Influence of the early bacterial biofilms developed on vats made with seven wood types on PDO Vastedda della valle del Belìce cheese characteristics

Microbial dynamics and quality characteristics of spontaneously fermented salamis produced by replacing pork fat with avocado pulp

The aim of this study was to develop a novel and healthier fermented meat product by replacing pork fat with avocado pulp (AVP) during salami production. Experimental salamis were produced under laboratory conditions by substituting pork fat with AVP partially (10-AVP) and totally (20-AVP), while control salamis (CTR) remained AVP-free. The microbial composition of control and experimental salamis was assessed using a combined culture-dependent and -independent approach. Over a 20-days ripening period, lactic acid bacteria, coagulase-negative staphylococci, and yeasts dominated the microbial community, with approximate levels of 9.0, 7.0 and 6.0 log CFU/g, respectively. Illumina technology identified 26 taxonomic groups, with leuconostocs being the predominant group across all trials [constituting 31.26-59.12 % of relative abundance (RA)]. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed changes in fatty acid composition and volatile organic compounds due to the substitution of pork fat with AVP. Specifically, monounsaturated fatty acids and terpene compounds increased, while saturated fatty acids and lipid oxidation products decreased. Although AVP influenced the sensory characteristics of the salamis, the highest overall satisfaction ratings were observed for the 10-AVP salamis. Consequently, substituting pork fat with AVP emerges as a viable strategy for producing healthier salamis and diversifying the meat product portfolio.

Selection of starter lactic acid bacteria capable of forming biofilms on wooden vat prototypes for their future application in traditional Sicilian goat's milk cheese making

In this study, 327 presumptive lactic acid bacteria (LAB) were isolated from goats' milk acid curds produced at a Sicilian dairy farm with the aim to identify potential starter cultures for traditional cheeses. All isolates were first processed by randomly amplified polymorphic DNA (RAPD)-PCR analysis. This approach identified 63 distinct strains which were evaluated for their acidifying capacity. Only 15 strains specifically stood out for their acidification capacity and were identified through 16S rRNA gene sequencing as Lactococcus lactis (11 strains) Enterococcus faecalis (three strains), and Ligilactobacillus animalis (one strain). Notably, all 15 LAB isolates produced bacteriocin-like inhibitory substances and anti-biofilm compounds, against both planktonic and biofilm forms of Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli, and Staphylococcus aureus, albeit at varying levels. Among these 15 LAB, En. faecalis RGM25 and Lc. lactis RGM55, susceptible to five antibiotics tested, were put in contact with wooden vat prototypes, because all equipment used in traditional cheese production in Sicily are made of wood. Scanning electron microscopy and bacterial plate counts of the wooden vat prototypes showed the development of biofilms at levels of approximately 6.0 log CFU/cm2. Overall, this study contributes to establishing a custom-made LAB starter cultures with bio-preservatives properties for Sicilian cheese productions.

Microbial screening of animal skin bags used in traditional cheesemaking

Bouhezza is a traditional Algerian cheese produced and ripened in goatskin bags called Djeld. The aim of this study was to characterize the microbial ecosystem from Djeld (fresh and dried Djeld for making Bouhezza cheese) and the changes introduced by Lben microflora during its preparation and to identify its role in cheesemaking and its safety. Two replicates of fresh and dried skin bags (FS and DS) were sampled and analyzed before and after contact with Lben. The microbiological results showed no pathogens. Skins observed before the addition of Lben were less populated 2.86 and 3.20 log CFU cm-2 than skins examined after the addition of Lben (approximately 6.0 log CFU cm-2), suggesting a potential role of Lben in releasing some microorganisms into the skin during its time in the Djeld. However, an increase in mesophilic lactic acid bacteria and yeasts was observed in Lben after different periods of interaction with the skin. PCR-TTGE revealed the predominance of lactic acid bacteria (Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Staphylococcus equorum subsp. linens, Lactococcus cremoris, Streptococcus thermophilus) and a few high-GC-content bacteria (Lacticaseibacillus paracasei, Brevibacterium casei). Transfer of several microbial species was observed between the goatskin bag biofilm and Lben during the overnight interaction. Bands corresponding to Lacticaseibacillus paracasei, Brevibacterium casei, and Lactobacillus delbrueckii subsp. lactis were detected in the fresh skin profile and in Lben after contact with the fresh skin. Lacticaseibacillus paracasei was found in dried skin and Lben after contact with dry skin. Lactobacillus helveticus and Enterococcus faecalis appeared in the Lben profile and persisted in Lben and the biofilm-covered dry skin after interaction. These results demonstrate an exchange of specific microbial populations between goatskin bag biofilm and Lben during the traditional preparation method, suggesting that the diversity of goatskin biofilm contributes to the microbial diversity of Lben used in the production of Bouhezza cheese.

Reduction of PDO Pecorino Siciliano cheese making duration: Microbial dynamics and quality attributes deriving from replacing whey permeate with hot water during cooking

This work was carried out with the aim to reduce the transformation duration of Protected Designation of Origin (PDO) Pecorino Siciliano cheese. To this purpose, the cooking in hot water (experimental production, EXP) was compared to the traditional cheese cooking under whey permeate (control production, CTR). The microbiological composition of under rind (UR) and core (Co) section of CTR and EXP cheeses was determined by a combined culture-dependent and -independent approach. Total mesophilic microorganisms and lactic acid bacteria (LAB) present in raw ewes' milk (5.0 log CFU/mL) increased during cheese making and reached values of about 8.0 log CFU/g in both sections (UR and Co) of 5-month ripened cheeses of both productions (CTR and EXP) monitored. The identification of the viable LAB populations in ripened cheeses showed that Enterococcus, Lacticaseibacillus, Lactiplantibacillus, Levilactobacillus, Limosilactobacillus and Streptococcus dominated UR and Co sections of all cheeses. MiSeq Illumina analysis demonstrated that LAB populations (lactobacilli, lactococci and streptococci) dominated the bacterial community of cheeses at 95.63-98.41 % of relative abundance. The two different cooking operations did not influence the physicochemical characteristics of PDO Pecorino Siciliano cheeses. Sensory evaluation performed by artificial senses analysis and trained panelists confirmed that the modification of PDO Pecorino Siciliano cheese production protocol did not significantly affect product characteristics and overall acceptance. Thus, data of this work confirmed that cooking under hot water allowed to reduce transformation duration and safeguard typicality of PDO Pecorino Siciliano cheese.

Improvement of Fresh Ovine "Tuma" Cheese Quality Characteristics by Application of Oregano Essential Oils

In the present work, oregano essential oils (OEOs) were applied to process the fresh ovine cheese "Tuma" obtained by pressed cheese technology. Cheese making trials were performed under industrial conditions using ewe's pasteurized milk and two strains of Lactococcus lactis (NT1 and NT4) as fermenting agents. Two experimental cheese products (ECP) were obtained through the addition of 100 (ECP100) and 200 (ECP200) µL/L of OEO to milk, while the control cheese product (CCP) was OEO-free. Both Lc. lactis strains showed in vitro and in vivo ability to grow in the presence of OEOs and to dominate over indigenous milk lactic acid bacteria (LAB) resistant to pasteurization. In the presence of OEOs, the most abundant compound found in cheese was carvacrol, constituting more than 65% of the volatile fraction in both experimental products. The addition of OEOs did not influence ash, fat, or protein content, but it increased by 43% the antioxidant capacity of the experimental cheeses. ECP100 cheeses showed the best appreciation scores by the sensory panel. In order to investigate the ability OEOs to be used as a natural preservative, a test of artificial contamination was carried out, and the results showed a significant reduction of the main dairy pathogens in OEO-added cheeses.

Relationship between the dynamics of volatile aroma compounds and microbial succession during the ripening of raw ewe milk-derived Idiazabal cheese

Cheese microbiota contributes to various biochemical processes that lead to the formation of volatile compounds and the development of flavour during ripening. Nonetheless, the role of these microorganisms in volatile aroma compounds production is little understood. This work reports for the first time the dynamics and odour impact of volatile compounds, and their relationship to microbial shifts during the ripening of a raw ewe milk-derived cheese (Idiazabal). By means of SPME-GC-MS, 81 volatile compounds were identified, among which acids predominated, followed by esters, ketones and alcohols. The ripening time influenced the abundance of most volatile compounds, thus the moments of greatest abundance were determined (such as 30-60 days for acids). Through Odour Impact Ratio (OIR) values, esters and acids were reported as the predominant odour-active chemical families, while individually, ethyl hexanoate, ethyl 3-methyl butanoate, ethyl butanoate, butanoic acid or 3-methyl butanal were notable odorants, which would provide fruity, rancid, cheesy or malt odour notes. Using a bidirectional orthogonal partial least squares (O2PLS) approach with Spearman's correlations, 12 bacterial genera were reported as key bacteria for the volatile and aromatic composition of Idiazabal cheese, namely Psychrobacter, Enterococcus, Brevibacterium, Streptococcus, Leuconostoc, Chromohalobacter, Chryseobacterium, Carnobacterium, Lactococcus, Obesumbacterium, Stenotrophomonas and Flavobacterium. Non-starter lactic acid bacteria (NSLAB) were highly related to the formation of certain acids, esters and alcohols, such as 3-hexenoic acid, ethyl butanoate or 1-butanol. On the other hand, the starter LAB (SLAB) was related to particular ketones production, specifically 3-hydroxy-2-butanone; and environmental and/or non-desirable bacteria to certain ketones, hydrocarbons and sulphur compounds formation, such as 2-propanone, t-3-octene and dimethyl sulphone. Additionally, the SLAB Lactococcus and Psychrobacter, Brevibacterium and Chromohalobacter were described as having a negative effect on aroma development caused by NSLAB and vice versa. These results provide novel knowledge to help understand the aroma formation in a raw ewe milk-derived cheese.

A Multivariate Approach to Study the Bacterial Diversity Associated to the Wooden Shelves Used for Aging Traditional Sicilian Cheeses

The present study was carried to correlate the microbial diversity of the biofilms developed on the wooden boards used for aging traditional Sicilian cheeses with cheese typology. To this end, the microbial diversity of the shelves in contact with the cheeses PDO Pecorino Siciliano, PDO Piacentinu Ennese, and TAP Caciocavallo Palermitano, during ripening, was evaluated by a multivariate statistical approach. The shelf biofilms of this study were previously analyzed for their microbial composition, but no correlation between biodiversity and cheese type was investigated. Canonical discriminant analysis confirmed a cheese typology effect on the microbial loads of the wooden shelves investigated. Regarding the plate count data, the centroids of different cheeses were statistically distant from one another. This analysis also showed a good graphic separation of data regarding bacterial order operational taxonomy units (OTUs). Thus, the microbiological differences imputed to the cheese typologies were not affected by the environmental conditions of the facilities. Furthermore, wooden shelf lactic acid bacteria (LAB) were investigated for their ability to inhibit the main dairy pathogens. Although inhibitors were mainly enterococci, P. pentosaceus WS287 and W. paramesenteroides WS581 showed the highest inhibition activity, indicating their possible application to control the undesired bacteria in situ.

The Quality of Five Natural, Historical Italian Cheeses Produced in Different Months: Gross Composition, Fat-Soluble Vitamins, Fatty Acids, Total Phenols, Antioxidant Capacity, and Health Index

Simple Summary

For the purposes of raising awareness of five historical cheeses of Southern Italy that are less known by consumers, and of restoring dignity to the breeders and producers of these cheeses, we studied their quality in terms of chemical composition, monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), conjugated linoleic acid (CLA), PUFA-ω6, PUFA-ω3, α-tocopherol, retinol, cholesterol, polyphenol content (TPC), total antioxidant capacity (FRAP and TEAC), and health index (GHIC). Two stretched-curd bovine cheeses, Caciocavallo Palermitano (CP) and Casizolu del Montiferru (CdM), two ovine cheeses, Vastedda della Valle del Belìce (VVB) and Pecorino Siciliano (PS), and one caprine cheese, Caprino Nicastrese (CN), were evaluated. These cheeses are produced in different months, with raw milk from animals reared in an extensive feeding system. In April, the CP cheese showed high values for CLA, TPC, and GHIC, while the CN cheese exhibited high PUFA, PUFA-ω6, PUFA-ω3, TEAC, and GHIC. In May, the CdM cheese exhibited high content of fat, saturated fatty acids, PUFA-ω3, α-tocopherol, TEAC, and GHIC, while the PS cheese showed high values of protein, CLA, PUFA, PUFA-ω3, α-tocopherol, and GHIC. These measured parameters characterize and distinguish each cheese due to links with numerous factors: species, breed, feeding system, pasture biodiversity, climate, production technology, traditional tools, and ripening type. It is highlighted that, in general, the highest nutritional quality, linked to the highest presence of healthy compounds, originates from the pasture of cheese production in the spring.

Abstract

Five natural historic cheeses of Southern Italy were investigated—Caciocavallo Palermitano (CP), Casizolu del Montiferru (CdM), Vastedda della Valle del Belìce (VVB), Pecorino Siciliano (PS), and Caprino Nicastrese (CN)—which are produced with raw milk and with traditional techniques and tools, from autochthonous breeds reared under an extensive system. The effects of the month of production on gross composition, MUFA, PUFA, PUFA-ω6, PUFA-ω3, α-tocopherol, retinol, cholesterol, TPC, TEAC, and GHIC were evaluated. In CP, CLA, TPC, and GHIC were higher in April than in February. CdM showed higher values in terms of fat, saturated fatty acids, PUFA-ω3, α-tocopherol, TEAC, and GHIC in May than in February and September, while low values in terms of protein, moisture, and CLA were found. In VVB, MUFA, PUFA-ω6, and α-tocopherol increased in June compared with April; conversely, protein, FRAP, and TEAC were higher in April. In PS, protein, CLA, PUFA, PUFA-ω3, α-tocopherol, and GHIC increased in May compared with January; on the contrary, moisture, NaCl, and TEAC showed high values in January. CN showed higher values in terms of PUFA, PUFA-ω6, PUFA-ω3, TPC, TEAC, and GHIC in April and June compared with January. It is shown that each cheese is unique and closely linked to the production area. Cheeses produced in the spring months showed a high nutritional quality due to the greatest presence of healthy compounds originating from an extensive feeding system.

The Use of Ozone as an Eco-Friendly Strategy against Microbial Biofilm in Dairy Manufacturing Plants: A Review

Managing spoilage and pathogenic bacteria contaminations represents a major challenge for the food industry, especially for the dairy sector. Biofilms formed by these microorganisms in food processing environment continue to pose concerns to food manufacturers as they may impact both the safety and quality of processed foods. Bacteria inside biofilm can survive in harsh environmental conditions and represent a source of repeated food contamination in dairy manufacturing plants. Among the novel approaches proposed to control biofilm in food processing plants, the ozone treatment, in aqueous or gaseous form, may represent one of the most promising techniques due to its antimicrobial action and low environmental impact. The antimicrobial effectiveness of ozone has been well documented on a wide variety of microorganisms in planktonic forms, whereas little data on the efficacy of ozone treatment against microbial biofilms are available. In addition, ozone is recognized as an eco-friendly technology since it does not leave harmful residuals in food products or on contact surfaces. Thus, this review intends to present an overview of the current state of knowledge on the possible use of ozone as an antimicrobial agent against the most common spoilage and pathogenic microorganisms, usually organized in biofilm, in dairy manufacturing plants.

Development of "Quadrello di Ovino", a Novel Fresh Ewe's Cheese

This work was performed to produce a new soft ewe's milk cheese, namely "Quadrello di ovino" (QdO) cheese, to enlarge ewe's dairy product portfolio of South Italy, barely limited to Pecorino cheese typology. Cheese making was performed applying the technology for "Crescenza" cheese typology with some modifications. In particular, pasteurized ewes' milk was inoculated with two commercial starter formulations (SF1 and SF2) of Streptococcus thermophilus to obtain two different productions (QdO-P1 and QdO-P2, respectively). Plate counts demonstrated the ability of both starter formulations to drive the fermentation process, since S. thermophilus counts reached 109 CFU/g in both productions. Generally, the two starter formulations did not affect the chemical composition of QdO cheeses that contained, on average, 64.08% dry matter of which approximately 54.99% were fats and 36.39% proteins. Among chemical parameters, significant differences were registered for secondary lipid oxidation state (significantly lower for QdO-P2), fatty acids and volatile organic compounds (VOCs). However, the differences registered among cheese VOCs from were not perceived by the panelists who recognized both cheese productions highly similar, although QdO-P2 cheeses were mostly appreciated by the judges. This study allowed to produce a novel fresh ovine cheese with specific chemical and sensorial characteristics well appreciated by consumers.

Selenium bio-enrichment of Mediterranean fruit juices through lactic acid fermentation

This work was carried out to elaborate selenium (Se) bio-enriched fermented Mediterranean fruit juices. To this purpose, pomegranate and table red grape juices were added with sodium selenite (Na₂SeO₃) and fermented by Levilactobacillus brevis CRL 2051 and Fructobacillus tropaeoli CRL 2034 individually or combined. To better evaluate the effect of selenite addition and starter strain inoculums on the total bacterial community of the fruit juices, fermentation trials were performed with raw and pasteurized fruit juices. No statistical significant differences were observed for total mesophilic microorganisms (TMM) and rod-shaped lactic acid bacteria (LAB) levels among raw and pasteurized juices inoculated with the starter strains, while significant differences between those juices with and without selenite were registered. LAB cocci, Pseudomonadaceae and yeasts were detected only for the raw juice preparations. The dominance of L. brevis CRL 2051 and F. tropaeoli CRL 2034 was confirmed by randomly amplified polymorphic DNA (RAPD)-PCR analysis. After fermentation, pH dropped for all inoculated trials and control raw juices. The soluble solid content (SSC) levels of the raw juices were higher than the corresponding pasteurized trials. The thermal treatment affected consistently yellowness of grape juice trials and redness of pomegranate juices. No microbial Se accumulation was registered for pomegranate juices, while F. tropaeoli CRL 2034 accumulated the highest amount of Se (65.5 μg/L) in the grape juice. For this reason, only trials carried out with raw grape juices were investigated by metagenomics analysis by Illumina MiSeq technology. Non-inoculated grape juices were massively fermented by acetic acid bacteria while Fructobacillus and Lactobacillus (previous genus name of Levilactobacillus) represented the highest operational taxonomy units (OTUs) relative abundance % of the trials inoculated with the starter strains as confirmed by this technique.

Current Trends of Enterococci in Dairy Products: A Comprehensive Review of Their Multiple Roles

As a genus that has evolved for resistance against adverse environmental factors and that readily exchanges genetic elements, enterococci are well adapted to the cheese environment and may reach high numbers in artisanal cheeses. Their metabolites impact cheese flavor, texture, and rheological properties, thus contributing to the development of its typical sensorial properties. Due to their antimicrobial activity, enterococci modulate the cheese microbiota, stimulate autolysis of other lactic acid bacteria (LAB), control pathogens and deterioration microorganisms, and may offer beneficial effects to the health of their hosts. They could in principle be employed as adjunct/protective/probiotic cultures; however, due to their propensity to acquire genetic determinants of virulence and antibiotic resistance, together with the opportunistic character of some of its members, this genus does not possess Qualified Presumption of Safety (QPS) status. It is, however, noteworthy that some putative virulence factors described in foodborne enterococci may simply reflect adaptation to the food environment and to the human host as commensal. Further research is needed to help distinguish friend from foe among enterococci, eventually enabling exploitation of the beneficial aspects of specific cheese-associated strains. This review aims at discussing both beneficial and deleterious roles played by enterococci in artisanal cheeses, while highlighting the need for further research on such a remarkably hardy genus.

Quality assessment of artisanal cheeses in the northwest region of Paraná

Artisanal unripened cheeses produced in northwestern Paraná, Brazil, were studied for microbiological quality and sensory quality. The cheeses analyzed showed high counts of aerobic mesophilic microorganisms and S. aureus. However, even with the results showing poor microbiological quality, from a sensory point of view, consumers considered cheeses acceptable (high acceptance index). The results may indicate that there is still a lack of training and knowledge of production procedures to reduce microbiological contamination of artisanal cheese produced in northwestern Paraná.

Biodiversity and dairy traits of indigenous milk lactic acid bacteria grown in presence of the main grape polyphenols

The present work was developed to select lactic acid bacteria (LAB) to be used as starter cultures in functional cheese production. The indigenous milk LAB populations were isolated from fermented raw ewes' milks (four bulks) added with 0.5 mg/mL of nine polyphenols commonly found in winery by-products. After 48 h of fermentation, all milks were characterized by an increase of LAB levels of about 3-4 Log cycles. All different colonies were purified and characterized for the main physiological and biochemical traits and then differentiated genetically at strain level and identified. Ten species belonging to the LAB genera Lactobacillus, Streptococcus, Enterococcus, Leuconostoc and Lactococcus were identified. Only Lactococcus lactis and Leuconostoc mesenteroides strains were evaluated for the technological traits including acidification and autolytic kinetics, diacetyl formation, exopolysaccharide production and generation of antimicrobial compounds. A total of four strains (Mise36, Mise94 Mise169 and Mise190) belonging to Lc. lactis displayed potential for production of cheeses containing grape polyphenols.

The Use of Winery by-Products to Enhance the Functional Aspects of the Fresh Ovine "Primosale" Cheese

Fresh ovine "primosale" cheese was processed with the addition of grape pomace powder (GPP). Cheese making was performed using pasteurized ewes' milk and four selected Lactococcus lactis strains (Mise36, Mise94, Mise169 and Mise190) inoculated individually. For each strain the control cheese (CCP) was not added with GPP, while the experimental cheese (ECP) was enriched with 1% (w/w) GPP. GPP did not influence the starter development that reached levels of 10⁹ CFU/g in all final cheeses. The comparison of the bacterial isolates by randomly amplified polymorphic DNA (RAPD)-PCR showed the dominance of the added strains over indigenous milk bacteria resistant to pasteurization. GPP addition reduced fat content and determined an increase of protein and of secondary lipid oxidation. Sensory tests indicated that cheeses CCP94 and ECP94, produced with the strain Mise94, reached the best appreciation scores. Following in vitro simulated human digestion, bioaccessible fraction of ECP94 showed antioxidant capacity, evaluated as radical scavenging activity and inhibition of membrane lipid oxidation, significantly higher than that from CCP94, with promising increase in functional properties. Thus, the main hypothesis was accepted since the functional aspects of the final cheeses improved, confirming that GPP is relevant for sustainable nutrition by using winemaking by-products.

Effect on the Antioxidant, Lipoperoxyl Radical Scavenger Capacity, Nutritional, Sensory and Microbiological Traits of an Ovine Stretched Cheese Produced with Grape Pomace Powder Addition

An innovative ovine cheese enriched with red grape pomace powder (GPP) was produced to improve the functional properties of Vastedda cheese typology. Vastedda cheese making was performed adding GPP and four selected Lactococcus lactis strains (Mise36, Mise94, Mise169 and Mise190). For each strain, 40 L of pasteurized ewe's milk was divided into two aliquots representing control and experimental trials. Control cheese (CC) production did not contain GPP, while the experimental cheese (EC) production was enriched with 1% (w/w) GPP. GPP did not slow down starter development and acid generation. Plate counts and randomly amplified polymorphic DNA (RAPD)-PCR analysis confirmed the dominance of the starters in all trials. The evolution of the physicochemical parameters showed that EC productions were characterized by lower fat content, higher protein content, and higher values of secondary lipid oxidation. Sensory evaluation indicated that the cheeses produced with the strain Mise94 were those more appreciated by the judges. Thus, the last cheeses were investigated for some functional aspects: GPP enrichment significantly increased antioxidant activity and lipoperoxyl radical scavenger capacity, confirming that grape polyphenol inclusion in cheese represents an optimal strategy for the valorization of ovine cheeses as well as winemaking industry by-products.

Improvement of Raw Milk Cheese Hygiene through the Selection of Starter and Non-Starter Lactic Acid Bacteria: The Successful Case of PDO Pecorino Siciliano Cheese

This review article focuses on the technological aspects and microbiological critical points of pressed-cooked cheeses processed from raw ewe's milk without the inoculation of starter cultures, in particular "Pecorino" cheese typology produced in Italy. After showing the composition of the biofilms adhering to the surface of the traditional dairy equipment (mainly wooden vat used to collect milk) and the microbiological characteristics of PDO Pecorino Siciliano cheese manufactured throughout Sicily, this cheese is taken as a case study to develop a strategy to improve its hygienic and safety characteristics. Basically, the natural lactic acid bacterial populations of fresh and ripened cheeses were characterized to select an autochthonous starter and non-starter cultures to stabilize the microbial community of PDO Pecorino Siciliano cheese. These bacteria were applied at a small scale level to prove their in situ efficacy, and finally introduced within the consortium for protection and promotion of this cheese to disseminate their performances to all dairy factories. The innovation in PDO Pecorino Siciliano cheese production was proven to be respectful of the traditional protocol, the final cheeses preserved their typicality, and the general cheese safety was improved. An overview of the future research prospects is also reported.

Identification and evaluation of antimicrobial resistance of enterococci isolated from raw ewes' and cows' milk collected in western Sicily: a preliminary investigation

The present work was carried out to investigate the Antimicrobial Resistance (AMR) of enterococci isolated from raw ewes' and cows' milk. The samples were collected from eighteen semi-extensive dairy sheep and cow farms throughout western Sicily. Plate counts, carried out on Rapid Enterococcus Agar commonly used to detect food enterococci, revealed a maximal enterococcal concentration of approximately 4.58 Log Colony Forming Unit (CFU)/mL. Colonies were isolated and differentiated based on genetic analysis by Randomly Amplified Polymorphic DNA (RAPD)-PCR. Thirty-eight different strains were identified. Analysis by a species-specific multiplex PCR assay grouped the strains into three Enterococcus species such as Enterococcus durans, Enterococcus faecalis and Enterococcus faecium. The 38 strains were also investigated for their antimicrobial resistance by a phenotypic approach. All 38 Enterococcus displayed resistance to at least one or more of the antimicrobials tested confirmed that the dairy enterococci could be a vector for the dissemination of antimicrobial resistance. This work showed that enterococci with AMR traits are commonly present in semiextensive dairy sheep and cow farms of western Sicily pointed out the relevance of informing dairy makers and veterinary regarding the antimicrobial use in order to mitigate problems of public health and veterinary medicine.

Experimental Parameters Influence the Observed Antimicrobial Response of Oak Wood (Quercus petraea)

The present investigation aimed to utilize a direct wood disc diffusion method to study the influence of plane of cutting, cutting method, sterilization method, and origin of tree on the antimicrobial activity of wood material. Six oak wood trees (Quercus petraea) were collected from 3 different locations in France. They were cut into 4 mm thick slices with either transverse (RT), tangential (LT) or radial (LR) faces. Round discs (diameter 9.95 ± 0.1 mm) were cut from the slices via a laser machine or a manual punch machine, and were sterilized with gamma irradiation (25 kGy) or autoclaving (121 °C). The antimicrobial activity of wood was tested using a direct diffusion method against Staphylococcus aureus and Acinetobacter baumannii isolates. The zone of inhibition around the wooden disc was recorded following the recommendations used for antibiotics tests. The results showed that S. aureus was more susceptible than A. baumannii, to the chemicals that diffused from the wood. The transverse face discs exhibited higher antimicrobial activity. Samples that had been sterilized by autoclaving showed significantly (p < 0.05) lower antimicrobial activity, whereas the cutting method and origin of tree did not influence the antimicrobial activity of wood material. Therefore, the choice of sterilization method and cutting planes must be taken into account while studying and interpreting the antibacterial properties of wood material.

Addition of selected starter/non-starter lactic acid bacterial inoculums to stabilise PDO Pecorino Siciliano cheese production

The present study was carried out to produce Protected Denomination of Origin (PDO) Pecorino Siciliano cheese with a multi-species lactic acid bacteria (LAB) culture, composed of starter and non-starter strains in order to reduce the microbiological variability of the products derived without LAB inoculums. To this end, cheese samples produced in six factories located in five provinces (Agrigento, Catania, Enna, Palermo and Trapani) of Sicily, and previously characterised for physicochemical, microbiological and sensory aspects, have been investigated in this work for bacterial microbiome, fatty acid (FA) composition as well as volatile organic compound (VOC) profiles. Analysis of the cheese microbiomes indicated that streptococci (30.62-77.18% relative abundance) and lactobacilli (on average 25.90% relative abundance) dominated the bacterial communities of control cheeses, produced without exogenous inoculums, whereas the cheeses produced with the selected multi-strain culture saw the dominance of lactococci (in the range 6.49-14.92% relative abundance), streptococci and lactobacilli. After the addition of the selected mixed culture, Shannon index increased in all cheeses, but only the cheeses produced with the selected LAB mixed culture in the factory 2 showed Gini-Simpson diversity index (0.79) closer to the reference value (0.94) for a perfect even community. FA composition, mainly represented by saturated FA (on average 69.60% and 69.39% in control cheeses and experimental cheeses, respectively), was not affected by adding LAB culture. The presence of polyunsaturated FA ranged between 7.93 and 8.03% of FA. VOC profiles were different only for the content of butanoic acid, registered for the experimental cheeses at higher concentrations (on average 662.54 mg/kg) than control cheeses (barely 11.96 mg/kg). This study validated addition of the ad hoc starter/non-starter culture for PDO Pecorino cheese production.

Effects of adding solid and molten chocolate on the physicochemical, antioxidant, microbiological, and sensory properties of ewe's milk cheese

A novel dairy product, namely "chocolate cheese", was produced with two typical Sicilian food products: Pecorino cheese, processed from ewe's milk, and Modica chocolate. The cheese, manufactured with 0%, 5%, 10%, and 15% (w/w) solid or molten chocolate, was evaluated after 0, 2, 4, and 6 weeks of vacuum storage for its nutritional and health properties. The addition of chocolate reduced the pH, protein, fat, and ash; the addition of 5% or 10% molten chocolate reduced hardness (N/mm² ). The addition of either solid or molten chocolate resulted in a slight increase (P < 0.1038) in the total polyphenol content, a higher oleic acid content, and less oxidative stability. The microbiological profile showed that the total mesophilic count and the number of mesophilic coccus lactic acid bacteria (LAB) were approximately equal (about 10⁸ CFU/g) in all cheese. The survival of the microorganisms was affected by both the chocolate added and the storage time. Chocolate cheese stored for 6 weeks had less Enterobacteriaceae than control cheese, whereas yeasts were detected at higher cell densities in the former cheese. Filamentous fungi were undetectable in some cheese. Differences were also observed in the number of mesophilic rod LAB, which increased progressively over time in all cheese, and in Enterobacteriaceae, yeasts, and filamentous fungi, which decreased during storage. Descriptive and hedonic sensory tests and principal component analysis showed that fresh cheese and cheese stored for 2 weeks, including 5% molten chocolate, were the most preferred by evaluators. Based on these results, chocolate cheese has the potential to be appreciated in the market for its nutritional, health, and sensory properties. PRACTICAL APPLICATION: Chocolate cheese, made by combining two typical Sicilian foods, Pecorino cheese and Modica chocolate, is proposed as a novel dairy product. The highest sensory acceptance was obtained with the addition of 5% molten chocolate and storage for 2 weeks. Given its improved antioxidant properties, healthier fat, and sensory properties, chocolate cheese has the potential to be appreciated in the market, especially by young consumers.

Evolution of indigenous starter microorganisms and physicochemical parameters in spontaneously fermented beef, horse, wild boar and pork salamis produced under controlled conditions

The present work was carried out to evaluate the microbiological and physicochemical composition of salamis produced with the meat of beef, horse, wild boar and pork. Salami productions occurred under controlled laboratory conditions to exclude butchery environmental contaminations, without the addition of nitrate and nitrite. All trials were monitored during the ripening (13 °C and 90% relative humidity) extended until 45 d. The evolution of physicochemical parameters showed that beef and pork salamis were characterized by a higher content of branched chain fatty acids (FA) and rumenic acid than horse and wild boar salamis, whereas the last two productions showed higher values of secondary lipid oxidation. Plate counts showed that lactic acid bacteria (LAB), yeasts and coagulase-negative staphylococci (CNS) populations dominated the microbial community of all productions with Lactobacillus and Staphylococcus as most frequently isolated bacteria. The microbial diversity evaluated by MiSeq Illumina showed the presence of members of Gammaproteobacteria phylum, Moraxellaceae family, Acinetobacter, Pseudomonas, Carnobacterium and Enterococcus in all salamis. This study showed the natural evolution of indigenous fermented meat starter cultures and confirmed a higher suitability of horse and beef meat for nitrate/nitrite free salami production due to their hygienic quality at 30 d.