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Enzimatik gliseroz ile kısmi gliserid üretimi

Başlık çevirisi mevcut değil.

  1. Tez No: 55887
  2. Yazar: NACİYE EL
  3. Danışmanlar: PROF.DR. H. AYŞE AKSOY
  4. Tez Türü: Yüksek Lisans
  5. Konular: Kimya Mühendisliği, Chemical Engineering
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 1996
  8. Dil: Türkçe
  9. Üniversite: İstanbul Teknik Üniversitesi
  10. Enstitü: Fen Bilimleri Enstitüsü
  11. Ana Bilim Dalı: Belirtilmemiş.
  12. Bilim Dalı: Belirtilmemiş.
  13. Sayfa Sayısı: 40

Özet

ÖZET Gıda, kozmatik ve ilaç endüstrisinde geniş bir kullanım alanına sahip, emülgatörlerden biri olan monogliseridlerin üretimi, günümüzde inorganik katalizörler varlığında yüksek sıcaklık ve basınç altında gliseroliz reaksiyonu ile gerçeHeştirilmektedir. Bu yöntemin çok fazla enerji gerektiren bir proses olması ve termal bozunma sonucu ürün kalitesinin bozulmasından dolayı, bazı yeni arayışlara girilmiştir. Bu amaçla enzLmatik yağ güseroHzinin, monogliserid üretiminde önemli bir potansiyel oluşturabileceği düşünülmüş ve son yıllarda bu konu hakkında çalışmalara hız verilmiştir. Bu çalışmada, lipaz kaynağı olarak çörekotu (Nigeîla sativa) tohumundan elde edilen aseton tozu kullanılarak, kullanılmış kızartma yağının enzimatik gliserolizi gerçeMeştirilmiştir. Çeşitli sıcaklıklar, aseton tozu miktarı, yağ / gliserin mol oram ve gliserin su içeriğinde yürütülen reaksiyonlarla gliseroliz reaksiyonunun optimum koşullarının belirlenmesine çalışılmıştır. Tampon çözelti (fosfat, pH:6) ile parçalanmış tohumlardan çöktürülmüş aseton tozunun en aktif ham enzim olduğu gözlenmiştir, %96'lık gliserin ile yürütülen reaksiyonlarda optimum sıcaklık 60°C, optimum aseton tozu miktarı % 30 olarak belirlenmiş, 1:1 ve 2:1 yağ /gliserin mol oranlarında 2 saatlik bir reaksiyon sonunda en yüksek monogliserid içeren ürünler elde edilmiştir. Ancak 60°C, 2:1 mol oranında % 25- 30 aseton tozu kullanılarak yürütülen deneylerde, 2 saat sonunda ürünlerin kısmi gliserid içeriklerinin yakın olduğu da gözlenmiştir. 60°Cde, 2:1 yağ /gliserin mol oram, % 96'lık gliserin ve % 25 aseton tozu koşulları altında gerçekleştirilen reaksiyon sonunda, ürün büeşiminin %15.2 Trigliserid, %19.5 Yağ asiti, % 23.2 1.3-Digliserid, % 9.5 1.2-Digliserid, % 19.5 1-Monogliserid ve %13.1 2-Monogliserid içerdiği tesbit edilmiştir. % 92'lik gliserin ile yürütülen deneylerde ürün asit içeriğinin yüksek olduğu görülmüştür. X

Özet (Çeviri)

PRODUCTION OF PARTIAL GLYCERWES BY ENZYMATIC GLYCEROLYSIS SUMMARY Monoglycerides are widely used in food and pharmaceutical industries to promote the formation and stability of emulsions. Current processes for monoglyceride production are based either on direct esterification of glycerol with fatty acids or on the interesterification of triglycerides with glycerol (glycerolysis). CH2OH CH2OCOR CH,OCOR CH2OCOR l a1 l l 1 CHOH + RCOoH CHOH + CHOH +CHOCOR+B,0 I off I I I CH2OH CHoOH CH2OCOR CH2OCOR Glycerol Fatty acid Monoglyceride Diglyceride Triglyceride CH2OH CH2OCOR 1 1 CHOH + CHOCOR I I CH2OH CH2OCOR Glycerol Triglyceride OH CH2OCOR I => CHOH + CH.OCOR 1 CHOH CH2OH CH2OCOR Monoglyceride Diglyceride Glycerolysis; a special type of alcoholysis is exemplified by the reaction between the triatomic alcohol glycerol and fat. This reaction is widely employed commercially for the production of partially esterified products. According to Markley, several different reactions are possible between glycerol and triglyceride molecules. According to these schemes, one mole of triglyceride can react with 1/2, 1 or 2 moles of glycerol to produce varying proportions of either mono- or diglycerides or both. These XIreactions are illustrated below ; CH2OH CHoOCOR I I CHOH + CHOCOR I I CH2OH CH2OCOR Glycerol Triglyceride CHoOCOR => CHOH i CH2OH Monoglyceride + CHoOCOR i CHOH I CHoOCOR Diglyceride CH2OH CH2OCOR I I 2 CHOH + CHOCOR I CH2OH Glycerol i CH2OCOR Triglyceride CHOOCOR 1 => 3 CHOH I CH2OH Monoglyceride CH2OH CH2OCOR I I CHOH +2 CHOCOR I I CH2OH CH2OCOR Glycerol Triglyceride CHoOCOR 1 3 CHOH I CH2OCOR Diglyceride Many workers have studied glycerolysis as a method of preparing monoglycerides. Most of the procedures involve heating glycerol and the triglyceride fat at 170-250 °C. Various catalysts such as xylene, caustic soda, caustic potash and sodium alcoholates are suggested in amounts of 0.05 to 0.20 % of the fat used. A molar excess of glycerol is used and because the reaction temperature is greater than 220°C, dark colored by products with an undesirable flavor are formed, necessitating purification by molecular distillation. Moreover, the yield of monoglyceride is rather low (30-40 %). To obtain a product of higher quality and higher yield and to millimize energy costs, several attempts have been made to synthesize monoglyceride at low temperature using lipase enzymes as a catalyst. The use of lipase is potentially advantageous because, it is an efficient and selective catalyst at ambient temperatures. The purpose of the present study is to investigate the enzymatic glycerolysis of used frying oil by Mgella sativa seed lipase, and elucidate xnthe effects of process parameters, i.e., temperature, molar ratios ofreactants, water concentration in the glycerol and enzyme concentration. Nigella sativa seeds of Turkish origin were purchased from herbal shop in İstanbul and used as a lipase source for the acetone powder preparation. Glycerolysis reactions were carried out in a three- necked flask (250 ml) equipped with a stirrer, a temperature controller and a tiiermometer. Agitation by stirring at 500 rpm and temperature control was achieved using a Grant LTD 6G (-20 to 100° C) Circulating thermostat (Grant Instruments Ltd. Cambridge /England ). Acetone powder of Nigella sativa seed used as catalyst in this study. Acetone powder were precipitated from orjinal and water or phosphate buffer solution (pH : 6) pre-treated seed. Acetone powder was prepared by charging blender, equipped with a 1000 ml glass container, with 100 g of Nigella sativa seed, followed by 200 ml of cooled acetone (4°C), then ground for 3.5 min. The resulting mixture was transferred into a 1000 ml beaker, which was cooled by salt-ice mixture and the glass container was rinsed with 150 ml of acetone. The acetone was added to the original mixture, then stirred for 1 min. The suspension containing low density material was carefully decanted into a Buchner funnel equipped for vacuum filtration. The seed residue was washed with two 250 ml portions of acetone. Acetone wash was added to the filter cake. The grayish filter cake was transferred into a 1000 ml beaker, washed with two 150 ml portions of acetone, followed by another 100 ml portion. The combined acetone wash was vacuum filtered to afford alight grayish powder. The powder was transferred and spread on to an appropriately sized filter paper, then air- dried under a hood to give 22.61 g of grayish powder (22.61 %). The powder was stored at 4° C until required. For the preparation of acetone powder from pre-treated seeds following procedure was applied: 100 g Nigella sativa seed was ground with 200 ml distilled water or phospahate buffer solution (pH :6) in the blender for 3.5 min. Then the ground seed was vacuum filtered and stored at 4°C for 16 h. and then blended with 200 ml cooled acetone (4° C) in the blender for 2 min. for the preparation of acetone powder according to the method described above. In all experiments, 80 g used frying oil and glycerol were placed into the reaction flask and heated to the reaction temperature by stirring. xmAt the reaction temperature lipase, acetone powder, was added to the mixture as catalyst. Samples were withdrawn at predetermined time intervals and placed in a 90°C water bath for 15 min. to inactivate the enzyme. Then they were centrifiiged. to separate the lipase, and the oil phase was washed with water to removal of excess glycerol, and then the oil phase was dried using anhydrous Na2S04. Analysis of the product mixture was carried out by thin-layer chromatography / flame ionization detection (TLC- FID). One \xL of chloroform extract was applied to the rod followed by development in Petroleum ether/ diethyl ether/ acetic acid (70:30:2) solvent. The rods were dried and scanned under the following conditions: hydrogen, 160 ml/min., airflow, 2200 ml/min. and 30 sec/scan. Complete separation of the lipid mixture was achieved into triglyceride (TG), fatty acid (FA), 1,3- diglyceride (1,3-DG), 1,2-digİyceride (l,2-DG),2-Monogiyceride (2-MG) and 1 Monoglyceride (1- MG). The highest convertion rate of oil with glycerol was obtained during the reaction catalysed by acetone powder from seeds pre- treated with phosphate buffer solution (pH: 6). Fig. 1 shows the effects of acetone powder prepared from original and pre- treated seed with phosphate buffer solution. The glycerolysis catalysed by acetone powder from seed pre- treated with water wasn't performed, because the reaction mixture had solidified and then all of the experiments were carried out using die acetone powder from seed pre- treated with buffer solution. 100 w © M I 3 4 5 PERIOD (h) Figure 1. The effect of the seed pre-treatment in enzymatic glycerolysis reaction of used frying oil XIVThe glycerolysis reactions were investigated at 40°, 50°, 60° and 70° C keeping the acetone powder content 30% and at an oil / glycerol molar ratio of 1:2 to determine the effect of temperature. The highest conversion was observed at 60° C. At 70° C the activity of the enzyme decreased (Table 1). Table 1. The effect of temperature on MG content of reaction mixture during enzymatic glycerolysis (Acetone powder: 30 %, 1:2 molar ratio) The effect of oil / glycerol molar ratio was investigated at the molar ratios of 1:1, 1:2, 1:3, 2:1 and 3:1 keeping the acetone powder content at 30 %, and the reaction temperature at 60 °C. TG content of the product was increased with increasing glycerol content (1:3, 1:2). MG and DG contents were decreased with increasing glycerol content. In the reactions conducted with 25% and 30% acetone powder contents at oil/ glycerol molar rations of 2:1 and 1:1, an equilibrium was achieved after 2 h. and the highest MG and DG contents were observed (Table 2,3). At an oil/ glycerol molar ratio of 1:1. after 4h. of glycerolysis the product contained 14% TG, 20% FA, 34% DG and 32% MG and at molar ratio of 2:1 the composion of product was as follows: 15 % TG, 25% FA, 31% DG and 29 % MG. XVTable 2 The effect of amount of lipase on the MG production Table 3 The effect of amount of lipase on the DG production The highest and the same amount of MG and DG contents were obtained in the giycerolysis reactions conducted at molar ratios of 1:1 and 2:1 keeping the acetone powder content at 20%, 25% and 30%, and the reaction temperature at 60 °C. Moreover, the effect of water content of glycerol was investigated and the highest MG content was obtained in the reaction conducted with glycerol of 96%. XVI

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