three-dimensional (3D) distances between colonies calculated on the basis of inoculation levels and considering colony distribution to be random and (ii) experimental measurements using confocal microscopy photographs of fluorescent colonies of a Lactococcus lactis strain producing green fluorescent protein (GFP) inoculated, at different levels, into a model cheese made by ultrafiltration (UF). Enumerations showed that the final numbers of cells were identical whatever the inoculation level (10 4 to 10 7 CFU/g). Bacterial colonies were shown to be randomly distributed, fitting Poisson's model. The initial inoculation level strongly influenced the mean distances between colonies (from 25 m to 250 m) and also their mean diameters. The lower the inoculation level, the larger the colonies were and the further away from each other. Multiplying the inoculation level by 50 multiplied the interfacial area of exchange with the cheese matrix by 7 for the same cell biomass. We finally suggested that final cell numbers should be discussed together with inoculation levels to take into account the distribution and, consequently, the interfacial area of colonies, which can have a significant influence on the cheese-ripening process on a microscopic scale.During cheese making, regardless of the cheese type, bacteria are immobilized in the curd during the coagulation step. It is generally accepted that 90% of the bacteria present in the milk are retained, trapped in the curd, while only 10% are lost in the whey during draining (16). In cheeses made by ultrafiltration (UF), the draining step is absent, and 100% of the cells are then retained in the curd. In any case, after immobilization by coagulation, each inoculated bacterial cell is assumed to grow, generating a colony inside the curd. Colonies are then spread within the cheese curd, and they interact with the cheese matrix during ripening. Consequently, the ripening process must take place on a microscopic scale around colonies. Only studies showing microscopic examinations of bacterial colonies in cheese either by electronic microscopy (24) or, more recently, by confocal laser scanning microscopy (7, 19) have been reported.The ripening process (proteolysis, lipolysis, amino acid catabolism, and the production of organic acids, etc.) relies on the metabolic activities of bacterial colonies, leading to the formation of flavors and textures of cheese (11,25). So far, ripening has always been described with average processes on the che...

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confidence: 99%

Spatial Distribution of Bacterial Colonies in a Model Cheese

Jeanson

Chadœuf

Madec

et al. 2011

Appl Environ Microbiol

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“…Teleme is another traditional Greek cheese made with non-pasteurized milk, which is currently produced on an industrial scale, using yogurt commercial starters ( Pappa et al, 2006 ). In Teleme processing, the curd is subjected to pressure to release whey and placed into the brine (18% w/v NaCl) for 20 h ( Litopoulou-Tzanetaki and Tzanetakis, 2011 ).…”

Section: Spoilage Yeast Species In White-brined Cheesesmentioning

confidence: 99%

Occurrence of Yeasts in White-Brined Cheeses: Methodologies for Identification, Spoilage Potential and Good Manufacturing Practices

et al. 2020

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Yeasts are generally recognized as contaminants in the production of white-brined cheeses, such as Feta and Feta-type cheeses. The most predominant yeasts species are Debaryomyces hansenii, Geotrichum candidum, Kluyveromyces marxianus, Kluyveromyces lactis, Rhodotorula mucilaginosa, and Trichosporon spp. Although their spoilage potential varies at both species and strain levels, yeasts will, in case of excessive growth, present a microbiological hazard, effecting cheese quality. To evaluate the hazard and trace routes of contamination, the exact taxonomic classification of yeasts is required. Today, identification of dairy yeasts is mainly based on DNA sequencing, various genotyping techniques, and, to some extent, advanced phenotypic identification technologies. Even though these technologies are state of the art at the scientific level, they are only hardly implemented at the industrial level. Quality defects, caused by yeasts in white-brined cheese, are mainly linked to enzymatic activities and metabolism of fermentable carbohydrates, leading to production of metabolites (CO 2 , fatty acids, volatile compounds, amino acids, sulfur compounds, etc.) and resulting in off-flavors, texture softening, discoloration, and swelling of cheese packages. The proliferation of spoilage yeast depends on maturation and storage conditions at each specific dairy, product characteristics, nutrients availability, and interactions with the co-existing microorganisms. To prevent and control yeast contamination, different strategies based on the principles of HACCP and Good Manufacturing Practice (GMP) have been introduced in white-brined cheese production. These strategies include milk pasteurization, refrigeration, hygienic sanitation, air filtration, as well as aseptic and modified atmosphere packaging. Though a lot of research has been dedicated to yeasts in dairy products, the role of yeast contaminants, specifically in white-brined cheeses, is still insufficiently understood. This review aims to summarize the current knowledge on the identification of contaminant yeasts in white-brined cheeses, their occurrence and spoilage potential related to different varieties of white-brined cheeses, their interactions with other microorganisms, as well as guidelines used by dairies to prevent cheese contamination.

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“…Proteolysis is an essential biochemical process in the ripening of most cheese varieties (Fox et al 2000;Pappa et al 2006). Proteolysis, which contributes to the development of cheese texture and flavor, is due to the action of enzymes from coagulant, milk (general plasmin), starter bacteria, the adventitious nonstarter microflora an secondary starter (in some cheese varieties).…”

Section: Proteolysismentioning

confidence: 99%