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    Inhibition of Aspergillus parasiticus and detoxification of aflatoxin derivatives in tomato paste by adding freeze-dried postbiotic from Lactiplantibacillus plantarum
    (Elsevier Sci Ltd, 2026) Tutuk, Zehra; Karatepe, Pinar; Akgol, Muzeyyen; Bayrak, Sinem; Vurmaz, Melike; Fidan, Serife; Hayaloglu, Ali Adnan
    In this study, it was aimed to inhibit the Aspergillus parasiticus and detoxify the aflatoxin derivatives (B1, B2, G1, and G2) by adding the postbiotic of Lactiplantibacillus plantarum in tomato paste. The bioactive compounds in the postbiotic were also identified. The minimum inhibitory (MIC) and fungicidal concentrations (MFC) of the postbiotic were found to be 12.5 and 100 mg/mL against A. parasiticus, respectively. In addition, 10 mg of the postbiotic displayed a 16.47 mm inhibition zone. The postbiotics were added to the tomato pastes at 4, 6 and 8-fold of the MIC, and the physico-chemical, microbiological parameters, and the amount of aflatoxins were monitored during 45 days of storage at 4 degrees C. The number of A. parasiticus was found to be below the detection limit in the 8-fold concentration of the postbiotic-added tomato pastes on the 45th day (P < 0.05). Compared to untreated samples, this treatment also significantly reduced the populations of mesophilic aerobes, psychrotrophs, lactic acid bacteria, and anaerobes (P < 0.05). Importantly, the pH, color, and titratable acidity remained constant in all groups during storage (P > 0.05). In addition, the postbiotic significantly reduced the levels of aflatoxins B1, B2, G1 and G2 compared to the control in a dose-dependent manner (P < 0.05). The results revealed that the postbiotic contains various bioactive constituents, including organic, free fatty, and free amino acids, polyphenols and volatiles, and also has a strong antioxidant capacity. In conclusion, the addition of freeze-dried postbiotics to tomato paste shows strong antifungal and anti-aflatoxigenic effects without compromising physicochemical quality of the tomato paste.
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    Lactiplantibacillus Plantarum Postbiotics Suppress Salmonella Typhimurium Invasion and Modulate Innate Responses in Human Intestinal Epithelial Cells
    (Springer, 2025) Cobur, Hazal; Loker, Neriman; Dishan, Adalet; Vurmaz, Melike; Karatepe, Pinar; Hizlisoy, Harun; Akcay, Aytac
    Postbiotics derived from Lactiplantibacillus plantarum (LPP) exhibit promising potential as safe modulators of intestinal health. Here, the chemical, antimicrobial, and host-regulatory properties of LPP against Salmonella enterica serovar Typhimurium were investigated using a human intestinal epithelial (Caco-2) cell model. The LPP exhibited broad-spectrum antimicrobial activity against major foodborne pathogens, with minimal inhibitory concentrations ranging between 12.5 and 25 mg/mL. Treatment of Caco-2 cells with sub-MIC doses of LPP (6.25 mg/mL) significantly suppressed intracellular invasion of Salmonella (P < 0.05). Gene expression analysis revealed consistent downregulation of NF-kappa B gene expression following LPP presence with sublethal doses (P < 0.001), while no significant changes were detected in the expression levels of other key proinflammatory cytokines during the early phases (six and 12 h) of infection. A significant increase (P < 0.001) in apoptotic cell rates occurred at six h post-infection (PI), while no significant differences were observed at 12 h PI. The results revealed that LPP not only suppresses Salmonella invasion but also shows time-dependent modulation of inflammatory signaling and apoptotic responses in intestinal epithelial cells. These observed effects can be attributed to the bioactive compounds present in LPP, including organic acids, free amino acids, free fatty acids, polyphenols, and volatiles. The findings suggest that L. plantarum postbiotics can attenuate bacterial invasion and modulate innate immune response mechanisms without compromising host cell viability.
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    Water kefir-assisted fermentation improved quality of plant-based cheese alternative comparable with cow's milk cheese by reducing plant-origin odor and enhancing cheese-like flavours
    (Elsevier Sci Ltd, 2025) Tekin, Ali; Vurmaz, Melike; Fidan, Serife; Dursun, Ahmet; Sekerli, Yunus Emre; Incili, Gokhan Kursad; Hayaloglu, Ali Adnan
    The growing human population in the world has led to a global food shortage and the environmental impact of animal food production is declared in various platforms. The challenges for animal breeding and the limited availability of dairy products have increased the search for alternatives to traditional cheese and other dairy products. In addition, the rising popularity of vegan diets has increased interest in plant-based food alternatives. However, these plant-based products have some limitations, especially having some difficulties to achieving the texture and flavours of dairy counterparts. This study aims to improve the cheese-like flavour of a plant-based cheese alternative (PCA) by incorporating water kefir into the product. The microbiota presents in the water kefir induced biochemical changes and altered the composition of volatiles in PCA. The addition of water kefir led to an increased level of organic acids in the PCA. Significant changes in key organic acids, relevant to cheese production, such as lactic and propionic acids, were observed during storage. In water kefir-free PCA, all free amino acids (FAAs) steadily decreased throughout storage, whereas in the water kefir-treated sample, many FAAs initially decreased and then increased at 60 days. Plant-origin compounds like benzaldehyde, responsible for apricot kernel odor, and green aldehydes associated with off-flavours, declined after 60 days. Meanwhile, compounds important for cheese flavour-e.g., ethanol, acetaldehyde, 3-methylbutanol, and ethyl acetate-increased. These findings suggest that water kefir can effectively improve the flavour of PCA.