Browsing by Author "Yildiz H."
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Item Research on Chemical Composition of Some Varieties of European Plums (Prunus domestica) Adapted to the Aegean District of Turkey(American Chemical Society, 1997) Nergiz C.; Yildiz H.The physical characteristics and chemical composition of 11 plum varieties adapted to the Aegean region of Turkey at Ege Agricultural Research Institute, Izmir, were investigated. Variety Giant had the most fruit weight within all the plum varieties and it was followed by Krikon Damson, Tuleu Timpuriu, and Baneasa 3/5. Mean chemical compositions for all varieties were as follows: moisture, 837.4 g kg-1; soluble solids, 155.5 g kg-1; titratable acidity, 15.1 g kg-1; soluble solids to titratable acidity ratio, 12.6; total sugar, 96.5 g kg-1; total sugar to acidity ratio, 7.59; reducing sugar, 51.9 g kg-1; sucrose, 42.4 g kg-1; ascorbic acid, 157.9 mg kg-1; protein, 7.5 g kg-1; ash, 5.5 g kg-1; sodium 161.53 mg kg-1; potassium, 2228.12 mg kg-1; calcium, 25.47 mg kg-1; iron, 4.70 mg kg-1; pH 3.46. Imperial Epineuse was the most suitable variety for drying. Grand Prize had the highest ascorbic acid content.Item Some analytical characters of cottonseed varieties grown in Turkey(Instituto de la Grasa, 1997) Nergiz C.; Yalçin H.; Yildiz H.Sixteen cottonseed varieties grown in Turkey were analysed. The average oil content in varieties ranged from 309.7g Kg-1 to 379.5g Kg-1 whereas the range in values of gossypol content for glanded varieties was 7.4-12.8g Kg-1. One glandless variety contained gossypol as 0.2g Kg-1. The samples contained 337.2-466.5g Kg-1 protein. Fatty acid composition of the oils obtained from cottonseed varieties were also determined. Generally total gossypol content of cottonseed varieties were below the limits established by the some nations for human food or animal feed.Item Peroxidase inactivation and colour changes during ohmic blanching of pea puree(2006) Icier F.; Yildiz H.; Baysal T.Ohmic heating is an alternative fast heating method for food products. In this study, the pea puree samples were blanched ohmically and conventionally. The ohmic blanching was performed by application of four different voltage gradients in the range of 20-50 V/cm. The puree samples were heated from 30 °C to 100 °C and held at 100 °C to achieve adequate blanching. The conventional blanching was performed at 100 °C water bath. The ohmic blanching applied by using 30 V/cm and above voltage gradient inactivated peroxidase enzyme at less time than the water blanching. The ohmic blanching at 50 V/cm gave the shortest critical inactivation time of 54 s with the best colour quality. First order reaction kinetics adequately described the changes in colour values during ohmic blanching. Hue angle is the most appropriate combination (R2 = 0.954), which describes closely the reaction kinetics of total colour changes of pea puree for ohmic blanching at 20 V/cm. © 2005 Elsevier Ltd. All rights reserved.Item Effects of alternative current heating treatment on Aspergillus niger, pectin methylesterase and pectin content in tomato(2006) Yildiz H.; Baysal T.The main purpose of using alternative current (AC) heating treatment is to inactivate enzymes and microorganisms. The inactivation of pectin methylesterase (PME) and Aspergillus niger, and the changes in total pectin content by AC heating with different electric field strengths in the range of 36-108 V/cm for different treatment times in tomato fruit were investigated. PME activity decreased with an increase in treatment time at 108 V/cm. However PME activity increased by AC treatment at 48 V/cm for 5 s and at 36 V/cm for 5, 10, 15, and 30 s. compared to untreated control. The highest amount of total pectin was determined as 3.56% at 89 °C by AC treatment at 36 V/cm for 80 s. The A. niger inactivation was increased with increase in electric field strength and increased temperature. The concentration of A. niger (cfu/g) was determined to be <10 at 108, 68, 48, and 36 V/cm electric field strengths for the treatment times of 6, 12, 20 and 30 s, respectively. © 2005 Elsevier Ltd. All rights reserved.Item Color and lycopene content of tomato puree affected by electroplasmolysis(2007) Yildiz H.; Baysal T.Tomato puree was produced using three different breaking methods, namely heating by steam injection, by electroplasmolysis, and combination of both steam injection and electroplasmolysis. In electroplasmolysis, the tomato pulp was treated at the electric field strength of 68 V/cm for 1.5 seconds. L, a, b, a/b, tomato color index, total color difference, chroma difference, hue angle, and lycopene content of purees were measured. Puree samples breaked by electroplasmolysis had better color values and the highest lycopene content. The a/b, tomato color index, and lycopene content of these samples were as 2.00; 49.94 and 273.9 mg/kg, respectively.Item Feasibility of using olive mill effluent (OME) as a wetting agent during the cultivation of oyster mushroom, Pleurotus ostreatus, on wheat straw(2008) Kalmis E.; Azbar N.; Yildiz H.; Kalyoncu F.In this study, cultivation of oyster mushroom, Pleurotus ostreatus, on wheat straw substrate containing tap water and olive mill effluent (OME) mixture containing varying volume of OME was studied in order to investigate the feasibility of using OME as an alternative wetting agent and OME's impact on some fundamental food quality characteristics of mushrooms. Time period for mycelial colonization, primordium initiation and first harvest were comparatively evaluated with the control group. It was shown that the use of OME and tap water mixture consisting of OME up to 25% volumetrically was possible for the purpose of commercial mushroom production. Experimental results obtained from substrate containing 25% OME mixture showed no statistically significant difference compared to control group. The negative effects of increasing volume of OME in the mixture were also indicated by bioefficiency, which was found to be 13.8% for substrates wetted with 100% OME, whereas bioefficiency was 53.6% for control group. Increasing volume of OME in the mixture resulted in deformation of fruit body shape, whereas no significant difference in food quality was observed due to the higher amount of OME. This work suggested that the use of OME up to 25% as moisturizer could be considered, especially for the locations having significant number of olive mills and mushroom producers, both as an environmentally friendly solution for the safe and ecological disposal of OME and a practical way for recovering OME's economic value thereby. © 2006 Elsevier Ltd. All rights reserved.Item Analysis of the dermatoglyphics in Turkish patients with Klinefelter's syndrome(2008) Sirri Cam F.; Gul D.; Tunca Y.; Fistik T.; Ozdemir Erdogan M.; Yildiz H.; Erdem S.; Solak M.The word "dermatoglyphics" indicates study of epidermal ridge configuration on palms, soles and fingertips. This investigation was aimed to analyze dermatoglyphic patterns in Klinefelter's syndrome (KS) patients. The study cohort consisted of 57 cases and 25 controls. The prints were taken by using the ink method. Fingertip patterns, triradial counts, a-t-d angle and a-b ridge count were studied. There were significant differences in radial loops and whorls (p < 0.05), and there were very highly significant differences in arches (p < 0.001) in KS patients as compared to controls. Dermatoglyphic patterns at the hypothenar area (p < 0.05), and areas between at the I. interdigital and thenar sites (p < 0.001) have been found to be significantly different in KS patients compared to controls. Total ridge counts (TRC), a-b, a-t-d angels were not different in the two groups (p > 0.05). A definite correlation between the dermatoglyphic patterns and the KS has been shown. © Journal compilation © 2008 Hereditas.Item Polyphenoloxidase deactivation kinetics during ohmic heating of grape juice(2008) Içier F.; Yildiz H.; Baysal T.The heating method affects the temperature distribution inside a food, and directly modifies the time-temperature relationship for enzyme deactivation. Fresh grape juice was ohmically heated at different voltage gradients (20, 30, and 40 V/cm) from 20 °C to temperatures of 60, 70, 80 or 90 °C and the change in the activity of polyphenoloxidase enzyme (PPO) was measured. The critical deactivation temperatures were found to be 60 °C or lower for 40 V/cm, and 70 °C for 20 and 30 V/cm. Various kinetic models for the deactivation of PPO by ohmic heating at 30 V/cm were fitted to the experimental data. The simplest kinetic model involving one step first-order deactivation was better than more complex models. The activation energy of the PPO deactivation for the temperature range of 70-90 °C was found to be 83.5 kJ/mol. © 2007 Elsevier Ltd. All rights reserved.Item Pomegranate: Its antioxidant activity and its effect on health(International Society for Horticultural Science, 2009) Yildiz H.; Obuz E.; Bayraktaroglu G.Recently, in the world and in our country, there is a breakaway from synthetic food additives and there is a growing tendency for the use of natural food additives. Antioxidants, by far, are the most important food additives in the food industry. Since antioxidants are almost used in all processed food products, preference for natural food additives over synthetic food additives has gained great importance. Pomegranate and pomegranate juice have important antioxidant effects and can possibly be used as natural antioxidants in food products. Moreover, epidemiologic studies showed that fruits such as pomegranate may decrease the risk of cardiovascular disease and cancer due to their high phenolic content. Pomegranate and pomegranate juice may also be a solution to bacterial and fungal infection and food poisoning. Studies done recently even showed that microbisid obtained from pomegranate juice is effective against the HIV virus, the cause of AIDS. Pomegranate is a widely grown fruit. Its benefit to health and the fact that it contains effective substances show the need for scientific studies on pomegranate. Opportunities to benefit from pomegranate throughout the year by processing it into different products must be investigated because pomegranate is only available in certain months. In this review, the antioxidant effect of pomegranate and its possible beneficial effects on health will be reviewed.Item Ohmic and conventional heating of pomegranate juice: Effects on rheology, color, and total phenolics(2009) Yildiz H.; Bozkurt H.; Icier F.Ohmic heating is an alternative fast-heating method especially for liquid foods. In this study, pomegranate juice samples, prepared by two different extraction methods, were heated ohmically by matching the same thermal history, with that of the conventional method. The ohmic heating application was conducted by changing the voltage gradient (10-40 V/cm) at 50 Hz. The samples were heated from 20 ° C to 90°C and held at 90 °C for different treatment times (0, 3, 6, 9 or 12 min). Although rheological properties, color, and total phenolic content (TPC) values changed at the initial heating up period, there were no significant changes during holding period (p < 0.05). Non-Newtonian (power law) rheology model had higher regression coefficient than Newtonian model, and the extraction method affected the consistency of pomegranate juice samples (p < 0.05). Color values of juice extracted from arils (APJ) was better than that of juice extracted from whole fruits (PPJ), as PPJ contained higher amount of TPC (p < 0.05). Since the heating method did not affect the rheological properties, color, and TPC values, it could be said that there was no electrical effect rather than thermal effects during ohmic heating of pomegranate juice. Ohmic heating could be recommended as an alternative fast-heating method for fruit juices. © 2009 SAGE Publications.Item Changes in β-carotene, chlorophyll and color of spinach puree during ohmic heating(2010) Yildiz H.; Icier F.; Baysal T.The spinach puree was heated from 30C to prescribed temperatures (60, 70, 80 or 90C) ohmically and conventionally. Ohmic heating was performed by application of four different voltage gradients in the range of 10-40 V/cm, while conventional heating was conducted at constant temperature in a water bath. Although ohmic heating time required from 30 to 70C was similar for water heating (129 ± 7 s) and ohmic heating by 20 V/cm (127 ± 2 s), faster heating (51 ± 0.5 s) could be obtained as the voltage gradient for ohmic heating increased to 30 V/cm. Ohmic heating caused browning more than conventional water heating for the same temperature range. The effect of voltage gradient applied was not found statistically significant on chlorophyll (total, a and b), β-carotene and color values (L, a, b, Lb/a, Lba, hue angle) (P < 0.05). On the other hand, temperature (60, 70, 80 or 90C) at constant voltage gradient (30 V/cm) affected color values of spinach puree (P < 0.05), whereas holding time (0 and 600 s) at constant temperature increased chlorophyll-a and β-carotene contents (P < 0.05). This increase could be caused by the possible enhancing effect of ohmic heating on β-carotene biosynthesis and formation of chlorophyll derivatives. It was concluded that ohmic heating could be applied to vegetable purees, resulting in high retention of color attributes and β-carotene. © 2009 Wiley Periodicals, Inc.Item Chemical composition of four wild edible mushroom species collected from southwest anatolia(Gazi Universitesi, 2010) Kalyoncu F.; Ergönül B.; Yildiz H.; Kalmiş E.; Solak M.H.Four different species of wild edible mushrooms (Armillaria mellea, Infundibulicybe geotropa, Meripilus giganteus and Sparassis crispa) representing four different families (Physalacriaceae, Tricholomataceae, Meripilaceae and Sparassidaceae) growing in southwest regions of Anatolia were analyzed for their Fe, Na, K, Zn, Cu, Cd and Pb contents and ash, dry matter, protein, and fat levels. All mineral concentrations were determined on a dry weight basis (d.w.). The mineral content of mushroom samples ranged from 54.00 to 112.33 μg/ g d.w. for Fe, 66.50 to 117.33 μg/ g d.w. for Na, 32.33 to 117.00 μg/ g d.w. for K, 47.40 to 87.40 μg/ g d.w. for Zn, 54.30 to 74.67 μg/ g d.w. for Cu and not detected for Cd and Pb. Na content was higher than other minerals in all mushroom species. This research proves that wild edible fungi can be used in wellbalanced diets due to their nutritive values. Also, their heavy metal contents (Pb, Cd) shows that collection areas are not polluted, therefore all collected mushroom species can be unreservedly consumed without any health risk.Item Effects of electroplasmolysis treatment on chlorophyll and carotenoid extraction yield from spinach and tomato(2011) Toprak Aktas E.; Yildiz H.In this study, the effects of electroplasmolysis on β-carotene, chlorophyll-a, chlorophyll-b and total chlorophyll contents of spinach extract and β-carotene and lycopene contents of tomatoes extracts were investigated. Three different voltage gradients (40, 60, 80 V/cm) and three different application periods (4, 8, 12 s) were used. The effects of water bath heating at different temperatures on the extraction yield of colorants were also studied. After pre-treatments, β-carotene, lycopene, chlorophyll-a, and chlorophyll-b extraction was performed. Total solid content, pH and titratable acidity of the spinach and tomato samples were also determined. In spinach, the highest extraction yield efficiency for β-carotene (19.7%) was obtained by water bath heating. The extraction yield efficiencies for chlorophyll-a, chlorophyll-b and total chlorophyll were 14.9%, 12.6% and 13.7% respectively, by the electroplasmolysis treatment at 60 V/cm for 8 s. In tomato, the highest increase in extraction yield efficiencies of β-carotene (139.1%) and lycopene (112.4%) was obtained by electroplasmolysis treatment at 80 V/cm for 4 s. © 2011 Elsevier Ltd. All rights reserved.Item Chemical composition and nutritional value of a wild edible ectomycorrhizal mushroom, Tricholoma anatolicum; [Yenilebilir yabani ektomikorizal bir makrofungus olan Tricholoma anatolicum'un kimyasal kompozisyonu ve besinsel deǧeri](2011) Kalmiş E.; Yildiz H.; Ergönül B.; Kalyoncu F.; Solak M.H.The chemical composition and nutritional value of a wild edible ectomycorrhizal mushroom from southwestern Anatolia, Tricholoma anatolicum, were analyzed. Moisture, crude oil, protein, ash, total carbohydrate content, and mineral composition of the mushrooms studied, including Fe, Na, K, Zn, Cu, Ca, Cd, and Pb, were determined. The energy values of the samples were also calculated. The analyses were conducted during the 3 different growing stages of the mushrooms: mycelium, young fruiting bodies, and mature fruiting bodies. The highest values for moisture and crude oil contents were found to be in the mycelium, ash, and carbohydrate content of young fruiting bodies. In addition, Na content was found to be the highest in mycelium. The highest values for Fe were found in the young fruiting bodies, and K, Zn, Cu, and Ca were at their highest values in mature bodies. None of the samples contained heavy metals Cd or Pb. ©TÜBİTAK.Item Processing of Fruits and Fruit Juices by Novel Electrotechnologies(2012) Evrendilek G.A.; Baysal T.; Icier F.; Yildiz H.; Demirdoven A.; Bozkurt H.Recent demands from consumers for fresh-like quality foods with less and/or no artificial additives have introduced innovative processing technologies. These technologies due to their potential for food processing with preservation of important properties may cause to introduce new products in the market, to improve the competitiveness of the food, to eliminate the use of some artificial food additives, and to reduce energy cost. Pulsed electric fields for microbial and enzyme inactivation, shelf-life extension, moderate electric fields for yield and extraction, and ohmic heating are among these novel technologies that are based on the application of electric current on food materials. It has been well established that these technologies can successfully be applied to different food products. Among all, fruit juices have special importance due to the suitability of their physical properties to be processed by the electrotechnologies. This article covers the fundamentals of these technologies, their current use, research activities, and trends. © 2011 Springer Science + Business Media, LLC.Item Ochratoxin A in grape pekmez (grape molasses) consumed in Turkey(2014) Tosun H.; Yildiz H.; Obuz E.; Seçkin A.K.In this study, ochratoxin A (OTA) in 55 home-made, 20 commercial and 7 organic grape pekmez (grape molasses) produced in Turkey was investigated. OTA was detected in 73% of home-made pekmez samples, in 35% of commercial pekmez samples and in 71% of organic pekmez samples. Eleven per cent of the samples had OTA levels higher than 10 μg/l. The highest OTA level (31 μg/l) was detected in organic pekmez. The maximum OTA levels were 15 μg/l and 12 μg/l in home-made and commercial pekmez samples, respectively. Mean OTA levels were 3.5 μg/l, 1.4 μg/l and 9.2 μg/l in home-made, commercial and organic pekmez samples, respectively. Organic pekmez samples and home-made pekmez samples had higher OTA contamination than commercial pekmez samples. Results confirm OTA contamination in grape pekmez samples, indicating that the OTA level in grape pekmez could be a potential risk for consumers. © 2013 © 2013 Taylor & Francis.Item Physico-chemical and biological activity of hawthorn (Crataegus spp. L.) fruits in Turkey; [Fizykochemiczna i biologiczna aktywność owoców głogu (Crataegus spp. L.) w Turcji](Wydawnictwo Akad Rolniczej W Lublinie, 2015) Ercisli S.; Yanar M.; Sengul M.; Yildiz H.; Topdas E.F.; Taskin T.; Zengin Y.; Yilmaz K.U.Hawthorn (Crataegus spp. L.) is a native fruit of great economic importance in Turkey and has been widely using in folk medicine particularly for the treatment of mild heart diseases for a long time. In the study, 18 previously selected hawthorn genotypes belong to several Crataegus species grown in the hawthorn repository collection in Malatya province in Turkey were evaluated. Fruit mass and soluble solid content of selected genotypes ranged from 0.76 to 4.27 g and 6.71 to 15.83%, respectively. The genotype 44MA12 belongs to C. monogyna subsp. azarella had distinct and the highest anthocyanin (516 mg per 100 g fresh fruit) content and the strongest 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity (2.91 μg·g−1). The genotype 44MA11 belongs to C. meyeri had the highest phenolic content (3460 mg per 100 g gallic acid equivalent in fresh fruits). All hawthorn genotypes displayed high antioxidant activity. The results suggest that hawthorn fruits including significant human health benefit substances and may be used for developing functional foods because of its high phenolic, anthocyanin content and antioxidant properties. © Copyright by Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie, Lublin 2015.Item Ohmic heating assisted vacuum evaporation of pomegranate juice: Electrical conductivity changes(Elsevier Ltd, 2017) Icier F.; Yildiz H.; Sabanci S.; Cevik M.; Cokgezme O.F.A novel electrical heating method, named as ohmic heating, was successfully integrated to vacuum evaporation system, and pomegranate juice was concentrated until its total soluble dry matter content reached to 40% by applying three different voltage gradients (7.5, 10, and 12.5 V/cm) at 180 mm Hg absolute pressure in this system. Total evaporation times were determined as 152, 78, and 53 min at the voltage gradients of 7.5, 10, and 12.5 V/cm, respectively. The concentration time of pomegranate juice was shortened about 56% by ohmic heating relative to conventional evaporation. The electrical conductivity values were increased up to reach 25% TSDM for 7.5 V/cm and at 35% TSDM for 10 V/cm, then showed a decreasing pattern. However, it was constant (0.55 ± 0.01 S/m) during evaporation process at 12.5 V/cm. It is recommended that the ohmic heating method could be successfully integrated to vacuum evaporation process to shorten the processing time significantly. Industrial relevance Ohmic heating has been utilized as alternative method for the purpose of heating, pasteurization, cooking etc., and relatively better products can be obtained by ohmic heating. Nowadays, energy efficient systems are needed in concentrated juice production. The integration of ohmic heating to the conventional vacuum systems could serve the production high quality juice concentrates with efficient use of energy. In present study, ohmic heating assisted vacuum evaporation of pomegranate juice was conducted, successfully. This method decreased the total process time for juice concentration, which is critically important for industrial scale productions. This novel method can be implemented to the fruit juice production lines by taking into account of design characteristics of ohmic systems such as electrical conductivity changes depending on both temperature and total soluble solids concentration. The effects of main process parameter, named as voltage gradient, on electrical conductivity changes during electrical heating assisted evaporation process has been also reported in the present study. © 2016Item Moderate Electric Treatment Applications on Pomegranate Juice Production: Yield and Physicochemical Properties(Blackwell Publishing Ltd, 2017) Demırdöven A.; Yildiz H.; İçıer F.; Baysal T.Moderate electric treatment (MET) is based on the growth of pores in cell membranes as a result of electric field applications. In this study, effects of MET applications on yield and quality of pomegranate juice production were investigated. MET was applied to whole pomegranate fruits between 10 and 60 V/cm voltage gradients for 15 s in a pilot scale continues drum-type MET system. Pomegranate juice yields were increased by 2.11–6.99% with electrical treatment. The highest total phenolics were determined at 60 V/cm applications and the highest anthocyanin, antioxidant capacity, ascorbic acid, a value and total color differences were determined at 10 V/cm applications. The electrical treatment significantly decreased the viscosity of juice. It was concluded that MET application could be applied as a pretreatment in pomegranate juice production. Practical Applications: Juice extraction is a slow and highly energy-consuming step in the production of fruit juices; thus, various methods have been tried to improve efficiency. And there is an additional effect on juice yield caused by the electric current. Moderate electric treatment (MET) is effective in destroying cellular membranes and different types of electroporation units could be used for the structure of fruits or vegetables and also according to the production method. Through this study, a high potential of MET for the yield and functional improvement of pomegranate juices was found. The drum-type MET system which was used in the study can be used for whole materials without significant temperature increases. In addition, MET treatments can be used to increase the press yield as a nonthermal application and it will eliminate heat exposures, and also drum-type MET system can be adapted to the industrial production lines. © 2016 Wiley Periodicals, Inc.Item Performance analyses for evaporation of pomegranate juice in ohmic heating assisted vacuum system(Elsevier Ltd, 2017) Cokgezme O.F.; Sabanci S.; Cevik M.; Yildiz H.; Icier F.Pomegranate juice having 17.5% total soluble solids (TSS) content was evaporated to 40%TSS by ohmic heating assisted vacuum evaporation (OVE; 7.5 V/cm, 10 V/cm and 12.5 V/cm) and vacuum evaporation (VE) methods. Thermodynamics’ first law and second law analyses were conducted for different TSS contents (20–40%) by taking into account of two different control boundaries; in terms of process boundary (PB) and system boundary (SB). Energy efficiency, specific water removal rate (SWRR) and exergy efficiency reached maximum values for 30% TSS content, then it decreased. It was determined that energetic and exergetic efficiencies of SB were lower than those of PB. For the same TSS content, exergy efficiency value increased and improvement potential (IP) value decreased as the voltage gradient increased. Since highest energy consumption (5844.20 ± 29.89 J) was determined at 40% TSS content for 7.5 V/cm (p < 0.05) this process condition need the improvement most. It can be concluded that OVE method used the energy more efficiently than VE method for the purpose of the concentration of pomegranate juice. © 2017 Elsevier Ltd