Mükerrem Kaya

Effects of starter cultures and nitrite levels on formation of biogenic amines in sucuk

The effects of starter cultures, starter A (Lactobacillus sakei+Staphylococcus carnosus) and starter B (Pediococcus acidilactici+Staphylococcus xylosus+Lactobacillus curvatus), nitrite levels (0, 75, and 150ppm) and ripening period on biogenic amine production were investigated in sucuk (Turkish dry-fermented sausage) production. Changes in biogenic amines, pH, water activity, moisture, non-protein nitrogen, nitrite and counts of lactic acid bacteria, Micrococcus/Staphylococcus, Enterobacteriaceae, and moulds-yeasts were determined. Ripening period had a very significant effect (P<0.01) on the all biogenic amines. Sausages produced by fermentation with starter cultures, as compared to natural fermentation (control), had lower amounts of putrescine, cadaverine and tyramine (P<0.05). Starter cultures A and B were found to have almost the same effect on the formation of biogenic amines. Use of nitrite in sucuk production affected the formation of biogenic amines except for spermidine and spermine (P<0.01). Lactic acid bacteria counts in the control group were lower than that of starter culture groups. Lactic acid bacteria, Micrococcus/Staphylococcus, and moulds-yeasts counts increased during ripening period while levels of species of Enterobacteriaceae decreased, which was also found to be under the detectable level (<100cfug(-1)), by day 3 of ripening.

The effect of α-tocopherol and butylated hydroxyanisole on the colour properties and lipid oxidation of kavurma, a cooked meat product

Kavurma is a cooked meat product and is consumed sliced. The amount of animal fat in kavurma (30-40%) is higher than in other meat products; therefore, lipid oxidation and colour defects are a major problem during storage and in the market place. To preserve the quality characteristics of kavurma in markets antioxidants must be added and the product must be packaged and stored at low temperature. In this study, the effects of α-tocopherol and butylated hydroxyanisole (BHA) levels on lipid oxidation and colour deterioration of sliced and vacuum-packaged kavurma were investigated. Kavurma was made from beef meat and melted beef fat in 5 groups: No-added antioxidant, 50mg/kg BHA, 100mg/kg BHA, 50mg/kg α-tocopherol and 100mg/kg α-tocopherol. The kavurma produced was sliced (3-4-cm thick) and vacuum packed and stored at 4°C for 300 days, and thiobarbituric acid reactive substance, pH, moisture, lightness, redness and yellowness values of sliced product were determined during storage. The use of antioxidants in kavurma production caused a significant (P<0.01) decrease in the thiobarbituric acid reactive substances (TBARS) values. The lipid oxidative stability effect of the antioxidants was in following order: 100mg/kg BHA>100mg/kg α-tocopherol>50mg/kg BHA=50mg/kg α-tocopherol>no-added antioxidant group. Also, TBARS values did not differ significantly (P>0.05) between 0 and 300 days in the 100mg/kg BHA and 100mg/kg α-tocopherol groups. In addition, the no-added antioxidant group had lower lightness and yellowness values than all the antioxidant groups. Sliced and vacuum-packaged kavurma with added antioxidant showed greater colour and lipid oxidative stability during storage than kavurma to which no antioxidant was added.

Identification of Lactic Acid Bacteria and Gram-Positive Catalase-Positive Cocci Isolated from Naturally Fermented Sausage (Sucuk)

The aim of the study was to identify lactic acid bacteria and Gram-positive catalase-positive cocci isolated from Turkish dry fermented sausage (sucuk) produced by 7 different manufacturers without using starter culture. A total of 129 isolates of lactic acid bacteria were identified phenotypically. Lactobacillus plantarum was the dominant species (45.7%) followed by L. curvatus (10.9%) and L. fermentum (9.3%). Pediococcus isolates were identified as P. pentosaceus and P. acidilactici. All the isolates of gram-positive and catalase-positive cocci (123 isolates) were classified as Staphylococcus except for 1 isolate assigned to Kocuria rosea. The species isolated most often were S. xylosus (41.5%) and S. saprophyticus (28.5%). Four isolates were identified as S. equorum (3.3%), 1 isolate was assigned to S. carnosus (0.8%).

Antagonistic effect on Listeria monocytogenes and L. innocua of a bacteriocin-like metabolite produced by lactic acid bacteria isolated from sucuk

Two Lactobacilli and four Pediococci strains producing bacteriocin-like metabolities isolated from sucuk were tested with agar spot tests and well diffusion assays for their inhibitory activity against 16 Listeria strains, also isolated from sucuk. The production of organic acids and hydrogen peroxide limited, L. sake Lb 706 (used as a bacteriocin producer strain) and the isolated lactic acid bacteria (LAB) showed inhibitory activity against all of the Listeria strains, while L. sake Lb 706-A (used as a bacteriocin non-producer mutant) had the same effects against only two Listeria monocytogenes strains (51, 52) in agar spot tests. In the well diffusion assays, while L sake Lb 706 and four Pediococci isolates (413, 416, 419, 446) exhibited inhibitory activity against all of the Listeria strains tested, L. sake Lb 706-A and two of the Lactobacilli isolates (77, 116) showed no effect on the Listeria strains tested.

Influence of weak organic acids and salts on the denaturation characteristics of intramuscular connective tissue. A differential scanning calorimetry study

Intramuscular connective tissue obtained from Longissimus dorsi muscle of a 4-year-old beef carcass was treated with NaCl solutions of 2, 4, and 6% (w/v), and CaCl(2) solutions of 50, 100, and 150 mM, and citric and lactic acid solutions of 0.5, 1.0, and 1.5% for three different marinating periods (24, 46, and 72 h). Changes in denaturation characteristics were investigated using differential scanning calorimetry and it was found that the denaturation onset temperature (T(o)) and the denaturation peak temperature (T(p)) increased as the NaCl concentration increased but decreased as the CaCl(2) concentration increased, irrespective of marinating time. Lactic and citric acid decreased T(o) to about 39°C, from over 60°C breaking the structure of fibrils.

Effect of Dietary Ram Horn Hydrolysate (RHH) on the pH and Color Characteristics of Carcasses, Breast Fillets and Drumsticks of Broilers

This study was conducted to define the effects of ram horn hydrolysate (RHH) on the pH and color properties of carcasses and dissected products in broilers. Two-hundred and forty male broiler chicks (Ross-308) were fed with basal diets supplied with RHH for 4 wks. Chicks were allocated to four dietary treatments (H0, H1, H2 and H3 groups) in a completely randomized experimental design. Feed and water were offered ad libitum consumption and lightening was continuous throughout the experimental period. H0 group was fed only the basal diet and given normal drinking water. Treatment groups were fed with basal diet plus a 1% (H1), 2% (H2), and 3% (H3)-RHH-added water in place of normal drinking water to meet the daily water requirements of chickens from 1 to 28 days of ages. At the end of the trial all birds were slaughtered, then the ranges of pH and skin color of carcasses were determined at various times during the first 24 hour (1, 3, 7, 12, 17, and 24). After standard dissection of carcasses, breasts and drumsticks were divided into two groups for vacuum and aerobic packaging. Packed breasts and drumsticks were stored at 3 60.58 C, for 12 days, and the color values were determined. The pH values of H3 group were lower than those of H0, H1 and H2 groups (p < 0.05). The lightness (L*), redness (a*) and yellowness (b*) values increased during the 24-h period. The H0 group had the higher b* values than those of RHH-added groups (p < 0.05). The L*, a* and b* values of drumstick meats were higher than those of the breast meats (p < 0.05). The values of b* in aerobic packaged breasts and drumsticks were higher than the vacuum packaged (p < 0.05) treatments. The b* values increased with storage. The a* values of RHH-supplied groups were higher than that of the control (p < 0.05), while b* value of control was higher than those of the RHH-supplemented groups (p < 0.05). While the L* and b* values of drumstick skin were higher than that of drumstick meat, a* values in drumstick meats were higher (p < 0.05). The vacuum packaging increased the a* value during storage. As a result, the use of RHH in broiler diets had a significant effect on the L*, a*, and b* values of carcasses and dissected tissue (p < 0.01).

Effects of Corn Oil and Broccoli on Instrumental Texture and Color Properties of Bologna-Type Sausage

The effects of substitution of sheep tail fat with corn oil (50%) and the addition of broccoli (0, 5, or 10%) on the instrumental texture and color properties of bologna-type sausage were investigated during chilled storage (90 days at 4°C). Thiobarbituric acid-reactive substances and pH analysis were also carried out in fresh and storaged samples. The substitution of sheep tail fat by corn oil had very significant (P < 0.01) effects on the color scores (L*, a*, and b*) and textural properties of samples. The use of broccoli affected significantly (P < 0.01) color scores and hardness, gumminess, and chewiness values. Storage time had significant effects (P < 0.01) on hardness, springiness and cohesiveness, and color scores. The use of corn oil in bologna-type sausage decreased thiobarbituric acid-reactive substances value. However, at the end of storage this value was not over 15 μmol MDA/kg in sausage with animal fat. The pH values were not below 6.1 at the end of the storage.

Volatile compounds and some physico-chemical properties of pastırma produced with different nitrate levels

Objective The aim of the study was to evaluate the effects of different nitrate levels (150, 300, 450, and 600 ppm KNO3) on the volatile compounds and some other properties of pastırma. Methods Pastırma samples were produced under the controlled condition and analyses of volatile compounds, and thiobarbituric acid reactive substances (TBARS) as an indicator of lipid oxidation, non-protein nitrogenous matter content as an indicator of proteolysis, color and residual nitrite were carried out on the final product. The profile of volatile compounds of pastırma samples was analyzed by gas chromatography/mass spectrometry using a solid phase microextraction. Results Nitrate level had a significant effect on pH value (p<0.05) and a very significant effect on TBARS value (p<0.01). No significant differences were determined in terms of aw value, non-protein nitrogenous substance content, color and residual nitrite between pastırma groups produced by using different nitrate levels. Nitrate level had a significant (p<0.05) or a very significant (p<0.01) effect on some volatile compounds. It was determined that the amounts and counts of volatile compounds were lower in the 450 and especially 600 ppm nitrate levels than 150 and 300 ppm nitrate levels (p<0.05). While the use of 600 ppm nitrate did not cause an increase in residual nitrite levels, the use of 150 ppm nitrate did not negatively affect the color of pastırma. However, the levels of volatile compounds decreased with an increasing level of nitrate. Conclusion The use of 600 ppm nitrate is not a risk in terms of residual nitrite in pastırma produced under controlled condition, however, this level is not suitable due to decrease in the amount of volatile compounds.

Volatile profile and fatty acid composition of kavurma (a cooked uncured meat product) produced with animal fat combinations

ABSTRACT In this research, the effects of animal fat combinations (100% beef intermuscular fat, BIF); 100% beef kidney fat, BKF; 100% sheep tail fat, STF; 50% BIF + 50% BKF; 50% BIF + 50% STF; 35% BIF + 35% BKF + 30% STF) on volatile profile and fatty acid composition as well as selected physicochemical and sensorial properties of kavurma (a traditional Turkish cooked uncured meat product) were investigated. The group containing 50% BIF + 50% BKF had higher scores than other groups in terms of overall apperance, and taste-odor. The use of STF had a negative effect on sensory parameters. The lowest and the highest saturated fatty acid ratio were determined in the group with 100% STF and the group with 100% BKF, respectively. Among volatile compounds identified, aldehydes were the mostly found chemical group and hexanal was determined as major compound in all groups. As a result, the use of sheep tail fat increased unsaturated fatty acid ratio but negatively affected sensory properties of kavurma.

Volatile compounds of olive oils from different geographic regions in Turkey

ABSTRACT In this research, changes in volatile compounds of olive oil were investigated in terms of cultivar, harvest year, and geographic regions (Mediterranean, Aegean, Southeastern Anatolia, Marmara, and Black Sea) were investigated. Volatile compounds of olive oils were extracted by using solid-phase microextraction (SPME) method and were identified with gas chromatography–mass spectrometry. A total of 59 volatile compounds from seven different chemical groups including aldehydes, ketones, hydrocarbons, alcohols, esters, terpenes, and furans were identified. Aldehydes were detected as the major group in all geographic regions. Among aldehydes, trans-2-hexenal was found to be relatively higher. Alcohols and esters were determined as other important compounds. While many volatile compounds were affected by olive cultivar factor, this factor had no significant effect on esters. Principal component analysis showed that volatile compounds could play an important role in the separation of regions.