Cheese Samples Research Articles

Effects of industrial slicing on the microbiological quality and safety of mozzarella cheese and ham

Slicing of animal origin food affects the final quality of products and potentially transfers pathogenic microorganisms as it occurs after microorganism control and elimination steps, such as cooking and pasteurization. Therefore, the food industry needs to ensure the safety of food products to reduce the incidence of foodborne diseases. This requires an understanding of the dangers involved in each stage of production, along with the microorganisms transferred during processing. In this study, we aimed to understand the impact of industrial slicing on mozzarella cheese and ham by investigating the quality indicator microorganisms, aerobic mesophiles, psychrotrophs, total coliforms, Staphylococcus aureus, and pathogens, such as Escherichia coli, Salmonella spp., and Listeria monocytogenes. Samples were collected from pieces (20) and slices (20) of mozzarella cheese and ham. The number of mesophilic aerobes differed significantly before and after slicing (P < 0.05) for mozzarella. However, no difference was observed in the psychrotrophic microorganism counts during slicing. The counts of total coliforms and S. aureus increased after slicing (P > 0.05). In total, 844 isolates were analyzed for pathogenic genes, and Salmonella spp. were identified in 40% of the piece and 20% of the sliced mozzarella cheese samples and in 30% of the piece and 50% of the sliced ham samples. Furthermore, S. aureus genes with the potential to produce enterotoxins C and D were identified in two sliced mozzarella cheese samples. Slicing of ready-to-eat food is an important step in food microbiology. Our results highlight the importance of maintaining hygienic practices during processing and demonstrate that the microbiological quality of the slicing sample affects the quality and safety of the sliced product.

Acid curd (Karish) cheese supplemented with ashwagandha and/or probiotics: Modulatory efficiency on induced behavioral and neurochemical changes in rats

Neurodegenerative disorder leads to a progressive memory loss that has only limited known medications. The use of ashwagandha, probiotics, or their combination may improve cholinergic activity, consequently providing therapeutic potency against amnesia and neuroplasticity disorders. We aimed to explore the modulatory benefits of ashwagandha extract and probiotics against induced behavioral and neurochemical retardations. &#x0D; Acid curd (Karish) cheese samples were supplemented with ashwagandha extract and/or probiotics and subjected to chemical, microbiological, rheological, sensorial, and biological investigations by standard techniques.&#x0D; The supplementation of Karish cheese with ashwagandha never deteriorated its chemical composition or rheological parameters. On the contrary, it exerted high antioxidant and phenolic potentials. Also, ashwagandha extract performed antimicrobial action against the tested pathogenic bacteria and showed better prebiotic effects with Lactobacillus plantarum. The biological study revealed that treating dementia-modeled rats with Karish cheese supplemented with ashwagandha and/or probiotics resulted in a detectable improvement in the behavioral and neurochemical measurements. However, the cheese supplemented with a formula of ashwagandha and probiotics had the greatest regenerating effect. &#x0D; The supplementation of Karish cheese with ashwagandha and/or probiotics exhibited a modulatory efficiency against experimentally induced behavioral and neurochemical disorders.

THE INFLUENCE OF POTASSIUM CHLORIDE AND MAGNESIUM CHLORIDE ON THE COLOR AND SENSORY PROPERTIES OF COOKED CHEESE

The aim of this paper is focused on reducing sodium chloride content by partial replacement with potassium chloride and magnesium chloride in cooked cheese samples. For the production of cheese, standardized cow's milk from a domestic market producer was used, and the cheese was produced by heating the milk to a temperature of 95°C and coagulation with acetic acid. The one salted only with NaCl was designated as the standard sample, and the other samples were salted with combinations of salts in which NaCl reduction was performed: sample A1 had a ratio of 15% KCl:85% NaCl, sample A2 30% KCl:70% NaCl, sample B1 15% MgCl2:85% NaCl and sample B2 30% MgCl2:70% NaCl. The cheese samples were stored at + 4°C and color parameters and sensory properties were analyzed on the 1st, 3rdand 5thdays of storage. Based on the performed analyses, it was concluded that it is completely acceptable to replace sodium chloride with potassium chloride in the ratio of 15% KCl:85% NaCl. It is acceptable to replace sodium chloride with potassium chloride inthe ratio of 30% KCl:70% NaCl, with the note that on the 5thday of storage there is a gradual deterioration of the sensory properties compared to the samples analyzed on the 1stday of storage. Replacement of sodium chloride with magnesium chloride in the ratios 15% MgCl2:85% NaCl and 30% MgCl2:70% NaCl is not acceptable.As such, it is not recommended in the production of cooked cheeses due to the appearance of a metallic and bitter taste that is present in cheese samples from the 1st to the 5th day of storage. KEYWORDS:cooked cheese, sodium chloride, potassium chloride, magnesium chloride

Insect protein-based composite film incorporated with E. purpurea-based nanoparticles augmented the storage stability of parmesan cheese

The objective of this study was to prepare an insect protein-based composite film containing plant extract-based nanoparticles to augment the lipid and microbial stability of cheese. An ultrasonication-mediated green method of synthesis was followed to develop the nanoparticles using E. purpurea flower extract (EP-NPs). The film was developed using locust protein (Loc-Pro) and different levels of EP-NPs [2.0% (T3), 1.5% (T2), 1.0% (T1), and 0.0% (T0)]. It was characterised and evaluated for efficacy using parmesan cheese (Par-Che) as a model system stored for 90 days (4 ± 1 °C). The addition of EP-NPs markedly enhanced the antioxidant and antimicrobial activities of the Loc-Pro-based film as indicated by the results of radical-scavenging activity (ABTS and DPPH), total-flavonoid and total-phenolic contents, ion-reducing potential (FRAP), and inhibitory halos (mm). It also increased (P < 0.05) the density (g/ml), redness (a*), and yellowness (b*) and reduced (P < 0.05) the WVTR (mg/m2t), transparency (%) and lightness (L*) of the Loc-Pro-based film. The film incorporated with EP-NPs showed a marked desirable impact on protein oxidation, lipid stability, microbial quality and antioxidant potential of Par-Che during 90 days of storage. While cheese samples without any film showed mean values of 2.24 mg malondialdehyde/kg, 0.79% oleic acid, 1.22 nm/mg protein, 2.52 log CFU/g and 1.24 log CFU/g on day 90 for TBARS, FFA, total carbonyl content, total plate count and psychrophilic count, samples within T3 films showed significantly lower values of 1.82, 0.67, 0.81, 2.15, and 0.81, respectively. A positive impact of the Loc-Pro-based film was found on the sensory characteristics of Par-Che. Both the Loc-Pro-based film and the digestion simulation improved the radical-scavenging activity and ion-reducing potential of the Par-Che. Our results indicate the potential of Loc-Pro-based film as a means to enhance the storage quality of cheese.

Free Fatty Acid Profile of Köy Cheese Consumed in Erzurum and Its Region

Köy cheese is a type of cheese with white interior, slightly yellowish exterior, a slightly firm texture, and a mild salty taste. It is produced and consumed in some regions in the Marmara and Aegean regions of Turkey, as well as in Bayburt, Yusufeli and Erzurum regions. The present study was conducted to determine the free fatty acid profile of Köy cheeses consumed in Erzurum and its surrounding areas. Analyzes were carried out by GC-MS using 10 cheese samples, and as a result, the presence of 25 free fatty acids was determined. Among these, short-chain fatty acids accounted for 2%, medium-chain fatty acids for 7%, and long-chain fatty acids for 91%. Palmitic acid (36.3563±5.4150%), oleic acid (22.0077±5.3136%), myristic acid (12.3104±2.1054%) and stearic acid (11.9837±3.1320%) were the prominent fatty acids among total free fatty acids. This study is considered to be significant in terms of providing data about the free fatty acid profile of Köy cheese produced and consumed widely in Türkiye.

New Genetic Determinants for qPCR Identification and the Enumeration of Selected Lactic Acid Bacteria in Raw-Milk Cheese.

Lactic acid bacteria (LAB) play an important role in the ripening of cheeses and contribute to the development of the desired profile of aroma and flavor compounds. Therefore, it is very important to monitor the dynamics of bacterial proliferation in order to obtain an accurate and reliable number of their cells at each stage of cheese ripening. This work aimed to identify and conduct a quantitative assessment of the selected species of autochthonous lactic acid bacteria from raw cow's milk cheese by the development of primers and probe pairs based on the uniqueness of the genetic determinants with which the target microorganisms can be identified. For that purpose, we applied real-time quantitative PCR (qPCR) protocols to quantify Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and Lactococcus lactis subsp. cremoris cells in cheese directly after production and over three-month and six-month ripening periods. While L. lactis subsp. cremoris shows good acidification ability and the ability to produce antimicrobial compounds, L. delbrueckii subsp. bulgaricus has good proteolytic ability and produces exo-polysaccharides, and S. thermophilus takes part in the formation of the diacetyl flavor compound by metabolizing citrate to develop aroma, they all play an important role in the cheese ripening. The proposed qPCR protocols are very sensitive and reliable methods for a precise enumeration of L. delbrueckii subsp. bulgaricus, S. thermophilus, and L. lactis subsp. cremoris in cheese samples.

Extension of ultrafiltered cheese shelf life using edible coatings containing supercritical rosemary, thyme and coriander extracts as antimicrobial agents

Currently, supercritical extraction allows for the “green” isolation of plant antimicrobial components and their subsequent use in the food industry. The study aims to extend the shelf life of ultrafiltered cheese by using edible coatings containing supercritical fluid extracts (SFEs) of Rosmarinus officinalis L., Thymus vulgaris and Coriandrum sativum L. The SFEs chemical profiling was studied using GC-MS. Ten emulsion coating formulations were prepared using whey protein concentrate and the SFEs. The antimicrobial activity of coatings was assessed using well diffusion assay. Their effect on shelf life, physicochemical and sensory characteristics of the ultrafiltered cheese samples was investigated. GC/MS analysis of Rosmarinus officinalis L., Thymus vulgaris and Coriandrum sativum L. showed that 1,8-Cineol, m-Cymene, and Linalool are the major compounds with 35.4, 41.6, and 61.3 % respectively. The particle size of all formulations ranged from 157.3 to 453.7 nm and had a broad size distribution with a low Polydispersity Index values ranging from 0.35 to 0.49. The obtained Zeta potential values from −27.8 to −36.0 mV indicate the stability of the SFE-emulsion formulations. The antimicrobial trials showed that formulations, that mainly contained Thymus vulgaris, demonstrated more inhibition effect against all tested strains than other formulas with inhibition zone diameter ranged between 10.7 and 16.3 mm and followed by formulations, that mainly contained Rosmarinus officinalis L., with inhibition zones diameter between 6.7 and 11.7 mm depending on microbial type. Combining rosemary and coriander extracts synergistically enhanced their antimicrobial effect and extended the shelf life of cheese beyond 40 days.

O efeito da adição da inulina na produção do queijo coalho: avaliação da caracterização

The present work proposed to analyze a coalho cheese with inulin. For that, inulin was added, in the stirring stage, during the process of making the coalho cheese to obtain two samples: SCC (standard coalho cheese) and ICC (coalho cheese with inulin). In the two studied samples, the following analyzes were carried out: pH, acidity, water activity and colorimetric. As well as it was possible to know the effect of the addition of inulin when stored under refrigeration for 14 days from the analysis of instrumental texture profile, melting capacity, acceptability test and purchase intention. The studied coalho cheese samples showed differences in physical-chemical and instrumental parameters evaluated. Inulin contributed to obtaining cheeses with less melting capacity and with a firm, soft texture and little adhesiveness. Both cheeses showed high luminosity (L*) and predominance of yellow color (b*) in detriment of green (a*). The various sensory attributes evaluated by tasters, as well as purchase intention, indicated good results for this new product. The proposed work contributes to the development of a profitable market for new dairy products enriched with physiologically active components, prebiotics, which is currently one of the research priorities of the food industry.

Investigation of the Microbiome of Industrial PDO Sfela Cheese and Its Artisanal Variants Using 16S rDNA Amplicon Sequencing and Shotgun Metagenomics.

Sfela is a white brined Greek cheese of protected designation of origin (PDO) produced in the Peloponnese region from ovine, caprine milk, or a mixture of the two. Despite the PDO status of Sfela, very few studies have addressed its properties, including its microbiology. For this reason, we decided to investigate the microbiome of two PDO industrial Sfela cheese samples along with two non-PDO variants, namely Sfela touloumotiri and Xerosfeli. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), 16S rDNA amplicon sequencing and shotgun metagenomics analysis were used to identify the microbiome of these traditional cheeses. Cultured-based analysis showed that the most frequent species that could be isolated from Sfela cheese were Enterococcus faecium, Lactiplantibacillus plantarum, Levilactobacillus brevis, Pediococcus pentosaceus and Streptococcus thermophilus. Shotgun analysis suggested that in industrial Sfela 1, Str. thermophilus dominated, while industrial Sfela 2 contained high levels of Lactococcus lactis. The two artisanal samples, Sfela touloumotiri and Xerosfeli, were dominated by Tetragenococcus halophilus and Str. thermophilus, respectively. Debaryomyces hansenii was the only yeast species with abundance > 1% present exclusively in the Sfela touloumotiri sample. Identifying additional yeast species in the shotgun data was challenging, possibly due to their low abundance. Sfela cheese appears to contain a rather complex microbial ecosystem and thus needs to be further studied and understood. This might be crucial for improving and standardizing both its production and safety measures.

Staphylococcus aureus in animal-derived food products: the prevalence, virulence, enterotoxin-encoding genes, antibiotic resistance and PFGE profiles in northern Turkey

The aim of this research was to investigate the prevalence of Staphylococcus aureus (S. aureus) in raw milk, Tulum cheese, and ground beef samples, and to determine their virulence, enterotoxins, antibiotic resistance, and genetic relatedness. A total of 300 food samples were purchased from public markets within different districts of Giresun, Turkey. Fifty-two (17.3%) of these food samples tested positive for S. aureus isolation. Fifty-two S. aureus isolates were further analyzed for the presence of virulence genes. The virulence genes detected were icaA (9.6%) and icaD (84.6%). Enterotoxin-encoding genes of the sea, seb, sec, sed, see, seg, seh, sei, sej, sek, sel, sem, sen, seo, seq, ser, and seu groups were detected individually or in combination. Of the 52 S. aureus isolates, 1 methicillin-resistant S. aureus strain (1.9%) was isolated as having the mecA. The antibiotic susceptibility test of positive isolates showed resistance to cefoxitin (1.92%), tetracycline (11.5%), erythromycin (3.84%), ciprofloxacin (1.92%), gentamicin (1.92%), and fusidic acid (5.76%). Pulsed-field gel electrophoresis (PFGE) of the 52 isolates revealed 46 PFGE types, with 21 (40.3%) isolates grouped into 7 clusters. Some of the isolates from different districts showed clonal relatedness. The high occurrence of S. aureus strains in these products indicated a potential risk to humans. The results of this study indicated that dairy and meat products could be reservoirs of S. aureus strains that harbor several virulence factors and enterotoxin genes and the presence of these bacteria in foods may be a cause of concern for human health from food poisoning; therefore, hygienic measures and periodic bacteriological controls are necessary in all areas that provide these foods to the public, such as bazaars and butchers, to reduce contamination with foodborne pathogens.

Discrimination of Cheese Products Regarding Milk Species’ Origin Using FTIR, 1H-NMR, and Chemometrics

The present study deals with the discrimination of various European cheese products based on spectroscopic data and chemometric analysis. It is the first study that includes cheese products from Cyprus along with cheese samples from abroad and several different cheese types. Therefore, forty-nine samples were collected, freeze-dried, and measured by using spectroscopic techniques, such as FTIR (Fourier-Transform Infrared Spectroscopy) and 1H-NMR (proton nuclear magnetic resonance). Discriminant analysis was applied, particularly OPLS-DA. All data obtained from 1H-NMR were included, whereas, regarding the FTIR data, only the spectral subregion between 1900 and 400 cm−1 was used in the extracted model. The cheese samples were classified according to the milk species’ origin. In the future, the samples of this study will be enriched for further testing with spectroscopic techniques and chemometrics.

Cultivable microbial diversity, peptide profiles, and bio-functional properties in Parmigiano Reggiano cheese.

Lactic acid bacteria (LAB) communities shape the sensorial and functional properties of artisanal hard-cooked and long-ripened cheeses made with raw bovine milk like Parmigiano Reggiano (PR) cheese. While patterns of microbial evolution have been well studied in PR cheese, there is a lack of information about how this microbial diversity affects the metabolic and functional properties of PR cheese. To fill this information gap, we characterized the cultivable fraction of natural whey starter (NWS) and PR cheeses at different ripening times, both at the species and strain level, and investigated the possible correlation between microbial composition and the evolution of peptide profiles over cheese ripening. The results showed that NWS was a complex community of several biotypes belonging to a few species, namely, Streptococcus thermophilus, Lactobacillus helveticus, and Lactobacillus delbrueckii subsp. lactis. A new species-specific PCR assay was successful in discriminating the cheese-associated species Lacticaseibacillus casei, Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus, and Lacticaseibacillus zeae. Based on the resolved patterns of species and biotype distribution, Lcb. paracasei and Lcb. zeae were most frequently isolated after 24 and 30 months of ripening, while the number of biotypes was inversely related to the ripening time. Peptidomics analysis revealed more than 520 peptides in cheese samples. To the best of our knowledge, this is the most comprehensive survey of peptides in PR cheese. Most of them were from β-caseins, which represent the best substrate for LAB cell-envelope proteases. The abundance of peptides from β-casein 38-88 region continuously increased during ripening. Remarkably, this region contains precursors for the anti-hypertensive lactotripeptides VPP and IPP, as well as for β-casomorphins. We found that the ripening time strongly affects bioactive peptide profiles and that the occurrence of Lcb. zeae species is positively linked to the incidence of eight anti-hypertensive peptides. This result highlighted how the presence of specific LAB species is likely a pivotal factor in determining PR functional properties.

Microfiltration of milk fat globules for particle size affects key sensory parameters of Cheddar cheese

AbstractDescriptive sensory analysis discriminated between the appearance, aroma, flavor, taste and texture of Cheddar cheese samples prepared from milk varying in fat globule size; small milk fat globule milk (SMM, d4,3 = 2.76 ± 0.07 μm), large milk fat globule milk (LMM, d4,3 = 5.07 ± 0.06 μm) and Control (d4,3 = 3.91 ± 0.09 μm), over a six‐month maturation period. Significant differences were measured between SMM, LMM and the Control as each cheese matured, where SMM was the most different across all parameters examined. SMM was lowest in color intensity (34.6 &lt; 38.8–47.0), firmness (29.4 &lt; 36.1–47.7), and fracturability (24.5 &lt; 28.8–30.7), and highest in cohesiveness (57.0 &gt; 39.8–45.8), adhesiveness (52.9 &gt; 39.0–45.4), and smoothness (50.4 &gt; 37.9–44.0). Moreover, SMM was more intense than the Control in cultured odor (34.9 &gt; 29.6–30.6) and flavor (45.5 &gt; 34.9–36.2), rancid (23.3 &gt; 16.0–18.6) and metallic (17.7 &gt; 14.3) flavor, salty taste (45.7 &gt; 40.3–40.5) and aftertaste (38.5 &gt; 34.9–35.8), sour (36.3 &gt; 28.9) and umami taste (19.6 &gt; 16.4); attributes that align with the degree of maturation. LMM showed similar differences to the Control, but was firmer (36.1 &gt; 29.4), less cohesive (45.8 &lt; 57.0), adhesive (45.4 &lt; 52.9) and smooth (44.0 &lt; 50.4) and had a less intense cultured odor (31.5 &lt; 34.9) than SMM. An increase in salty taste was associated with a decrease in cheese firmness (−0.91, p &lt; 0.0001). These results could provide process‐driven solutions that allow the dairy industry to decrease maturation time or create differentiated cheese products to meet specific consumer tastes or function.

Which Method Is Better for Preserving Meat and Cheese: Coating Propolis on The Packaging Material or Spraying Directly onto The Food?

This study was carried out to determine whether it is better to spray a preservative coating of propolis on the food packaging material or directly onto meat and cheddar cheese. To test this, the surfaces of a vacuum bag (Polyamide/Polyethylene-PA/PE), some stretch film (Low Density Polyethylene- LDPE) and a ziploc bag (Oriented Polypropylene-OPP) and food samples were coated by spraying them with a propolis-ethyl acetate (PEA) solution. Moreover, a propolis-propylene glycol (PPG) solution was sprayed directly on the food surfaces (cheese and meat) to study the shelf life of these products without packaging. Meat and cheddar cheese placed in packages and covered with a PPG solution were stored at 4°C for 30 and 45 days, respectively. The predominant phenolic compound in the propolis used in the study was caffeic acid phenethyl ester (CAPE) at a level of 27.523,4 μg g-1, and the lowest amount of phenolic acid was epigallocatechin gallate at 287.53 μg g-1. At the end of the storage period, the Enterobacteriaceae count of the meat sample stored in propolis sprayed vacuum packaging decreased by 1.01 log CFU g-1 (p˂0.05) compared to the control, and achieved the best result. It was concluded that the PPG solution applied onto the meat did not adhere well to it and the solution could not achieve its antimicrobial effect. At the end of the storage period, while the cheddar cheese sample kept in a propolis-treated vacuum bag had the lowest TMAB count for 21 days (p˂0.05), PPG directly sprayed on cheddar cheese had the lowest TMAB count at the end of storage with 6.64 log CFU g-1 (p˂0.05). The PPG solution was able to adhere to the surface of the cheddar cheese and propolis was able to show its antimicrobial activity. In addition, the LAB (MRS) value for the cheddar cheese sample stored in propolis-treated vacuum packaging decreased by 0.60 log CFU g-1 (p˂0.05) compared to the control and achieved the best result. Microbiological analysis showed that propolis coating in vacuum packaging improved the microbiological quality of the meat and the cheddar cheese.

Alginate/whey protein isolate-based emulgel as an alternative margarine replacer in processed cheese: Impact on rheological, mechanical, nutritional, and sensory characteristics

Effects of partial or full replacement of margarine by alginate/whey protein isolate-based olive oil emulgel (E) on nutritional, physicochemical, mechanical, and rheological properties of processed cheese (PC) were investigated in this work. All formulated samples had the same amount of total fat, dry matter, and pH. According to the results of the fatty acids profile, the processed cheese sample in which the margarine was fully replaced by the emulgel (EPC100) had the highest (49.84%) oleic acid content and showed a reduction of 23.7% in saturated fatty acids compared with the control sample (EPC0: formulated just with margarine). EPC0 had the highest hardness among various cheese samples, which was also confirmed by its compact microstructure. Dynamic oscillatory measurements revealed that EPC100 had the highest crossover strain (or resistance to deformation). The high rigidity of this sample was related to the 3-dimensional structure of emulgel. According to the creep test results, EPC100 showed the lowest relative recovery (flowability). A high temperature-dependency of viscoelastic moduli was observed in EPC0 at 42°C. No significant differences were observed between color attributes and sensory properties of various cheese samples. Alginate/WPI-based olive oil emulgel can be considered as a healthy margarine replacer in processed cheese.

Unveiling ochratoxin A and ochratoxigenic fungi in Brazilian artisanal Cheeses: Insights from production to consumption

Ochratoxin A (OTA) is a toxin produced by several Aspergillus species, mainly those belonging to section Circumdati and section Nigri. The presence of OTA in cheese has been reported recently in cave cheese in Italy. As artisanal cheese production in Brazil has increased, the aim of this study was to investigate the presence of ochratoxin A and related fungi in artisanal cheese consumed in Brazil.A total of 130 samples of artisanal cheeses with natural moldy rind at different periods of maturation were collected. Of this total, 79 samples were collected from 6 producers from Canastra region in the state of Minas Gerais, since this is the largest artisanal cheese producer region; 13 samples from one producer in the Amparo region in the state of São Paulo and 36 samples from markets located in these 2 states. Aspergillus section Circumdati occurred in samples of three producers and some samples from the markets. A. section Circumdati colony counts varied from 102 to 106 CFU/g. Molecular analysis revealed Aspergillus westerdijkiae (67 %) as the most frequent species, followed by Aspergillus ostianus (22 %), and Aspergillus steynii (11 %). All of these isolates of A. section Circumdati were able to produce OTA in Yeast Extract Sucrose Agar (YESA) at 25 °C/7 days. OTA was found in 22 % of the artisanal cheese samples, ranging from 1.0 to above 1000 µg/kg, but only five samples had OTA higher than 1000 µg/kg. These findings emphasize the significance of ongoing monitoring and quality control in the artisanal cheese production process to minimize potential health risks linked to OTA contamination.

Staphylococcal food poisoning outbreaks occurred in Sicily (Italy) from 2009 to 2016.

Notification of foodborne outbreaks has been mandatory in Europe since 2005, and surveillance is carried out along the entire food chain. Here we report the results obtained from laboratory investigations about four cases of foodborne outbreaks that occurred in Sicily between 2009 and 2016, deemed to be related to staphylococcal enterotoxins (SEs) and coagulase-positive Staphylococci (CPS) by the Local Public Health Authority. Primosale cheese samples were processed by culture methods for enumeration of CPS and immunoenzymatic assays for detection and differentiation of the SEs possibly contained in food samples. In all cases, the mistrusted foods were found to be contaminated by CPS at bacterial loads between 5 and 8 log CFU/g and contained SE type C (SEC). The reported data confirm the risk of staphylococcal food poisoning associated with the consumption of raw milk cheese. SEC is the most commonly occurring SE in goat milk and dairy products and the most represented enterotoxin in Sicilian dairy products. Our results highlighted the need for improving the current monitoring efficiency and implementing the available laboratory methods to collect more faithful epidemiological data on the current prevalence of staphylococcal toxins in the food chain, including SEs currently not detectable by validated analytical methods.

Occurrence of Aflatoxin M1 and Estimate of Dietary Exposure in Cheeses from Organic and Conventional Production Systems

This study aimed to compare AFM1 occurrence in different cheese types produced by organic and conventional systems; and to evaluate the risk of food exposure to AFM1. A total of 176 commercial cheeses of 17 types were analyzed, 84 of organic and 92 of conventional production. Determination of AFM1 was performed by high- performance liquid chromatography (HPLC), being detected in 30.5% of samples, with 4.8% of organic cheese samples presenting quantifiable AFM1 values between 0.88 and 1.50 μg/kg. On the other hand, 4.3% of conventional cheese samples with values between 0.79 and 6.70 μg/kg. Two conventional cheese samples were above the limit of AFM1 allowed for cheeses by the Brazilian legislation. No statistical difference were found between organic and conventional cheeses regarding the occurrence (p = 0.1780) and concentration of AFM1 (p = 0.1810), according to the Chi-square and the T test, respectively. Estimated daily intake (EDI) and hazard index (HI) of dietary exposure to AFM1 were 0.26 ng/kg/day and 1.28 ng/kg/day, respectively, for conventional cheese samples, and 0.09 ng/kg/day and 0.47 ng/kg/day for organic samples, with no statistical difference for EDI (p = 0.1729) and HI (p = 0.1802) between the two production systems. Comparison between several cheese types from conventional and organic systems indicated that AFM1 is an obstacle to dairy production. Control and prevention of AFM1 contamination, as well as detoxification methods in the final products, are necessary. In the case of organic products, additional research is needed in order to determine which control and detoxification methods should be allowed in this production system.

Physicochemical and Sensory Characterization of Whey Protein-Enriched Semihard Cheese.

In view of potential future changes of German food legislation with regard to cheese product quality parameters, this study aimed to evaluate the quality of whey protein-enriched semihard cheese (WPEC). Model WPEC was produced in a pilot plant and on an industrial scale by adding defined amounts of high-heat (HH) milk to the cheese milk and comprehensively analyzed during cheese processing. The dry matter, total protein, pure protein, fat, and sodium chloride content of six-week ripened cheese samples were not significantly different (p < 0.05) when the technologically necessary heating of the curd was adapted to the amount of HH milk. However, the ripening, firmness, and melting behavior of WPEC was different compared to cheese without HH milk. During ripening, no formation of whey protein peptides was observed, but differences in the amount of some bitter peptides deriving from the casein fraction were found. Sensory data suggested a slightly more bitter taste perception by the panelists for the WPEC. Further technological adjustments are recommended to obtain marketable WPEC.

SORPTION ISOTHERM, PROXIMATE COMPOSITION AND SENSORY EVALUATIONS OF OVEN DRIED AND FRIED CHEESE PRODUCTS FROM LOCAL SOFT CHEESE

In this study, the sorption isotherm, proximate composition and sensory characteristics of oven dried and fried cheese were investigated. The understanding of the moisture sorption properties, nutrient composition and sensory properties of the oven dried and fried cheese can help quality, shelf-life prediction and overall acceptance. The experimental methodology for this study followed a standard procedure to determine the sorption isotherm of oven-dried and fried cheese samples. First, the raw milk samples were obtained from white Fulani cows at the Teaching and Research Farm, Ekiti State, University, Ado-Ekiti, Nigeria and processed into cheese. The cheese was divided into two portions: one group was oven-dried at 50 0C for 16 hours, while the other group was fried in pre-heated edible canola to internal temperature of 68oC. Sorption parameters, proximate and sensory characteristics were carried out according to standard methods. This study revealed that the monolayer moisture was higher in fried cheese than oven dried cheese. Oven-dried cheese had 0.299 water activity and 21.26 monolayer moisture while fried cheese had higher water activity of 0.32 and monolayer moisture of 29.67. Fitness of curve (R2) of 0.731 0.903 were computed for oven-dried and fried cheese. The results of proximate composition and sensory characteristics showed that processing methods influenced the sensorial properties and nutritional composition of oven-dried and fried cheese. In conclusion, oven-dried cheese can be predicted to be more stable than fried cheese. KEYWORDS: Adsorption, Equilibrium, GAB Equation, Monolayer, Salts.