Murat Yilmaztekin

Survival of Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-02 in white-brined cheese

The viability of probiotic cultures used as adjunct cultures including Bifidobacterium bifidum BB-02 and Lactobacillus acidophilus LA-5 in white-brined cheese was investigated. The microbiological and biochemical properties of cheeses were assessed throughout 90 days of storage. Two inoculum rates for probiotic starters (2.5% and 5.0%, v/v, corresponding to (1.0–1.3)×109 cfu/g and (2.0–2.1)×109 cfu/g, respectively) were compared with the control cheese. Results obtained showed that a higher inoculum rate resulted in faster proteolysis. The cheese inoculated with 5% probiotic strains had higher water-soluble nitrogen, non-protein nitrogen, proteose-peptone nitrogen and tyrosine values than the other experimental cheeses. At the end of storage, the cheese supplemented with 5% probiotic culture had a ripening coefficient of 28.3%, followed by 2.5% probiotic strains containing the sample being 24.9%, and the control being 23.6%, respectively. It was also found that the colony counts of both probiotic microorganisms declined during storage. After 90 days of storage, the number of probiotic colonies were still around the threshold for a minimum probiotic effect (106 cfu/g).

Characterization of Potent Aroma Compounds of Cape Gooseberry (Physalis Peruviana L.) Fruits Grown in Antalya Through the Determination of Odor Activity Values

This article presents the investigation of the aroma profile of cape gooseberry (Physalis peruviana L.) grown in Antalya, Turkey. The analyses were carried out by means of liquid-liquid extraction followed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry for quantification and identification, respectively. Sensory analysis confirmed that the organic extract obtained by liquid–liquid extraction was representative of cape gooseberry odor. A total of 83 volatile compounds were identified and quantified in fruit pulp, including 23 esters, 21 alcohols, 11 terpenes, 8 ketones, 8 acids, 6 lactones, 4 aldehydes, and 2 miscellaneous. The main aroma components of the cape gooseberry (concentration >3%) were γ-hexalactone (17.66%), benzyl alcohol (17.22%), dimethylvinylcarbinol (6.54%), 1-butanol (5.71%), 2-methyl-1-butanol (5.22%), cuminol (3.98%), γ-octalactone (3.64%), and 1-hexanol (3.25%). The calculated odor activity values suggest that γ-octalactone, γ-hexalactone, ethyl octanoate, 2-heptanone, nonanal, hexanal, citronellol, 2-methyl-1-butanol, benzyl alcohol, phenethyl alcohol, 1-heptanol, ethyl decanoate, and 1-butanol were the potent aroma compounds of cape gooseberry. Within these, γ-octalactone (OAV: 46.9) was the most powerful contributor to the aroma of the fruit. It was concluded that cape gooseberry has characteristic indicator odorants that contribute to the overall aroma, which also can be used as quality-freshness markers of this fruit.

Effect of Maceration Time on Free and Bound Volatiles of Red Wines from cv. Karaoğlan (Vitis vinifera L.) Grapes Grown in Arapgir, Turkey

Skin maceration is an essential winemaking technique that affects sensory properties and aroma of red wines. The aim of this study was to investigate aroma profiles of red wines made from cv. Karaoğlan, a grape variety grown in Arapgir (Malatya, Turkey) and the effect of maceration time (5, 10, and 15 d) on free and bound aroma compounds and sensory properties. Three maceration times were applied in durations of 5, 10, and 15 d. Free and glycosidically bound aroma compounds were analyzed using gas chromatography-mass spectrometry (GC-MS) in Karaoğlan wines, and the effect of different maceration times on aroma composition were evaluated. Results indicate that extended maceration time significantly influenced the aroma composition of wines both qualitatively and quantitatively. A total of 59 free and 22 bound aroma compounds were identified in the final wines. The maximum of free aroma content was achieved with 5 d of maceration, while 15 d of maceration gave the highest amount of glycosidically bound aroma compounds. From sensorial point of view, the wine produced with 10 d of maceration had the best panel score compared to wines with 5 and 15 d of maceration. This is the first study referring to the composition of aroma compounds of red wines made from cv. Karaoğlan. It was concluded that this cultivar resulted in a good quality wine in terms of bound and free aroma compounds. This information of vinification practices that influence the chemical properties of wine is useful for grape growers and winemakers.

Analysis of Volatile Components of Cape Gooseberry (Physalis peruviana L.) Grown in Turkey by HS-SPME and GC-MS

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts.

Effects of fermentation temperature and aeration on production of natural isoamyl acetate by Williopsis saturnus var. saturnus.

Isoamyl acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeast which can produce isoamyl acetate by esterification of amyl alcohols with acetyl coenzyme A via fermentation. The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15°C and 25°C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of isoamyl acetate by Williopsis saturnus var. saturnus from sugar beet molasses were examined. According to the results obtained, isoamyl acetate production rate and specific productivity were higher at 25°C than at 15°C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703 mg L−1 h−1 and a specific productivity of 0.0297 mg L−1 cell−1 h−1 isoamyl acetate with semiaerobic condition at 25°C. The maximum amount of isoamyl acetate reached with these conditions was 118 mg/L.

Changes in Volatile Compounds and Some Physicochemical Properties of European Cranberrybush (Viburnum opulus L.) During Ripening Through Traditional Fermentation

The changes in volatile compounds and some physicochemical properties of European Cranberrybush (Viburnum opulus L.) were investigated during traditional fermentation. Using the principal component analysis (PCA), relations between volatile compounds and fermentation were associated with dynamics of these compounds. In total, 58 volatile compounds were identified, 3-methylbutanoic acid (25.4% to 66.4% of identified volatile compounds) being the major constituent in raw, 2-, 3-, and 4-mo fermented European Cranberrybush fruits, while 2-octanone was dominant in 1-mo fermented sample with a 30% of the total identified volatiles. The amount of total volatile compounds was increased in the 1st month of fermentation and then decreased gradually in the following months. Acids were the dominant volatile compounds in raw and 3- to 4-mo fermented European Cranberrybush. Ketones and alcohols had the highest percentage in total volatile compounds in the 2nd and 3rd months of fermentation, respectively.

Essential Oil Constituents of Tanacetum cilicicum: Antimicrobial and Phytotoxic Activities

Aerial parts of Tanacetum cilicicum were hydrodistillated for 3 h using Clevenger. Essential oil (EO) yield was 0.4% (v/w). According to the GC/MS analyses, EO of T. cilicicum consisted of monoterpenes [α-pinene (2.95 ± 0.19%), sabinene (2.32 ± 0.11%), and limonene (3.17 ± 0.25)], oxygenated monoterpenes [eucalyptol (5.08 ± 0.32%), camphor (3.53 ± 0.27%), linalool (7.01 ± 0.32%), α-terpineol (3.13 ± 0.23%), and borneol (4.21 ± 0.17%)], and sesquiterpenes [sesquisabinene hydrate (6.88 ± 0.41%), nerolidol (4.90 ± 0.33%), α-muurolol (4.57%  ± 0.35), spathulanol (2.98 ± 0.12%), juniper camphor (2.68 ± 0.19%), (-)-caryophyllene oxide (2.64 ± 0.19%), 8-hydroxylinalool (2.62 ± 0.15%), and -cadinene (2.48 ± 0.16%)]. In the antimicrobial assay, MIC/MBC values of the EO were the most significant on B. subtilis (0.39/0.78 µL/mL) and B. cereus (0.78/1.56 µL/mL). The most prominent phytotoxic activities of the EO were observed on L. sativa, L. sativum, and P. oleracea. The results of the present study indicated that EO of T. cilicicum includes various medicinally and industrially crucial phytoconstituents that could be in use for industrial applications. The finding of this study is the first report on this species from the East Mediterranean region.

Antimicrobial and Herbicidal Activities of the Essential Oil from the Mediterranean Thymus eigii

Abstract Essential oil (EO) of Thymus eigii (Lamiaceae) was hydrodistillated and characterized using with GC/MS. Forty-three constituents were determined accounting 100 % of the EO. The predominant constituents were thymol (24.77 %), carvacrol (14.00 %), p-cymene (10.91 %), γ-terpinene (6.53 %) and borneol (6.48 %). EO showed different levels of antimicrobial activities on test microorganisms. C. albicans, C. parapsilosis and S. aureus ATCC 29213 had the MIC/MFC/MBC values with 0.07/0.18 mg/ml, 0.18/0.36 mg/ml and 0.36/1.22 mg/ml respectively. EO of T. eigii exhibited pronounced herbicidal activities by inhibiting the germination and the growth of the seedlings of all plant species.