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1.
Int J Food Microbiol ; 347: 109192, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-33836444

RESUMO

Brucellosis is one of the most prevalent zoonotic diseases with worldwide distribution. Although the incidence of brucellosis varies widely in different regions, it is a major concern for public health around the world. This study aimed to determine the prevalence and quantity of Brucella spp. in sheep and goat raw milk, as well as artisanal cheeses produced in the North-west of Iran. To evaluate the intrinsic parameters that may affect the survival of Brucella spp., some of the cheese properties (e.g., pH, salt, moisture, and storage time before selling) were also assessed. A total of 572 samples consisting in 214 sheep raw milk, 92 goat raw milk, and 266 local artisanal cheese samples were collected. The artisanal cheeses were manufactured from a mixture of raw sheep and goat milk. According to the results, using quantitative real-time PCR (qPCR), 17.29%, 15.22%, and 22.93% of the sheep raw milk, goat raw milk, and artisanal cheese samples were found positive for Brucella spp., respectively. In comparison with culture assay, qPCR was 3.5 to 5 times (p < 0.05) more sensitive in the detection of Brucella spp. The results also revealed that the mean values of Brucella spp. load in sheep and goat raw milk and artisanal cheeses were 1.22, 1.55, and 1.43 log cell/ml or g, respectively. A positive correlation was found between Brucella load and successful detection of Brucella spp. by culture assay. Data also suggested a correlation (p < 0.01) between the load of Brucella spp. estimated by qPCR and pH value, salt content, and storage period of the cheese samples. However, Brucella spp. load did not correlate significantly with the moisture content. Based on the results, in any of the cheese samples with a pH value less than 4.5 and a storage period more than five months, no contamination with Brucella spp. was detected.


Assuntos
Brucella/isolamento & purificação , Queijo/microbiologia , Leite/microbiologia , Animais , Carga Bacteriana , Técnicas Bacteriológicas , Brucella/genética , Queijo/análise , Armazenamento de Alimentos , Cabras , Irã (Geográfico) , Prevalência , Reação em Cadeia da Polimerase em Tempo Real , Ovinos
2.
Molecules ; 26(8)2021 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-33918775

RESUMO

The objective of this study was to compare the effects of the incorporation of microcapsules or nanoemulsions with Opuntiaoligacantha on the quality of fresh cheese. Three treatments were established: Control, cheese with microcapsules (Micro), and cheese with nanoemulsion (Nano). The parameters evaluated were physicochemical (moisture, ash, fat, proteins, and pH), microbiological (mesophilic aerobic bacteria, mold-yeast, and total coliforms), functional (total phenols, flavonoids, and antioxidant capacity), and texture (hardness, elasticity, cohesion, and chewiness) during storage for 45 days at 4 °C. The results showed that adding microcapsules and nanoemulsion did not affect the physicochemical parameters of the cheese. Total coliforms decreased in all samples from the first days of storage (Control: 4.23 ± 0.12, Micro: 3.27 ± 0.02, and Nano: 2.68 ± 0.08 Log10 CFU), as well as aerobic mesophiles and mold-yeast counts. Regarding the functional properties, an increase in total phenols was observed in all treatments. The texture profile analysis showed that the addition of microcapsules and nanoemulsion influenced hardness (Control: 8.60 ± 1.12, Micro: 1.61 ± 0.31, and Nano: 3.27 ± 0.37 N). The antimicrobial effect was greater when nanoemulsions were added, while adding microcapsules influenced the antioxidant activity more positively.


Assuntos
Anti-Infecciosos/farmacologia , Antioxidantes/farmacologia , Queijo/análise , Composição de Medicamentos , Nanopartículas/química , Queijo/microbiologia , Fenômenos Químicos , Emulsões/química , Flavonoides/análise , Óleos Voláteis/análise , Tamanho da Partícula
3.
Food Microbiol ; 98: 103789, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33875217

RESUMO

Lentilactobacillus parabuchneri, a member of the non-starter microbiota in cheese, was recently associated with fast and effective histamine-formation ability, a safety issue. The present study was performed to investigate Lentilactobacillus parabuchneri KUH8, a histamine-producer (HP) in reduced-salt Cheddar cheese. Four cheeses were manufactured: 1) normal-salt (NS); 2) reduced-salt (RS); 3) normal-salt with HP (NS+HP); 4) reduced-salt with HP (RS+HP). Two replicates were produced with milk from the same batch, and the cheeses ripened at 10 and 15 °C. Cheeses were sampled immediately after manufacture and after 1, 3 and 6 months of ripening. Ultra-high-performance-liquid chromatography indicated that with the HP, histamine reached higher levels in reduced-salt cheeses (3.5-3.7% S/M) at 15 °C (86, 1112, 2149 and 3149 mg kg-1), compared to normal-salt cheeses (5.4-6.3% S/M) at 10 °C (78, 584, 593 and 1389 mg kg-1), at each respective cheese-sampling point. Higher salt-content reduced the growth rate of non-starter microbiota, but after six months the levels in all cheeses were similar, according to the ripening temperature: at 10 °C (8.05-8.30 log10 cfu g-1), and at 15 °C (6.00-6.94 log10 cfu g-1). A correlation between increased histamine levels, non-starter-cell development and pH was found. This study highlights the importance of normal-salt content and low-ripening temperature as measures to control histamine-formation and to improve safety in cheese.


Assuntos
Queijo/análise , Queijo/microbiologia , Histamina/metabolismo , Lactobacillaceae/metabolismo , Cloreto de Sódio/análise , Animais , Bovinos , Fermentação , Manipulação de Alimentos , Histamina/análise , Leite/química , Leite/microbiologia , Cloreto de Sódio/metabolismo
4.
Int J Food Microbiol ; 347: 109175, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-33812165

RESUMO

Pecorino is a typical Italian cheese, mostly produced in central and southern Italy regions using ewe raw milk and following traditional procedures. The use of raw milk constitutes a risk linked to the potential survival or multiplication of pathogenic microorganisms, as Shiga toxin-producing Escherichia coli (STEC). The aim of this study was to compare different Italian traditional Pecorino production methods to determine if there were any phases that could influence the Escherichia coli O157 survival rate, but also if they could negatively influence lactic acid bacteria survival rate, during the phases of production and ripening. Therefore batches of Pecorino cheese were prepared using different production methods, representing the real and typical cheese production in southern and central Italy regions: 1) heating the milk at 37 °C for about 40 min before curding, 2) heating the milk at 60 °C (thermization) for 13 min, so that the alkaline phosphatase reaction is still positive before curding, 3) cooking curd at 41 °C and 4) at 45 °C, both for 5 min. Our results demonstrated that traditional milk treatments different from pasteurization can help but do not eliminate serious microbiological treats, as E. coli O157, especially if the raw milk is heavily contaminated. The heat treatment at 60 °C applied to raw milk was able to decrease the concentration of E. coli O157 of 1.7 log10CFU/ml and, according to the inactivation slope, it would be further reduced prolonging the heating treatment. The results obtained also showed that, during the Pecorino cheese ripening, E. coli O157 was always enumerable for 60 days, remaining detectable after 90 days of ripening.


Assuntos
Queijo/microbiologia , Escherichia coli O157/fisiologia , Manipulação de Alimentos/métodos , Leite/microbiologia , Animais , Contagem de Colônia Microbiana , Escherichia coli O157/isolamento & purificação , Microbiologia de Alimentos , Itália , Lactobacillales/isolamento & purificação , Lactobacillales/fisiologia , Viabilidade Microbiana , Ovinos , Temperatura
5.
Appl Environ Microbiol ; 87(10)2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33712427

RESUMO

ε-Poly-l-lysine is a potent antimicrobial produced through fermentation of Streptomyces and used in many Asian countries as a food preservative. It is synthesized and excreted by a special nonribosomal peptide synthetase (NRPS)-like enzyme called Pls. In this study, we discovered a gene from cheese bacterium Corynebacterium variabile that showed high similarity to the Pls from Streptomyces in terms of domain architecture and gene context. By cloning it into Streptomyces coelicolor with a Streptomyces albulus Pls promoter, we confirmed that its product is indeed ε-poly-l-lysine. A comprehensive sequence analysis suggested that Pls genes are widely spread among coryneform actinobacteria isolated from cheese and human skin; 14 out of 15 Brevibacterium isolates and 10 out of 12 Corynebacterium isolates contain it in their genomes. This finding raises the possibility that ε-poly-l-lysine as a bioactive secondary metabolite might be produced and play a role in the cheese and skin ecosystems.IMPORTANCE Every year, microbial contamination causes billions of tons of food wasted and millions of cases of illness. ε-Poly-l-lysine has potent, wide-spectrum inhibitory activity and is heat stable and biodegradable. It has been approved for food preservation by an increasing number of countries. ε-Poly-l-lysine is produced from soil bacteria of the genus Streptomyces, also producers of various antibiotic drugs and toxins and not considered to be a naturally occurring food component. The frequent finding of pls in cheese and skin bacteria suggests that ε-poly-l-lysine may naturally exist in cheese and on our skin, and ε-poly-l-lysine producers are not limited to filamentous actinobacteria.


Assuntos
Proteínas de Bactérias/genética , Corynebacterium/enzimologia , Peptídeo Sintases/genética , Queijo/microbiologia , Clonagem Molecular , Corynebacterium/genética , Humanos , Polilisina/metabolismo , Pele/microbiologia , Streptomyces/genética , Streptomyces coelicolor/genética
6.
Int J Food Microbiol ; 344: 109113, 2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33652337

RESUMO

Ochratoxins are a group of mycotoxins that frequently occur as contaminants in agricultural commodities and foods, including dry-cured meats and cheeses. The fungus Aspergillus westerdijkiae is frequently isolated from aged foods and can produce ochratoxin A (OTA). However, individual strains of the fungus can have one of two OTA production phenotypes (chemotypes): OTA production and OTA nonproduction. Monitoring and early detection of OTA-producing fungi in food are the most effective strategies to manage OTA contamination. Therefore, we examined genome sequence data from five A. westerdijkiae strains isolated from the surface of cheese from southern Italy to identify genetic markers indicative of the twoOTA chemotypes. This analysis revealed a naturally occurring deletion of the OTA regulatory gene, otaR, in an OTA-nonproducing isolate.We used this information to design a polymerase chain reaction (PCR) method that could identify A. westerdijkiae and distinguish between the two OTA chemotypes. In this method, the PCR primers were complementary to conserved sequences flanking otaR and yielded different-sized amplicons from strains with the different chemotypes. The primers did not yield ota-region-specific amplicons from other OTA-producing species. Because the method is specific to A. westerdijkiae and can distinguish between the two OTA chemotypes, it has potential to significantly improve OTA monitoring programs.


Assuntos
Aspergillus/metabolismo , Queijo/microbiologia , Alimentos em Conserva/microbiologia , Carne/microbiologia , Ocratoxinas/biossíntese , Reação em Cadeia da Polimerase/métodos , Aspergillus/genética , Aspergillus/isolamento & purificação , Primers do DNA/genética , Contaminação de Alimentos/análise , Itália
7.
Int J Food Microbiol ; 345: 109130, 2021 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-33735781

RESUMO

Pélardon is an artisanal French raw goat's milk cheese, produced using natural whey as a backslop. The aim of this study was to identify key microbial players involved in the acidification and aroma production of this Protected Designation of Origin cheese. Microbial diversity of samples, collected from the raw milk to 3-month cheese ripening, was determined by culture-dependent (MALDI-TOF analysis of 2877 isolates) and -independent (ITS2 and 16S metabarcoding) approaches and linked to changes in biochemical profiles (volatile compounds and acids). In parallel, potential dominant autochthonous microorganism reservoirs were also investigated by sampling the cheese-factory environment. Complex and increasing microbial diversity was observed by both approaches during ripening although major discrepancies were observed regarding Lactococcus lactis and Lacticaseibacillus paracasei fate. By correlating microbial shifts to biochemical changes, Lactococcus lactis was identified as the main acidifying bacterium, while L. mesenteroides and Geotrichum candidum were prevalent and associated with amino acids catabolism after the acidification step. The three species were dominant in the whey (backslop). In contrast, L. paracasei, Enterococcus faecalis, Penicillium commune and Scopulariopsis brevicaulis, which dominated during ripening, likely originated from the cheese-making environment. All these four species were positively correlated to major volatile compounds responsible for the goaty and earthy Pélardon cheese aroma. Overall, this work highlighted the power of MALDI-TOF and molecular techniques combined with volatilome analyses to dynamically follow and identify microbial communities during cheese-making and successively identify the key-players involved in aroma production and contributing to the typicity of Pélardon cheese.


Assuntos
Bactérias/classificação , Bactérias/metabolismo , Queijo/microbiologia , Fungos/classificação , Fungos/metabolismo , Leite/microbiologia , Animais , Bactérias/isolamento & purificação , Enterococcus faecalis/isolamento & purificação , Enterococcus faecalis/metabolismo , Fungos/isolamento & purificação , Geotrichum/isolamento & purificação , Geotrichum/metabolismo , Cabras , Lactobacillus paracasei/isolamento & purificação , Lactobacillus paracasei/metabolismo , Lactococcus lactis/isolamento & purificação , Lactococcus lactis/metabolismo , Microbiota , Odorantes/análise , Penicillium/isolamento & purificação , Penicillium/metabolismo , Scopulariopsis/isolamento & purificação , Scopulariopsis/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
8.
Food Microbiol ; 97: 103738, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33653517

RESUMO

Paneer is a fresh, soft ready-to-eat cheese that is susceptible to Listeria monocytogenes contamination, exemplified by product recalls in Australia, Canada, and the USA. Previous research demonstrates that L. monocytogenes grows in paneer, however there are no paneer-specific predictive models that quantify the effect of environmental conditions on L. monocytogenes viability. This study measured the viability of a five-strain cocktail of L. monocytogenes in freshly prepared paneer incubated at 4-40 °C. Growth rates were fitted with the extended Ratkowsky square root model, with growth rates ranging from 0.014 to 0.352 log10 CFU/h. In comparison with published models, only the ComBase L. monocytogenes broth model acceptably predicted growth (Bf = 1.01, Af = 1.12) versus the developed model. The influence of paneer pH (5.0-6.0) and storage temperature (41-45 °C) on L. monocytogenes growth at the upper temperature growth boundary was described using a logistic model. These models provide quantitative tools to improve the safety of paneer processing conditions, shelf-life estimation, food safety management plans, and risk assessment.


Assuntos
Queijo/microbiologia , Listeria monocytogenes/química , Listeria monocytogenes/crescimento & desenvolvimento , Queijo/análise , Contagem de Colônia Microbiana , Armazenamento de Alimentos , Concentração de Íons de Hidrogênio , Cinética , Viabilidade Microbiana , Modelos Biológicos , Temperatura
9.
Food Microbiol ; 95: 103671, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33397606

RESUMO

The lack of proper gastrointestinal models assessing the inter-strain virulence variability of foodborne pathogens and the effect of the vehicle (food matrix) affects the risk estimation. This research aimed to propose a dynamic and integrated in vitro/ex vivo gastrointestinal model to evaluate the probability and severity of infection of foodborne pathogens at different matrices. An everted gut sac was used to determine the adhesion and invasion of Salmonella enterica and tissue damage. S. Typhimurium ATCC 14028 was used as a representative bacterium, and two matrices (water and cheese) were used as vehicles. No differences (p > 0.05) in the probability of infection (Pinf) were found for intra-experimental repeatability. However, the Pinf of cheese-vehiculated S. Typhimurium was different compared to water- vehiculated S. Typhimurium, 7.2-fold higher. The histological analysis revealed Salmonella-induced tissue damage, compared with the control (p < 0.05). In silico proposed interactions between two major Salmonella outer membrane proteins (OmpA and Rck) and digested peptides from cheese casein showed high binding affinity and stability, suggesting a potential protective function from the food matrix. The results showed that the everted gut sac model is suitable to evaluate the inter-strain virulence variability, considering both physiological conditions and the effect of the food matrix.


Assuntos
Doenças Transmitidas por Alimentos/microbiologia , Trato Gastrointestinal/microbiologia , Salmonella typhimurium/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Queijo/microbiologia , Água Doce/microbiologia , Humanos , Modelos Biológicos , Probabilidade , Salmonella typhimurium/genética , Salmonella typhimurium/patogenicidade , Virulência
10.
Food Microbiol ; 95: 103672, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33397607

RESUMO

Enumeration and isolation of Streptococcus salivarius subsp. thermophilus from cheese is challenging, due to the relatively high number of species it may host. We describe medium SPY9.3 for the cultivation of S. salivarius subsp. thermophilus from cheese. The medium and related incubation conditions (SPY) was compared with 2 other protocols, M17 and ST: sensitivity was assessed by parallel cultivation of 55 strains of S. salivarius subsp. thermophilus, and selectivity by (i) parallel cultivation of 60 strains belonging to 20 different non-target species and sub-species and (ii) isolating bacteria from 3 raw-milk cheeses. Colony counts were similar on SPY9.3 and M17 (mean difference 0.07 log(cfu/mL), p > 0.001) and significantly higher on ST than on M17 and SPY9.3 (mean differences 0.42 and 0.48 log(cfu/mL), respectively, p < 0.001). SPY was more specific than ST and M17, with respectively 20%, 40%, and 50% of the investigated non-target species able to grow. S. salivarius subsp. thermophilus, Enterococcus spp., and Staphylococcus aureus were indistinguishable using all 3 protocols. Only SPY avoided growth of Lactobacillus delbrueckii subsp. lactis. Finally, ST and SPY displayed higher recoveries of S. salivarius subsp. thermophilus colonies from cheese than M17 (5.6, 5.5, and 3.0 adjusted log(cfu/mL), respectively) and the lowest proportion of non-specific isolates. The protocol described here and based on SPY9.3 presents a promising alternative to existing protocols for the enumeration and isolation of S salivarius subsp. thermophilus from cheese or other complex fermented products.


Assuntos
Queijo/microbiologia , Meios de Cultura/metabolismo , Microbiologia de Alimentos/métodos , Streptococcus thermophilus/crescimento & desenvolvimento , Streptococcus thermophilus/metabolismo , Animais , Bovinos , Contagem de Colônia Microbiana , Meios de Cultura/química , Microbiologia de Alimentos/instrumentação , Leite/microbiologia , Streptococcus thermophilus/genética
11.
Food Microbiol ; 95: 103683, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33397615

RESUMO

Listeria monocytogenes can form persistent biofilms on food processing surfaces, resulting in cross-contamination of food products, including milk and milk products. Natural glycolipids are a promising intervention to control undesirable microbes due to their antimicrobial activity and low toxicity. This study aimed to determine the antimicrobial activity of glycolipids to control L. monocytogenes biofilms as well as in milk and on Queso Fresco. Application of a natural glycolipid product significantly reduced biofilm-associated L. monocytogenes on both polystyrene and stainless steel at concentrations as low as 45 mg/L. When added to UHT skim milk, a concentration of 1000 mg/L inhibited L. monocytogenes growth through 7 days of storage at 7 °C, and application of 1300 and 1500 mg/L reduced counts to levels below the limit of enumeration at day 21. In contrast, 2000 mg/L were necessary to inhibit growth through 7 days in whole milk. Glycolipid solutions at concentrations ≥10% reduced L. monocytogenes counts on Queso Fresco through 7 days when applied as a dip. Overall, natural glycolipids have potential as a natural alternative for the removal of biofilms and as an antimicrobial to control L. monocytogenes in milk and milk products with short shelf lives.


Assuntos
Biofilmes/efeitos dos fármacos , Queijo/microbiologia , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Glicolipídeos/farmacologia , Listeria monocytogenes/efeitos dos fármacos , Leite/microbiologia , Animais , Bovinos , Contagem de Colônia Microbiana , Contaminação de Alimentos/análise , Conservação de Alimentos/instrumentação , Listeria monocytogenes/crescimento & desenvolvimento
12.
J Agric Food Chem ; 69(2): 717-729, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33406836

RESUMO

This work aimed to determine the formation over time of 3-methylbutanal and 3-methylbutan-1-ol recognized as malty during the manufacture of Raclette-type cheese and the fermention of reconstituted skim milk, and filter-sterilized MRS broth. Using dynamic headspace-vacuum transfer in trap extraction followed by gas chromatography coupled with mass spectrometry-olfactometry (DHS-VTT-GC-MS-O) as a screening method for the malty compounds, five compounds (2-methylpropanal, 2- and 3-methylbutanal, and 2- and 3-methylbutan-1-ol) were identified as potential compounds causing the malty aroma in starter culture development and Raclette-type cheeses. Focus on compounds having a predominant sensorial effect (3-methylbutanal and 3-methylbutan-1-ol), spikings of leucine, 13C-labeled leucine, α-ketoisocaproic acid, and α-ketoglutaric acid provided a better understanding of their formation pathway. This study highlighted the discrepancies in the formation of 3-methylbutanal and 3-methylbutan-1-ol between the growth media; namely, despite the presence of free leucine available in MRS and the addition of an excess, no increase of the target compounds was observed. The concentration of these compounds in MRS increased only when α-ketoglutaric acid or α-ketoisocaproic acid was added, and a preference for the pathway to α-hydroxyisocaproic acid instead of 3-methylbutanal was shown. In addition, a formation of 3-methylbutanal when the bacteria were not yet active was observed when spiking α-ketoisocaproic acid, which potentially indicates that this part of the metabolism could take place extracellularly. These results could potentially unveil other, not-yet-identified reactants, directly influencing the production of compounds responsible for the malty aroma in Raclette cheese.


Assuntos
Aldeídos/metabolismo , Queijo/análise , Leite/química , Odorantes/análise , Animais , Bovinos , Queijo/microbiologia , Fermentação , Cromatografia Gasosa-Espectrometria de Massas , Lactobacillales/metabolismo , Leite/microbiologia , Olfatometria , Suíça
13.
J Med Microbiol ; 70(3)2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33475480

RESUMO

Introduction. In May-June 2018, an outbreak of campylobacteriosis involved students and school staff from kindergartens and primary schools in Pescara, southern Italy.Aim. We present details of the epidemiological and microbiological investigation, and the findings of the analytical study, as well as the implemented control measures.Methodology. To identify possible risk factors associated with the observed outbreak, a case control study was conducted using a questionnaire to collect information on the date of symptoms onset, type and duration of symptoms, type of healthcare contact, school attendance, and food items consumed at school lunches during the presumed days of exposure. Attack rates were calculated for each date and school. Logistic regression models were used to estimate the odds ratios of being a case and the odds of illness by food items consumed, respectively. Moreover, we carried out a comparative genomic analysis using whole genome multilocus sequence typing (wgMLST) of Campylobacter jejuni strains isolated during the outbreak investigation to identify the source of the outbreak.Results. Overall, 222 probable cases from 21 schools were identified, and C. jejuni was successfully isolated from 60 patients. The meals in the schools involved were provided by two cooking centres managed by a joint venture between two food companies. Environmental and food sampling, epidemiological and microbiological analyses, as well as a case control study with 176 cases and 62 controls from the same schools were performed to identify the source of the outbreak. The highest attack rate was recorded among those having lunch at school on 29 May (7.8 %), and the most likely exposure was 'caciotta' cheese (odds ratio 2.40, 95 % confidence interval 1.10-5.26, P=0.028). C. jejuni was isolated from the cheese, and wgMLST showed that the human and cheese isolates belonged to the same genomic cluster, confirming that the cheese was the vehicle of the infection.Conclusion. It is plausible that a failure of the pasteurization process contributed to the contamination of the cheese batches. Timely suspension of the catering service and summer closure of the schools prevented further spread.


Assuntos
Infecções por Campylobacter , Campylobacter jejuni/isolamento & purificação , Queijo/microbiologia , Surtos de Doenças , Microbiologia de Alimentos , Doenças Transmitidas por Alimentos/microbiologia , Adulto , Infecções por Campylobacter/epidemiologia , Infecções por Campylobacter/microbiologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Doenças Transmitidas por Alimentos/epidemiologia , Humanos , Itália , Masculino , Pasteurização , Instituições Acadêmicas , Inquéritos e Questionários
14.
Food Microbiol ; 93: 103613, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32912585

RESUMO

The composition of the bacterial community of Grana Padano (GP) cheese was evaluated by an amplicon-based metagenomic approach (DNA metabarcoding) and RAPD-PCR fingerprinting. One hundred eighteen cheeses, which included 118 dairies located in the production area of GP, were collected. Two hundred fifty-four OTUs were detected, of which 82 were further discriminated between dominant (32 OTUs; > 1% total reads) and subdominant (50 OTUs; between 0.1% and 1% total reads) taxa. Lactobacillus (L.) delbrueckii, Lacticaseibacillus (Lact.) rhamnosus, Lact. casei, Limosilactobacillus fermentum, Lactococcus (Lc.) raffinolactis, L. helveticus, Streptococcus thermophilus, and Lc. lactis were the major dominant taxa ('core microbiota'). The origin of samples significantly impacted on both richness, evenness, and the relative abundance of bacterial species, with peculiar pattern distribution among the five GP production regions. A differential analysis allowed to find bacterial species significantly associated with specific region pairings. The analysis of pattern similarity among RAPD-PCR profiles highlighted the presence of a 'core' community banding pattern present in all the GP samples, which was strictly associated with the core microbiota highlighted by DNA metabarcoding. A trend to group samples according to the five production regions was also observed. This study widened our knowledge on the bacterial composition and ecology of Grana Padano cheese.


Assuntos
Queijo/microbiologia , Código de Barras de DNA Taxonômico/métodos , Impressões Digitais de DNA/métodos , Microbiologia de Alimentos , Microbiota/genética , Bactérias/classificação , Bactérias/genética , Biodiversidade , Biologia Computacional , DNA Bacteriano/genética , Técnicas de Genotipagem , Lactobacillus/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Streptococcus thermophilus/genética , Tilacoides
15.
Food Microbiol ; 94: 103668, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33279091

RESUMO

Nisin is an antimicrobial peptide that is commonly used as a food preservative and capable of inhibiting the pathogen Listeria monocytogenes. However, nisin is ineffective in controlling L. monocytogenes in Queso Fresco (QF). To address the challenge, in this work, we used synthetic biology strategies to create a series of nisin A derivatives by substituting residues 27, 30, 31 and 32 with positively charged amino acids (H, K and R). Our results showed that nisin derivatives exhibited reduced antilisterial activity in vitro compared to nisin A; however, they were all more stable under QF-like experimental conditions (pH 7 + 22% milk fat), notably H27/31K. Compared to nisin A, the derivatives H31K and V32K exhibited slight antilisterial improvement in QF and H27/31K was able to reduce the initial population of L. monocytogenes by up to 1.5 Log CFU/g. L. monocytogenes isolates exhibited similar susceptibility to nisin A or H27/31K after 7 or 14 days of nisin exposure in QF. Notably, when combined with endolysin PlyP100, the application of H27/31K resulted in non-enumerable levels of L. monocytogenes after 14 days of cold storage. Our results highlight the potential of bioengineered nisin derivatives for stabilized and enhanced control of L. monocytogenes in QF.


Assuntos
Antibacterianos/farmacologia , Queijo/microbiologia , Endopeptidases/farmacologia , Conservação de Alimentos/métodos , Listeria monocytogenes/efeitos dos fármacos , Nisina/análogos & derivados , Nisina/farmacologia , Contagem de Colônia Microbiana , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Conservantes de Alimentos/farmacologia , Listeria monocytogenes/crescimento & desenvolvimento
16.
J Sci Food Agric ; 101(2): 555-563, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32672836

RESUMO

BACKGROUND: In Southern European countries, whey cheeses are normally produced with ovine or caprine whey. Cow's cheese whey can also be used, although the whey cheese yield is low (2-3%, w/v) which discourages its use. In the present study, bovine cheese whey was concentrated by ultrafiltration for the production of four types of whey cheeses (Requeijão): conventional, without any addition (WC); with 10% (w/w) addition of cream (WCC); with cream fermented with Kefir culture (WCCK); and with cream fermented with Bifidobacterium sp. culture (WCCBB12). RESULTS: Whey cheeses with cream presented lower protein content (330-360 g kg-1 , dry basis) and higher levels of total solids (220-250 g kg-1 ) and fat (300-330 g kg-1 , dry basis) than WC. C16:0 and C18:1 were the most abundant fatty acids present, with 31% and 38%, respectively. The small differences found concerning instrumental determination of colour and texture were not perceived by panelists. However, the presence of Kefir and probiotics decreased the elastic modulus (G') of the samples, as well as their viscosity. Fermentation with Kefir presented the highest counts of lactic acid bacteria (7 logUFC g-1 ). However, after 14 days of refrigerated storage, the counts of yeasts and moulds reached 6 logUFC g-1 in all products, indicating the need for appropriate packaging solutions. CONCLUSION: Ultrafiltration of bovine whey allows for the efficient production of bovine whey cheeses. The addition of cream fermented with Kefir or BB12 appears to be an efficient methodology to incorporate Kefir or probiotic bacteria in Requeijão, improving its nutritional and sensory characteristics, alongside the potential for the extension of its shelf-life. © 2020 Society of Chemical Industry.


Assuntos
Bifidobacterium/metabolismo , Queijo/microbiologia , Microbiologia de Alimentos/métodos , Kefir/microbiologia , Probióticos/metabolismo , Ultrafiltração/métodos , Soro do Leite/microbiologia , Animais , Bovinos , Queijo/análise , Módulo de Elasticidade , Fermentação , Kefir/análise , Lactobacillales/crescimento & desenvolvimento , Lactobacillales/metabolismo , Leite/química , Leite/microbiologia , Probióticos/análise , Ovinos , Soro do Leite/química
17.
J Dairy Sci ; 104(2): 1504-1517, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309377

RESUMO

Fresh unripened curd cheese has long been a well-known Eastern European artisanal dairy product; however, due to possible cross-contamination from manual production steps, high moisture content (50-60%), and metabolic activity of present lactic acid bacteria, the shelf life of curd cheese is short (10-20 d). Therefore, the aim of this study was to improve the shelf life of Eastern European acid-curd cheese by applying an antimicrobial protein-based (5%, wt/wt) edible coating. The bioactive edible coating was produced from liquid whey protein concentrate (a cheese production byproduct) and fortified with 0.3% (wt/wt, solution basis) Chinese cinnamon bark (Cinnamomum cassia) CO2 extract. The effect of coating on the cheese was evaluated within package-free (group 1) and additionally vacuum packaged (group 2) conditions to represent types of cheeses sold by small and big scale manufacturers. The cheese samples were examined over 31 d of storage for changes of microbiological (total bacterial count, lactic acid bacteria, yeasts and molds, coliforms, enterobacteria, Staphylococcus spp.), physicochemical (pH, lactic acid, protein, fat, moisture, color change, rheological, and sensory properties). The controlled experiment revealed that in group 1, applied coating affected appearance and color by preserving moisture and decreasing growth of yeasts and molds during prolonged package-free cheese storage. In group 2, coating did not affect moisture, color, or texture, but had a strong antimicrobial effect, decreasing the counts of yeasts and molds by 0.79 to 1.55 log cfu/g during 31 d of storage. In both groups, coating had no effect on pH, lactic acid, protein, and fat contents. Evaluated sensory properties (appearance, odor, taste, texture, and overall acceptability) of all samples were similar, indicating no effect of the coating on the flavor of curd cheese. The edible coating based on liquid whey protein concentrate with the incorporation of cinnamon extract was demonstrated to efficiently extend the shelf life of perishable fresh curd cheese, enhance its functional value, and contribute to a more sustainable production process.


Assuntos
Anti-Infecciosos/farmacologia , Queijo/normas , Cinnamomum zeylanicum/química , Contaminação de Alimentos/prevenção & controle , Lactobacillales/metabolismo , Extratos Vegetais/farmacologia , Proteínas do Soro do Leite/farmacologia , Animais , Dióxido de Carbono/farmacologia , Queijo/microbiologia , Filmes Comestíveis , Armazenamento de Alimentos , Casca de Planta/química , Extratos Vegetais/química , Paladar
18.
Int J Biol Macromol ; 170: 94-106, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33358950

RESUMO

Considering the need of new lactic acid bacteria (LAB) for the production of novel biosurfactant (BS) molecules, the current study brings out a new insight on the exploration of cheese samples for BS producers and process optimization for industrial applications. In view of this, Lactobacillus plantarum 60FHE, Lactobacillus paracasei 75FHE, and Lactobacillus paracasei 77FHE were selected as the most operative strains. The biosurfactants (BSs) described as glycolipoproteins via Fourier-transform infrared spectroscopy (FTIR) exhibited antimicrobial activity against the food-borne pathogens. L. plantarum 60FHE BS showed an anticancer activity against colon carcinoma cells and had a week antiviral activity against Hepatitis A virus. Furthermore, glycolipoprotein production was enhanced by 1.42-fold through the development of an optimized process using central composite design (CCD). Emulsifying activities were stable after 60-min incubation from 4 to 120 °C, at pH 2-12, and after the addition of NaCl (2-14%). Characterization by nuclear magnetic resonance spectroscopy (1H NMR) revealed that BS produced from strain 60FHE was glycolipoprotein. L. plantarum produced mixed BSs determined by Liquid Chromatography/Mass Spectrometry (LC-MS). Thus, indicating that BS was applied as a microbial food prevention and biomedical. Also, L. plantarum 60FHE BS was achieved with the use of statistical optimization on inexpensive food wastes.


Assuntos
Anti-Infecciosos/isolamento & purificação , Antineoplásicos/isolamento & purificação , Proteínas de Bactérias/isolamento & purificação , Queijo/microbiologia , Glicoproteínas/isolamento & purificação , Lactobacillus plantarum/química , Lipoproteínas/isolamento & purificação , Tensoativos/isolamento & purificação , Anti-Infecciosos/química , Anti-Infecciosos/economia , Anti-Infecciosos/farmacologia , Antineoplásicos/química , Antineoplásicos/economia , Antineoplásicos/farmacologia , Proteínas de Bactérias/química , Proteínas de Bactérias/economia , Proteínas de Bactérias/farmacologia , Linhagem Celular Tumoral , Cromatografia Líquida , Neoplasias do Colo/patologia , Glicoproteínas/química , Glicoproteínas/economia , Glicoproteínas/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Vírus da Hepatite A/efeitos dos fármacos , Humanos , Lactobacillus paracasei/química , Lactobacillus paracasei/isolamento & purificação , Lactobacillus plantarum/isolamento & purificação , Lipoproteínas/química , Lipoproteínas/economia , Lipoproteínas/farmacologia , Espectrometria de Massas , Ressonância Magnética Nuclear Biomolecular , Filogenia , Ribotipagem , Espectroscopia de Infravermelho com Transformada de Fourier , Tensoativos/química , Tensoativos/economia , Tensoativos/farmacologia , Resíduos/análise
19.
Int J Food Microbiol ; 337: 108937, 2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33171308

RESUMO

Since cheese is poor in energy for bacterial growth, it is believed that non-starter lactic acid bacteria growth and flavour development are supported by the nutrients from lysis of the starter culture. This study was performed to investigate the dynamics of interaction between starter and non-starter strains from cheese. A starter culture lysate was prepared by enzymatic digestion and tested as a growth substrate for Lactobacillus sp. strains. The two starter culture strains of Lactococcus lactis were also tested on the starter-lysate. All seventeen strains were individually inoculated at the level of 5.0 log10 cfu mL-1 in M17 broth, with or without 10% starter-lysate, and incubated at 30 °C for 140 h. The optical density600 nm was modelled with the primary log-transformed Logistic model with delay and lag phase duration, maximum specific growth rate as well as maximum population density obtained. Biphasic growth was mainly observed when the strains were able to utilize the starter-lysate as an energy source. To deal with the lack-of-fit related to the biphasic growth, the observed data points of the curve were divided after graphic evaluation and according to deviation of the residuals from the range ±0.05. Modelling was then performed in two phases by applying the same primary Logistic model in each of the two parts of the growth curve. Values of root-mean-square error and graphic evaluation indicated the good fitting of the data with the suggested approach. The growth of the two Lactococcus lactis strains was not affected by the starter-lysate. However, thirteen of the non-starter strains had their growth rates increased. The increase was greatest for Lactobacillus rhamnosus KU-LbR1, which reached maximum optical densities of 0.23 and 0.58 in the absence and the presence of starter-lysate, respectively. No effect of the starter-lysate was shown for the growth of Lactobacillus curvatus strains. The extend of the growth of non-starter strains on the starter-lysate was shown to be species and strain dependent.


Assuntos
Queijo/microbiologia , Microbiologia de Alimentos , Lactobacillales/crescimento & desenvolvimento , Modelos Biológicos , Animais , Concentração de Íons de Hidrogênio , Leite/microbiologia , Paladar
20.
Food Chem ; 340: 128154, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33010641

RESUMO

Numerous bacteria are responsible for hydrolysis of proteins during cheese ripening. The raw milk flora is a major source of bacterial variety, starter cultures are needed for successful acidification of the cheese and proteolytic strains like Lactobacillus helveticus, are added for flavor improvement or acceleration of ripening processes. To study the impact of higher bacterial diversity in cheese on protein hydrolysis during simulated human digestion, Raclette-type cheeses were produced from raw or heat treated milk, with or without proteolytic L. helveticus and ripened for 120 days. Kinetic processes were studied with a dynamic (DIDGI®) in vitro protocol and endpoints with the static INFOGEST in vitro digestion protocol, allowing a comparison of the two in vitro protocols at the level of gastric and intestinal endpoints. Both digestion protocols resulted in comparable peptide patterns after intestinal digestion and higher microbial diversity in cheeses led to a more diverse peptidome after simulated digestion.


Assuntos
Queijo/microbiologia , Proteínas do Leite/metabolismo , Leite/microbiologia , Aminoácidos/análise , Animais , Queijo/análise , Cromatografia Líquida de Alta Pressão , Digestão , Microbiologia de Alimentos , Humanos , Lactobacillus helveticus/genética , Lactobacillus helveticus/crescimento & desenvolvimento , Lactobacillus helveticus/metabolismo , Espectrometria de Massas , Leite/metabolismo , Peptídeos/análise , Proteólise , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo
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