On the frame of this research survey, a novel potentially probiotic strain (Lactobacillus paracasei SP5) recently isolated from kefir grains was evaluated for chokeberry juice fermentation. Chokeberry juice was retrieved from the variety Aronia melanocarpa, a plant known to provide small, dark berries and to be one of the richest sources of antioxidants. The juice was subsequently fermented inoculating L. paracasei SP5 for 48 h at 30 °C. The fermented juices were left at 4 °C and tested regarding microbiological and physicochemical characteristics for 4 weeks. The potentially probiotic strain was proved capable of performing lactic acid fermentation at 30 °C. Cell viability of L. paracasei was detected in high levels during fermentation and the whole storage period, while the fermented juice showed higher levels of viability in juice with 40.3 g/L of initial sugar concentration. No ethanol was detected in the final fermented juice. Fermented chokeberry juice was characterized by aromatic desirable volatiles, which were retained in adequate levels for the whole storage period. Specifically, the occurrence of organic esters detected in fermented juices is considered as positive evidence of the provision of fruity and floral notes to the final product. During storage, total phenolics content and antioxidant activity were observed in higher levels in fermented chokeberry juice compared with non-fermented juice. Subsequently, fermentation of chokeberry juice by potentially probiotic lactic acid bacteria could provide high industrialization potential, providing the market with a nutritional beverage of good volatile quality with an enhanced shelf-life compared with an unfermented fresh juice.

The aim of this study was to determine the antimicrobial efficiency of piperitenone epoxide (PEO) – a principal component of various aromatic plants’ essential oil – in combination with various antibiotics against 28 strains of Staphylococcus aureus and 10 strains of Escherichia coli isolated from clinical samples. Mentha spicata’s essential oil, initially collected by hydrodistillation, was then subjected to flush column chromatography affording PEO of high purity. Minimum inhibitory concentrations of PEO alone and in combination with various concentrations of antibiotics were assessed using the microdilution method. The combined action was estimated calculating the fractional inhibitory concentration (FIC) index from checkerboard assays. Our results showed that the average minimum inhibitory concentration (mg/l) of PEO alone against E. coli was 512 ± 364.7 μg/ml, which was significantly higher than 172.8 ± 180.7 μg/ml observed for S. aureus. From checkerboard assays, FIC values below the 0.5 index, indicating synergy, were observed for 59% of the drugs tested. Twelve percent of FIC index values were between 0.5 and 1, indicating additive effects, while 21% were indifferent. According to our results, PEO could be a promising antimicrobial compound when combined with specific antibiotics and deserves further study.

Rising demand for functional dairy products has stimulated interest in incorporating traditional fermented ingredients into modern food systems. This study investigated the use of traditional Greek trahanas as a functional ingredient in yogurt and evaluated its effects on physicochemical, microbiological, antioxidant-related, and sensory characteristics. Five formulations were produced: a control yogurt inoculated with a commercial yogurt starter culture, two starter-inoculated yogurts supplemented with 2% and 4% (w/w) trahanas, and two starter-free fermented dairy formulations supplemented with 2% and 4% (w/w) trahanas. All products were evaluated over 30 days of refrigerated storage (4 °C) in terms of pH evolution, lactose consumption, lactic acid production, protein content, total solids, syneresis, antioxidant activity, total phenolic content, microbial stability, and sensory properties. The trahanas-enriched yogurts inoculated with a starter culture exhibited enhanced acidification, higher protein and total solid contents, reduced syneresis, and increased antioxidant activity and phenolic content compared with the control and starter-free formulations. In particular, the 4% trahanas formulation inoculated with a commercial starter culture exhibited the highest DPPH and ABTS radical scavenging activities, suggesting a synergistic effect between trahanas-derived bioactive compounds and fermentation-associated lactic acid bacteria. Microbiological analyses confirmed the maintenance of high lactic acid bacterial populations throughout storage, particularly in the 4% trahanas formulation, which exhibited the highest Streptococcus thermophilus counts during refrigerated storage. The detected lactic acid bacterial populations originated both from the commercial yogurt starter culture and from the traditional preparation of trahanas itself, which involves fermentation with sour sheep’s milk and traditional yogurt. In addition, coliforms, Enterobacteriaceae, and Staphylococci remained undetectable in all formulations, while only limited yeast and mold growth was observed during the later stages of storage, mainly in starter-free samples. Sensory evaluation indicated good overall acceptability of trahanas-enriched formulations, particularly at 4% (w/w). Overall, the incorporation of traditional Greek trahanas into yogurt systems represents a promising approach for the development of fermented dairy products with improved technological, antioxidant-related, and functional properties.