Ayla Soyer

Effect of processing conditions on the quality of naturally fermented Turkish sausages (sucuks)

Effects of temperature and different fat levels on the quality of Turkish sausages (sucuks) were studied during the ripening period. Sausage batters prepared at 10%, 20% and 30% fat levels were processed at 20-22 and 24-26 °C. A high ripening temperature and low fat level caused fast dehydration. Fat level affected water activity, colour, total viable and lactic acid bacteria counts of the sausages. Increasing fat content and ripening temperature resulted in high lightness (L*) and yellowness (b*) and low redness (a*) at the end of ripening. The sausages with 10% fat resulted in higher redness values. Growth of total viable and micrococci-staphylococci bacteria was affected by ripening temperature. Sausages ripened at 24-26 °C had a rapid increase in micrococci-staphylococci counts.

Effect of processing methods and starter culture (Staphylococcus xylosus and Pediococcus pentosaceus) on proteolytic changes in Turkish sausages (sucuk) during ripening and storage

Proteolytic changes in Turkish sausages (sucuk) produced by two methods (heat processing and traditional) were determined during processing and storage for 90 days. The sausages were produced with or without starter culture in both methods. A mixture of Staphylococcus xylosus and Pediococcus pentosaceus was used as starter culture for their acidic and proteolytic characteristics. The major changes in proteolytic characteristics of sucuk took place during the fermentation stage, with an increase in non-protein nitrogen (NPN) and a decrease in protein solubility. Proteolytic activity was observed in both starter-inoculated and non-inoculated (control) sausages during processing. Moreover, a slight increase in proteolytic activity was detected during storage in both starter-inoculated and control traditional sausages, and also in heat-processed sausages due to some heat-resistant proteolytic enzymes. Protein solubility was significantly affected by processing time and heat treatment. Sarcoplasmic and myofibrillar proteins were also affected by starter addition, fermentation, drying and heat processing. During fermentation, starter-inoculated and control sausages showed intense proteolysis in both the traditional and heat processing methods. After heating, intensive degradation of both sarcoplasmic and myofibrillar proteins due to denaturation was observed in heat-processed samples.

Effect of pomegranate peel extract on lipid and protein oxidation in beef meatballs during refrigerated storage

Antioxidant effect of pomegranate peel extract (PE) to retard lipid and protein oxidation was investigated in meatballs during refrigerated storage at 4±1°C. Concentrated lyophilised water extract of pomegranate peel was incorporated into freshly minced beef meat at 0.5% and 1% concentrations and compared with 0.01% butylated hydroxytoluene (BHT) as a reference and control (without any antioxidant). PE showed high phenolic content and antioxidant activity. In PE added samples, thiobarbituric acid reactive substances (TBARS) value, peroxide formation, loss of sulfhydryl groups and formation of protein carbonyls were lower than control (P<0.01) after 8 days of storage. Sensory evaluation with respect to colour and rancid odour revealed that PE incorporation in meatballs prolonged the refrigerated storage up to 8 days. Addition of both 0.5 and 1% PE in meatballs reduced lipid and protein oxidation and improved sensory scores. These results indicated that PE was effective on retarding lipid and protein oxidation.

Antioxidant activity of pomegranate peel extract on lipid and protein oxidation in beef meatballs during frozen storage

Antioxidant effect of pomegranate peel extract (PE) to retard lipid and protein oxidation in beef meatballs was investigated during frozen storage at -18±1°C. Concentrated and freeze dried aqueous extract of pomegranate peel was incorporated into freshly prepared meatball mix at 0.5% and 1.0% concentrations, and compared with 0.01% butylated hydroxytoluene (BHT) and control (without any antioxidant). In PE treated samples, particularly in high PE concentration, peroxide, malondialdehyde and carbonyl formation, loss of total protein solubility and sulfhydryl groups were significantly lower than control after 6months of storage. A diminution of both myofibrillar (MP) and sarcoplasmic (SP) proteins of high molecular weight was detected after 6months of the storage according to gel electrophoresis patterns. The 1.0% PE led to maintain colour intensity (C) and hue (h°) value. The results from sensory analyses revealed that PE addition to meatballs was effective on preventing rancid odour formation. Addition of both 0.5 and 1% PE in meatballs reduced lipid and protein oxidation and improved sensory scores. These results indicated that PE was effective on retarding lipid and protein oxidations.

Effects of chitosan as a surface fungus inhibitor on microbiological, physicochemical, oxidative and sensory characteristics of dry fermented sausages

The study aimed to improve the quality characteristics of Turkish dry-fermented sausages (sucuk) using different concentrations of chitosan (CH) coating as superficial mold inhibitor. The sausages were treated (w/w) with chitosan (0.2%, CH1; 0.5%, CH2 and 1%, CH3), potassium sorbate (20%, PS), acetic acid (1%, AA) and distilled water. Treatment with PS and CH3 resulted in a remarkable reduction of mold and yeast counts in the sausages and on casings at the end of ripening. Total aerobic mesophilic bacteria and lactic acid bacteria (LAB) varied from 7.19-7.29 to 9.01-9.27 and from 6.37-6.44 to 8.53-8.93 log CFU/g at day 0 and 12, respectively. Treatment with chitosan did not affect the natural microbiota of the sausages. Enterobacteriaceae counts were lowered from 5.79-5.89 to 2.08-2.53 log CFU/g by chitosan. Moreover, the rate of lipid oxidation in the sausages decreased by chitosan treatment. Sensory attributes were also notably enhanced in the cooked sausages treated with chitosan.

Physicochemical, oxidative and sensory changes in chitosan coated fermented Turkish sausage (Sucuk) during processing and storage

A consumers are increasingly concerned about the impact of beef on health, the studies about beef contents are becoming popular recently. Oleic acid, the main components of Korean native beef (Hanwoo) fat, is usually known as beneficial material in reducing cardiovascular disease. Therefore, we studied the effects of oleic acid on lipid metabolism of rats, and then tried to see the possible effects on humans. To each twenty rats, 5% of olive oil, 10% of olive oil or 10% of coconut oil (control) in diet was added at a total feed amount of 30g/day. After 4 or/and 8 weeks, the rats feeding the oleic acid were increased oleic acid concentration in blood (P=0.001). In adipose tissue, there was a significant difference in C18-long chain fatty acid in the group fed with olive oil compared with control. Especially, cis-9 C18:1 contents had a big difference (P<0.0001). There was an increase in C18-long chain fatty acid, arachidonic acid(C20:4) and docosahexaenoic acid(C22:6) when fed with olive oil, but there was no effect of olive oil on adipose tissue except for C18 long chain fatty acid. Based on these results, followed experiment were conducted for finding the effects of Hanwoo fat, which is higher oleic acid than the other American beef (Angus) fat, on lipid metabolism of blood and adipose tissues of rats. The content of unsaturated fatty acid in blood was higher in the rats fed with diet including 7% of Hanwoo fat (HF) than the group fed with 7% of Angus fat (AF) (P<0.0001). High density lipoprotein was also higher in HF (P=0.005). However, AF was higher trans-type oleic acid in adipose tissue (P<0.0001). From these results, we have predicted that Hanwoo fat (high oleic acid) will have a positive effect on index of cardiovascular disease.E of physical treatments with mild heating and freezing (H: heating at onset gelatinization temperatures-T0 for 1hr; HC: heating at T0 for 1hr and then cooling at 4oC for 12hr; HFT: heating at T0 for 1hr, freezing at -20oC for 12hr and then thawing at 25oC for 1 hr; HCFT: heating at T0 for 1hr, cooling at 4oC for 12hrs freezing at -20 ̊C for 12hrs and then thawing at 25oC for 1hr) on normal corn, waxy corn, potato, and tapioca starches were investigated. After the treatments, starches recovered by centrifugation and drying were examined in their pasting/thermal properties and microstructure. Comparing with H, HC and HFT treatments, HCFT significantly modified the granule structure, crystalline properties, and pasting properties. HCFT-treated potato starch increased its final viscosity and onset gelatinization temperature for crystal melting, from 2773 to 3930cP and 60.2o to 66.0oC, respectively. However, the breakdown and setback in viscogram decreased. The change in gelatinization enthalpy was more significant than that of other HCFT-treated starches. No significant change could be observed in waxy corn starch, possibly due to the absence of amylose. Overall, B-type starches (potato and tapioca) were more significantly modified than A-type starches (normal corn and waxy corn), resulting in more changes in pasting properties and microstructure. Heating at T0 is the first key step to increase the amylose leaching and seduce more water molecules, while cooling treatment as a preparatory and necessary work to improve the effects of followed FT treatment and during FT-treatment the mechanical force was produced which acts as a final key step in this study. The physical treatment using mild heating and freezing (HCFT) could be utilized to modify granule structure of starches which may replace some of chemical modification processes.

BİTKİSEL EKSTRAKTLARIN DONDURULARAK DEPOLANAN USKUMRU (Scomber scombrus) KIYMASINDAKİ KALİTE DEĞİŞİMLERİNE ETKİSİ

Bu calismada, dondurularak depolanan uskumru kiymasinin bazi kalite ozelliklerine yesil cay (YCE), uzum cekirdegi (UCE) ve nar kabugu (NKE) ekstraktlarinin etkisi incelenmistir. Bitkisel ekstraktlarin fenolik madde miktarlari dikkate alinarak, son urunde toplam fenolik madde miktari 100 mg/kg olacak sekilde ornekler hazirlanmistir. Donmus depolama sirasinda bitkisel ekstraktlarin etkinligi, sentetik antioksidan (BHT) iceren ve hicbir katki icermeyen kontrol (K) ornekler ile karsilastirilmistir. Bitkisel ekstrakt ilavesi ve dondurma islemi birlikte toplam aerob psikrofil bakteri (TAPB) sayisini azaltmistir ( P <0.01). Depolama sonunda TAPB sayisi en dusuk NKE ilaveli orneklerde (3.23 log KOB/g) belirlenmistir ( P <0.01). Ekstrakt ilavesi, toplam ucucu bazik nitrojen (TVB-N) ve trimetilamin nitrojeni (TMA-N) olusumunu sinirlandirmistir ( P <0.01). TAPB sayisi, TMA-N ve TVB-N miktarlari dikkate alindiginda nar kabugu ekstrakti ilavesi dondurarak depolanan kiyma uskumrularin kalitesini korumada alti ay sureyle etkili olmustur. Elde edilen sonuclar, NKE ve UCE’nin dondurularak depolanan uskumru kiymasinin kalitesinin daha uzun sure korunmasi acisindan uygun dogal antimikrobiyel katkilar oldugunu gostermistir.

Oxidation of Fish Sarcoplasmic Reticular Lipids and Proteins

The kinetics of oxidation of lipids and proteins of cod sarcoplasmic reticulum in system in which ferric iron(10µM)is reduced to the active ferrous form either nonenzymically with ascorbate,or enzymically with NADH was studied.Lipid and protein oxidations occurred at different rates of formation of thiobarbituric acid reactive substances(TBARS)was less rapid,but the ultimate amount of TBARS produced was greater than in the nonenzymic system.Loss of ultimate amount of TBARS produced was greater than in the nonenzymic system.Loss of protein sulfhydryl groups,presumably by oxidation to disufides,occurred to a great extent in both system.Oxidations of sulfhydryl groups was accompanied by polymerization of the major membrane protein,Ca2+-ATPase,as determined by SDS-PAGE