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Süperkritik karbondioksit ile çörek otu yağının ekstraksiyonu ve rafinasyonu

Başlık çevirisi mevcut değil.

  1. Tez No: 55939
  2. Yazar: SEVİM ÖZMEN
  3. Danışmanlar: PROF.DR. EKREM EKİNCİ
  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: 46

Özet

ÖZET çörek otu (Nigella Sativa L.) düğün çiçeğigiller ailesinden, susam iriliğinde, tohumları olan yıllık bir bitkidir. % 1 civarında uçucu yağ ve % 35-40 civarını trigliserid yağları içeren çörek otu tohumları başlıca baharat olarak kullanılmaktadır Çörek otu tohumlarının preslenmesi veya heksan gibi organik bir çözücü ile ekstraksiyon sonunda elde edilen çörek otu yağı, kırmızımsı kestane renkli, yarı kuruyan yağlar grubundan olan bir yağdır. Trigliserid yapısındaki başlıca yağ asitleri linoleik. oleik ve palmitik asitlerdir. Çörek otu yağının yağ asitleri bileşimi gıda sektöründe değerlendirilmesi için uygun olmakla birlikte, oldukça fazla miktarlarda serbest yağ asiti içermesi bu amaca yönelik değerlendirilmesinde en büyük sakıncayı oluşturmaktadır, çörek otu tohumlarının içerdiği lipaz enzimleri, hasat depolama ve yağ ekstraksiyonu sırasında yağlı dokunun parçalanması ile. tohumdaki neminde etkisiyle derhal trigliseridlerin hidrolizlenmesine ve yağların serbest asit içeriklerinin giderek artmasına neden olurlar. Son 10-15 yılda çözücü olarak süperkritik karbondi oksit kullanımı ile hem endüstriyel, hem de analitik amaçlar için çeşitli yağlı tohumlardan yağların ekstrakiyonu, özellikle karbondioksidin yanıcı ve zehirli olmaması ucuz ve çevreye“dost”olması gibi nedenlerle yoğun ilgi toplamaktadır. Süperkritik karbondioksit ekstraksiyonunun geleneksel heksan ekstraksiyonuna göre bir diğer önemli üstünlüğü de. çalışma sıcaklığı ve basıncını değiştirerek ekstraksiyon işleminin seçimli olarak yürütülebilmesidir. Belirli sıcaklık ve basınçta yağ asitlerinin çözünürlüğü trigliseriderin çözünürlüğünden çok daha fazla olduğundan, yüksek oranda serbest asit içeren yağlardan seçimli süperkritik karbondioksit ekstraksiyonu ile yağ asitlerinin giderilmesi mümkündür. Bu çalışmada öncelikle süperkritik karbondioksit ekstraksiyonu ile çörek otu tohumlarından ekstrakte edilen yağın karakterizasyonu ve aynı tohumlardan presleme ve heksan ekstraksiyonu ile elde edilen yağlar ile karşılaştırılması yapılmıştır. Daha sonra seçimli ekstraksi yon koşullarında, asitli yağ içeren çörek otu tohumları ekstrakte edilerek, ekstrakta geçen ve tohumda kalan yağ komponentlerinin bileşim ve miktarları saptanmıştır.

Özet (Çeviri)

EKSTRACTION AND REFINING OF BLACK CUMIN OIL WITH SUPERCRITICAL CARBON DIOXIDE SUMMARY Black cumin (Nigella Stave L. ) which belongs to the Ranunculaceae family, is cultivated in various part of the world and is especially grown in East Mediterranean countries. The seeds, on account of their aromatic nature, are used as a spice in cooking, particularly in Italy and Southern France. They are also used as a carminative and diuretic by oriental people. Nigella sative L. is cultivated in the areas of Afyon. Burdur and İsparta of Turkey. The seeds are sold in the markets to be used a contiment and native medicine. The proximate and mineral compasitions of Turkish Nigella Sativa L. seeds are shown in Table 1. Table l. Proximate and mineral composition of Nigella Sativa L. Seeds. IIThe crude fibre, protein, fat, ash and total corbohydrate of Turkish seeds are in a good agreement with the values reported in other countries. The major differences are in the amounts of calcium and potassium. In the Turkish seeds, potassium was found to be higher; whereas calcium was lower. The general physical and chemical characteristics of the black cumin seed oils are summarized in Table 2. Table 2. Oil Characteristics of Black Cumin Seed Oils from Some Countries. Fatty acid and sterol compositions of the oil extracted from the seeds are given in Table 3; this tablo shows that the major fatty acid is linoleic acid. Table 3. fatty acid and sterol composition of Black Cumin seed Oil IIIThe most important property of black cumin seeds is its high content of lipase enzymes. In the dormant seeds, lipase enzymes are generally inactive, but when the seeds are ground to obtain the oil, the lipase and oil come into contact and enzymatic hydrolysis reactions immediately commence. Thus grinding the sample may increase the free fatty acid content (FFA wt%) of oil to 50% or hgher. depending mainly on the time between grinding and extraction, the storage temperature of ground seeds, the moisture content of the seeds and the relative humidity of the storage medium. Deacidification of high acidity oils can be accomplished either by miscella refining or by physical refining instead of conventional alkali neutralization processes, since these later methods normally cannot be applied to oils containing more than 8-10 wt% FFA. Another deacidification method for high acidity oils is liquid-liquid exraction based on different solubilities of fatty acids and triglycerides in various organic solvent such as ethanol, methanol and acetone. A new alternative deacidification process is supercritical fluid extraction (SFE) of oils or oil bearing seeds containing high acidity oils with carbon dioxide as extraction solvent. Several researchers have demonstrated the suitability of supercritical carbon dioxide (SF-OO2) as a solvent for the extraction of various seed oils for both industrial and analytical applications. The attractive features of SF-CO2 over the presently used organic solvents, such as hexane are is noon-toxicity, safety, ease of separation and cheapness Another advantage of using SFE as opposed to hexane extraction is that SFE can be made highly selective by controlling the supercritical fluid temperature and pressure. The solubility data of fatty acids and triglycerides in SF-OO2 show that the fatty acids are more soluble in the CO2 than the corresponding triglycerides, at certain temperatures and pressures. In this study and exhaustive supercritical OO2 extraction of black cumin seed was performed in order to compare the oil with those obtained by hexane extraction and mechanical pressing. A selective supercritical GO2 extraction was also performed to Characterize the oil remaining in the seeds after the extraction. ivBlack cumin seeds were obtained from Mısır Çarşısı in Istanbul. The seeds were ground in a coffee mill, and then sieved. Particles between 300-500 urn were used in the study. The oil (37.9 %) content of the seeds was determined by a six hour Soxhlet extraction with hexane. The moisture (9,3 %) content was determined by oven drying the seeds at 105 °C. Supercritical CO2 extraction experiments were performed dynamically with a pilot supercritical fluid extractor (Sitec, Zurich, Switzerland). Ground seeds (100 g) were looded into the extraction basket (2 L), and glass wool plugs were used to retain the seeds in the cell. Carbon dioxide at the desired pressure and temperature was delivered to the temperature-controlled extractor with a pump. The oil-laden gas leaving the extractor was collected in the high-pressure separator of the extraction system. The exhaustive extraction of black cumin seeds was performed at 40°C and 250 bar for 2 hours. The selective extraction of the seeds was performed at 60 °C and 150 bar for 1-2 hours. After the extraction, the extracts in the separator and the seeds in the basket were analyzed to determine the oil characteristics. To compare the oils with different extraction methods the seeds were extracted with hexane by Soxhlet apparatus; with hexane at room temperature and pressed by a hydrolic oil press. The oils thus obtoined were analyzed according to the standart methods.The characteristic of the oils were compared in Table 4. Table 4. Oil Characteristic of Black Cumin Oils Obtained With Different Extraction Methods. The apparent difference among the oils obtained by different extraction method was the colour of the oils. The oil obtained with SC-CO2 extraction was yellow whereas the others were dark redish-brown. The SC-CO2 extracted oil had also high hydroxyl value and unsaponi fiable matter content compared with the others. Peroxide values of, the all oil samples which indicated their contents of reactive oxygen were found very high compared with the other vegetable oils. This was mainly due to the high volatile oil content of the black cumin oil. viAfter the supercritical GO2 extraction performed at 60°C and 150 bar. the oil remaining in the seeds was extracted by hexane and the characteristics of the oil were compared with the hexane extracted oil in Tablo 4. Table 4, Comparition of the oils remaining in the seeds after the selective SC-CO2 extraction and the hexane extracted oil. As can be seen in this table, peroxide value of the oil after selective SC-CO2 extraction decreased, because of the volatile oil was also extracted with SC-CO2, Most of the free fatty acids present in the seeds were extracted with SC-CO2 and then the oil remaining in the seeds had a low FFA content compared with the initial oil. vii

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