Aylin AKOVA, Güldem ÜSTÜN

Boraj yağının enzimatik hidrolizi ile gamma-linolenik asit zenginleştirilmesi

Lipaz enzimleri deterjan sanayiinde, süt, ilaç, meyve suyu, tekstil, yağ ve margarin endüstrisinde, yem sanayiinde kimyasal maddelerin üretiminde yaygın olarak kullanılmaktadır. Bu çalışmada; boraj yağından gamma-linolenik asit (GLA) 'ce zengin ürünler elde edebilmek amacıyla, boraj yağının immobilize ve serbest çörekotu lipazı ile hidrolizi gerçekleştirilmiş ve sonuçlar karşılaştırmalı olarak incelenmiştir. Hidroliz reaksiyonu serbest enzim varlığında fosfat tampon çözelti ortamında (pH 6), immobilize enzim varlığında ise, hekzan ortamında yürütülmüştür. Boraj yağının hekzan ortamında immobilize çörekotu enzimi ile 24 saat hidrolizi sonunda, % 50 verimle ve içerisinde % 38 gamma-linolenik asit bulunan, 1.73 kat GLA'ca zenginleşmiş gliserid karışımı elde edilebileceği ortaya çıkarılmıştır.

Enrichment of gamma-linolenic acid by enzymatic hydrolsis of borage oil

Lipases one of the most important classes of industrial enzymes, which are used in detergent, food, textile industry. Since most of the industrial applications carried out in aqueous medium, regaining of Upases from reaction medium without loosing activity is impossible and controlling of the reaction is difficult. For this reason Upases are stabilized by immobilization Lipases immobilized in the presence o fhexane showed high thermal stability and activation energy with respect to native enzyme. On the other hand Km and Vm constants of lipases decreases slightly after immobilization. Nigella saliva seed lipase both free and immobilized form shown specificity, oils contains saturated fatty acids showed negative specifity to oils containing polyunsatutared fatty acids. Fatty acid specifity did not change after immobilization. Borage oil, containing % 23 $gamma$ linolenic acid, was used to determine fatty acid specifity of free and immobilized lipase. In this study borage oil was hydrolysed in the presence of free lipase and immobilized lipase to obtain gamma-linolenic enriched products. Hydrolysis reaction was carried out in phosphate medium the presence of free lipase on the other hand, reaction was carried out in hexane medium in the presence of immobilized lipase. It was found that, free and immobilized lipase showed negative specifity to gamma linolenic acid and $gamma$-linolenic acid was enriched in unhydrolyzed TG fraction to % 38.

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