Dataset Information

Indigenous Lactic Acid Bacteria Isolated from Raw Graviera Cheese and Evaluation of Their Most Important Technological Properties.

ABSTRACT: The aim of the present study was to characterize LAB isolates from raw-milk cheeses, to evaluate some of their technological properties and to select a few 'wild' LAB strains that could potentially be used as starter cultures. LAB strains were isolated and identified from raw milk, curd, and cheese at 30, 60, and 90 days of ripening. A total of 100 strains were isolated, 20 from each phase of ripening. All isolates were tested for acidification ability, curd formation, and aroma production at 32 °C and 42 °C after 24 and 48 h. Following the acidification test, 42 strains were selected for identification and characterization of their technological properties. A high proportion of lactic acid bacteria and Gram + cocci were found throughout the cheese-making process. Enterococci reached their maximum proportion on the 7th day of ripening while Lactobacilli increased significantly during the first month of ripening. Forty-two strains were identified by phenotypic, biochemical, and molecular techniques. Lactococci were predominant in raw milk and curd while Lactobacilli in the ripening of the cheese. Four LAB strains including one Leuconostoc pseudomenteroides, two Lacticaseibacillus paracasei subsp. paracasei and one Enterococcus hirae, were proposed for their potential use as starters or secondary cultures.

SUBMITTER: Psomas E

PROVIDER: S-EPMC9858605 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature

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Indigenous Lactic Acid Bacteria Isolated from Raw Graviera Cheese and Evaluation of Their Most Important Technological Properties.

Psomas Evdoxios E Sakaridis Ioannis I Boukouvala Evridiki E Karatzia Maria-Anastasia MA Ekateriniadou Loukia V LV Samouris Georgios G

Foods (Basel, Switzerland) 20230112 2

The aim of the present study was to characterize LAB isolates from raw-milk cheeses, to evaluate some of their technological properties and to select a few 'wild' LAB strains that could potentially be used as starter cultures. LAB strains were isolated and identified from raw milk, curd, and cheese at 30, 60, and 90 days of ripening. A total of 100 strains were isolated, 20 from each phase of ripening. All isolates were tested for acidification ability, curd formation, and aroma production at 32 ...[more]

PMID: 36673462

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Project description:Lactic Acid Bacteria (LAB) exert a fundamental activity in cheese production, as starter LAB in curd acidification, or non-starter LAB (NSLAB) during ripening, in particular in flavor formation. NSLAB originate from the farm and dairy environment, becoming natural contaminants of raw milk where they are present in very low concentrations. Afterward, throughout the different cheesemaking processes, they withstand chemical and physical stresses becoming dominant in ripened cheeses. However, despite a great body of knowledge is available in the literature about NSLAB effect on cheese ripening, the investigations regarding their presence and abundance in raw milk are still poor. With the aim to answer the initial question: "which and how many LAB are present in cow raw milk used for cheese production?," this review has been divided in two main parts. The first one gives an overview of LAB presence in the complex microbiota of raw milk through the meta-analysis of recent taxonomic studies. In the second part, we present a collection of data about LAB quantification in raw milk by culture-dependent analysis, retrieved through a systematic review. Essentially, the revision of data obtained by plate counts on selective agar media showed an average higher concentration of coccoid LAB than lactobacilli, which was found to be consistent with meta-taxonomic analysis. The advantages of the impedometric technique applied to the quantification of LAB in raw milk were also briefly discussed with a focus on the statistical significance of the obtainable data. Furthermore, this approach was also found to be more accurate in highlighting that microorganisms other than LAB are the major component of raw milk. Nevertheless, the variability of the results observed in the studies based on the same counting methodology, highlights that different sampling methods, as well as the "history" of milk before analysis, are variables of great importance that need to be considered in raw milk analysis.

Project description:The multifunctional properties of autochthonous lactic acid bacteria can be of use for enhancing the sensorial properties of food, as well as in food preservation. An initial screening for antimicrobial, proteolytic, and lipolytic capacities was done in 214 presumptive lactic acid bacteria isolates obtained from Chihuahua cheese manufacturing and during a ripening period of nine months. The antimicrobial screening was done by spot-on-the-lawn tests, using Listeria monocytogenes and Escherichia coli as indicator microorganisms; proteolysis was tested in casein-peptone agar and lipolysis in Mann-Rogosa-Sharpe (MRS)-tributyrin agar. More than 90% of the isolates hydrolyzed the casein, but only 30% hydrolyzed tributyrin; the inhibition of L. monocytogenes in the spot-on-the-lawn assay was used to select 39 isolates that had a bigger inhibition zone (>11.15 mm ± 0.3) than the control (Nisin producer Lactococcus lactis BS-10 Chr Hansen). The selected isolates were grown in MRS to obtain the neutralized cell-free supernatants and verify their antimicrobial activity by agar diffusion and the percentage of growth inhibition techniques. The selected isolates were also growth in casein peptone broth, and the cell-free supernatants were used for the determination of antioxidant activity by the radical scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) techniques. The results were analyzed to identify similarities by cluster analysis, based on their antimicrobial and antioxidant capacities. The isolates were arranged into six clusters; one cluster that included 12 isolates demonstrated L. monocytogenes (784-2811 mm2/mL AU by agar diffusion assay) and E. coli (41%-47% growth inhibition) antimicrobial activity. The isolates clustered in these groups also showed competitive inhibition of both radicals (11%-19% of DPPH and 50%-60% of ABTS). The isolates from cluster one were also identified by 16S rDNA amplification and were identified as Enterococcus faecium. Traditional products such as Chihuahua cheese can be a source or lactic acid bacteria with metabolic properties that can be used in food preparation and preservation.

Dataset Information

Indigenous Lactic Acid Bacteria Isolated from Raw Graviera Cheese and Evaluation of Their Most Important Technological Properties.

Publications

Indigenous Lactic Acid Bacteria Isolated from Raw Graviera Cheese and Evaluation of Their Most Important Technological Properties.

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