Pirinç kepeğinin yerinde erterleşmesinde ester verim ve safiyetine etki eden değişkenler
Başlık çevirisi mevcut değil.
- Tez No: 46199
- Danışmanlar: DOÇ.DR. SELMA TÜRKAY
- Tez Türü: Yüksek Lisans
- Konular: Kimya Mühendisliği, Chemical Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1995
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 48
Özet
GZET Bitkisel ve hayvansal yağların alifatik monohidroksi alkollerle alkoliz reaksiyonu sonucu üretilen yağ asidi mono esterleri, kullanımı ve önemi giderek artan yağ kimyasallarındandır. Yağlama ve yumuşatma gibi özelliklerinin yanında, 1980'li yıllarda yenilenebilen enerji kaynağı olarak dizel yakıtı yerine kullanılabileceğinin saptanması, bu maddelerin üretim ve özelliklerinin daha yoğun şekilde incelenmesini zorunlu hale getirmiştir, Bu çalışmada pirinç kepeği yağından yağ asidi mono esterlerinin üretimi, halen endüstriyel olarak uygulan makta olan geleneksel yöntemlerden farklı olarak“ yerinde (in-situ) esterleşme”yöntemi ile incelenmiştir. Yerin de esterleşme yönteminde yağ tohumdan ekstrakte edilme den, doğrudan alkol ile reaksiyona sokulmaktadır. Bu durumda alkol hem yağ çözücüsü hem de esterleşme reaktifi olarak görev yapmakta ve ekstraksiyon ile rafinasyon işlemleri uygulanmadan yağ asidi esterleri elde edilebilmektedir. Çalışmada hammadde olarak pirinç kepeğinin seçil mesindeki en önemli nedenlerinden biri, pirinç kepeğinin % 20 civarında yüksek yağ potansiyeline sahip olmasıdır. İkinci bir neden olarak da, yağı alınmış -pirinç küspesinin hayvan beslenmesinde, gübre ve yakıt yapımında ham madde olmasıdır. Deneysel çalışmalarda pirinç kepeğinin, aynı koşullarda ve katalizör olarak derişik sülfürik asit kullanılarak, metanol, n-propanol ve izo-propanol ile hem ekstraksiyonu hem de yerinde esterleştirilmesi ele alınmış, pirinç kepeğinin serbest asit ve nem içeriği ile reaksi yon süresinin elde edilen esterlerin miktarı ve bileşimine etkisi incelenmiştir. Reaksiyon ürünlerinin verim ve safiyet yönünden karşılaştırılması ile yerinde esterleşme reaksiyonlarına etki eden en önemli faktörün pirinç kepeğinin serbest asit içeriği olduğu anlaşılmıştır.Fatty acid esters are undoubtedly one of the oldest classes of chemical subtances which have been used by man as an aid to work or for the care and beautif ication of his exterior. The ever-increasing rate of technologi cal progress in this century made it difficult for the natural fatty acid esters to fulfill the requirement arising as a consequence of these developments. The constantly increasing rate of new processing technologies and rising demands made on quality soon necessitated the manufacture and uses of tailor-made esters from fatty acids and alcohols possessing specific molecular structures. Commercial use of such synthetic fatty acid esters has developed in the last 5D years. Considering the products actually used in technology fatty acid esters can be classified into three groups: esters of polyf unctional alcohols; ethoxylates of fatty acids or esters; and esters of ma noalcohols. If one takes a look at fatty acid esters of mono- afcohols on the-market, then it is seen that there is a preponderance of products derived from C. /--C^ R fatty acids. The alcohol components are, in contrast, much more varied, including methanol, i-propanol, butanol, 2-ethyl-hexanol, oleyl alcohol and stearly alcohol. Depending on the chain length of the fatty acids and alcohols, products vary in consistency from liquids to waxes. The main uses for these quite hydrophobic com pounds are clearly to be found in the regions of oiling, lubricants and plasticizer. Many of these products are used in cosmetics. Methyl esters of the fatty acids are an exception in so far as they find almost exclusive use as intermediate materials for the synthesis of other chemicals. Direct vx
Özet (Çeviri)
methyl ester applications are few: They are mostly used as intermediates to produce fatty alcohols, alkanolamides o< - sulfonated methyl esters, sucrose esters, and other fatty esters.by interesterif ication reaction. Of these uses, fatty alcohols are the dominant application. One of the feu direct applications for methyl esters is the use of methyl esters as an alternative for No:2 diesel fuel. Oil shortages during the 1970 s triggered T'OBBaTT'h -in + h -î ç! annliratinn in qpuprnl fnıın + Tp-ıoa The primary method of producing methyl esters is alcoholysis of fats and oils with methanol. A second method consists of a tuo-step process. The first step is splitting the fat or oil. The resulting fatty acids are then esterified with methanol. Rice bran; which is obtained as a by-product in the milling of brown rice Kernel to yield the familiar white rice, has an oil content that varies from 12 to 23 %, depending on the variety of rice and the degree of milling. Oil extracted from bran may have low or high acidity, depending on the conditions and duration of storage. The rapid increase of free fatty acids in the bran after milling has been recognized as a serious problem for rice bran oil industries. The principal cause of oil deterioration in the bran during storag.e is the activity of lipase enzyme in the presence of misture. Temperature and the relative humidity of the storage atmosphere favour the hydrolysis of oil in bran. Active lipase is located in the testa layer and oil is located in the aleurone and sub-aleuron layers of the rice kernel. Milling abrades the external cell layers down to the endosperm, and the bran material is thoroughly mixed, resulting in rapid hydrolysis of the neutral oil to free fatty acids and glycerol. Free fatty acids release of 5-7 % in single day or up to 70 % in a month has been widely recorded. In spite of an annual world production of above 410 million tonnes of rice grain with a theoretical potential production of 7 million tonnes of rice bran oil, the estimated production of oil ranges between 400.000-450.000 tonnes. VllThe esterif icatian of high-acidity oils, such as rice bran oil, presents a problem because these materials contain, in addition to triglycerides, varying amounts of free fatty acids, as well as mono-and diglycerides. Attempts to prepare methyl esters with acidic catalysts and excess methanol affords rapid and essentially complete conversion of the free fatty acids but, unfor tunately, slow alcoholysis of the oils, and mono-and diglycerides, even at temperatures of 1 00-200°C and pressures up to 20 atm. occurs. On the other hand, while alkali-catalyzed alcoholysis of oils is reasonably rapid, alkali-catalyzed direct esterif ication of fatty acids is imposible because alkaline catalyst is activated by the soap formation. For this reason, a rapid and efficient conversion of high-acidity oils to methyl esters by a one-step process is not yet practical. For the efficient methyl esterif ication of high acidity oils it is usually best to split the oils, remove the glycerol, and directly esterify the resulting acids uith acidic catalysts; thus about 9k % conversion to methyl esters can be readly achieved. An alternate method consists in first esterifying the free fatty a.cids with the proper amount of glycerol ( uncatalyzed) at temperatures in the range 210-230 C at 5-1 OmmHg pressure, followed by inter- esterifying the triglycerides so produced with methanol using NaOH, KOH, or ZnO. The concept of alcoholysis of sunf lowerseed oil in- situ was described by Harrington et al., and they demonstrated that significant increases in ester yields could be achieved by such a method because of the fal lowing reasons : (i) by subjecting the whole seed to the esterif ication process, the lipid content of the hull itself could contribute to the overall yield of esters from the seeds, and (ii) the esterified lipids, which viscosities and solubilities different from those of triglycerides, could prove easier to recover from the solid residue. In-situ esterif ications of high-acidity rice bran oil with methanol and ethanol and with sulfuric acid as catalyst were also investigated, and it was reported that the amount of methyl esters obtained from a given rice bran was dependent on the free fatty acid content of the rice bran oil. In the esterif ication with ethanol, it was not passible to obtain pure esters as in methanol esterif ication, because the solubilities of ail components in ethanol were much higher than those in methanol. VlllIn this study, in-situ esterif ications of rice bran oil with methanol, n-propanol and i-propanol were investiga ted in order to determine the effects of some parameters, such as free fatty acid content of the oil, moisture content of bran, and reaction time on the yield and purity of the product esters. The rice bran used in this study urns obt a local rice mill in Istanbul. For in-situ tion, rice bran (50 g) mas transferred to a f 2DD ml of alcohol was added. The mixture was with a catalyst of concentrated sulfuric acid stirring with a magnetic stirrer for 0.5 or 3 the end of the reaction, the mixture was filt the bran was washed with alcohol. After dryi temperature, the bran was reextracted in a So apparatus with hexane to obtain the oil fract in the bran. The filtrate was extracted with to remove the esterified product. The oil le bran and the esterified product obtained in e were investigated qualitatively by thin layer graphy. The ester content of the esterified was determined gravimetrically by column chro ained from esterif ica- lask, and ref luxed while h. At ered and ng at room xhlet ion left hexane ft in the ach reaction chromato- product matography. Table 1 shows the results obtained from in-situ esterif ication of rice bran oil with various alcohols for 3 hours. TABLE 1.In-5itu Esterif ication of Rice Bran Gil IXBased on these experiments, it was determined that the main parameter that effected the yield and purity of the esterified product was the free fatty acid content of the oil in bran. Drying of bran before esterif ication had a negative effect on the purity of ester, because solubility of neutral oil in methanol phase increased.
Benzer Tezler
- Pirinç kepeği yağının yerinde esterleşmesi ile yağ asitleri monoesterleri üretimi
Production of fatty acids monoesters by in-situ esterification of rice bran oil
SEVİL YÜCEL
Doktora
Türkçe
1999
Kimya Mühendisliğiİstanbul Teknik ÜniversitesiKimya Mühendisliği Ana Bilim Dalı
PROF. DR. ZEYNEP SELMA TÜRKAY
- Pirinç kepeği yağının metanol ve etanol ile yerinde esterleştirilmesi
In situ esterification of rice bran oil with methanol and ethanol
SEVİL ÖZGÜL
- Pirinç kepeğinin kısa dalga infrared (kızılötesi) enerji ile stabilizasyonu ve stabilize kepeğin gıda ürünlerinde değerlendirilmesi
Stabilization of rice bran with short wave infrared energy and utilization of stabilized rice bran in food products
NEŞE YILMAZ
Doktora
Türkçe
2014
Gıda MühendisliğiÇanakkale Onsekiz Mart ÜniversitesiGıda Mühendisliği Ana Bilim Dalı
DOÇ. DR. NECATİ BARIŞ TUNCEL
- Ekmeklik unlara farklı oranlarda katılan pirinç kepeğinin unun kimyasal ve reolojik özellikleri ile ekmek kalitesi üzerine etkileri
Başlık çevirisi yok
SELDA GÜNDOĞDU
Yüksek Lisans
Türkçe
1997
Gıda MühendisliğiTrakya ÜniversitesiGıda Mühendisliği Ana Bilim Dalı
YRD. DOÇ. DR. MEHMET ALPASLAN
- Pirinç kepeği proteinlerinden ultrason ve mikrodalga destekli enzimatik hidroliz yoluyla antihipertansif ve antioksidan hidrolizat üretiminin optimizasyonu
Optimization of antihypertensive and antioxidant bioactive hydrolysate production of from rice bran proteins through ultrasound and microwave assisted enzymatic hydrolysis
BÜŞRA BENLİ
Doktora
Türkçe
2018
Gıda MühendisliğiErciyes ÜniversitesiGıda Mühendisliği Ana Bilim Dalı
PROF. DR. MEHMET HAYTA