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1.
Food Chem ; 398: 133932, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35987010

RESUMO

A simple, rapid, sensitive and robust gas chromatographic method was developed for the simultaneous determination of free volatile carboxylic acids (FVCA) in cheese and bacterial cultures. The target analytes were extracted and converted directly from the aqueous phase to their ethyl esters using headspace. The lower detection limits for the volatile carboxylic acids in the cheese samples were less than 0.3 and less than 0.6 µmol kg-1 in the bacterial culture samples. The lower limits of quantitation in cheese were better than 0.001 mmol kg-1 for all analytes. The upper limits of quantitation varied from 39 to 136 mmol kg-1 in cheese and 78 to 272 mmol kg-1 in bacterial cultures depending on the analyte. The Horwitz ratio showed good precision for all analytes (less than 0.77). The proposed method is suitable for the determination of target metabolites directly from aqueous extracts and can also be validated for other matrices.


Assuntos
Queijo , Ácidos Carboxílicos/análise , Queijo/análise , Cromatografia Gasosa , Esterificação , Cromatografia Gasosa-Espectrometria de Massas/métodos
2.
Food Res Int ; 160: 111672, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36076384

RESUMO

Untargeted metabolomics was used to investigate the changes in small molecules of non-volatile metabolites and related mechanisms in the production process of Mongolian cheese. In addition, the changes in volatile compounds, free amino acids and bacterial community succession were also studied. A total of 37 differential metabolites were screened at 5 different stages of the production process by multivariate analysis of metabolomics datasets. The differential metabolites associated with amino acids, glycerophospholipid and pyrimidine metabolism were found to be mainly changed. In addition, the total nine functional core bacterial genera that significantly influenced compounds distribution in the cheese production process were identified based on correlation analysis and bidirectional orthogonal partial least squares (O2PLS) analysis. Lactococcus and Acinetobacter had positive effects on the formation of flavor volatiles and beneficial amino acids (p < 0.05); Streptococcus and Serratia showed strong correlations with amino acid catabolism (p < 0.05). This research revealed comprehensive insights into the metabolite alterations, bacterial succession and their dynamic correlations in the cheese process and would provide a theoretical basis for better quality control of Mongolian cheese production.


Assuntos
Queijo , Aminoácidos/metabolismo , Bactérias , Queijo/microbiologia , Sequenciamento de Nucleotídeos em Larga Escala , Metabolômica
3.
Food Res Int ; 160: 111707, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36076456

RESUMO

Izmir Brined Tulum (IBT) Cheese is a traditional semi hard cheese produced in the Aegean region of Türkiye. Lactic acid bacteria (LAB) isolates from IBT cheese samples taken during manufacture and from mature IBT cheeses were investigated for their acid producing capability with the aim of detecting LAB strains responsible for acid production in IBT cheese. Forty two out of 216 isolates decreased the pH of milk to 5.0 or below in 18 h at 37 °C or 42 °C. 16S rRNA Sanger sequencing revealed the presence of LAB species that had not been detected in IBT cheese previously and, indeed, were identified for the first time as the primary acid producers. The majority of these acid producing isolates were identified as putative Streptococcus lutetiensis/Streptococcus infantarius subsp. infantarius (Sii). Further analysis by sequencing the groES/groEL genes of these isolates established that they were Sii. The remaining isolates from cheese samples taken during manufacture were identified as Streptococcus macedonicus, S. thermophilus, Lactococcus lactis subsp. lactis, Lactobacillus delbrueckii subsp. sunkii and L. delbrueckii subsp. indicus and, from mature cheeses, as Enterococcus faecalis and L. delbrueckii subsp. sunkii. Pulsed-field gel electrophoresis (PFGE) results revealed a large genetic diversity amongst the Sii isolates recovered from the IBT cheeses. It was also established that the Sii strains exhibited efficient and consistent acidification ability equivalent to S. thermophilus. Whole-genome sequencing (WGS) and comparative genome analysis of the representative Sii AYB210 strain provided further insights. More specifically, the genome of AYB210 differed from the previously sequenced African dairy isolate Sii CJ18 and the human isolate ATCC®BAA-102™. Modifications in the lactose operon, which may be an indicator of dairy adaptation, were identified and a high number of CRISPR spacers and putative bacteriocin, virulence factor and antibiotic resistance genes were also detected.


Assuntos
Queijo , Lactobacillales , Lactococcus lactis , Animais , Queijo/microbiologia , Humanos , Lactobacillales/genética , Lactobacillus , Lactococcus lactis/genética , Leite/microbiologia , RNA Ribossômico 16S/genética , Streptococcus
4.
Food Res Int ; 160: 111735, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36076465

RESUMO

Lentilactobacillus parabuchneri is the main bacteria responsible for the accumulation of histamine in cheese. The goal of this study was to assess the efficiency of potential histamine-degrading microbial strains or, alternatively, the action of the diamine oxidase (DAO) enzyme in the reduction of histamine accumulation along the ripening process in cheese. A total of 8 cheese variants of cow milk cheese were manufactured, all of them containing L. parabuchneri Deutsche Sammlung von Mikroorganismen 5987 (except for the negative control cheese variant) along with histamine-degrading strains (Lacticaseibacillus casei 4a and 18b; Lactobacillus delbrueckiisubsp. bulgaricus Colección Española de Cultivos Tipo (CECT) 4005 and Streptococcus salivariussubsp.thermophilus CECT 7207; two commercial yogurt starter cultures; or Debaryomyces hansenii), or DAO enzyme, tested in each cheese variant. Histamine was quantified along 100 days of cheese ripening. All the degrading measures tested significantly reduced the concentration of histamine. The highest degree of degradation was observed in the cheese variant containing D. hansenii, where the histamine content decreased up to 45.32 %. Cheese variants with L. casei, or L. bulgaricus and S. thermophilus strains, also decreased in terms of histamine content by 43.05 % and 42.31 %, respectively. No significant physicochemical changes (weight, pH, water activity, color, or texture) were observed as a consequence of the addition of potential histamine-degrading adjunct cultures or DAO in cheeses. However, the addition of histamine-degrading microorganisms was associated with a particular, not unpleasant aroma. Altogether, these results suggest that the use of certain histamine-degrading microorganisms could be proposed as a suitable measure in order to decrease the amount of histamine accumulated in cheeses.


Assuntos
Amina Oxidase (contendo Cobre) , Queijo , Lactobacillus casei , Animais , Bovinos , Queijo/análise , Feminino , Microbiologia de Alimentos , Histamina , Streptococcus thermophilus
5.
J Dairy Sci ; 105(10): 7891-7903, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36055836

RESUMO

The amount of intact casein provided by dairy ingredients is a critical parameter in dairy-based imitation mozzarella cheese (IMC) formulation because it has a significant effect on unmelted textural parameters such as hardness. From a functionality perspective, rennet casein (RCN) is the preferred ingredient. Milk protein concentrate (MPC) and micellar casein concentrate (MCC) cannot provide the required functionality due to the higher steric stability of casein micelle. However, the use of transglutaminase (TGase) has the potential to modify the surface properties of MPC and MCC and may improve their functionality in IMC. The objective of this study was to determine the effect of TGase-treated MPC and MCC powders on the unmelted textural properties of IMC and compare them with IMC made using commercially available RCN. Additionally, we studied the degree of crosslinking by TGase in MPC and MCC retentates using capillary gel electrophoresis. Three lots of MCC and MPC retentate were produced from pasteurized skim milk via microfiltration and ultrafiltration, respectively, and randomly assigned to 1 of 3 treatments: no TGase (control); low TGase: 0.3 units/g of protein; and high TGase: 3.0 units/g of protein, followed by inactivation of enzyme (72°C for 10 min), and spray drying. Each MCC, MPC, and RCN was then used to formulate IMC that was standardized to 21% fat, 1% salt, 48% moisture, and 20% protein. The IMC were manufactured by blending, mixing, and heating ingredients (4.0 kg) in a twin-screw cooker. The capillary gel electrophoresis analysis showed extensive inter- and intramolecular crosslinking. The IMC formulation using the highest TGase level in MCC or MPC did not form an emulsion because of extensive crosslinking. In MPC with a high level of TGase, whey protein and casein crosslinking were observed. In contrast, crosslinking and hydrolysis of proteins were observed in MCC. The IMC made from MCC powder had significantly higher texture profile analysis hardness compared with the corresponding MPC powder. Further, many-to-one (multiple) comparisons using the Dunnett test showed no significant differences between IMC made using RCN and treatment powders in hardness. Our results demonstrated that TGase treatment causes crosslinking hydrolysis of MCC and MPC at higher TGase levels, and MPC and MCC have the potential to be used as ingredients in IMC applications.


Assuntos
Caseínas , Queijo , Animais , Caseínas/análise , Queijo/análise , Emulsões , Manipulação de Alimentos/métodos , Comportamento Imitativo , Micelas , Proteínas do Leite/análise , Pós , Transglutaminases , Proteínas do Soro do Leite/análise
6.
J Dairy Sci ; 105(10): 7904-7916, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36055846

RESUMO

Melt and stretch properties in dairy-based imitation mozzarella cheese (IMC) are affected by the amount of intact casein provided by dairy ingredients in the formulation. Rennet casein (RCN) is the preferred ingredient to provide intact casein in a formulation. Ingredients produced using membrane technology, such as milk protein concentrate (MPC) and micellar casein concentrate (MCC), are unable to provide the required functionality. However, the use of transglutaminase (TGase) has potential to modify the physical properties of MPC or MCC and may improve their functionality in IMC. The objective of this study was to determine the effect of TGase-treated MPC and MCC retentates on melt and stretch properties when they are used in IMC and to compare them with IMC made using RCN. The MCC and MPC retentates were produced using 3 different lots of pasteurized skim milk and treated with 3 levels of TGase enzyme: no TGase (control), low TGase: 0.3 units/g of protein, and high TGase: 3.0 units/g of protein. Each of the MCC and MPC treatments was heated to 72°C for 10 min to inactivate TGase and then spray dried. Each MCC, MPC, and RCN powder was then used in an IMC formulation that was standardized to 48% moisture, 21% fat, 20% protein, and 1% salt. The IMC were manufactured in a twin-screw cooker by blending, mixing, and heating various ingredients (4.0 kg). Due to extensive crosslinking, the IMC formulation with the highest TGase level (MCC or MPC) did not form an emulsion. The IMC made from MCC treatments had significantly higher stretchability on pizza compared with their respective MPC treatments. The IMC made from TGase-treated MCC and MPC had significantly lower melt area and significantly higher transition temperature (TT) and stretchability compared with their respective controls. Comparison of IMC made using TGase-treated MCC and MPC to the RCN IMC indicated no difference in TT or texture profile analysis-stretchability; however, the Schreiber melt test area was significantly lower. Our results demonstrated that TGase treatment modifies the melt and stretch characteristics of MCC and MPC in IMC applications, and TGase-treated MPC and MCC can be used to replace RCN in IMC formulations.


Assuntos
Queijo , Animais , Caseínas , Queijo/análise , Emulsões , Manipulação de Alimentos/métodos , Comportamento Imitativo , Micelas , Proteínas do Leite/metabolismo , Pós , Transglutaminases
7.
Food Microbiol ; 108: 104101, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36088116

RESUMO

Four batches of Cebreiro-type cheese were made in duplicate from pasteurized milk. A control batch was manufactured with only a commercial O-starter. The other three batches were made with the same starter plus: (i) a commercial culture of Enterococcus faecium; (ii) a selected Kluyveromyces lactis adjunct culture used in a cheese-milk pre-ripening step; and (iii) the combination of both adjunct cultures. The cheeses made with the yeast adjunct were characterized by higher values of overall proteolysis, pH and aw, and showed total and lactic acid bacteria (LAB) counts at least 2 log units than the batches made with only LAB. The volatile profiles of the cheeses made with added K. lactis were distinguished by high contents of esters, branched-chain alcohols, fatty acids, acetoin and 2-pnenylethanol. These batches had a more friable and sticky texture, and exhibited differential piquant, yeasty, alcoholic, acetic and fruity flavors. Furthermore, the addition of enterococci seemed to help achieve more desirable sensory characteristics. The batches manufactured with both adjunct cultures were awarded the highest scores for texture preference, flavor intensity, flavor preference, and overall sensory preference. The sensory profiles of the cheeses made with added yeast closely resembled those of traditional 'good quality' raw-milk Cebreiro cheese.


Assuntos
Queijo , Enterococcus faecium , Kluyveromyces , Queijo/microbiologia , Leveduras
8.
Microb Cell Fact ; 21(1): 184, 2022 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-36076243

RESUMO

BACKGROUND: Efficient upgrading of inferior agro-industrial resources and production of bio-based chemicals through a simple and environmentally friendly biotechnological approach is interesting Lactobionic acid is a versatile aldonic acid obtained from the oxidation of lactose. Several microorganisms have been used to produce lactobionic acid from lactose and whey. However, the lactobionic acid production titer and productivity should be further improved to compete with other methods. RESULTS: In this study, a new strain, Pseudomonas fragi NL20W, was screened as an outstanding biocatalyst for efficient utilization of waste whey to produce lactobionic acid. After systematic optimization of biocatalytic reactions, the lactobionic acid productivity from lactose increased from 3.01 g/L/h to 6.38 g/L/h in the flask. In batch fermentation using a 3 L bioreactor, the lactobionic acid productivity from whey powder containing 300 g/L lactose reached 3.09 g/L/h with the yield of 100%. Based on whole genome sequencing, a novel glucose dehydrogenase (GDH1) was determined as a lactose-oxidizing enzyme. Heterologous expression the enzyme GDH1 into P. putida KT2440 increased the lactobionic acid yield by 486.1%. CONCLUSION: This study made significant progress both in improving lactobionic acid titer and productivity, and the lactobionic acid productivity from waste whey is superior to the ever reports. This study also revealed a new kind of aldose-oxidizing enzyme for lactose oxidation using P. fragi NL20W for the first time, which laid the foundation for further enhance lactobionic acid production by metabolic engineering.


Assuntos
Queijo , Pseudomonas fragi , Dissacarídeos , Fermentação , Lactose/metabolismo , Oxirredução , Pseudomonas fragi/metabolismo , Soro do Leite/metabolismo
9.
Molecules ; 27(17)2022 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-36080289

RESUMO

The stability of milk proteins is affected by changes in the pH value of milk, the heating temperature, and the addition of calcium compounds or chelating agents, which can cause alterations in calcium distribution. The purpose of this study was to determine the potential of the use of calcium citrate to manufacture fresh acid rennet cheese from high-temperature-pasteurized goat's milk (90 °C, 15 s) from the spring and autumn season and the effect of the calcium dose used on the physicochemical and organoleptic properties of the cheese. Autumn milk was found to be a richer source of total solids, confirming the effect of the production season on milk quality. The applied doses of calcium did not cause the denaturation of goat milk proteins and allowed pasteurization to take place at 90 °C for 15 s. The addition of calcium citrate resulted in a significant increase in the pH value of milk and cheese compared to the control sample. Adding 15 and 20 mg of Ca 100 g-1 to milk as citrate had the most beneficial effect on increasing protein retention in cheese in both seasons, showing a rise from 1.33% to 2.40%. The production season significantly influenced the cheese yield. The control goat cheese from the autumn season showed a 6.85% higher yield compared to the spring cheese. An increase in cheese yield was also observed as the calcium dose of milk increased. The content of micro- and microelements in cheese was affected by the production season. The addition of calcium citrate to milk resulted in a significant increase in the calcium content of cheese-from 120.83 to 147.45 mg 100 g-1 in the spring season and from 130.66 to 151.21 mg 100 g-1 in the autumn season. Increasing the dose of calcium increased the hardness of cheese samples by 1.37 N in the spring and 0.90 N in the autumn. The organoleptic evaluation showed that adding calcium to milk did not significantly affect the organoleptic characteristics of goat cheese.


Assuntos
Queijo , Animais , Cálcio , Citrato de Cálcio , Queijo/análise , Quimosina , Cabras , Temperatura Alta , Proteínas do Leite/análise , Estações do Ano
10.
Molecules ; 27(17)2022 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-36080356

RESUMO

Hafnia alvei is receiving increasing attention from both a medical and veterinary point of view, but the diversity of molecules it produces has made the interest in this bacterium extend to the field of probiotics, the microbiota, and above all, to its presence and action on consumer foods. The production of Acyl Homoserine Lactones (AHLs), a type of quorum-sensing (QS) signaling molecule, is the most often-studied chemical signaling molecule in Gram-negative bacteria. H. alvei can use this communication mechanism to promote the expression of certain enzymatic activities in fermented foods, where this bacterium is frequently present. H. alvei also produces a series of molecules involved in the modification of the organoleptic properties of different products, especially cheeses, where it shares space with other microorganisms. Although some strains of this species are implicated in infections in humans, many produce antibacterial compounds, such as bacteriocins, that inhibit the growth of true pathogens, so the characterization of these molecules could be very interesting from the point of view of clinical medicine and the food industry. Lastly, in some cases, H. alvei is responsible for the production of biogenic amines or other compounds of special interest in food health. In this article, we will review the most interesting molecules that produce the H. alvei strains and will discuss some of their properties, both from the point of view of their biological activity on other microorganisms and the properties of different food matrices in which this bacterium usually thrives.


Assuntos
Queijo , Hafnia alvei , Acil-Butirolactonas , Bactérias/metabolismo , Hafnia alvei/metabolismo , Humanos , Percepção de Quorum
11.
Ethiop J Health Sci ; 32(4): 799-808, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35950059

RESUMO

Background: Enterococci are naturally found in the gastrointestinal (GI) tract of animals and humans, as well as animal-derived foods and vegetables. We here aimed to determine the prevalence, antibiotic resistance, and virulence determinants of E. faecium and E. faecalis in traditional cheese in the North-west of Iran. Materials and Methods: Fifty specimens of popular traditional cheese from dairy stores of Urmia and Tabriz, Iran, were collected. Identification of the genus and species of enterococci was done using molecular and phenotypic techniques. Results: Forty-eight (96 %) of 50 traditional cheese samples were harboring Enterococcus spp, including Enterococcus faecalis (n= 40; 83.33 %) and E. faecium (n= 8; 16.67 %). The prevalence of enterococci ranged from 1.1×105 to 9.7×104 CFU/g, and 1.1×103 to 9.8×103 CFU/g in Urmia and Tabriz samples, respectively. Rifampicin resistance (n= 38; 79.2 %) was the most common pattern observed in the susceptibility test, which was followed by quinupristin/dalfopristin (n= 33; 68.75 %). Among E. faecalis isolates, cpd (100 %), ace (92.5 %) and gelE (87.5 %), and among E. faecium isolates, gelE (100 %) and asa1 (75 %) were found to have the most common virulence genes. Conclusion: E. faecalis was the predominant species, displaying more virulence determinants. It also had high antibiotic resistance, as compared to E. faecium. The enterococci identified here commonly expressed virulence and antibiotic resistance determinants. So, it is required to improve the maintenance and production quality of traditional cheese to avoid enterococci contamination.


Assuntos
Queijo , Infecções por Bactérias Gram-Positivas , Animais , Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Enterococcus/genética , Enterococcus faecalis/genética , Humanos , Testes de Sensibilidade Microbiana , Prevalência , Virulência , Fatores de Virulência/genética
12.
Molecules ; 27(15)2022 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-35956892

RESUMO

The objective of this study was to determine the trace element composition and the toxic metal residues in Galician cow's milk cheese produced in different systems (artisan, industrial, and organic). Fourteen elements (As, Cd, Co, Cr, Cu, Fe, Hg, I, Mn, Mo, Ni, Pb, Se, and Zn) were determined in 58 representative samples of Galician cheeses by inductively coupled plasma mass spectrometry. The toxic elements were present at low concentrations, similar to those reported for other unpolluted geographical areas. The essential elements were also within the normal range in cheeses. There were no statistically significant differences between smoked and unsmoked cheeses for any of the elements. Chemometric analyses (principal component analysis and cluster analysis) revealed that the industrial cheeses produced in Galicia using the milk from intensive dairy farms were different, in terms of elemental content, from artisan and organic cheeses, in which the elemental contents were similar.


Assuntos
Queijo , Oligoelementos , Animais , Bovinos , Queijo/análise , Fazendas , Feminino , Leite/química , Análise Espectral , Oligoelementos/análise
13.
Food Res Int ; 159: 111627, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35940766

RESUMO

The roles of mesophilic lactobacilli in cheese manufacturing and ripening have been widely studied, but their impacts, especially as additives in preserving liquids, on the high-moisture mozzarella cheese quality parameters remained underexplored. The current study studied and compared the effects of four preserving liquid formulations - brine solution (sodium chloride, as control), a salt mixture solution, and two lactobacilli solutions (Lactiplantibacillus plantarum IMC 509 in brine solution) or SYNBIO® (a 1:1 ratio of Lacticaseibacillus rhamnosus IMC 501 and Lacticaseibacillus paracasei IMC 502) - on the microbial, chemical (volatile fatty acids), physicochemical (moisture, weight, pH, colour), texture (adhesiveness, hardness, cohesiveness, gumminess, springiness, chewiness) and sensorial qualities of mozzarella stored for 30 days at 4 °C. The quality of the governing solution, including microbial content, lactobacilli viability, pH, turbidity, and smell, was also monitored. For the first 10 days of storage, all samples demonstrated similar physicochemical variations: the firmness and chewiness of the mozzarella lessened, the pH values of the liquid decreased, but cheese microbial growth increased, as did the levels of free fatty acids, the mozzarella pH values and skin whiteness. At day 20, mozzarella stored in mesophilic lactobacilli liquid, especially SYNBIO®, had a spongy structure, tasted more bitter and sour, and had lower pH values than mozzarella in the simple brine solution. Moreover, the cheese sample and liquid of SYNBIO® also presented higher coliform and Pseudomonas spp. counts than that detected in the control, the SYNBIO® liquid, especially in the later period of storage, exhibited a yogurt smell and increased turbidity. By contrast, Mozzarella packed into salt mixture liquid exhibited somewhat more adhesiveness and gumminess, a saltier taste and slightly higher microbial counts than the control sample. The mozzarella samples differed slightly in colour and texture as well. The overall quality changes suggested that the use of the studied mesophilic lactobacilli as governing liquid additives may not be appropriate for high-moisture mozzarella cheese preservation.


Assuntos
Queijo , Olfato , Cloreto de Sódio , Paladar
14.
Exp Appl Acarol ; 87(4): 309-323, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35984584

RESUMO

The opisthonotal glands of Astigmata contain monoterpenes, aromatics, aliphatics, and other volatile compounds; some of these compounds act as pheromones and have antifungal effects. This study analyzed volatile compounds secreted by mites on three traditional mite-ripened cheeses from producers (Milbenkäse from Germany, Mimolette and Artisou from France). The mites obtained from various traditional ripened French cheeses (Mimolette, Laguiole, Salers, and Cantal vieux) from stores were also investigated. The gas chromatography (GC) profiles of all their hexane extracts, except the Cantal vieux one, showed almost no differences and were identical to that of Tyrolichus casei Oudemans except for trace components. Based on the GC results, the mites of Cantal vieux were identified as Acarus siro L. For the Artisou and Cantal vieux, not studied before, the influence of the mite secretions on their characteristics was investigated by analyzing the headspace volatiles from the cheeses. According to the results, neral secreted from T. casei is the main compound responsible for the lemon-like flavor of the mite-ripened cheeses, which is, hence, due to a component of the mite secretions rather than the fermentation of the cheese itself. Moreover, the compounds secreted by the mites are not directly added to the cheese through ripening as they were not detected in the odors of the Artisou and Cantal vieux after the mites were removed. However, the consumers of the Artisou usually eat also the cheese rind, and thus, can enjoy its lemon-like flavor fully.


Assuntos
Queijo , Ácaros , Animais , Queijo/análise , Fermentação , Monoterpenos/análise , Odorantes/análise
15.
J Dairy Sci ; 105(10): 7951-7958, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35965117

RESUMO

Cheese, especially ripened varieties, harbor a very complex and heterogeneous microbiota. In addition to the desired microorganisms (starter cultures) added during cheese production, potentially harmful bacteria may also enter the production chain. Regarding the latter, the focus of this study was on coagulase-negative staphylococci (CNS) and Macrococcuscaseolyticus. Both are known to harbor a variety of genes coding for antibiotic resistance, including mecA, mecB, mecC, and mecD. Coagulase-negative staphylococci or macrococci carrying such genes or other virulence factors should not be present in cheese. Cheese samples (101 in total) were collected from retail sources. Coagulase-negative staphylococci and M. caseolyticus were isolated utilizing selective agars, and species were identified by phenotypical tests and partial sequencing of the sodA gene. The results allowed identification of 53 CNS strains and 19 M. caseolyticus strains. Among the CNS, 11 isolates of Staphylococcus saprophyticus and one Staphylococcus epidermidis isolate were obtained. Both species are potential human pathogens and may thus adversely affect the safety of these food products. Screening for antimicrobial resistance was performed by application of disc diffusion tests, a gradient strip-test, and 14 different PCR tests. Evidence for methicillin resistance (by either positive disc diffusion assay for cefoxitin or by mec PCR) was found in CNS isolates and M. caseolyticus (9 isolates each). Regarding other virulence factors, no genetic determinants for coagulase or the most common staphylococcal enterotoxins sea, seb, sec, sed, and see were detected in any of the CNS or M. caseolyticus isolates by PCR testing. In conclusion, the presence of facultatively pathogenic CNS and carriers of genes for antibiotic resistance in both groups of microorganisms, especially mec genes, and the respective food safety issues need further evaluation and surveillance.


Assuntos
Anti-Infecciosos , Queijo , Animais , Cefoxitina , Queijo/microbiologia , Coagulase/genética , Enterotoxinas/genética , Humanos , Staphylococcus , Fatores de Virulência/genética
16.
J Dairy Sci ; 105(10): 8143-8157, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36028343

RESUMO

Concentration is a key determinant in the overall positive impact of terpenes on milk and cheese aroma; additionally, route of intake may affect the achievable concentrations of dietary terpenes in milk and cheese. In this study, we explored the possibility that the amount of the monoterpene limonene transferred to sheep milk and its corresponding cheese could differ depending on the route of intake and that the aroma profile of these products could also differ. To this aim, 12 lactating dairy ewes were repeatedly exposed to limonene by the oral or respiratory route during a 48-h test period, according to a 3 × 3 Latin square experimental design. Limonene content was measured in individual and bulk milk samples, in 1-d-old and 15-d-old Caciotta cheese obtained from that milk, in the related whey and curd, and in the air inhaled by the ewes in the respiratory treatment group (to obtain an estimate of the dose actually supplied by this route). Bulk milk and fresh (1-d-old) cheese underwent sensory analysis by ortho-olfactory evaluation. Both intake routes demonstrated transfer of limonene to milk, but the respiratory route transferred limonene with greater efficiency than the oral route. Moreover, according to the protocol used in this study, a short period of respiratory exposure induced a slightly higher limonene content in milk compared with oral exposure. As to the fate of limonene during cheesemaking, an important part of it was lost into the whey, perhaps through volatilization. The differences between milk and cheese tended to dissipate in curd and fresh cheese and disappeared completely after 15 d of ripening. Finally, it was possible to distinguish between the 2 routes of limonene intake using sensory analysis, even though no direct relationship was identified between the different aroma profiles of milks and cheeses from the oral and respiratory groups and their respective limonene contents. Overall, our results expand current knowledge on the biological pathways of terpene transfer from feed to sheep milk and cheese, as well as on the role played by terpenes in the formation of aroma in these products. Our observations may contribute to future development of strategies for external control and better standardization of the presence of odor compounds in milk and cheese from dairy ruminants.


Assuntos
Queijo , Animais , Queijo/análise , Feminino , Lactação , Limoneno/análise , Leite/química , Odorantes/análise , Projetos Piloto , Ovinos , Proteínas do Soro do Leite/análise
17.
J Food Sci ; 87(9): 3822-3840, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35986575

RESUMO

The antifungal activity of natural antimicrobials such as essential oils (EOs), citrus extracts, and other natural derivatives was evaluated against 10 fungal strains using minimum inhibitory concentration (MIC) analysis. Compounds having the highest inhibitory activity at the lowest concentrations were subsequently selected to evaluate the possible synergistic interactions by checkerboard method (FIC). The results showed that citrus extract A (CEA) and EOs rich in cinnamaldehyde had the highest inhibitory capacity against evaluated strains (Aspergillus niger, Aspergillus versicolor, Aureobasidium pullulans, Eurotium rubrum, Paecilomyces spp., Penicillium chrysogenum, Penicillium citrinum, Penicillium commune, Penicillium crustosum, and Penicillium roqueforti). The stability of the antifungal mixture was then optimized using lecithin and sucrose monopalmitate (SMP) as surfactants. Stability test showed that lecithin:SMP at HLB 10 maintains emulsion stability for 15 days of storage at 4°C. Encapsulation process for the loaded emulsion was optimized using whey protein isolate (WPI) and maltodextrin (MD) blend with ratios WPI:MD (1:2) and WPI:MD (1:3). The results showed that WPI:MD (1:3) led to a higher physicochemical stability (-40.5 mV), encapsulation efficiency (91%), and antifungal activity (315 ppm). Microencapsulation maintained the available active compounds content more prolonged with an average interval of 7 days compared to the nonencapsulated formulations during storage at 4°C.


Assuntos
Queijo , Óleos Voláteis , Antifúngicos/farmacologia , Aspergillus niger , Emulsões/química , Lecitinas , Óleos Voláteis/farmacologia , Polissacarídeos , Tensoativos , Proteínas do Soro do Leite/química , Proteínas do Soro do Leite/farmacologia
18.
Food Microbiol ; 107: 104067, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35953187

RESUMO

Milk contamination with Staphylococcus aureus can lead to food poisoning in consumers. One strategy to minimize this risk is the use of phage-derived lysins, which are innocuous for humans and do not readily select for resistant variants. However, it remains necessary to find new candidate lysins and define the conditions for their utilization. This study compares the potential of LysRODI and its derivative LysRODIΔAmi (lacking the amidase domain), which displays high activity and storage stability, to successfully decrease staphylococcal contamination in milk under different conditions. Our results show that the engineered protein is more efficacious than the parent endolysin in practically all cases. For instance, while LysRODI only decreased the number of cells by 1-2 log units in different types of commercial milk and contamination levels, the chimeric lysin eliminated them below detection. Also, LysRODIΔAmi was more active against four strains with varying degrees of susceptibility. Regarding incubation temperature, both proteins were faster at 32 °C and 37 °C. Significantly, the engineered lysin eliminated detectable contamination in just 15 min. Finally, LysRODIΔAmi proved very successful at reducing staphylococcal contamination below detection during lab-scale fresh cheese production by enzymatic coagulation. Our data show that LysRODIΔAmi is a promising candidate for biocontrol in milk.


Assuntos
Queijo , Amidoidrolases , Animais , Endopeptidases/genética , Endopeptidases/metabolismo , Humanos , Leite/metabolismo
19.
Food Microbiol ; 107: 104087, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35953192

RESUMO

Fermented foods constitute a wide source of exogenous lactic acid bacteria (LAB) which could modify the endogenous microbiota of the consumer's digestive tract. This assumption depends on the ability of LAB to persist, at least transiently, in the oral cavity. The aim of this study was to evaluate the persistence of 3 LAB species, Streptococcus thermophilus, Lactococcus lactis, and Lacticaseibacillus paracasei in the oral cavity of rats by feeding them with a daily portion of model cheese containing the three bacteria for one week. Saliva samples were collected 16 h and one week after the last daily cheese intake. Their cheese bacteria contents were quantified by qPCR. When 16 h after cheese consumption, cheese bacteria were detected in the oral cavity of about ⅓ of the rats ranging from 10-3% to 10-1% of the total bacteria. One week after the last cheese intake, 1/8 LAB remains in the oral cavity. This study is a proof of concept showing that LAB can remain in the oral cavity several days after fermented food consumption with variability depending on individuals.


Assuntos
Queijo , Lactobacillales , Animais , Queijo/microbiologia , Microbiologia de Alimentos , Boca , Ratos , Streptococcus thermophilus
20.
Food Microbiol ; 107: 104060, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35953193

RESUMO

An extensive cardinal parameter growth and growth boundary model for C. sporogenes, as a surrogate for proteolytic C. botulinum, was developed to include the inhibitory effect of 11 environmental factors. 626 maximum specific growth rates (µmax) in broth were generated to determine cardinal parameter values for the growth inhibiting effect of temperature, pH, NaCl/water activity (aw), organic acids (acetic, benzoic, citric, lactic, sorbic) and phosphate melting salts (ortho-, di- and tri-phosphates). µmax-values for C. sporogenes growing in well-characterized processed cheeses were used for product calibration (n = 10) and for product evaluation of the developed broth-model (n = 29). 112 growth/no-growth responses and including 104 µmax-values from the scientific literature for 58 different isolates of proteolytic and toxigenic C. botulinum (Group I) were used for further model evaluation. The developed model had less bias and a higher percentage of correct predictions than available models and was acceptable for processed cheese and good for meat products. The new and extensive model can predict combinations of environmental factors that prevent growth of C. sporogenes and of proteolytic C. botulinum. These predictions are expected to facilitate development or re-formulation of processed cheese and meat products where growth is prevented.


Assuntos
Queijo , Clostridium botulinum , Clostridium , Microbiologia de Alimentos
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