In this study, the composition of essential oils (EOs) obtained from Citrus limon L. and Citrus sinensis L. peels and their biological activities on foodborne pathogenic bacteria and food-borne saprophytic yeasts and molds were investigated. In the lemon peel EO, 16 components were identified, mainly limonene (68.65 %) and γ-terpinene (10.81 %). Similarly, 8 components were determined in the orange peel EO, mainly limonene (95.51 %) and β-myrcene (1.98 %). The lemon and orange peel EOs showed a higher antibacterial effect on gram-positive bacteria used in the study compared to gram-negative bacteria. The highest antibacterial activity was detected on Staphylococcus aureus with 22.55 and 26.23 mm, respectively (P <0.05) The highest anti-fungal effects were determined at lemon peel EO, on Candida tropicalis (23.61 mm) and Rhizopus nigricans (14.15 mm) and orange peel EO, on Debaromyces hanseni spp hanseni (30.68 mm) and R. nigricans (17.23 mm) (P<0.05). The lowest minimum inhibitory concentration values were determined on S. aureus (0.023 mg/L, 0.006 mg/L), C. tropicalis (0.017 mg/L, 0.011 mg/L) and Aspergillus flavus (0.058 mg/L, 0.017 mg/mL) (P<0.05). The minimum bactericidal and fungicidal concentration values of lemon and orange peel EOs were determined on S. aureus (0.011 mg/L, 0.004 mg/L), C. tropicalis (0.011 mg/L, 0.003 mg/L) and Aspergillus flavus (0.023 mg/L, 0.015 mg/mL) (P<0.05).

In this study, the composition of the essential oil of tea tree (Melaleuca alternifolia) leaves and the antifungal effects of the essential oil on food-borne molds isolated from meat products were investigated. The α-pinene (21.64 %), γ-terpinene (21.09 %), terpinen-4-ol (17.31 %), limonene (9.37 %), and o-cymene (6.54 %) were found to be the major components of M. alternifolia essential oil. The essential oil showed the highest antifungal activity on Aspergillus niger (25.82 mm zone diameter), followed by Aspergillus fumigatus (22.27 mm), Aspergillus flavus (21.092 mm), and Penicillium notatum (20.30 mm) (p<0.05), respectively. The minimum inhibitory concentration (MIC) values of M. alternifolia essential oil on the mold species used in the study varied between 0.032 and 0.376 mg/L, and the value of minimum fungicidal concentration (MFC) values ranged from 0.021 to 0.341 mg/L (p<0.05). The MIC/MFC ratio of M. alternifolia essential oil on 10 different mold species varies between 1.05 and 1.68 mg/L. According to the MIC/MFC ratio, the M. alternifolia essential oil showed a lethal effect on all of the mold species studied in this research.

Mozzarella produced with high moisture curd method was filled into a fibrous casing and was stored at 4C and 85% relative humidity for 5 days. Sliced cheese was packed in aerobic packaging (AP), vacuum packaging (VP) and modified atmosphere packaging (MAP) and was stored at 4C for 21 days. L* (lightness) value of the AP sample decreased, while an increased in other two treatments was detected. The a* (redness) values of VP and MAP samples decreased, while the values of AP samples increased. Mesophilic aerobic bacteria, yeast and mold counts increased in the AP samples, while that of the VP and MAP samples counts decreased. Lactic acid bacterial count decreased in all three samples and the greatest decrease with a value of 3.90 log cfu/g was detected in samples packed in aerobic conditions. Samples with MAP had significantly better sensory score (P < 0.05) than any other samples. Mozzarella cheese is a popular processed dairy product. Mozzarella cheese is primarily produced with water buffalo milk and cow milk. Mozzarella is produced using two different methods, which are based on dry matter ratio and shelf life. Mozzarella with low moisture is used in the pizza industry and has a longer shelf life. The other mozzarella has higher humidity content and a limited shelf life. Modified atmosphere packaging (MAP) is becoming more common and is successfully applied to different processed dairy products for extending the shelf life. To sum up, our study proves the efficacy of using different packaging methods (AP, VP or MAP) on the microbiological, chemical and sensory properties of sliced mozzarella.

In this study, 3 different spice mixes were added just after blanching to mozzarella cheese produced by high moisture production method. The dough was kneaded and filled into to fibrous cases. After filling process, cheeses were stored for 28 days at 4 °C and 85 % of relative humidity. The following characteristics were measured: color parameters, milk acidity, total dry matter, maturation index, total aerobic mesophilic bacteria, coliform bacteria, coagulase positive staphylococci, lactic acid bacteria, species of Lactococcus bacteria, proteolytic bacteria, lipolytic bacteria and mold /yeast count were examined on 0, 5, 15,21 and 28 days after storage. Although L* (lightness) and a* (redness) values decreased during storage period, while moreover b* (yellowness) values increased. In addition acidity, dry matter and maturation index values increased during storage. Total aerobic mesophilic bacteria, lactic acid bacteria, Lactococcus spp., lipolytic bacteria and mold/ yeast counts decreased, but proteolytic bacteria count increased.