During Pecorino Romano PDO cheese production, scotta (residual whey from ricotta cheese manufacturing) or siero (whey) can be integrated with autochthonous starters, natural and composed of an indefinite number of species and strains, or commercial selected starters to obtain scotta/siero-innesto. In this study, three biodiverse autochthonous natural starter cultures (SR30, SR56, and SR63) belonging to the Agris Sardegna BNSS microbial collection, composed of different strains belonging to the species Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Enterococcus faecium, and Limosilactobacillus reuteri were lyophilized and combined into two starter mixes (A and B). The scotta/siero-innesto and the Pecorino Romano obtained using natural starters were compared with those obtained using commercial selected starters during three seasons of the cheesemaking campaign. Different pH and microbial compositions for the scotta/siero-innesto obtained using natural or commercial starters were found, attributable to their different biodiversity. The six-month-ripened cheese microbiota was influenced mostly by the season of cheesemaking, whereas physico-chemical and sensory analyses did not highlight differences among the products obtained. In general, no effect attributable to the type of scotta/siero-innesto used was observed, allowing the conclusion that natural starter cultures can be used also in industrial-scale production, ensuring high stability in the technological performances and preserving the microbial, chemical, and sensory characteristics of Pecorino Romano PDO cheese.

Fish populations play an active role in the maintenance of aquatic ecosystems biodiversity. Their intestinal microbiota and fillet chemistry depend on abiotic and biotic factors of the water environments that they inhabit. The present study investigated the grey mullets’ gut microbiota from a transitional aquatic ecosystem (Santa Giusta Lagoon, Sardinia, Italy) by a multidisciplinary approach which refers the results of (1) gut cultivable microbiota analyses (MA), (2) the trace metal assessment of fish muscle (TM), (3) the physico-chemical water monitoring (PC). MA detected the greatest number of total aerobic heterotrophic bacteria, Enterobacteriaceae and coliforms in Autumn (mean values 1.3 × 10⁵, 2.4 × 10⁴, 1.1 × 10⁴ cfu g⁻¹, respectively) when the accumulated rain and mean values of nutrients (reactive phosphorous and silica) were the highest. Marine bacteria were more numerous in Summer (mean value 7.4 × 10⁵ cfu g⁻¹) when the highest mean values of water temperature and salinity were registered. The gut bacteria were identified as Pseudomonas spp. (64%), Aeromonas spp. (17%), Ochrobactrum pseudogrignonense (10%), Providencia spp. (5%), Enterobacter ludwigii (2%) and Kocuria tytonicola (2%). TM showed that Ca, Na, B and Ni increased their concentrations in Winter while maxima of P, Zn, Cu and Fe were found in muscles of fish sampled in Summer. This study highlighted that the fish intestinal microbiota and metal composition of the fillet reflected the seasonal aquatic environmental variability.

Salsiccia sarda or Sardinian fermented sausage is a traditional dry-fermented sausage included in the list of traditional food products of Sardinia (Italy). At the request of some producing plants, the possibility of extending the shelf life of the vacuum-packed product up to 120 days was evaluated. Manufacturing of 90 samples, representing 3 different batches of Sardinian fermented sausage was carried out in two producing plants (A and B). In the packaged product and subsequently every 30 days for four months (T0, T30, T60, T120), the following analyses were conducted on all samples: physicochemical characteristics, total aerobic mesophilic count, Enterobacteriaceae count, detection of Listeria monocytogenes, Salmonella spp., mesophilic lactic acid bacteria, and coagulase-positive Staphylococci. Moreover, surfaces in contact and surfaces not in contact with food were sampled in both producing plants. Sensory profile analysis was also performed for every analysis time. At the end of the extended shelf life, pH values were equal to 5.90±0.11 (producing plant A) and 5.61±0.29 (producing plant B). Water activity mean values at T120 were 0.894±0.02 (producing plant A) and 0.875±0.01 (producing plant B). L. monocytogenes was detected in 73.3% (33/45) of the samples from producing plant A, with mean levels of 1.12±0.76 log10 CFU/g. In producing plant B, L. monocytogenes was never detected. Enterobacteriaceae were detected in 91.1% (41/45) of samples in producing plant A with mean values of 3.15±1.21 log10 CFU/g, and in 35.5% (16/45) samples in producing plant B samples with mean values of 0.72±0.86 log10 CFU/g. Salmonella and Staphylococcus aureus were never detected. Regarding environmental samples, the sites that were most contaminated by L. monocytogenes were the bagging table (contact surface) and processing room floor drains (non-contact surface) with a prevalence of 50% each (8/16 positive samples for both sampling sites). Sensory analysis results showed that at T30 the overall sensory quality was at its highest; moreover, the visual-tactile aspect, the olfactory characteristics, the gustatory aspects, and the texture showed significant differences in samples throughout the shelf life, with a decreased intensity at 120 days of storage. Overall, the quality and sensory acceptance of the vacuum-packed Sardinian fermented sausage were not affected until 120 days of shelf-life. However, the possible contamination by L. monocytogenes calls attention to the hygienic management of the entire technological process. The environmental sampling was confirmed as a useful verification tool during control.

Authors: Barbara De Nicolo, Carlo Piga, Vlad Popescu and Giovanna Concu

A freeze-dried natural starter culture (NSC) was developed and assessed for its suitability in producing a semi-cooked, 60-day-ripened cheese resembling the protected designation of origin (PDO) Pecorino Sardo. The culture, derived from raw ewe’s milk from a dairy farm involved in the study, without thermal decontamination to preserve indigenous microbiota, was enriched with two strain-level-characterised, biodiverse mixtures of Streptococcus thermophilus (Str-mix) and Lactobacillus delbrueckii (Lb-mix). This study evaluated the technological robustness and adaptability of NSC enriched with biodiverse Str-mix and Lb-mix across three different artisanal dairy-processing environments with varying milk compositions and equipment levels at plants located in different geographic areas. During cheesemaking, technological, physico-chemical, and compositional parameters were monitored, along with microbial characterisation of milks and 1-day cheeses. After 60 days of ripening, cheeses were characterised from the microbiological, physico-chemical, and compositional perspectives. Furthermore, nutritional labelling was established, and consumer acceptance was determined. Results showed that the starter (NSC + Str-mix + Lb-mix) demonstrated strong and reproducible technological performance in all dairies, regardless of the milk’s chemical and microbial composition variability. Sensory quality was preserved in cheeses ripened for up to 180 days. These preliminary findings seem to support the use of freeze-dried, raw-milk-derived natural cultures in artisanal cheesemaking as a way to preserve microbial diversity and to reconnect with traditional practices that enhance both the tangible and intangible assets of modern society.

This study aimed to conduct a preliminary investigation in eight Sardinian fermented sausage (SFS) production plants to acquire knowledge about the differences in the applied technological process and their influence on the safety and sensory characteristics of the finished product. Two audits were conducted in each plant to evaluate structural characteristics and process technologies; 72 samples of SFS at the end of seasoning and 48 environmental samples were analyzed. Listeria monocytogenes, Listeria spp., Salmonella spp., and Yersinia enterocolitica were investigated, and chemical-physical analyses were also performed. A panel of consumers was subjected to the Check All That Apply test and acceptability test to determine the qualities perceived by consumers and assess the product acceptance rating. A water activity value of >0.941, permissive for the growth of L. monocytogenes, was detected in SFS produced by one producing plant; L. monocytogenes, Salmonella spp., and Y. enterocolitica were detected in 2.8% of SFS samples, and Listeria spp. in 20.8% of samples. Environmental samples tested positive for 45.8% of Listeria spp. and 16.7% of L. monocytogenes. Correct drying and ripening steps, applied for at least 20 days, are critical for the development of hurdles required to guarantee the safety of fermented sausages. The application of proper hygiene and cleaning procedures is required to reduce environmental contamination. Sensory analysis results show how the production processes applied determine the marketing of sensorially different products. The ideal profile suggested by consumers confirms that the attributes that allow for improved liking are “moderate spicing”, “moderate spiciness”, “seasoned product”, and “artisanal character”.