Production of commercially suitable pectin methylesterase and polyphenol oxidase from agro-industrial wastes

Thesis(Master)--Izmir Institute of Technology, Food Engineering, Izmir, 2004Includes bibliographical references (leaves: 68)Text in English; Abstract: Turkish and Englishxiii, 80 leavesIn this study, some simple and effective extraction and/or partial purification procedures were developed to obtain pectin methylesterase (PME) and polyphenol oxidase (PPO) enzymes from orange peels and mushroom stems, respectively. Also, some characteristics of enzymes were investigated and their stable preparations were obtained in liquid or lyophilized forms. Valencia orange peels contain considerable PME activity (300-350 mL NaOH/min/100 g) that is quite stable during season for at least 5 months. The enzyme was ionically bound to cell walls and can not be extracted by homogenization with water. However, the addition of suitable amounts of NaCl (10 g /100 g extraction mixture) to pellet, obtained by homogenization of peels several times with water, and 30 min mixing (at 200 rpm) may be effectively used to extract the enzyme. The PME in orange peels contains almost the same amount of heat stable and heat labile fractions and the enzyme can not be activated by mild heating. A slight activation (almost 20 %) may be achieved by adding 1 mM CaCl2 to enzyme extracts. However, at higher concentrations the addition of CaCl2 was inhibitory. The PME activity in extracts, stabilized by use of 0.1 % Na-benzoate and 0.1 % K-sorbate, is stable almost 5 months at + 4 oC (maintains > 90 % of its activity). Thus, the commercial preparations of enzyme may be obtained in liquid form. The extracted PME was successfully used to prepare edible films from citrus pectin For the extraction of PPO, on the other hand, mushroom stems were first processed to acetone powder. The acetone powders were then extracted with Na-phosphate buffer and partially purified with ammonium sulfate (90 % saturation) or acetone precipitation (2-fold). Following dialysis, the recoveries and purification folds obtained from the partial purification of monophenolase activity of PPO from the same acetone powder were 74-86 % and 3.4-4.3 and 55-67 % and 5.4-6.2 for ammonium sulfate and acetone precipitations, respectively. Thus, it appears that the ammonium sulfate precipitation gives a higher yield but lower purity. The monophenolase activity of partially purified PPO is heat labile and showed inactivation above 45 oC. The enzyme exhibited a pH optimum between pH 6.0 and 8.0. The pH stability of enzyme was maximal at pH 7.0 and 8.0. However, at pH 4.0 the enzyme lost most of its activity after 24 h incubation. The optimum temperature of enzyme was found as 40 C. The monophenolase activity of PPO enzyme showed no stability in acetone powders at + 4 oC. However, it showed good stability at -18 oC for two months with retention of 60-70 % of its activity. The PPO partially purified with ammonium sulfate precipitation and dialysis, and lyophilized by using dextran or saccharose as supporting materials also retained its monophenolase and diphenolase activities for three months at -18 oC. The effect of lyophilization with dextran on temperature stability of enzyme was insignificant. However, lyophilization with dextran reduced the pH stability of monophenolase activity at 4.0 moderately. In addition to its monophenolase activity on tyrosine and diphenolase activity on L-DOPA, PPO lyophilized with dextran can also use phloridzin as substrate. Thus, it appears that the enzyme may be used in different food applications including the production of antioxidants and colorants, modification of proteins, fermentation of cocoa and black tea, etc

Valencia portakal kabuklarından ticari olabilecek pektin metilesteraz eldesi

Bu çalışmada pektin metilesteraz (PME) enziminin Valencia portakal kabuklarından eldesi için basit ancak etkili bir yöntem geliştirilmiştir. Portakal kabukları 25 ile 34 ?mol COOH dak$^{-1}g^{-1}$ kabuk arasında değişen düzeyde PME aktivitesi içermektedirler. Enzim, hücre duvarına iyonik olarak bağlı bulunmakta ve su ile ekstrakte edilememektedir. Dolayısıyla bu durum enzim ekstraksiyonu öncesinde suyla homojenizasyon uygulanarak suda çözünen pektik maddelerin ve kabuk yağının ortamdan uzaklaştırılabilmesine olanak sağlamaktadır. Enzim ekstraksiyonu, kabuk homojenatına uygun miktarda NaCl eklenmesi (optimum: 10 g NaCl 100 $g^{-1}$ ekstraksiyon karışımında) ve karıştırma (optimum: 200 rpm’de 30 dak.) ile kolaylıkla gerçekleştirilebilmektedir. Kabuklardaki enzimin yaklaşık yarısı ısıya dirençli, diğer yarısı ise ısıya duyarlı fraksiyonlardan oluşmakta olup, enzim ılımlı ısıtmayla aktive olmamaktadır. Enzim ekstraktına 1 mM $CaCl_2$ ilavesi ile az da olsa bir aktivasyon (yaklaşık %20) sağlanabilmekte, ancak yüksek konsantrasyonlardaki $CaCl_2$ ilavesi enzimi inhibe edici etki göstermektedir. Na-benzoat ve K-sorbat ile stabilize edilmiş ekstraktlardaki PME, + 4 °C’de en az 5 ay süre ile aktivitesini %90’nın üzerinde korumaktadır. Elde edilen PME, $CaCl_2$ varlığında, yenilebilir film eldesinde kullanılan düşük metoksilli pektininin hazırlanmasında başarılı şekilde kullanılmıştır. Bu çalışma Valencia portakal kabuklarının ticari PME üretimi için potansiyel bir kaynak olabileceğini göstermiştir.A simple and effective procedure was developed to extract pectin methylesterase (PME) from Valencia orange peels. Orange peels contain 25-34 μmol of COOH min$^{-1}g^{-1}$ of peel PME activity. The enzyme was ionically bound to cell walls and could not be extracted with water. This enables removal of water soluble pectic substances and oils from peels via homogenization and washing with water before enzyme extraction. Enzyme extraction can be conducted simply by addition of suitable amounts of NaCl (optimum: 10 g of NaCl 100 $g^{-1}$ of extraction mixture) to peel homogenate and stirring (optimum: 30 min at 200 rpm). The PME extracted from orange peels contains almost the same amount of heatstable and heat-labile fraction, and the enzymes cannot be activated by mild heating. A slight activation of enzyme (almost 20%) was achieved by adding 1 mM $CaCl_2$ to enzyme extracts, but this agent was inhibitory at higher concentrations. The extracts stabilized by Na-benzoate and K-sorbate maintained more than 90% of their PME activity at 4 °C for at least 5 months. The obtained PME was successfully used to prepare low-methoxyl citrus pectin used in edible film formation in the presence of $CaCl_2$. This study shows the potential of using Valencia orange peels as a source of commercial PME

How do contaminated reservoir bottom sediments affect water quality? An assessment using SWIM model

In this study, an approach for the assessment of long term effects of contaminated sediments on the surface water quality of a future reservoir is presented. A one-dimensional sediment-water interaction model designed to simulate contaminants associated with the sediments, and the transfer of these contaminants to the overlying water column, was developed. The effect of contaminated bottom sediments on water quality was investigated under different stratification conditions. The numerical model was applied to an existing reservoir (Tahtali Reservoir) for validation and projected contaminant concentrations based on the soil and water samples collected before inundation of the land. Results were compared with the concentrations obtained from water samples collected during its operation. Next, transfer to a planned reservoir (Çamli Basin, Izmir) of four heavy metals - copper, zinc, chromium, and lead - existing in bottom sediments of the planned reservoir is modeled. A ten year projection of heavy metal concentrations for the Çamli Reservoir showed concentrations to be higher than those acceptable by the World Health Organization (WHO). Construction of a treatment facility is recommended if the reservoir is to be utilized for providing domestic water

MESLEKÎ VE ÖRGÜTSEL BAĞLILIĞIN, ÖRGÜTSEL DAVRANIŞA İLİŞKİN SONUÇLARLA İLİŞKİLERİ

Çalışmanın amacı, meslekî bağlığın üç öğesiyle, örgütsel bağlılığın üç öğesi arasındaki ilişkileri incelemektir. Araştırmanın bir diğer amacı, meslekî bağlılığın ve örgütsel bağlılığın üç öğesinin, temel iş özellikleri, rol stresi, meslekî faaliyete katılım, iş doyumu, örgütsel sonuçlar ve yaşam doyumuyla ilişkilerini araştırmaktır. Çalışmanın kapsamını Konya ilindeki 272 hemşire oluşturmaktadır. Araştırmanın sonucunda, meslekî bağlılık örgütsel bağlılıkla ilişkili bulunmuştur. Meslekî ve örgütsel bağlılık, iş doyumu, rol stresi, temel iş özellikleri, örgüte ilişkin davranış sonuçlarıyla ilişki göstermiştir. Meslekî faaliyete katılım, devamlılık bağlılığı hariç, bağlılık türleriyle anlamlı ilişki göstermemiştir. Yaşam doyumuyla tüm bağlılık türleri pozitif ilişki göstermiştir. Rol stresi, yaşam doyumunu açıklamada anlamsız bulunmuştur. Yaşam doyumunu en fazla etkileyen değişken olarak, iş doyumu tespit edilmiştir. Son olarak, her iki bağlılık türü, demografik değişkenler açısından farklılık göstermiştir. Araştırmanın diğer sonuçları, çalışmada detaylı olarak incelenmektedir

Investigating the GMO Existence in Chips and Breakfast Cereals Marketed in Turkey

In this research, processed or low processed samples containing corn or corn products (corn semolina, flour, etc.) and soybean were randomly collected from the market, and 25 products in total (chips, nuts, cereals, flour) were analyzed for genetic modification using DNA based detection method, the polymerase chain reaction. First, homogenization of the samples was performed. Then DNA isolation was done by using Cetyl Trimethyl Ammonium Bromide (CTAB) and Roche High Pure DNA Isolation Kit. Since the Roche High Pure DNA Isolation Kit gave better results, the analysis was completed with this method. After DNA isolation, the detection of the Lectin gene, Zein gene, CaMV 35S Promoter and NOS Terminator regions was performed by conventional PCR. Zein gene determination was done for searching and proving corn presence and similarly, Lectin gene determination was done for searching and proving soybean presence in the samples by conventional PCR. GMO3/GMO4 and Zein3/Zein4 primer pairs were used for Lectin and Zein gene determination, respectively. The amplification of DNA was observed in agarose gel electrophoresis. Lectin or Zein genes were detected in 17 samples while these genes were not detected in 8 samples. Samples, in which Lectin or Zein gene was detected were scanned for 35S promoter or NOS terminator. 35S-3/35S-6 and tNOS2F/tNOS2R primer pairs were used for scanning 35S Promoter and NOS Terminator, respectively. To observe possible contamination in the mix sterilized deionized water was used and 0% Bt-11 and 0% GTS 40-3-2 were used as a negative control, 5% Bt-11 and 10% GTS-40-3-2 were used as a positive control. All of the 25 samples did not provide enough DNA with the required quality. This result was considered to be sourced by the applications (frying, extruding, pressing etc.) that samples had been exposed to during processes. Neither 35S Promotor nor NOS Terminator was determined from any of the samples.Namik Kemal University Scientific Research Projects Coordination DepartmentNamik Kemal University [NKUBAP.00.24, AR.13.13]This study was financially supported by Namik Kemal University Scientific Research Projects Coordination Department, project number NKUBAP.00.24.AR.13.13. This article is produced from M.S. thesis of Sebnem Mutlu

Potential application of hot rehydration alone or in combination with hydrogen peroxide to control pectin methylesterase activity and microbial load in cold-stored intermediate-moisture sun-dried figs

Sun-dried figs contain a considerable amount of pectin methylesterase (PME) activity (22 μM COOH/ min/g). The enzyme causes softening and loss of desired gummy texture in cold-stored intermediate-moisture (IM) sun-dried figs brought to a 28% to 29% moisture range. Partial reduction of PME activity (28%) delayed undesirable textural changes in IM figs rehydrated at 80°C for 16 min. The heat treatment did not cause a considerable reduction in microbial load. However, the addition of 2.5% H2O2 to the rehydratlon medium at 80°C reduced the initial total mesophilic aerobic count of figs by at least 90% and turned the figs from a brown color to a desirable and stable yellow-light brown. The in situ fig catalase remains after rehydration at 80°C. Thus, by reducing the contact period of figs with H2O2 or by pureeing figs, it is possible to eliminate residual H2O2 and to obtain safe and SO2-free light-colored fig products

Mechanical properties of hydroxyapatite composites reinforced with hydroxyapatite whiskers

Proceedings of the 8th Conference and Exhibition of the European Ceramic Society; Istanbul; Turkey; 29 June 2003 through 3 July 2003Sintering and mechanical behavior of pure and hydroxyapatite (HA) whisker reinforced HA composites were investigated in this work. Pure and composite samples were prepared by using a commercial powder and whiskers prepared by molten salt synthesis. The dry-pressed samples were sintered in the 800 and 1300°C range. The effect of whisker-addition on the mechanical properties of HA was investigated through compression and hardness testing. Compressive strength and fracture strain were observed to increase by the addition of whiskers

Low level of Nesfatin-1 is associated with gestational diabetes mellitus

Introduction: Gestational diabetes mellitus (GDM) occurs in similar to 10-25% of pregnancies. Nesfatin-1, plays a role in carbohydrate metabolism by inhibiting glucagon secretion, besides has a glucose-dependent insulinotropic effect. Explanation of the GDM pathogenesis is important due to preventing gestational complications. We aimed to investigate relationship between GDM and Nesfatin-1. Material and methods: Seventy-nine pregnant subjects were randomly allocated to either GDM group (GDG, n = 38) or control group (CG, n = 41). For GDM diagnosis, 50 and 100 g oral glucose tolerance test (OGTT) were used. Nesfatin-1, insulin and other parameters were measured for all subjects. The homeostasis model assessment-insulin resistance (HOMA-IR) was calculated. Results: Nesfatin-1 was found lower and insulin was found higher in GDG than CG. Negative correlation has been founded between Nesfatin-1 with weight, BMI, fasting glucose, serum glucose level at first hour of the 50 g OGTT and HOMA-IR. Conclusion: In this study, patients with GDM had lower Nesfatin-1 levels than without GDM. Therefore, when the Nesfatin-1 effects on the GDM pathogenesis is clear, it may be contributed to diagnosis and treatment of the GDM.This work was supported by Hitit University [grant number: TIP 19003.14.001]