Ayça Gedikoğlu

The antimicrobial effect of Eucalyptus radiata essential oil nanoemulsion (EON) on Staphylococcus aureus and spoilage microorganisms was evaluated on fresh beef chunks during cold storage at days 0, 2, 4, 6, and 8. For this purpose, nanoemulsion was prepared using 2% eucalyptus oil combined with high methoxyl pectin, glycerol, and Tween 80, employing high shear force. Then the following were evaluated: (1) the essential oil’s chemical profile and in vitro antioxidant and antimicrobial capacities; (2) the nanoemulsion characteristics; and (3) the microbial counts of the beef treatments. The results showed that the essential oil’s primary components were o-cymene (45.4%), 2-bornene (26.29%), 1,8-cineole (11.31%), and α-pinene (9.25%). The EON had a particle size of 52.04 nm and a zeta potential of −9.16 mV. The in vitro studies revealed that both the essential oil and its nanoemulsion demonstrated significant antibacterial activity. Similarly, in in situ examinations, when the meat samples were spiked with S. aureus (0.1 × 10⁸ CFU/mL), the EON-treated meat samples had significantly (p ≤ 0.05) lower microbial counts than the untreated meat samples throughout the storage period; the difference between the treatments ranged between 1.62 and 2.44 log CFU/g. Additionally, the EON exhibited excellent antimicrobial efficacy against spoilage microorganisms on beef pieces during shelf life. On day 4, the maximum inhibitory activity was observed against total coliform, Pseudomonas spp., and yeast in reductions of 1.96, 2.09, and 2.18 log CFU/g in microbial counts, respectively. Moreover, application of meat samples with the EON delayed spoilage by 4 days. Therefore, the results of this study showed that coating beef chunks with the EON enhanced both product safety and shelf life.

This study compares the chemical composition, antioxidant capacity, and antibacterial properties of lavender essential oils extracted using microwave-assisted extraction (MAE) and supercritical CO₂ extraction (SCDE). Gas chromatography–mass spectrometry analysis revealed that the MAE oil contained higher levels of linalyl acetate (36.19%) and linalool (28.29%) compared with the SCDE oil, which had values of 28.72% and 27.48%, respectively. The MAE oil also showed superior antioxidant activity, with DPPH IC₅₀ values of 72.99 mg/mL and FRAP values of 1.31 mM Fe²⁺/g, compared with 80.84 mg/mL and 1.14 mM Fe²⁺/g for the SCDE oil. Antibacterial tests indicated that the MAE oil exhibited lower MIC values, demonstrating twice the antibacterial activity against Bacillus cereus NRRL B3711, Bacillus subtilis PY79, and Enterococcus faecalis ATCC 29212 compared with the SCDE oil. These results highlight the superior bioactivity of MAE-extracted lavender oil, making MAE a preferred method for high-quality oil extraction from drought-affected lavender plants.

Bu bölümde gıdalar da mikrobiyal bozulmanın nasıl gerçekleştiği açıklanmıştır. Mikrobiyal bozulma ya canlı mikroorganizmaların gıdalardaki besin maddelerini kullanarak hızlı şekilde gelişmeleri sonucu veya parçalanan ya da ölen mikroorganizmalardan salınan enzimlerin besin maddelerini parçalaması sonucu oluşturdukları metabolik ürünlerle gıdaların koku, tat ve dokularında oluşan ve insan tüketimi açısından kabul edilemez değişimler olarak tarif edilir. Bu bozulmalar gıdalarda kötü kokuşmuş koku, renkte solma, kararma, lekeler, paketli gıdalarda gaz oluşumu, şişme, ürün yüzeylerinde görülebilecek yapışkanımsı, sümüksü sıvılar, pıhtılaşma, jelleşme şeklinde olabilir. Mikroorganizmaların gıdalarda bozulmalara yol açmasında birçok faktör etkilidir. Bu faktörler, mikroorganizma türleri, mikroorganizma sayısı ve baskın mikroorganizmaların gıdalarda varlığı şeklinde sıralanabilir. Mikrobiyal bozulmalarda üzerinde durulması gereken önemli diğer bir konuda gıdalardaki farklı besinlerin varlığı, miktarı ve bunların hangi şekilde mikroorganizmalar tarafından değerlendirildiğidir. Karbonhidrat, protein ve lipit gibi besin maddelerinin mikroorganizmalar tarafından hidrolize edildiğinde oluşan farklı metabolitler ve bu metabolitlerin farklı gıdalarda sebep olduğu duyusal (koku, tat, doku ve renk) değişiklikler detaylı bir şekilde ela alınmıştır. Son olarak, gıdalarda bozulmalardan sorumlu olan mikroorganizmalar; bakteri (spor oluşturmayan ve oluşturan), maya ve küflerin özellikleri ve bu mikroorganizmaların gıdalarda sebep oldukları bozulmalara örnekleri ile yer verilmiştir.

Tarihçe ve Gıda Mikrobiyolojisinin Gelişimi Aysun ORAÇ Gıdalarda Bulunan Mikroorganizmaların Özellikleri Şebnem ÖZTÜRKOĞLU BUDAK Ceren AKAL Gıdalardaki Önemli Mikroorganizma Grupları Kübra ERYAŞAR ÖRER Ercan SARICA Gıdalarda Bulunan Mikroorganizmaların Kaynakları Ezgi TELLİ Yusuf BİÇER Gıdalarda Mikrobiyal Gelişimi Etkileyen Faktörler Hale İnci ÖZTÜRK Gıdalarda Mikrobiyal Gelişme Kinetiği Sencer BUZRUL Starter Kültürler ve Gıdaların Fermentasyonunda Kullanılan Mikroorganizmalar Enes DERTLİ Fatma Nur DEMİRBAŞ Probiyotikler ve Yeni Nesil Probiyotikler Talha DEMİRCİ Mikrobiyal Orijinli Gıda Biyokoruyucuları Çiğdem KONAK GÖKTEPE Mikrobiyal Orijinli Gıda Bileşenleri Mehmet YÜKSEL Gıda Mikroorganizmalarının Tespiti ve TanımlanmasındaKullanılan Yöntemler Onur BULUT Gıdalarda Bozulmaya Neden Olan Mikroorganizmalar Ayça GEDİKOĞLU Hale İnci ÖZTÜRK Gıda Kaynaklı Mikrobiyal Hastalıklar Aysun ORAÇ Gıdalarda Mikrobiyal İnaktivasyon Sencer BUZRUL

Bu çalışma, Salvia officinalis L., yaygın adıyla adaçayı bitkisinden elde edilen uçucu yağın kimyasal bileşimini, serbest radikal temizleme aktivitesini (IC50), ferrik indirgeyici antioksidan güç (FRAP) değerini ve antimikrobiyal özellikler üzerindeki etkisini belirlemeyi amaçlamıştır. GC-MS analizi sonuçlarına göre, sırasıyla 3-thujen-2-bir (%26,21), (+)-2-bornanone (%16,47) ve 1,8-sineol’ün (%15,09) ada çayı uçucu yağında en yüksek yüzdeye sahip bileşikler olduğu görülmüştür. Ayrıca, uçucu yağ yüksek antioksidan aktivitesi göstermiş olup, IC50 değeri 5,507 ± 0,723 mg/ml ve FRAP değeri 2,129 ± 0,136 mM/g olarak bulunmuştur. Agar disk difüzyon testinin bulguları, en yüksek inhibisyon bölgelerinin Bacillus cereus NRRL B3711 ve Bacillus subtilis PY79 bakterilerine karşı olduğu görülürken, en düşük antibakteriyel etkinin Listeria monocytogenes ATCC 19115 ve Escherichia coli ATCC 25922 bakterilerine karşı olduğu tespit edilmiştir. Benzer şekilde, ada çayı uçucu yağı mikro tüp dilüsyon testinde en yüksek antibakteriyel etkiyi Bacillus cereus NRRL B3711 bakterisine karşı 2,94 mg/ml MİK (minimum inhibisyon konsantrasyonu) değeri ile göstermiş olup, Staphyloccoccus spp., Enterococcus faecalis ATCC 29212, ve Salmonella typhimurium ATCC 14028 bakterilerine karşı 23,5 mg/ml MİK değeri ile etkinliği en düşük çıkmıştır.

The aims of this study were (1) to assess the extract yield, antioxidant activity, and antimicrobial activity of Cistus creticus extracts obtained from different locations in Türkiye (2) to evaluate the effect of water and methanol solvents on chemical composition, total polyphenol and flavonoid content, IC50, and FRAP values of C. creticus. The extracts had a weak inhibitory effect against tested microorganisms. However, the results of antioxidant assays were very promising. The IC50 values of methanol and water extracts were 13.94 µg/mL and 34.41 µg/mL, respectively. Similarly, the FRAP value of methanolic extract (1.27 M/g) was higher than the water extract (0.72 M/g). The results of HPLC analysis demonstrated that rutin was found only in the methanol extract (13.252%). In addition, the methanol extract had a higher content of quercetin (7.909%), benzoic acid (4.226%), and chlorogenic acid (2.168%), whereas the water extract possessed a higher amount of gallic acid (13.705%).

This study aimed to determine the effect of pink rock rose extract (PRR) with or without ascorbic acid and sodium ascorbate for improving the shelf life of sausages. Analyzed parameters were DPPH radical scavenging capacity of PRR extract; total aerobic count, thiobarbituric acid reactive substance, heme iron, pH, water activity, proximate composition, and color values of MAP packaged sausages for 12 weeks at 4 °C. Treatments: (1) Control (0.02% ascorbic acid and 0.05% sodium ascorbate – AA-SA), (2) electrostatic spray application of PRR extract (2%) – ES-PRR, (3) 0.02% AA and, 0.05% PRR extract, (4) 0.05% SA and 0.02% PRR, (5) 0.07% PRR extract. PRR extract had the half maximal inhibitory concentration (IC50) value of 13.04 ± 0.133 µg/mL. Sausages formulated with 0.07% PRR had the lowest microbial growth rate, followed by AA-PRR formulation. The AA-PRR treatment had the lowest TBARS values for most of the storage. This study reveals that PRR extract can be added as a natural antioxidant in sausages, and it could be used as a replacement or for the reduction of ascorbic acid and sodium ascorbate in sausage formulations.

Propolis is a resinous substance produced by bees that is rich with phenolic and flavonoid compounds. Extract of propolis has a high antioxidant and antimicrobial properties due to the presence of these compounds. Therefore, the main objectives of this study were to examine the antibacterial and the antioxidant activities of standardized, commercial water extract of propolis in vivo assays, and to assess its impact on preservation of raw beef meatballs aerobically packaged and stored at 4ºC for 7 days. The results showed that the propolis extract demonstrated the highest antibacterial activity against Staphylococcus epidermidis in vivo test. Furthermore, meatballs prepared with the propolis extract had an extended shelf life about a week in comparison to the regular meatballs. Besides, the propolis extract was a very effective natural antioxidant agent for controlling the oxidative changes in meatballs. The propolis treatment provided 64.6% reduction in the malondialdehyde formation at the final day of storage. Color lightness and yellowness values of meatballs were not affected by the propolis treatment, only difference was observed in redness values. The pH of the meatballs prepared with the propolis extract almost stayed constant during storage, while the pH of the control meatball samples increased. In summary, propolis extract exhibited a strong antimicrobial and antioxidant activity in vivo assays and in a meat product. Accordingly, it should be used in meat product formulations to enhance preservation of meat products.