Differences in Chemical, Physical and Microbiological Characteristics of Italian Burrata Cheeses Made in Artisanal and Industrial Plants of Apulia Region

Exposure to Bacillus cereus in Water Buffalo Mozzarella Cheese

Bacillus cereus is a spoilage bacterium and is recognized as an agent of food poisoning. Two food-borne illnesses are caused by B. cereus: a diarrheal disease, associated with cytotoxin K, hemolysin BL, non-hemolytic enterotoxin and enterotoxin FM, and an emetic syndrome, associated with the cereulide toxin. Owing to the heat resistance of B. cereus and its ability to grow in milk, this organism should be considered potentially hazardous in dairy products. The present study assessed the risk of B. cereus poisoning due to the consumption of water buffalo mozzarella cheese. A total of 340 samples were analyzed to determine B. cereus counts (ISO 7932:2005); isolates underwent molecular characterization to detect the presence of genes encoding toxins. Eighty-nine (26.1%) samples harbored B. cereus strains, with values ranging from 2.2 × 102 to 2.6 × 106 CFU/g. Isolates showed eight different molecular profiles, and some displayed virulence characteristics. Bacterial counts and the toxin profiles of isolates were evaluated both separately and jointly to assess the risk of enteritis due to B. cereus following the consumption of buffalo mozzarella cheese. In conclusion, the results of the present study showed that the risk of poisoning by B. cereus following the consumption of this cheese was moderate.

"Burrata di Andria" PGI Cheese: Physicochemical and Microbiological Features

In the last century, the exponential increase of industrial food production led to the disappearance of "Italian traditional niche products". However, national regulations allowed the preservation of several of these products, including the burrata cheese. Twenty-one samples from three different batches of "Burrata di Andria" Protected Geographical Indication (PGI) were purchased from dairy factories of the PGI consortium. Moisture value of PGI Burrata cheese was significantly higher than that before the PGI release. Moreover, a significantly lower NaCl value was detected in PGI raw milk Burrata cheeses with respect to non-PGI ones, while an opposite situation was detected in pasteurized milk Burrata cheeses. As for pH, in all PGI products lower values were observed with respect to non-PGI products, which resulted significant only in pasteurized ones. No Salmonella spp., Listeria monocytogenes, and Bacillus cereus were detected, while nine samples were positive for a nonpathogenic strain of Yersinia enterocolitica. Total viable count (TVC) and Escherichia coli resulted significantly lower in pasteurized than in raw milk PGI Burrata cheese samples. Although samples analyzed can be considered microbiologically safe, these were borderline and/or unsatisfactory for E. Coli and coagulase-positive staphylococci (CPS) according to process hygiene criteria established by European regulation. Therefore, different strategies should be adopted to improve products hygiene in the considered dairy factories.

Evolution of VOC and Sensory Characteristics of Stracciatella Cheese as Affected by Different Preservatives

Undesired volatile organic compounds (VOCs) can negatively affect the flavor of fresh food products; especially those characterized by a mild and delicate aroma. Finding connections between chemical and sensory analyses is a useful way to better understand the arising of off-flavors. A study was conducted on stracciatella; a traditional Italian cream cheese that is emerging on international markets. Samples were prepared by adding two different preservatives (alone or combined): sorbic acid and an olive leaf extract. Their influence on flavor preservation during refrigerated storage was investigated by chemical, microbiological and sensory analyses. A strong change of the VOC profile was ascertained after 8 days in the control cheese and in the sample added with leaf extract alone. The samples containing sorbic acid, alone or in combination with leaf extract, gave the best chemical and sensory results, demonstrating a significant shelf-life extension. In particular, these samples had lower concentrations of undesired metabolites, such as organic acids and volatiles responsible for off-flavor, and received better scores for odor and taste. Ex and Ex-So samples had significantly higher antioxidant activity than Ctr and So throughout the entire storage period, and the color parameter shows no differences among samples taken on the same day. The use of the olive leaf extract, at the concentration tested, seemed to be interesting only in the presence of sorbic acid due to possible synergic effect that mainly acted against Enterobacteriaceae.

Dietary Fibers and Protective Lactobacilli Drive Burrata Cheese Microbiome

This study was aimed at improving the functional attributes and shelf life of burrata cheese by using protective lactobacilli (Lactobacillus plantarum LPAL and Lactobacillus rhamnosus LRB), fructooligosaccharides, and inulin. Six burrata cheeses were made using (i) the traditional protocol (control), (ii) the addition of 0.5% fructooligosaccharides and inulin (DF cheese), (iii) protective lactobacilli in milk alone (PL cheese), (iv) protective lactobacilli in milk and governing liquid (2PL cheese), (v) protective lactobacilli in milk and dietary fibers (DF_PL cheese), and (vi) protective lactobacilli in milk and governing liquid and dietary fibers (DF_2PL cheese). As expected, DF, DF_PL, and DF_2PL cheeses showed 1.5% of total fibers. Burrata cheeses produced by adding protective lactobacilli only in milk (PL and DF_PL cheeses) showed the lowest acidification during cheese making and storage. Lactic and acetic acids and ethanol were found at the lowest concentrations in these samples. Analyses of cultivable microbiota and the microbiome showed that protective lactobacilli reduced the house microbiota components (e.g., Streptococcus thermophilus, Lactococcus lactis, and Leuconostoc lactis) during cheese making and storage. Protective lactobacilli slowed the growth of staphylococci, coliforms, and Pseudomonas spp., especially in early storage. According to the different microbiome assemblies, burrata samples differed in peptide profiles and the levels of free amino acids. As shown by a sensory analysis, the addition of protective lactobacilli in milk improved the flavor and increased the shelf life of burrata cheese. In comparison to cheeses made using protective cultures only in milk, the shelf lives of those containing cultures also in the governing liquid were not further prolonged and they received lower acceptability scores by the panelists.IMPORTANCE This study provides more in-depth knowledge of the microbiome of burrata cheese and the set-up for a novel biotechnology using prebiotic dietary fibers and protective probiotic Lactobacillus plantarum LPAL and Lactobacillus rhamnosus LRB in milk. The biotechnology proposed in this study should be considered a useful tool to improve the functional value of burrata cheese. The use of protective lactobacilli in milk enhanced the flavor formation and shelf life of burrata cheese.