Agathi Giannouli

Soft spread cheese is highly perishable, and conventional packaging offers limited protection against surface spoilage. Here, we present a sustainable, multifunctional solution: edible films made from whey protein concentrate (WPC), a valuable by-product of the cheese industry, incorporated with the probiotic Lactobacillus acidophilus LA5 (LA5). The objective of this study was to evaluate these films as active coatings for soft cheese, specifically assessing their physicochemical properties, probiotic viability during storage and simulated gastric transit, and their impact on cheese microbial stability and sensory quality over 60 days. Applied as active coatings on soft cheese stored at 4 °C for 60 days, these films were evaluated for their physicochemical properties, probiotic viability, microbial stability, and sensory acceptance. The incorporation of LA5 did not significantly alter film thickness (control: 0.20 ± 0.03 mm; test: 0.18 ± 0.02 mm), moisture content (control: 33.42 ± 0.54%; test: 32.34 ± 1.28%), or water solubility (control: 21.44 ± 1.14%; test: 22.89 ± 0.75%) (p > 0.05). However, mechanical properties were markedly modified: tensile strength decreased from 35.42 ± 5.38 MPa (control) to 6.04 ± 0.55 MPa (test), while elongation at break increased from 4.87 ± 0.93% to 68.23 ± 3.46% (p < 0.05), indicating a transition from rigidity to flexibility upon probiotic incorporation. The probiotic strain exhibited exceptional resilience, retaining 100% viability during simulated gastric exposure at both day 0 and day 30 of storage. During cheese storage, LA5 counts in test film-coated samples remained above the recommended therapeutic threshold (10⁶ cfu/g), starting at 7.44 ± 0.15 log(cfu/g) on day 0 and maintaining 6.56 ± 0.20 log(cfu/g) after 60 days. Critically, yeast and mold spoilage were delayed in probiotic-coated cheese, with detectable growth appearing only at day 60 (1.64 ± 1.34 log(cfu/g)), whereas uncoated cheese showed spoilage as early as day 28 (1.33 ± 1.62 log(cfu/g)). Sensory evaluation revealed no significant differences (p > 0.05) between the coated and uncoated samples for color, appearance, texture, flavor, or overall acceptability. By valorizing a dairy by-product into an active, probiotic-loaded edible film, this approach offers a sustainable, waste-reducing strategy that enhances cheese preservation while delivering added functional value—bridging the gap between food packaging and nutrition. Sensory evaluation (n = 8, preliminary) indicated no significant differences between coated and uncoated samples, but these results require confirmation with a larger, validated panel.

Dairy products play a crucial role in human nutrition as they provide essential nutrients. However, the presence of diverse microorganisms in these products can pose challenges to food safety and quality. Here, we provide a comprehensive molecular characterization of a diverse collection of lactic acid bacteria (LAB) and staphylococci isolated from raw sheep’s milk. Whole-genome sequencing, phenotypic characterization, and bioinformatics were employed to gain insight into the genetic composition and functional attributes of these bacteria. Bioinformatics analysis revealed the presence of various genetic elements. Important toxin-related genes in staphylococci that contribute to their pathogenic potential were identified and confirmed using phenotypic assays, while adherence-related genes, which are essential for attachment to host tissues, surfaces in the dairy environment, and the creation of biofilms, were also present. Interestingly, the Staphylococcus aureus isolates belonged to sequence type 5, which largely consists of methicillin-susceptible isolates that have been involved in severe nosocomial infections. Although genes encoding methicillin resistance were not identified, multiple resistance genes (RGs) conferring resistance to aminoglycosides, macrolides, and fluroquinolones were found. In contrast, LAB had few inherently present RGs and no virulence genes, suggesting their likely safe status as food additives in dairy products. LAB were also richer in bacteriocins and carbohydrate-active enzymes, indicating their potential to suppress pathogens and effectively utilize carbohydrate substrates, respectively. Additionally, mobile genetic elements, present in both LAB and staphylococci, may facilitate the acquisition and dissemination of genetic traits, including RGs, virulence genes, and metabolic factors, with implications for food quality and public health. The molecular and phenotypic characterization presented herein contributes to the effort to mitigate risks and infections (e.g., mastitis) and enhance the safety and quality of milk and products thereof.

Kashkaval of Pindos cheese was successfully produced using 100% sheep milk (KS) or with the addition of 10% goat milk (KG). Urda cheese was manufactured using 100% sheep (US) or 90% sheep–10% goat (UG) whey from the production of kashkaval of Pindos cheese. Both cheeses were made taking into account their traditional cheese-making methods. The cheeses were assessed for their chemical, microbiological and organoleptic characteristics. Generally, no significant differences were observed between KS and KG cheese and between US and UG cheese regarding their physicochemical, textural characteristics, soluble nitrogen fraction and total fatty acid content. The fat content of Urda cheese was low, in accordance with the demand of consumers for healthy products. KS cheeses showed higher total volatile compounds than KG cheeses at 60 and 90 days of ripening and storage as well as lower counts of thermophilic–mesophilic lactic acid bacteria. No differences were observed in the microbial counts between US and UG cheeses. Acetone, hexanal, 2 heptanone, ethanol and toluene were found in abundance in Urda cheeses. Both kashkaval of Pindos and Urda cheeses received high scores during the organoleptic evaluation. The obtained data may lead to the production of both cheeses with standard characteristics according to the traditional recipes and improve their recognition.