Protected Designation Of Origin Cheese Research Articles

The real subsumption of nature and cryopolitics: Temporal fixes in dairy farming in Southern Italy

Water buffaloes have a seasonal cycle of reproduction. Normally they tend to reproduce more when the daylight hours decrease. This seasonal reproduction also means that most of the buffalo calves would be born in autumn and winter in Italy where buffaloes are dairy animals, and milk production would be the highest in these seasons. However, consumer demand for the PDO (Protected designation of origin) mozzarella cheese is the highest in spring and summer. In order to deal with the imbalances between the seasonality of milk production and mozzarella consumption, and the strict regulations of the PDO cheese production, farmers and veterinarians resort to a temporal fix, and they regularly deseasonalise buffalo reproduction. However, there is an obvious discrepancy between the use of this and other fixes (cryotechnologies) generally associated with industrial agriculture, and the idea of traditional and sustainable food production. By engaging with relevant economic geography and political ecology literature, this paper investigates the temporal fixes in dairy farming and agri-food production through an in-depth empirical analysis of deseasonalisation, as a particular form of the real subsumption of nature, and cryopolitics in buffalo mozzarella cheese production in Southern Italy. The work presented in this article is based on multi-sited qualitative field research of buffalo farming and mozzarella cheese production in Campania region. This paper also has wider implications on how socio-ecological fixes shape ‘just-in-time’ animal agriculture and agri-food production.

Metagenomic analysis of the bacterial microbiome, resistome and virulome distinguishes Portuguese Serra da Estrela PDO cheeses from similar non-PDO cheeses: An exploratory approach

This study aimed to evaluate the microbiome, resistome and virulome of two types of Portuguese cheese using high throughput sequencing (HTS). Culture-dependent chromogenic methods were also used for certain groups/microorganisms. Eight samples of raw ewe’s milk cheese were obtained from four producers: two producers with cheeses with a PDO (Protected Designation of Origin) label and the other two producers with cheeses without a PDO label. Agar-based culture methods were used to quantify total mesophiles, Enterobacteriaceae, Escherichia coli, Staphylococcus, Enterococcus and lactic acid bacteria. The presence of Listeria monocytogenes and Salmonella was also investigated. The selected isolates were identified by 16S rRNA gene sequencing and evaluated to determine antibiotic resistance and the presence of virulence genes. The eight cheese samples analyzed broadly complied with EC regulations in terms of the microbiological safety criteria. The HTS results demonstrated that Leuconostoc mesenteroides, Lactococcus lactis, Lactobacillus plantarum, Lacticaseibacillus rhamnosus, Enterococcus durans and Lactobacillus coryniformis were the most prevalent bacterial species in cheeses. The composition of the bacterial community varied, not only between PDO and non-PDO cheeses, but also between producers, particularly between the two non-PDO cheeses. Alpha-diversity analyses showed that PDO cheeses had greater bacterial diversity than non-PDO cheeses, demonstrating that the diversity of spontaneously fermented foods is significantly higher in cheeses produced without the addition of food preservatives and dairy ferments. Despite complying with microbiological regulations, both PDO and non-PDO cheeses harbored potential virulence genes as well as antibiotic resistance genes. However, PDO cheeses exhibited fewer of these virulence and antibiotic resistance genes compared to non-PDO cheeses. Therefore, the combination of conventional microbiological methods and the metagenomic approach could contribute to improving the attribution of the PDO label to this type of cheese.

Sustainability implications and relevance of using omics sciences to investigate cheeses with protected designation of origin.

Cheese, a fundamental component of the human diet and a cornerstone of the global food economy, has a significance beyond its role as a commodity, playing a crucial part in the cultural identity of various communities. The intricate natural aging process known as maturation involves a series of reactions that induce changes in the cheese's physical, biochemical, microbiological, and particularly sensory characteristics, making it a complex aspect of cheese production. Recently, the adoption of omics sciences (e.g., metagenomics, metabolomics, proteomics) has emerged as a new trend in studies related to protected designation of origin (PDO) cheese. This mini-summary aims to outline the relationship between omics studies in these food matrices and all the sustainability facets of the production chain in general, and to discuss and recognize that the importance of these studies goes beyond comprehending the cheese biome and extends to fostering and ensuring the sustainability of the production chain. In this context, numerous studies in recent years have linked the identification of intrinsic characteristics of PDO cheeses through omics sciences to crucial sustainability themes such as territoriality, biodiversity, and the preservation of product authenticity. The trajectory suggests that, increasingly, multidisciplinary studies spanning various omics sciences will not only contribute to the characterization of these products but will also address sustainability aspects directly related to the production chain (e.g., authenticity, microbial biodiversity, functionality). This expansion underscores the multidisciplinary nature of these studies, broadening their social impact beyond the academic realm. Consequently, these pivotal studies play a crucial role in advancing discussions on PDO products and sustainability. © 2024 Society of Chemical Industry.

Consumer Perception and Liking of Parmigiano Reggiano Protected Designation of Origin (PDO) Cheese Produced with Milk from Cows Fed Fresh Forage vs. Dry Hay.

This study aimed to investigate consumer sensory profiles and liking of Parmigiano Reggiano PDO cheese produced with milk from cows reared indoors and fed with different forage sources, i.e., dry hay and fresh forage. Two cheese samples were tested by 119 Italian subjects, following a protocol that included a Check-All-That-Apply method to assess the sensory profile, a Just-About-Right scale to evaluate the adequacy of attributes, and questions on liking (9-point hedonic scale). A questionnaire related to personal information and consumption habits was also submitted. The color of the two samples, based on image analysis, was different: the sample produced with milk from the dairy cows fed fresh forage had a higher intensity of yellow than the other; they were also described differently (p ≤ 0.05) by participants in the consumer test. Indeed, Parmigiano Reggiano produced with milk from the cows that were fed dry hay was mainly characterized by a "fresh milk" and "solubility", while the sample produced with milk from cows fed fresh forage was described as "yellow", "seasoned", "pungent", and with a "cheese crust" flavor. Even if no significant differences were observed between the two samples in terms of liking (p ≤ 0.05), the attribute "graininess" showed a great impact on liking ratings together with "yellow" (p ≤ 0.05), apparently corresponding to a specific expectation regarding the intensity of these attributes. Data were also analyzed according to the gender of consumers, highlighting that for women, the adequacy of "fresh milk", "sweet", and "graininess" greatly impacted liking for the cheese from cows fed dry hay.

Sensory Attributes and Instrumental Chemical Parameters of Commercial Spanish Cured Ewes' Milk Cheeses: Insights into Cheese Quality Figures.

The external appearance of some of the Protected Designation of Origin (PDO) cured cheeses is similar to other cheese samples made in Spain: 1 kg and 2.5-3 kg formats, cylindrical, and with or without a pleita mark on the surface. In this work, commercial cured ewe's milk cheese samples with a similar external appearance were analyzed, including five PDO and five non-PDO samples. The parameters analyzed were color, texture, pH, humidity, water activity, and the volatile profile. Additionally, a descriptive and consumer-sensory analysis of the cheese samples was carried out. Statistical analysis of the results showed that luminosity, color coordinates a* and b*, percentage of deformation, humidity, water activity, and acid contents were significantly higher in non-PDO cheese samples. The breaking force, maximum force, and the content of esters were significantly higher in those cheese samples with PDO. In addition, PDO cheese samples showed higher scores for all attributes evaluated by consumers, except for color. These results suggest that PDO cheeses are placed on the market with a higher degree of ripening than non-PDO ones and that consequently they are more positively valued by consumers.

Metabarcoding analysis reveals a differential bacterial community profile associated with ‘Torta del Casar’ and ‘Queso de la Serena’ PDO cheeses

A detailed understanding of the microbial ecology of artisanal cheeses is a crucial factor for implementation practices that can help to update their quality. In this study, the bacterial communities of Protected Designation of Origin (PDO) ‘Queso de la Serena’ and ‘Torta del Casar’ cheeses were characterised by 16S rRNA gene metabarcoding sequencing over 60 days of ripening at three dairies for each cheese variety. Both PDO cheeses presented a distinctive and unique bacterial community, suggesting that the manufacturing practices of each PDO shaped the microbiota. Lactococcus lactis and, to a lesser extent, Leuconostoc mesenteroides were the key lactic acid bacteria (LAB) species that drove the ripening process of PDO ‘Torta del Casar’, whereas in PDO ‘Queso de la Serena’, Leu. mesenteroides was the main LAB species, followed by Lactococcus raffinolactis and Lc. lactis, depending on the dairy. Furthermore, a wide range of non-starter LAB, Gram-negative bacteria and Gram-positive catalase-positive cocci were found, with a variable presence and abundance between dairies. In this regard, the dairy was a strong contributing factor to the variability in the composition of the bacterial community in each cheese type. In contrast, the impact of the ripening process was limited. Overall, this study enhances the understanding of the bacterial dynamics that occur during the ripening of these traditional PDO cheeses, highlighting the need to improve the standardisation of the raw materials and manufacturing practices to minimise inter-dairy variability, ensuring final quality and their unique sensory traits.

Effect of Commercial and Autochthonous Bioprotective Cultures for Controlling Listeria monocytogenes Contamination of Pecorino Sardo Dolce PDO Cheese.

The composition and physicochemical characteristics of short-aged Pecorino Sardo PDO (Protected Designation of Origin) cheese makes it permissive to Listeria monocytogenes growth. The PDO product specification stipulates that this cheese is produced with whole sheep's milk inoculated with cultures from the area of origin. Therefore, the use of bioprotective cultures for the inhibition of pathogens in PDO cheeses is allowed only if autochthonous microorganisms are used. Furthermore, bioprotective cultures are generally used on the cheese surface to prevent the outgrowth of L. monocytogenes, the application of which can be time-consuming and require specialist technical knowledge. In this study, we examine the direct addition of bioprotective cultures to the cheese vat and compare the activity of a commercial bioprotective culture (Lactiplantibacillus plantarum) and an autochthonous lactic acid bacterium with bioprotective properties (Lactobacillus delbruekii sups. sunkii), for the inhibition of L. monocytogenes in Pecorino Sardo PDO cheese. Three types of Pecorino Sardo PDO cheese were made with bioprotective cultures added directly to the cheese milk along with the starter inoculum: PSA, with the commercial bioprotective culture; PSB, with the autochthonous bioprotective culture; and a CTRL cheese with no bioprotective culture. A challenge test was performed on each of these cheeses by artificially contaminating the cheese surface with L. monocytogenes (2 Log10 CFU/g). Three batches of each cheese type were analyzed to enumerate mesophilic and thermophilic lactic acid bacteria and to investigate the growth potential of L. monocytogenes during manufacturing, at the end of ripening, at the end of shelf-life, and after 180 days from cheese production. Both bioprotective cultures tested in this study showed inhibitory action against the pathogen with 0.3-1.8 Log10 CFU/g (colony-forming unit per gram) reduction levels. The autochthonous organism, L. sunkii, was as effective as the commercially supplied culture, and the addition of the bioprotective cultures to the cheese-making procedure offered protection against L. monocytogenes. The direct addition of bioprotective cultures to the making procedure of Pecorino Sardo PDO cheese is a potentially innovative strategy to improve the safety of this product.

Characterization of artisanal saffron ricotta cheese produced in Sicily: Physicochemical, microbiological, sensory, and antioxidant characteristics

The present study aims to characterize the artisanal saffron ricotta cheese produced from the whey of Piacentinu Ennese protected designation of origin (PDO) cheesemaking, including via technological parameters detected during the production process and by assessment of the main physicochemical, microbial, sensory, and antioxidant characteristics. A survey on the manufacture process of saffron and control ricotta cheese was conducted on 3 farms, located in the production area of the Piacentinu Ennese PDO cheese. pH and temperature followed a specific behavior, characterized by an inverse trend where pH decreased and temperature increased, playing an important role in the production process. All the analytical parameters were affected by the presence of saffron, also showing high between-farm variability, with significantly higher total solids and fat contents in saffron ricotta cheese compared with the control cheese (28.68% vs. 23.86%, and 19.83% vs. 14.22%, respectively). Microbial analysis showed significantly lower values in saffron compared with control ricotta cheese, for coliforms (1.51 vs. 1.91 log10 cfu/g, respectively), yeasts (1.55 vs. 2.06 log10 cfu/g, respectively), and molds (1.03 vs. 1.30 log10 cfu/g, respectively), denoting potential reduction of microbial growth asserted by saffron. Escherichia coli concentration (1.26 log10 cfu/g) in saffron ricotta cheese was in accordance with EU Regulation 2073/2005 and then safe for consumption. The presence of saffron influenced all sensory attributes, particularly color and aroma. Interestingly, high total antioxidant activity was found in saffron ricotta cheese (372 µC) compared with the control cheese. Thus, this artisanal dairy production could be considered a suitable option for functional foods with antimicrobial properties, due to the presence of saffron, which may contribute to extend the shelf life of the product. Further studies need to focus on the bioactive compounds that affect the antioxidant proprieties, characterization of the microbiota of saffron ricotta cheese, and evaluation of consumers' acceptance and perception as well as market demand.

Microbiological Characterization of Protected Designation of Origin Serra da Estrela Cheese.

Serra da Estrela is the oldest and most recognizable traditional protected designation of origin (PDO) cheese from Portugal. It has been extensively studied over the years, but the latest microbial characterization is 20 years old. Hence, this work aimed to perform an updated characterization of Serra da Estrela PDO cheeses and raw materials. Our analysis showed that lactic acid bacteria content on Serra da Estrela cheeses exceeded 8.8 log CFUsg-1, in all analyzed samples, with lactococci, lactobacilli and Leuconostoc spp. predominating over enterococci strains. Moreover, lactococci and lactobacilli abundance increased across the production season, while enterococci dropped considerably in late manufactures. Lastly, Leuconostoc spp. content remained unchanged in all analyzed periods. A correspondence analysis showed that L. paracasei, L. lactis, E. durans, E. faecium and L. mesenteroides are transversal in Serra da Estrela cheese manufacturing and were closely associated with milk, curd and cheese matrices. Additionally, L. casei, L. plantarum and L. curvatus were specifically associated with cheese matrices, possibly active during ripening and contributing for the development of these cheeses' organoleptic characteristics.

Comparison of Activity of Commercial Protective Cultures and Thermophilic Lactic Acid Bacteria against Listeria monocytogenes: A New Perspective to Improve the Safety of Sardinian PDO Cheeses.

Listeria monocytogenes contamination that occurs during and post-processing of dairy products is a serious concern for consumers, and bioprotective cultures can be applied to control the growth of the pathogen in sheep milk cheeses. However, to respect specifications provided for protected designation of origin (PDO) cheeses, only autochthonous microorganisms can be used as bioprotective cultures in these products. This in vitro study aimed to evaluate thermophilic lactic acid bacteria (LAB) isolated from sheep milk as bio-preservative agents to control L. monocytogenes growth in PDO cheese. Results were compared with those obtained with a commercial protective culture (cPC) composed of a Lactiplantibacillus plantarum bacteriocin producer designed to inhibit L. monocytogenes growth in cheese. The in vitro antilisterial activities of n.74 autochthonous LAB and a cPC were tested against 51 L. monocytogenes strains using an agar well diffusion assay. In addition, 16S rRNA sequencing of LAB isolates with antilisterial activity was conducted and strains of Lactobacillus helveticus, Lactobacillus delbrueckii subsp. indicus, Lactobacillus delbrueckii subsp. sunkii, Lactobacillus delbrueckii subsp. lactis and Enterococcus faecalis were identified. In this study, 33.6% (74/220) bacterial strains isolated from milk had characteristics compatible with thermophilic LAB, of which 17.6% (13/74) had in vitro antilisterial activity. These results demonstrate that raw sheep milk can be considered an important source of autochthonous thermophilic LAB that can be employed as protective cultures during the manufacturing of Sardinian PDO cheeses to improve their food safety. The use of bioprotective cultures should be seen as an additional procedure useful to improve cheese safety along with the correct application of good hygienic practices during manufacturing and the post-processing stages.

Distinct Bacterial Communities in São Jorge Cheese with Protected Designation of Origin (PDO)

São Jorge cheese is an iconic product of the Azores, produced from raw cow's milk and natural whey starter (NWS). Although it is produced according to Protected Designation of Origin (PDO) specifications, the granting of the PDO label depends crucially on sensory evaluation by trained tasters. The aim of this work was to characterize the bacterial diversity of this cheese using next-generation sequencing (NGS) and to identify the specific microbiota that contributes most to its uniqueness as a PDO by distinguishing the bacterial communities of PDO and non-PDO cheeses. The NWS and curd microbiota was dominated by Streptococcus and Lactococcus, whereas Lactobacillus and Leuconostoc were also present in the core microbiota of the cheese along with these genera. Significant differences (p < 0.05) in bacterial community composition were found between PDO cheese and non-certified cheese; Leuconostoc was found to play the chief role in this regard. Certified cheeses were richer in Leuconostoc, Lactobacillus and Enterococcus, but had fewer Streptococcus (p < 0.05). A negative correlation was found between contaminating bacteria, e.g., Staphylococcus and Acinetobacter, and the development of PDO-associated bacteria such as Leuconostoc, Lactobacillus and Enterococcus. A reduction in contaminating bacteria was found to be crucial for the development of a bacterial community rich in Leuconostoc and Lactobacillus, thus justifying the PDO seal of quality. This study has helped to clearly distinguish between cheeses with and without PDO based on the composition of the bacterial community. The characterization of the NWS and the cheese microbiota can contribute to a better understanding of the microbial dynamics of this traditional PDO cheese and can help producers interested in maintaining the identity and quality of São Jorge PDO cheese.

Impact of LAB from Serpa PDO Cheese in Cheese Models: Towards the Development of an Autochthonous Starter Culture.

Serpa is a protected designation of origin (PDO) cheese produced with raw ewes' milk and coagulated with Cynara cardunculus. Legislation does not allow for milk pasteurization and starter culture inoculation. Although natural Serpa's rich microbiota allows for the development of a unique organoleptic profile, it also suggests high heterogeneity. This raises issues in the final sensory and safety properties, leading to several losses in the sector. A possible solution to overcoming these issues is the development of an autochthonous starter culture. In the present work, some Serpa cheese Lactic acid bacteria (LAB)-isolated microorganisms, previously selected based on their safety, technological and protective performance, were tested in laboratory-scale cheeses. Their acidification, proteolysis (protein and peptide profile, nitrogen fractions, free amino acids (FAA)), and volatiles generation (volatile fatty acids (VFA) and esters) potential was investigated. Significant differences were found in all parameters analyzed, showing a considerable strain effect. Successive statistical analyses were performed to compare cheese models and Serpa PDO cheese. The strains L. plantarum PL1 and PL2 and the PL1 and L. paracasei PC mix were selected as the most promising, resulting in a closer lipolytic and proteolytic profile of Serpa PDO cheese. In future work, these inocula will be produced at a pilot scale and tested at the cheese level to validate their application.

Evaluation of gamma-aminobutyric acid content in Portuguese cheeses with protected designation of origin status.

Health-conscious consumers are increasingly paying attention to healthy diets and focusing on natural bioactive compounds in foods and their effects on mental health. This opens new opportunities for the study of artisanal cheeses as biofunctional foods. In the work described in this Research Communication, the gamma-aminobutyric acid (GABA) content of seven different Portuguese cheeses produced from unpasteurized cow, sheep, and goat milk and granted with protected designation of origin (PDO) status was analysed. The PDO cheeses made from cow milk analysed in this study were São Jorge (3, 4, 7, 12 and 24 months of maturation) and Pico cheeses. PDO cheeses made from sheep milk were Serra da Estrela, Serpa, Nisa and Azeitão. Cheeses made from sheep and goat milk included Beira Baixa yellow cheese. The GABA content in the Azorean PDO cheeses (made from cow milk) ranged from 1.23 to 2.64 g/kg of cheese. Higher variations in GABA content were observed in cheeses made from sheep and goat milk (0.73-2.31 g/kg). This study provides information on the GABA content in different Portuguese PDO cheeses and shows that hard or semi-hard ripened cheeses are a suitable matrix for GABA production by lactic acid bacteria.

Seasonal Variations of the Protein Fractions and the Mineral Contents of the Cheese Whey in the Parmigiano Reggiano Cheese Manufacture

The milk whey remaining at the end of the cheese-making process is the main by-product of the dairy industries and it is currently used as a source of high added-value compounds by the food and pharmaceutical industries. The aim of this research was to study the effects of the season on the residual whey characteristics in the Parmigiano Reggiano cheese-making process. Over two years, a total of 288 cheese-making trials of Parmigiano Reggiano PDO (Protected Designation of Origin) cheese were performed in three commercial cheese factories and, in each trial, a sample of the vat milk (V-milk) and of the residual whey (C-whey) were collected. The C-whey values of dry matter and non-fat matter were higher in winter and autumn than in spring and summer. Moreover, the C-whey fat and crude protein contents were also higher in autumn (0.52 and 0.89 g/100 g, respectively) and lower in spring (0.44 and 0.83 g/100 g, respectively) and summer (0.46 and 0.84 g/100 g, respectively). Furthermore, crude whey protein resulted to be the major fraction of crude protein (97.96%). Crude whey protein and true whey protein were higher in autumn and lower in spring and summer and their values mainly depended on milk whey protein. Finally, the C-whey average contents of phosphorus and magnesium were higher in autumn and winter than in summer.

Microbiological, morpho-textural, and volatile characterization of Portuguese Queijo de Nisa PDO cheese

Queijo de Nisa PDO (Protected Designation of Origin) is a semi-hard cheese obtained from raw ewe's milk clotted with cardoon (Cynara cardunculus, L.) rennet. The aim of the present study was to characterize the bacterial communities naturally occurring in Queijo de Nisa PDO cheese samples through viable counting and metataxonomic analysis. Moreover, physico-chemical and morpho-textural analyses were also performed, together with the analysis of volatile organic compounds (VOCs) through solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC–MS). In the analyzed samples, pH values were comprised between 4.84 and 5.74. As for lactic acid, the concentration varied between 0.83 and 2.10 g 100 g-1. Water activity varied between 0.942 and 0.960. Lightness of the samples ranged from 107.82 to 119.16, whereas hardness ranged between 34.45 N and 126.05 N. As for microbiological analyses, lactococci and lactobacilli counts were up to 9.01 Log CFU g-1. Coagulase-negative cocci and enterococci counts were up to 7 Log CFU g-1. Metataxonomic analysis revealed that Lactococcus lactis and Leuconostoc mesenteroides occurred at high frequency in all the analyzed samples. Moreover, Lactiplantibacillus plantarum, Lactococcus piscium, and Lacticaseibacillus zeae were also detected. The most represented VOCs were carboxylic acids, carbonyl compounds, alcohols, and esters. In the analyzed cheese samples, significant relationships between bacteria and VOCs were also evidenced. Of note, research on the microbiological and chemical features, as well as on morpho-textural characteristics, of Queijo de Nisa PDO cheese can increase the knowledge on the interactions between raw materials, environment, and autochthonous microorganisms, thus enabling protection of biodiversity and tradition.

Organoleptic Chemical Markers of Serpa PDO Cheese Specificity.

Serpa is a protected designation of origin cheese produced with a vegetable coagulant (Cynara cardunculus L.) and raw ovine milk. Despite the unique sensory profile of raw milk cheeses, numerous parameters influence their sensory properties and safety. To protect the Serpa cheese quality and contribute to unifying their distinctive features, some rheologic and physicochemical parameters of cheeses from four PDO producers, in distinct seasons and with different sensory scores, were monitored. The results suggested a high chemical diversity and variation according to the dairy, month and season, which corroborates the significant heterogeneity. However, a higher incidence of some compounds was found: a group of free amino acids (Glu, Ala, Leu, Val and Phe), lactic and acetic acids, some volatile fatty acids (e.g., iC4, iC5, C6 and C12) and esters (e.g., ethyl butanoate, decanoate and dodecanoate). Through the successive statistical analysis, 13 variables were selected as chemical markers of Serpa cheese specificity: C3, C4, iC5, C12, Tyr, Trp, Ile, 2-undecanone, ethyl isovalerate, moisture content on a fat-free basis, the nitrogen-fractions (maturation index and non-protein and total nitrogen ratio) and G’ 1 Hz. These sensory markers’ identification will be essential to guide the selection and development of an autochthonous starter culture to improve cheese quality and safety issues and maintain some of the Serpa authenticity.

Insights into in vitro digestion properties and peptide profiling of Chinese rubing PDO cheese prepared using different acidification technology

Rubing cheese is a traditional Chinese Protected Designation of Origin (PDO) cheese consumed for more than six hundred years, but to date, the digestion properties and peptide profiling during simulated gastrointestinal digestion are still uncertain. This study aimed to investigate the effects of traditional direct acidification technology (TRB) and fermentation acidification technology on digestion properties and peptide profiling of rubing cheese (FRB) proteins after simulated gastrointestinal digestion by protein digestomics, coupled with bioinformatic in silico analyses to identify potential bioactive peptides. The results demonstrated that FRB could significantly improve the in vitro digestibility, protein degradation, and polypeptide content than TRB (P ＜ 0.05). Furthermore, a total of 369 and 332 peptides were identified in FRB- and TRB-pancreatic digests, respectively, using LC-MS/MS. FRB could release more low molecular weight peptides of 400–1200 Da from α-casein and β-casein after digestion. These low peptides included 16 reported potential ACEIPs (angiotensin I-converting enzyme inhibitory peptides), 11 dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides, and 6 antioxidant peptides, while TRB contained more than the reported potential antimicrobial peptides (10). In vitro activity determination showed that FRB had significantly higher ACEI, α-glucosidase inhibitory, and antioxidant activities than TRB during the entire digestion time (P ＜ 0.05), which was correlated to the reported potential bioactive peptides released during the digestion of FRB. Our study is the most comprehensive protein digestomic analysis of Chinese rubing cheese to date and provides a new positive outlook on rubing cheese consumption.

Behaviour and adhesion capacity of Listeria monocytogenes on Mozzarella di Bufala Campana PDO cheese and in fluids involved in the production process

Listeria monocytogenes is a foodborne pathogen for humans. It can be found in ready-to-eat (RTE) products and its presence represents one of the biggest food safety concerns. Most of the cases of cheese contamination reported by the Rapid Alert System for Food and Feed (RASFF) in the last 10 years did not involve Mozzarella di Bufala Campana (MBC) Protected Designation of Origin (PDO) cheese. Suddenly, in the last years, RASFF has disposed of the withdrawn from the market of this product contaminated with L. monocytogenes on two different occasions (RASFF 2018/1198 and 2018/2459), and the Canadian Food Inspection Agency disposed one withdrawn in 2019. Following these events, this study aimed to evaluate the behaviour of L. monocytogenes in Mozzarella di Bufala Campana PDO cheese. First of all, the adhesion capacity of the pathogen to MBC cheese was studied through microbial challenge tests simulating the passage of MBC in hardening water and in covering liquid used for cheese storage during the production process. In addition, the ability of L. monocytogenes to grow in MBC cheese and covering liquid during shelf life, at refrigerated condition, was evaluated also this time employing microbial challenge tests. Results demonstrated that L. monocytogenes can adhere to the surface of the cheese and be released during the contact of contaminated cheese with other fluids. However, the presence of an abundant microbiota on the cheese exerted a protective role against this pathogen preventing the growth of L. monocytogenes. Indeed, the pathogens artificially contaminating the covering liquid at 2 log CFU/mL and 4 log CFU/mL remained at the inoculum level during 32 days of storage at 4 °C.

Genetic variations associated with the soapy flavor perception in Gorgonzola PDO cheese

Food preferences are influenced by several factors including individual differences in the physiological perception of the sensory properties and genetic factors. This study was aimed to investigate the genetic bases underlying the perception of the soapy flavor, a sensory attribute identified as a driver of disliking for blue-veined cheese. Responses on soapy flavor perception (SFP) in six Gorgonzola Protected Designation of Origin (PDO) cheese samples were collected from 219 genotyped Italians (age 18–77 y) applying a Rate-All-That-Apply (RATA) test combined with a liking test.Genome-Wide Association Studies (GWAS) were performed on three phenotypic traits: the SFP in at least one cheese (SFP_1), the number of cheese samples in which each individual perceived the soapy flavor (SFP_N) and the SFP in the cheese in which the highest number of individuals perceived the soapy flavor (SFP_P95).Results showed that 144 individuals (65.8%) perceived the soapy flavor in at least one cheese. Our analysis allowed identifying four loci that resulted shared in all the three GWAS and have been confirmed by the SFP in at least other two Gorgonzola cheese samples. Particularly, we highlighted four genes (SYT9, PDE4B, AVL9 and HTR1B) that are involved in olfactory or taste processes, suggesting that they could play a relevant role in determining the individual differences in the SFP. In addition, a SNP near the HTR1B gene affected also the liking for Gorgonzola PDO cheese.Overall, our work suggests possible candidate genes associated with the perception of soapy flavor, providing a starting point to better understand the individual differences in blue-veined cheese perception and expanding the current scientific knowledge in the emerging research area linking genetic individual differences to food perception and preferences.

Characterization of autochthonal yeasts isolated from Spanish soft raw ewe milk protected designation of origin cheeses for technological application

The yeasts involved in the ripening process of artisanal soft raw ewe milk Protected Designation of Origin (PDO) Torta del Casar and Queso de la Serena cheeses produced in Extremadura, Spain, were isolated throughout their ripening process, strain typed, and characterized for some important technological properties. A total of 508 yeast isolates were obtained and identified by inter-single sequence repeat anchored PCR amplification analysis and subsequent sequencing of the internal transcribed spacer ITS1/ITS2 5.8S rRNA. A total of 19 yeast species representing 8 genera were identified. Debaryomyces hansenii, Pichia kudriavzevii, Kluyveromyces lactis, and Yarrowia lipolytica were the predominant species. We selected 157 isolates, by genotyping and origin, for technological characterization. The evaluation of yeast isolates' growth under stress conditions of cheese ripening showed that 87 presented better performance. Among them, 71 isolates were not able to catabolize tyrosine to produce a brown pigment. Principal component analysis of the biochemical features of these isolates showed that 9 strains stood out, 3 K. lactis strains (2287, 2725, and 1507), 2 Pichia jadinii (1731 and 433), 2 Yarrowia alimentaria (1204 and 2150), Y. lipolytica 2495 and P. kudriavzevii 373. These strains displayed strong extracellular proteolytic activity on skim milk agar as well as an adequate enzymatic profile (strong aminopeptidase and weak protease activity), suggesting their great potential for cheese proteolysis. Extracellular lipolytic activity was mainly restricted to Yarrowia spp. isolates and weakly present in P. kudriavzevii 373 and K. lactis 2725, although enzymatic characterization by API-ZYM (bioMérieux SA) evidenced that all may contribute, at least in part, to the lipolysis process. Moreover, these strains were able to assimilate lactose, galactose, and glucose at NaCl concentrations higher than that usually found in cheese. However, lactate and citrate assimilation were limited to Y. lipolytica 2495, P. kudriavzevii 373, and P. jadinii 433, and may contribute to the alkalinizing process relevant to biochemical processes that take place in the last stages of ripening. By contrast, K. lactis strains showed acidifying capacity and β-galactosidase activity and may take part in the initial stages of ripening, together with lactic acid bacteria. Thus, considering the technological characteristics studied, the 9 selected strains presented biochemical features well suited to their potential use as adjunct cultures, alone or in combination with autochthonous starter bacteria in the cheesemaking process, to overcome the heterogeneity of these PDO cheeses, preserving their unique sensory characteristics.