Biogeochemistry of humic compounds.

Ph.D. - Doctoral Progra

Sensory and chemical qualities of marinated African catfish (Clarias gariepinus, B., 1822) preserved in oil and tomato sauce

In this study, the sensory criteria and chemical analysis of catfish marinades in tomato sauce and oil was investigated. After the marinating process, catfish fillets were packed in airproof plastic containers; one being plain (Group A: sun flower oil) and the other being sauced (Group B: sunflower oil and tomato sauce). Then, they were stored in +4 °C for 200 days. During storage, sensory and chemical analyses were carried out. At the end of 200 days of storage, TVB-N, TBA, PV and pH values were found to be 15.82/16.29 mg/100g, 4.94/4.81 mg MA/kg, 3.57/3.40 meq/kg and 4.35/4.36 in sample marinates packaged as plain and sauced respectively. At the end of storage process, it was determined that African catfish marinates packaged as plain (Group A) and sauced (Group B) can be stored in +4 °C for 200 days and maintained the chemical quality criteria. According to the results of sensory assessments, the shelf life of marinated catfish was found to be 110 days for Group A and 80 days for Group B

Determination of some quality properties of marinated sea bream (Sparus aurata L., 1758) during cold storage

In this study, it was aimed to determine the effect of sea bream (Sparus aurata) marinated some quality properties during cold storage. The fillets of fish were immersed into brine including 3.5% acetic acid 11% salt in the ratio of 1: 1.5 (fish: marinate brine) for marination process. After the process of ripening, samples were grouped into two and packed in plastic containers; one being plain (in sunflower oil) and the other being sauced (sauced prepared with sunflower oil). During storage, sensory, crude protein, lipid, dry matter and crude ash, TBA, TVB-N, TMA-N and peroxide analyses were done periodically. According to results of 200 days of storage, TVB-N values of sea bream marinates packaged as plain and sauced were 15.86/14.89 mg/100g, TBA 7.06/7.99 mg MA/kg, TMA-N 2.97/3.12, mg/100g, the value of peroxide was 7.23/7.45 meq/kg respectively. According to chemical and sensory analyses results obtained in the study; it was concluded that sea bream marinates packaged as plain and sauced can be stored in +4 degrees C for 200 days

Determination of some quality properties of marinated sea bream (Sparus Aurata L., 1758) during cold storage

In this study, it was aimed to determine the effect of sea bream (Sparus aurata) marinated some quality properties during cold storage. The fillets of fish were immersed into brine including 3.5% acetic acid 11% salt in the ratio of 1: 1.5 (fish: marinate brine) for marination process. After the process of ripening, samples were grouped into two and packed in plastic containers; one being plain (in sunflower oil) and the other being sauced (sauced prepared with sunflower oil). During storage, sensory, crude protein, lipid, dry matter and crude ash, TBA, TVB-N, TMA-N and peroxide analyses were done periodically. According to results of 200 days of storage, TVB-N values of sea bream marinates packaged as plain and sauced were 15.86/14.89 mg/100g, TBA 7.06/7.99 mg MA/kg, TMA-N 2.97/3.12, mg/100g, the value of peroxide was 7.23/7.45 meq/kg respectively. According to chemical and sensory analyses results obtained in the study; it was concluded that sea bream marinates packaged as plain and sauced can be stored in +4 °C for 200 days

Organoleptic and Chemical Changes during Storage of Sea Bass Marinades (Dicentrarchus labraxL., 1758)

Chemical and organoleptic changes in sea bass (Dicentrarchus labrax) preserved at 4C for 200 days have been investigated in this study. To prepare the fish fillets for study, they were put, at a ratio of 1:1.5 (fish:marinade brine), for marination into the brine containing 11% salt and 3.5% acetic acid. After the maturation process, samples were divided into two groups and packed in sealed plastic containers as plain and sauced and preserved for 200 days. At both groups packed as plain and sauced, TVB-N, TBA, TMA-N and peroxide number values were at acceptable limits during the storage of 200 days. It can be determined that both of the groups were approved in organoleptic terms; however, the sea bass marinades packed as plain were better approved. Our study shows that sea bass marinades packed as plain and sauced can be stored for 200 days without any quality problems. Practical Applications As the processed products are easy to store and bring a large margin of profit and always ready for the market, developing new products will contribute greatly to the aquaculture processing sector. Marinade processing technology is one of the cheapest technologies in aquaculture products processing and preservation methods, and it is very important in that it enriches the taste of fish, adds flavor and provides a longer shelf life. In the Mediterranean countries, sea bass ranks first in saltwater aquaculture and is among the most important aquaculture products. However; making use of the fish, especially which could not be sold or are undersold in the yield period, with the help of alternative processing methods can contribute to producers, the fisheries processing sector and the national economy. It was determined that sea bass marinades packed as plain and sauced can be stored for 200 days and can still retain their quality

Gökkuşağı alabalığı (Oncorhynchus mykiss W.,1792) havyarında starter kültür kullanımının raf ömrü üzerine etkisi

Bu çalışmada laktik asit bakterilerinin alabalık havyanın raf ömrü üzerine etkisini belirlemek amaçlanmıştır. Bu amaçla; rnikrobiyal, duyusal ve pH analizleri depolama periyodu boyunca yapılmıştır. Çalışmada, özel bir firma tarafından üretilerek markette satışa sunulmuş her biri 100g’lık 6 paket dondurulmuş alabalık havyarı kullanılmıştır. Dondurulmuş örnekler polistiren kutularda laboratuvara transfer edilerek örneklerin yarısına starter kültür eklenmiş diğer yarısına ise kontrol grubu oluşturmak üzere starter kültür eklenmemiştir. Starter kültür olarak Gewürzmüller firması tarafından üretilen ve laktik asit bakterilerini içeren Bitec Aquaferm kültürü kullanılmış ve starter kültür ilave edilecek her bir kutuya 1’er gram eklenmiştir. Bütün örnekler 5±1 °C'de muhafaza edilmiş depolamanın 0, 3, 7, 14, 21 ve 28. günlerinde mikrobiyolojik ve duyusal analizler yapılmıştır. Mikrobiyal kalite için laktik asit bakterileri, toplam canlı sayımı, maya-küf ve koliform bakterileri araştırılmıştır. Deneme kapsamına alınan örneklerin hiçbirinde koliform bakteriye rastlanmamıştır. Starter kültür içeren hayvar örneklerinin ilk günkü özelliklerini 7 gün boyunca korudukları, kontrol grubu örneklerinde ise 3. günden itibaren özellikle küf sayısında artış olduğu gözlenmiştir. Yapılan mikrobiyolojik ve duyusal analizler sonucunda 5 °C depolanan havyarların uzatmak için, starter kültürün kullanılabileceği sonucuna varılmıştır

The investigation of quality changes in marinades obtained from frozen African catfish (Clarias gariepinus, B., 1822)

In this study, it is aimed to investigate the suitability of African catfish (Clarias gariepinus, B.,1822) caught intensively, especially in Mersin-Silifke for marinating and determine its shelf life. After their heads and tails were cut off and they were eviscerated first and then washed and drained of the water, the samples were put into plastic refrigerator bags and kept at -18 degrees C for 3 months. At the end of 3 months, the frozen samples were defrosted and boiled in boiling water for 5 min. They were put in brine after cooling and preserved at 4 +/- 1 degrees C. In the raw material, raw protein, lipid, moisture, raw ash analyses of the samples kept frozen for 3 months and the marinated samples were done in order to monitor the changes in the food composition at 3 month intervals and Thiobarbituric Acid number (TBA), Total Volatile Basic-Nitrogen (TVB-N), peroxide number, pH and sensory analyses were done in order to monitor the changes in chemical quality

Spatial Isopycnal Analysis of the Main Pycnocline Chemistry of the Black Sea: seasonal and interannual variations

The results of 1991-1994 basin-wide investigations have been analysed using the method of spatial isopycnal analysis. Seasonal and interannual variations of phosphates, nitrates, dissolved oxygen and the suboxic zoneare revised. The range and possible reasons of spatial and temporal variations in the density-dependent vertical profiles of nutrients and oxygen in the layer of the main pycnocline, in the thickness and the position of suboxic zone of the Black Sea are discussed

PHYTOPLANKTON FLUORESCENCE AND DEEP CHLOROPHYLL MAXIMA IN THE NORTHEASTERN MEDITERRANEAN

Two expeditions in the northeastern Mediterranean by the R/V Bilim (in July 1988 and March 1989) scanned an area of about 3 x 10(5) km2 to determine, in situ, the relative fluorescence intensities of the upper layer waters. The in situ fluorescence intensities exhibited a fair correlation with the discrete chlorophyll-a concentrations when the concentrations exceeded 0.1 mug/L. Light intensities indicated that the euphotic zone had an average thickness of 100 m in the open waters. The deep chlorophyll-a maxima (DCM) at the bottom of the euphotic zone usually coincided with the maxima observed by in situ fluorometry and were a prevalent characteristic of the oligotrophic northeastern Mediterranean. The formation, maintenance and location of the DCM were controlled by the changes in light attenuation and nutrient concentrations occurring in the anticyclonic and cyclonic gyres. Accordingly, DCM with relatively high chlorophyll concentration formed at shallower depths in late winter (e.g. 50 m for March, 1989) whilst in summer DCM possessed lower chlorophyll concentrations and were found as deep as 100 m in the anticyclonic regions. Although the depths of the maximum fluorescence intensity varied in space and time, they remained within a relatively narrow range of isopycnal surfaces, namely, from 28.8 to 29.0 in March 1989, and from 28.6 to 29.0 in July 1988; the appearance of maximum fluorescence intensities at larger density values but at shallower depths in late winter is principally the result of lower light intensity, available nutrients and hydrological changes in the upper layer