Feta Cheese Research Articles

In Silico Identification of Antimicrobial Peptides in the Proteomes of Goat and Sheep Milk and Feta Cheese.

Milk and dairy products are a major functional food group of growing scientific and commercial interest due to their nutritional value and bioactive “load”. A major fraction of the latter is attributed to milk’s rich protein content and its biofunctional peptides that occur naturally during digestion. On the basis of the identified proteome datasets of milk whey from sheep and goat breeds in Greece and feta cheese obtained during previous work, we applied an in silico workflow to predict and characterise the antimicrobial peptide content of these proteomes. We utilised existing tools for predicting peptide sequences with antimicrobial traits complemented by in silico protein cleavage modelling to identify frequently occurring antimicrobial peptides (AMPs) in the gastrointestinal (GI) tract in humans. The peptides of interest were finally assessed for their stability with respect to their susceptibility to cleavage by endogenous proteases expressed along the intestinal part of the GI tract and ranked with respect to both their antimicrobial and stability scores.

Proteolysis and textural properties of low‐fat ultrafiltered Feta cheese as influenced by maltodextrin

Maltodextrin was used as a fat replacer in low‐fat ultrafiltered cheese. Fat was replaced with 25% maltodextrin milk solution (w/w) in cheese at 15 and 50% (w/w). The chemical, rheological and sensory properties as well as the microstructure of the cheese samples were evaluated after storage for 2 months at 8 °C. Maltodextrin affected the chemical (pH, dry matter, fat, water‐soluble nitrogen to total nitrogen, nonprotein nitrogen to total nitrogen, total free amino acid) and rheological (mean relaxation time) properties, as well as the microstructure. In general, based on textural properties, sensory evaluation and economic aspects, the 50%‐fat‐reduced sample was selected as the best treatment.

Progressive ultrastructural changes in the casein matrix during the ripening of inadequately acidified feta cheese

This study investigated the ultrastructural changes underlying the undesired softening of insufficiently acidified feta cheese during cold storage. Experimental feta cheeses with a range of pH values before brining were manufactured by allowing the cheese blocks to ferment overnight at 3 temperatures (35, 20, and 3°C), which resulted in pH values of 4.80, 4.88, and 5.17, respectively. Cheese blocks were stored in pH-adjusted whey brine solutions for up to 120 d, at which point significant decreases in the cheese firmness were confirmed with compression and shear tests. Samples for transmission electron microscopy were taken during the make procedure, after overnight fermentation, and after 7 and 90 d of cold storage. Increasing the initial pH from 4.80 to 5.17 resulted in a fundamentally different ultrastructure at d 90, with the protein matrix as the continuous phase having markedly decreased density compared with the typically open porous and discontinuous protein matrix of high density in the low-pH control feta cheese. Ultrastructural changes were progressive, and the first signs were evident after only 20 h (the overnight fermentation), when fine, proteinaceous material dissociated from the edges of the casein strands into the serum phase. By d 7, the serum phase was completely filled with the loosely aggregated casein closely surrounding the spheroidal fat globules. A further breakdown of the protein matrix was observed after 90 d, with the complete loss of open porous network structure. Image analysis quantitatively confirmed the progressive and significant decrease in density of the protein matrix. In summary, this is the first study to provide a comprehensive and in-depth view of the progressive and most likely irreversible ultrastructural changes that lead to this textural defect.

Elongational flow studies of processed cheese spreads made from traditional greek cheese varieties

Five series of cheese spreads were prepared and pasteurized at either 92 or 98 °C. The basic ingredient of the samples was a blend of traditional greek cheeses i.e. Myzithra, a whey cheese and Feta cheese in proportion 0.9/0.1. The first series of samples contained only this mixture whereas the other series consisted of samples to which apart from the mixture of the cheeses, either UHT milk or water or olive oil were added in various proportions. The flow properties of the samples were studied by performing lubricated squeeze flow experiments. The results indicated that the elongational viscosity values exhibited, under steady conditions, by the samples were considerably lower to that of the sample contained only the blend of the two cheeses which was not heat treated. It was found that the various ingredients added to the samples affected their flow behavior in various degrees with the olive oil to cause the most noticeable changes. Creep experiments performed using the same samples supported, in general, the findings from the elongational flow measurements.

Palm Kernel Oil as a Substitute of Milk Fat in Feta Cheese

Four samples of Feta cheese 5 Kg/each made by substituting buffalo milk fat with palm kernel oil (PKO). The substituting ratios were 25%, 50%, 75% and 100% (PKO) to milk fat (MF). Fat content of the obtained cheese was 40% fat/dry matter. A control batch contained milk fat with the same fat content was prepared. The resultant cheese samples were stored at room temperature for three months. Samples were analyzed monthly during pickling period to investigate the effect of the treatment with (PKO) on cheese yield, gross composition, organoleptic properties and the changes in fatty acids pattern of fat content of the resultant cheese samples. The results showed that substituting of milk fat with different ratios of (PKO) caused a significant increase in moisture content, when compared with the control, while the total solids decreased. Cheese yield of all cheese treatments decreased as pickling period progressed. Moisture content of the cheese decreased, whereas fat, total protein and ash contents increased as pickling period progressed. Cheese flavor was enhanced in cheese containing different ratios of (PKO), while the texture of cheese widely depended on the ratio of (PKO) added. Cheese samples showed a similar color and appearance to the control.The changed occurred in fatty acids pattern of the examined samples showed that the addition of (PKO) as a milk fat substitute at ratios 25%, 50%, 75% and 100%, resulted in an increase in the total medium chain fatty acids of the cheese fat when compared with milk fat. Cheese samples treated with 25% and 50% (PKO) were of the higher score of the acceptability due to the presence of medium chain fatty acids. It could be concluded that the use of (PKO) as buffalo's milk fat substitute succeeded in making Feta cheese of healthy and of acceptance for the consumers..

Relationship between farmers’ perception of sustainability and future farming strategies: A commodity-level comparison

The environmental challenges have become increasingly integrated into the European Union’s Common Agricultural Policy (CAP). The Europe 2020 CAP Framework defines new rules for farmers and targets on innovation, resource efficiency, economic viability, and environmental sustainability. Given the continual evolution of the CAP, it is relevant to focus on sustainable agriculture and which indicators can be employed to aid our understanding of the future farming strategies. This study examines the relationship between perceived sustainability and future farming strategies for three different commodities: sugar beet, dairy, and feta cheese. Survey data collected between 2017–2018 from 191 Belgian sugar beet farmers, 524 dairy farmers (from UK, Denmark, France, and Latvia), and 150 Greek sheep and goat farmers producing milk for feta cheese were analysed using multinomial logistic regressions. Our results show that the farmers’ attitude towards sustainability affects intentions to implement specific farming strategies. Belgian sugar beet farmers who perceive their supply chain arrangements (SCAs) environmentally sustainable are less likely to reduce the scale of their farms’ operations rather than to maintain them. Dairy farmers are more likely to change the existing scale than to maintain scale if they perceive that production choices affect environmental sustainability to a higher extent. Dairy farmers who perceive their SCAs economically sustainable are less likely to abandon farming. Greek sheep and goat farmers who perceive their SCAs economically sustainable are more likely to expand the existing scale. The observed differences at commodity-level show the importance of well targeted policy measures towards more sustainable farming systems in the European Union.

The Vitamine Source, Usual Food Intake at Students.

Introduction:Inadequate vitamin B 12, folate status and B6 are associated with an increased risk for chronic diseases that may have a negative impact on the health.Aim:The aim of our study was to investigate dietary intake of vitamin B12, B6 and folates from various foods among the university students.Methods:Dietary intake of foods having vitamins B12, B6 and folate was assessed among the students of University of Sarajevo, 19-22 years old, from 2017 to 2018. The participants were interviewed to collect information regarding age, socioeconomic status, B12, folate, B6 vitamin, and usual food intake during one week.Results:The main sources of vitamin B12 and B6 in the students’ diet were chicken white meat (51.8-53.7 %), beef (45-63 %), cream (62.2 -72.1 %), sardines in oil (47.9-52.2 %), tuna (55.2 -60.4 %), cheese edamer (80.1%) and cheese feta (67.4%-73%). The foods with a high source of vitamin B12 and B6 but rarely consumed were fish, shellfish, salmon, roasted trout and mackerel. Sufficient folate intake was mainly achieved through dietary intake of beans (48.5-57.2%) and oatmeal (46.3-48.2%), while folate-insufficient diet resulted from intake of spinach (30.9-35 %), turkey (26.2-33.4 %), lentils (16.9-19.7 %) and soy (9.4-15.5%).Conclusion:Our results show that there is an important percentage of the students in Canton Sarajevo that do not meet the recommended intakes for vitamin B12 and B6 and folate. Additional research is needed to establish the best cost-effective public health approach to achieve sufficient intake of these vitamins.

Volatile organic compounds of mountainous plant species and the produced milk as affected by altitude in Greece: A preliminary study

The objective of this study was to characterise the volatile organic compounds (VOCs) profile of plant species, bulk forage grazed by sheep and produced milk at different mountainous areas of Greece. The most abundant plant species of vegetation at 800 m (hill‐land) and 1300 m (highland) altitude, bulk forage and milk samples, were collected. The VOCs profiles of the plant species and milk varied. Common VOCs in milk from both areas were identified, whereas others were discriminatory for each area. Overall, the VOCs composition of mountainous milk could provide a basis for Feta cheese identification with its region.

Development and characterization of probiotic UF Feta cheese containing Lactobacillus paracasei microencapsulated by enzyme based gelation method.

In this study probiotic microcapsules with three different shell compositions were produced through enzymatic gelation of skim milk powder by rennet, skim milk powder by transglutaminase and sodium caseinate by transglutaminase. Fabricated microcapsules and free Lactobacillus paracasei cells were incorporated into Iranian UF Feta cheese with different salt levels. Viability of L. paracasei (LAFTI L26), antioxidative capacity, ripening index, titrable acidity, salt content and texture profile analysis (TPA test) parameters including hardness, cohesiveness and stringiness were monitored during 45days of storage time. Rennet based encapsulation was the most efficient method and could keep L. paracasei viable in all cheese samples (> 7log10CFU/g) at the end of storage time. Proteolysis pattern and acidification rate were strongly influenced by shell composition, salt level and storage time. Hardness and stringiness of probiotic cheese samples were influenced by shell composition of microcapsules and storage time but cohesiveness was only dependent on storage time. Therefore, storage time was the only effective factor on free radical scavenging activity of cheese samples.

Research on Intellectual Property Right Dispute among Nations: A Case of "China-EU Geographical Indications Dispute over FETA Cheese" and Implications for North Korea

Research on Intellectual Property Right Dispute among Nations: A Case of "China-EU Geographical Indications Dispute over FETA Cheese" and Implications for North Korea

Phenotypic and genotypic characterization of listeria species isolated from poultry and milk products

Listeria monocytogenes has become increasingly important as a food-associated pathogen. It cancause a rare but serious disease called listeriosis with high fatality rates (20–30%) compared withother foodborne microbial pathogens. To estimate the incidence and levels of Listeria spp. indifferent food sources, A total of 200 random samples which collected from different sources 65samples isolated from poultry , 45 from poultry byproducts (Frozen chicken meat balls (kofta),Frozen chicken burger and frozen chicken sausages), 20 from pasteurized milk ,30 from milkproducts (Feta cheese ,cream cheese )and 40 from poultry eggs .Only 7 of total 200 samples (14%)that collected from suspected isolates and detected on Oxford agar, PALCAM agar and ALOA agarwere suspected to be Listeria spp. In poultry, poultry byproducts, pasteurized milk, milk byproductsand poultry eggs, listeria percentage were 0/65(0%), 4/45(1.8), 0/20(0%), 0/30(0%), 3/40(1.2%)isolates, respectively. The in-vitro antimicrobial sensitivity test showed that the isolated L.monocytogenes were sensitive to Sulphamethoxazole /trimethoprim, Gentamycin, Ceftazidime andCephazoline followed by Sulphamethoxazole, ceftriaxone , weak sensitivity to Penicillin . Whilethey were resistant to Erythromycin, Clindamycin, Ampicillin. The results of virulence tests forisolated listeria strains appeared that all of L .monocytogenes were virulent strains as all of themwere positive to CAMP test; showed narrow zone of β–hemolysis on sheep blood agar .The PCRresults for Listeria isolates showed that all strains are L. monoctogenes and have Inl A and hly Agenes positive as virulence genes while negative Inl B, iap and prf A genes.

Para-κ-casein during the ripening and storage of low-pH, high-moisture Feta cheese.

The hypothesis of this research paper was that the physicochemical conditions in a low-pH, high-moisture white brined cheese such as Feta would make para-κ-casein vulnerable to residual chymosin activity during ripening and storage. It was important to address this hypothesis, since cheese para-κ-casein could theoretically be used for the assessment of the origin of cheese milk by means of various analytical methods. Feta cheese was manufactured from sheep milk and from four different mixtures of sheep and goat milk in triplicate. The para-κ-casein of Feta samples taken during 120 d of ripening and storage was estimated by means of cation-exchange HPLC and proteolysis was determined in terms of free amino groups. Despite their similarity, sheep and goat para-κ-casein were efficiently separated and the changes of their chromatographic areas indicated that hydrolysis took place during the first stage of ripening. In accordance to the evolution of free amino groups, para-κ-caseins remained stable thereafter. The hydrolysis pattern was not affected by the composition of the cheese milk mixture and after 120 d at least two thirds of the initial quantity remained intact. Considering the efficient separation of sheep and goat para-κ-caseins and their stability during Feta storage, the same method was used for the evaluation of the percentage of goat milk in the cheese milk. The actual and the estimated percentage of goat milk within the range 0-40 were strongly correlated (R = 0·997, n = 60) and the standard error of estimation was 0·914.

Prevalence and antimicrobial susceptibility of Enterococcus spp. in ready-to-eat salads (dips), the environment and the personnel of a salad processing plant in Northern Greece

A total of 225 samples from the dips (cheese, roe, egg plant and tzatziki dip), the environment and the handlers of a salad manufacturing plant in Northern Greece were examined for the presence and antibiotic susceptibility of Entervcocccus spp. Enterococcus faecium was the isolated species from 12% of the samples. 38.1% and 15% of egg plant and cheese dip samples were positive, respectively. Among the dip ingredients, 30% of mayonnaise, 20% of feta cheese and 10% of myzithra were positive. Positive were, also, 8.6 % of the environmental samples, 20% from handlers' skirts, 20% from handlers' gloves and 16.7% from their nasal cavity. All isolates were sensitive to glycopeptides (vancomycin and teicoplanin). Isolates from handlers' nasal cavities were resistant to penicillin and ampicillin, while one of them was, also, resistant to chloramphenicol. All isolates from the environment, the dips and their ingredients were susceptible to these three antibiotics, but they presented resistance to more than 3 antibiotic categories. Ready-to-eat foods may be potential source of contamination to humans of multidrug resistant enterococci. Further research is needed to elucidate their epidemiology in these foods.

Greek functional Feta cheese: Enhancing quality and safety using a Lactobacillus plantarum strain with probiotic potential

The aim of the study was to investigate the performance of Lactobacillus plantarum T571 with probiotic potential as a co-starter culture in Feta cheese production and in its long-term storage. For this reason, Feta cheese was manufactured without (control) or with the probiotic T571 strain (probiotic) and then monitored during storage at 4 and 12 °C, respectively. The products were also inoculated with Listeria monocytogenes (3-strain cocktail). The results showed that lactic acid bacteria exceeded 6 log CFU/g during storage in all trials. The probiotic samples displayed higher acidity (≈1.5% lactic acid) and lower pH (≈4.2). Coliforms and L. monocytogenes, were inactivated in shorter time in probiotic samples, in comparison with the control ones. Pulsed field gel electrophoresis verified the presence of the probiotic strain in the cheese, until the end of storage at both temperatures, whilst the survival and distribution of the pathogenic strains depended on the trial. The sensory evaluation showed that the probiotic cheeses had desirable sensory characteristics similar to the control ones, with scores of ca. 8 on a 10 cm-scale. Finally, Fourier transform infrared spectroscopy was applied for the first time during Feta cheese storage with promising results for the rapid estimation of the microbiological counts and sensory status of cheese. Results showed that Lb. plantarum T571 highlighted desirable and robust technological properties and may be used in cheese making as an adjunct culture.

Dipteran species in agricultural region of eastern Thessaloniki

In an agricultural region of Thessaloniki province, fly traps were placed, which contained substances in order to attract flies with the purpose to trap and identify them. The substances were, pieces offish, meat and feta cheese, sugar and faeces of small ruminants. Fifteen different flies species were trapped, of which, thirteen are mentioned in the international bibliography, as parasites, such as, Musca domestica, Muscina sp, Fannia sp, Phormia regina, Lucilia (Phaenicia) sericata, Calliphora erythrocephala (vicina), Sarcophaga sp, Oestrus ovis, Gasterophillus sp, Stomoxys calcitrans, Haematobia (Shiphona) irritans, Chrysops sp and Hydrotaea (Ophyra) spp and two, as no parasites, such as Drosophilla melanogaster and Apis mellifera. From the trapped flies, Hydrotaea sp, Muscina sp, Fannia sp and Phormia regina, were identified for the first time in Greece. From the substances which were used in order to attract the flies, the fish was the one that all flies showed preference to, in the greater number, while the rest of the substances they chose descending order, was meat, sugar and feta cheese. Finally, only one fly was found in the excrement of small ruminants.

Survival of Escherichia coli 0157:H7 in Feta cheese during storage

The survival of E. co/i0157:H7 in Feta cheese and the brine used after 2 months ripening of cheese, was studied during storage at 4°C and 12°C. An inoculum of 5.3 log10CFU/ml of E. coli Ol57:H7 was added in brine, for the contamination with the pathogen of Feta cheese. E. coli Ol 57:H7 was detectable in brine by direct plating on SMAC up to 40th day and 32th day during its storage at 4°C and 12°C respectively, while by enrichment and following plating on SMAC up to 44th day (4°C) and 36th day (12°C). The E. coli 0157:H7 was detectable in Feta by direct plating on SMAC up to 44th day (4°C) and 38th day (12°C), while by enrichment and following plating on SMAC up to 50th day (4°C) and 42th day (12°C). The results showed that E. coli Ol57:H7 survived longer in Feta than in its brine, for both storage temperatures but the difference was very low. The survival of E. coli 0157:H7 in feta and brine was longer during the storage at 4°C than at 12°C.

Compositional characteristics and volatile organic compounds of traditional PDO Feta cheese made in two different mountainous areas of Greece

The compositional characteristics of Feta cheese manufactured in two mountainous areas from raw milk, from sheep fed by grass, and the forages’ volatile organic compounds (VOC) were studied, to differentiate the Feta cheese. Although the main compositional features did not vary greatly, the proteolysis mode was altered. The VOC profiles of the cheeses varied. While some VOCs were common to both groups of cheeses, others were discriminatory for each production area. There were common terpenes in both the bulk forage and the mature cheeses. Overall, the VOC composition of Feta could provide a basis for identification with regard to its region of origin.

EFFECT OF ADDITIVE ON THE PROCESS PARAMETERS AND COAGULATION IN A PRODUCTION OF FETA CHEESE

Milk and milky products are multycomponent systems. The technology of milk processing mostly depends on the ways of separating these components. In addition to classic methods of separation (evaporation, suction and distillation), modern methods allows separation similiar compounds and mixtures that are sensitive to temperature changes, pH, light, etc. The most important separation processes are: reverse osmosis, microfiltration and ultrafiltration. The membrane technique of the ultrafiltration process is the separation of the components of one solution depending on its molecular size (10-1000). In the process of milk tetrating, two separate fractions are obtained: retentate - a fraction containing proteins with minimal amounts of lactose and mineral matter and permeate - fraction containing lactose, mineral matter, non-protein nitrogen, free amino acids and vitamins. In this paper, the results of physical and chemical testing of feta in the process of ripening after 15 days, after a month, after month and a half and after 2 months are presented. The results of the material balance in feta are also given in the paper. They are calculated by the relationship between the standard quantity of milk (100 l) and the amount of feta cheese that is obtained as the final product after ripening.

Effect of high pressure on structural modifications and enzymatic activity of a purified X-prolyl dipeptidyl aminopeptidase from Streptococcus thermophilus

PepX aminopeptidase from Streptococcus thermophilus ACA DC 0022, used in Greek Feta cheese manufacturing, was purified. PepX comprises two subunits of equal molecular mass estimated, using SDS-PAGE and native-PAGE electrophoresis, to be 86 kDa.The effects of high pressure processing (100–450 MPa, combined with 20–40 °C) on purified PepX activity and structure were studied. Activation of the enzyme was observed after processing at 100–200 MPa and 20–30 °C. More intense processing conditions led to enzyme inactivation. PepX HP-induced conformational changes were also investigated through application of Circular Dichroism spectroscopy (CD). Pressures up to 200 MPa resulted in a structurally molten globule-like state where PepX maintained its secondary structure but the tertiary structure was substantially affected and enzyme activity increased. Both secondary and tertiary structures were affected severely by higher pressures (450 MPa), which reduced enzyme activity.

Categorization of control measures in food safety management systems

Purpose All food safety management standards require effective control measures of food safety hazards in order to ensure that food is safe at the time of human consumption. Furthermore, ISO 22000:2005 requires a logical approach to be carried out for the selection and categorization of the control measures according to the level of effect on identified food safety hazards. The purpose of this paper is to describe the COntrol MEasures CATegorization (COMECAT) method for the categorization of control measures in food safety management systems (FSMS) in order to assist organizations to prioritize and deploy their efforts and limited resources mainly to control significant hazards. Design/methodology/approach A thorough clarification of the characteristics of the different control measures used in FSMS has been achieved based on the definitions and the descriptions given by the different food safety standards such as the ISO 22000, the IFS and the BRC standards. The basic approaches for the determination of control measures found in literature and web pages have been examined and the proposed methodology has been implemented in feta cheese production in order to evaluate its applicability. Findings A decision tree model has been proposed as the most suitable approach for the categorization of control measures in FSMS. The implementation of the proposed COMECAT method in feta cheese production revealed its applicability. The method was able to identify the different risk level of food hazards and prioritize and deploy the organization’s efforts and limited resources for their management accordingly. Originality/value In the literature, there is a lack of justified methodologies for the categorization of control measures in FSMS. Most of the approaches concern attempts of private companies operating in the food industry or business consultancies and which can be found in their web pages. This paper describes a well-justified model for the categorization of control measures which is easy to implement and which results in more robust decisions.