Kısmi gliserid karışımından monogliseridin ekstraksiyonu
The Extraction of monoplycedes from partial glycerides mixture
- Tez No: 101131
- Danışmanlar: DOÇ.DR. ÜLKER BEKER
- Tez Türü: Yüksek Lisans
- Konular: Kimya Mühendisliği, Chemical Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2000
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 42
Özet
KISMI GLİSERID KARIŞIMINDAN MONOGLISERIDLERIN EKSTRAKSİYONU ÖZET Gıda, kozmetik ve ilaç endüstrisinde geniş bir kullanım alanına sahip emülgatörlerden birisi olan ve ayrıca yüzey kaplama, yüzey aktif madde üretiminde de kullanılan monogliseridlerin endüstriyel üretimi genellikle esterleşme reaksiyonu ile yapılmaktadır. Esterleşme reaksiyonu, yağ asidinin gliserin ile reaksiyona sokulması ile gerçekleştirilen bir reaksiyondur. Bu reaksiyon yüksek sıcaklıkta, azot atmosferi altında, inorganik katalizör varlığında gerçekleşmektedir. Bu reaksiyon sonucunda elde edilen ürün, monogliserid, digliserid, trigliserid ve serbest yağ asitlerinin karışımıdır. Bu çalışmada, yüksek ve düşük konsantrasyonda monogliserid içeren örnekler kullanılarak elde edilen sonuçlar saf monogliserid eldesi ve yağ rafinasyonunda monogliserid uzaklaştırma yönlerinden değerlendirilmiştir. Çalışmada ekstraksiyon için % 90'lık asetik asit ve % 90' lık asetik asit içerisine değişik oranlarda borik asit eklenerek elde edilen çözücü sistemleri kullanılmış, sonuçlar birbirleri ile ve sulu etil alkol çözücü sistemi kullanılarak yapılan ekstraksiyon sonuçları ile karşılaştırılmıştır. Ester ürünlerinin bileşimi öncelikle kalitatif olarak TLC yöntemiyle ve daha sonra kantitatif olarak FID/TLC cihazı kullanarak belirlenmiştir. Vll
Özet (Çeviri)
THE EXTRACTION OF MONOGLYCERIDES FROM PARTIAL GLYCERIDES MIXTURE SUMMARY Fats and oils are water-insoluble substances of plant or animal origin which consist predominantly of glyceryl esters of fatty acids, or triglycerides. Structurally a triglyceride is the condensation product of one molecule of glycerol with fatty acids to yield three molecules water and one molecule of triglyceride. A mixed triglyceride contains three different fatty acids whereas a simple triglyceride contains same fatty acids. Mono- and diglycerides contain in their molecules only one and two fatty acids, respectively, and consequently have two and one free hydroxyl groups. Monoglycerides can be readily separated from di- and triglycerides by molecular distillation, and commercial products containing over 90 % monoglyceride are now available. The structure of a-monoglycerides are shown below. a-Monoglycerides are more stable than p-isomers; the latter are readily converted to the former. Hence commercial products consist predominantly of a-monoglycerides. CH2OH I CHOH CH2- O- C- CH2- CH2- CH2- (CH2)n- CH2- CH3 O The structure of a-monoglycerides In this study the enrichment of monoglycerides present in the partial glycerides mixture was carried out by the extraction method using a special solvent. This solvent is % 90 acetic acid including boric acid. The boric acid amount differs from zero to saturated level. Partial glyceride mixture to be used in the study was prepared in the laboratory according to the direct esterification method. For this purpose glycerol and oleic acid have been subjected to esterification Vlllreaction in the presence of NaOH as catalyst. The reaction is conducted at high temperature partly to hasten the reaction and partly to increase the miscibility of the reaction mixture with glycerol. Current process for monoglyceride production is based on direct esterification of glycerol with fatty acids or on the interesterification of triglycerides with glycerol (glycerolysis). These reactions are stated below: CH2OH I CH20COR CH20COR CH20COR I CHOH + RC02H ^ CHOH + CHOH + CHOCR +H20 I III CH20H CH2OH CH20COR CH20COR Glycerol Fatty Acid Monoglyceride Diglyceride Triglyceride CH20COR CH2OCOR ^ CHOH + CHOH I I CH2OH CH20COR Monoglyceride Diglyceride CH2OCOR I ^ 3 CHOH I CH2OH Monoglyceride CH2OCOR CHOH + 2 CHOCOR ^ 3 CHOH CH2OH Glycerol CH2OCOR Triglyceride CH2OCOR Diglyceride The glycerolysis reaction cannot be performed in a way that a high quality and a high yield of monoglyceride is obtained. Excess amount of glycerol is used in the reaction and because the reaction temperature is higher than 170°C, dark colored by products with an IXundesirable flavor are formed. To obtain a product of higher quality and higher yield several studies were done. In the last two decades, several chromatographic and spectrophotometric methods have been developed for the estimation of monoglycerides. One of these methods has been done by Halvarson and Qvist. They intended to determine monoglycerides in crude oils and to follow their changes during the refining of edible oils. The method denoted by its authors as simple, consists in an enrichment of monoglycerides by extraction with acetonitrile, silylation of the residue obtained after the evaporation of the solvent, and gas chromatographic (GC) analysis of the silylation products using silylated cholesterol as an internal standard. In the case of coconut and palmkernel oils, the extraction with acetonitrile is followed by a thin layer chromatography to separate the monoglycerides from short chain diglycerides which could interfere with the GC analysis, whereupon the monoglyceride zone is cut out, subjected to the silylation, and gas chromatographed. The proposed method in this study is based on the enrichment of monoglycerides by repeated extraction of the oil dissolved in hexane with 90 % acetic acid including different amount of boric acid as mentioned before. The experiments are tested with TLC and FID/TLC method. To test and compare the efficiency of this method, the conventional method with 80, 96 % ethyl alcohol extraction is applied and the results are compared to each other. Finally the obtained results were evaluated from the stand point of oil refining and the method for pure monoglyceride preparation.
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