Gokhan Durmaz

Inonu University · Department of Food Engineering

"Vitamin D is one of the important fat-soluble vitamins for human health. The fact that this vitamin is much lower or higher than needed creates some problems. The World Health Organization (WHO) has recognized fortification as the most effective and safest method to meet the daily requirements of Vitamin D, addressing malnutrition. However, it has...

In this study, lipid oxidation evaluation methods were compared for a krill-oil-in-water emulsion system. With this aim, thiocyanate and DPPP (diphenyl-1-pyrenylphosphine) fluorescence methods were comparatively examined to determine primary oxidation products. 2-thiobarbituric acid reactive substances (TBARS), hexanal and propanal formation were a...

In this study, apricot juice powders (AJPs) were obtained via freeze‐drying using different maltodextrins (MDs) as carrier agents. The Hacıhaliloğlu cultivar, which is the most common variety in Turkey, was used as an apricot sample. Three different MDs: low (4–7), medium (13–17) and high (17–20) dextrose equivalence (DE) were used as the carrier a...

The fat content and fatty acid composition, oxidative stability, tocopherol composition, antioxidant capacity and carotenoid content of 12 different domestic and imported groundnut varieties grown in Osmaniye conditions were determined. Cultivars were found to contain oil ranging from 45.5% to 51.6% and Halisbey was found to be the richest in oil....

Antioxidant efficiency of thymol and carvacrol in walnut oil triacylglycerols (WO-TAGs) was investigated. WO-TAGs alone or fortified with thymol/carvacrol were emulsified with sodium caseinate-lactose mixture. Oxidative stability of freeze dried emulsions was assessed via Rancimat and accelerated oven tests. Bulk WO-TAGs with and without thymol/car...

In this study, the effect of refining process on the content of phytochemicals, antioxidant capacity and oxidative stability of hazelnut oil was investigated. The oil samples were taken at the consecutive steps of hazelnut refining process and analyzed for some compositional properties along with the antioxidant capacity and oxidative stability. Th...

The present paper deals with the study of adsorption of β-carotene in tetrahydrofuran solution on activated carbon. Activated carbon was prepared from apricot waste, which is a by-product of apricot processing by means of chemical activation with ZnCl2. BET surface area of activated carbon was measured to be 1060 m2 g−1. The effect of adsorption ti...

Hazelnut skin arises as a by-product in the roasting process of hazelnuts. This study aimed to investigate the potential of its utilization as a brown colored functional ingredient. Chemical composition analyses revealed that hazelnut skin is a very rich source of dietary fibers (67.7%) and phenolic compounds (233 mg GAE/g). Its oil fraction (14.5%...

In the present study, mulberry seed oil (MSO) samples obtained from seeds of different mulberry varieties as well as concentrated mulberry juice production waste (mulberry pomace) were investigated. Radical scavenging capacity, tocopherol and total phenolic content of MSO were determined. It was observed that MSO contain unique amounts of δ-tocophe...

The aim of this study was to investigate the antioxidative, antimicrobial and aroma characteristics of the most popular herbs, with local, namely Sirmo (Allium schoenoprasum [Liliaceae]), Mendi (Chaerophyllum macropodum [Apiaceae]), Siyabo (Silene vulgaris [Caryophyllaceae]), Yarpuz (Mentha spicata [Lamiaceae]) and Heliz (Prangos ferulacea [Apiacea...

Pomegranate was a popular fruit in ancient civilizations as a symbol of fertility, longevity, and even immortality. It is believed that polyphenols, the potent antioxidant constituents of pomegranate juice, can prevent obesity, diabetes, erectile dysfunction, and the onset of some degenerative diseases such as Alzheimer's disease, atherosclerosis,...

A new approach to 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTSradical dot+) assay was conducted. ABTSradical dot+ radical solution in water was obtained by using classical method of incubating ABTS with potassium peroxodisulphate. The resulting radical solution was freeze-dried and tested for its radical efficiency by comparing freshly...

The effect of roasting on oxidative stability, antioxidant capacity and the content of antioxidant phytochemicals in Pistacia terebinthus oil was investigated. Oils were extracted from P. terebinthus fruits roasted at 180 degrees C for 0-40 min. Roasting was found to cause an increase in the passage of phenolic compounds to the oil whereas the leve...

Propolis samples from important honey producing locations of Anatolia namely; Bingol (BG), Rize (RZ), Tekirdag (TK) and Van (VN), were evaluated for their antiradical capacities, total phenolic contents and individual phenolic compounds which was recovered by means of pressurized liquid extraction (PLE). Several extraction parameters of PLE such as...

In vitro antioxidant properties of 3 different extracts of black mulberry (Morus nigra L.) were investigated. Acidified methanol, acidified water, and non-acidified methanol/water solutions were used to prepare extracts. Different solvents caused different protonation on black mulberry anthocyanin structures, which were predicted according to their...

a b s t r a c t Propolis samples from important honey producing locations of Anatolia namely; Bingol (BG), Rize (RZ), Tekirdag (TK) and Van (VN), were evaluated for their antiradical capacities, total phenolic contents and individual phenolic compounds which was recovered by means of pressurized liquid extraction (PLE). Several extraction parameter...

In vitro antioxidant properties of 3 different extracts of black mulberry (Morus nigra L.) were investigated. Acidified methanol, acidified water, and non-acidified methanol/water solutions were used to prepare extracts. Different solvents caused different protonation on black mulberry anthocyanin structures, which were predicted according to their...

This study describes a method for the determination of 5-hydroxymethyl-2-furfural (HMF) and 2-furfural (F) in oils. The method entails liquid-liquid extraction and reversed-phase liquid chromatography. Spiked hazelnut oil was used to test the accuracy and reliability of the method. Furan compounds were extracted from oil using 70% methanol. Mean re...

The C18 unsaturated fatty acid (UFA) selectivity of three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanuginosa, Lipozyme RM IM from Rhizomucor miehei, and Novozym 435 from Candida antarctica, was determined in acidolysis conducted in hexane. Tripalmitin with a mixture of equimolar quantities of C18 UFAs was used as the substrate....

During industrial processing of seeds and nuts to produce edible oils, roasting is often applied before oil extraction. Moreover, seeds and nuts are generally consumed as snack food after appropriate roasting. These processes affect both the seeds and their extracted oils in many ways. Beside changes in macronutrients such as protein denaturation/d...

Five apricot (Prunus armeniaca L.) cultivars were examined throughout fruit development period to monitor the changes in quality characteristics including hardness, °Brix, color, titratable acidity and pH. Changes in the amount of sugars (fructose, glucose and sucrose) and organic acids (citric, malic and quinic) were also determined by HPLC. The p...

With the aim of determining the fatty acid (FA) selectivity of lipases, a mixture of oleic acid and monoacid triacylglycerols (TAGs) including tricaproin (T6), tricaprylin (T8), tricaprin (T10), trilaurin (T12), trimyristin (T14), tripalmitin (T16) and tristearin (T18) was used as the substrate in acidolysis performed in hexane. Three immobilized l...

The chain length selectivity of three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanoginosus, Lipozyme RM IM from Rhizomucor miehei, and Novozym 435 from Candida antarctica, was determined in acidolysis performed in hexane using the homologous series of even carbon number, saturated fatty acids (SFAs) of 6-22 carbons. Triolein wit...

Apricot kernel oil is a rich source of MUFA and PUFA, including mainly oleic (about 70%) and linoleic acids, respectively. In addition, apricot kernel oil could be considered as a good source of bioactive compounds such as tocopherols and phytosterols consisting mainly of the γ-isomer and β-sitosterol, respectively. Given to its high content of ole...

Apricot kernels were roasted for various lengths of time (0–30min) at 180°C and changes in the oxidative stability, antioxidant capacity, color, as well as the level of tocopherols and fatty acids of the apricot kernel oil (AKO) were monitored. While the level of tocopherols decreased, the oxidative stability and antioxidant capacity of AKO increas...

Pomegranate juices obtained from ten pomegranate cultivars of Turkey were analysed for their sugars, organic acids and the other quality parameters including pH, total soluble solids, and titratable acidity. Statistically significant differences were determined among the cultivars for parameters analysed. Citric acid was the predominant acid of all...

The antioxidant capacity of pomegranate juices (PJs) obtained from eight cultivars were determined by the scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and β-carotene-linoleate model system. Total phenolic content (TPC) and total anthocyanin content (TAC) were also d...

This study was carried out to understand the preventive effect of selenium (Se4+) on heavy metal stress induced by lead and copper in rainbow trout (Oncorhynchus mykiss). Variation in glutathione peroxidase (Se-GSH-Px) and superoxide dismutase (SOD) activity, and in malondialdehyde (MDA) levels in liver, spleen, heart, and brain tissues of rainbow...

The antioxidant properties of peeled, defatted and roasted apricot kernel flours were evaluated by determining radical scavenging power (RSP), anti-lipid peroxidative activity (ALPA), reducing power (RP), total phenolic content (TPC), assessed by DPPH test, β-carotene bleaching method, iron (III to II) reducing test and Folin method, respectively....

This study was undertaken to determine the reducing characteristics, metal chelating capability, anti-lipid peroxidative and antiradical properties of propolis compared to two widely used artificial antioxidants, Butylated Hydroxyanisole (BHA) and Butylated Hydroxytoluene (BHT). The water and ethanol extracts of propolis showed significantly a diff...