Derin yağda kızartma işleminin bazı bitkisel sıvı yağların yağ asiti bileşimleri ile oksidatif stabiliteleri üzerine etkileri
Küçük Resim Yok
Tarih
2008
Yazarlar
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Cilt Başlığı
Yayıncı
Trakya Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu çalışmada, derin yağda (ev tipi) kızartma işlemlerinde bazı bitkisel sıvı yağların yağ asiti bileşimleri ile oksidatif stabilitelerindeki değişimlerin belirlenmesi amaçlanmıştır. Kızartma işlemleri, ön kızartma uygulanmış dondurulmuş patates dilimleri kullanılarak riviera zeytinyağı, rafine ayçiçeği, rafine soya, rafine fındık ve rafine mısırözü yağlarında ev tipi kapaklı ve otomatik termostat kontrollü elektrikli fritözde (530,7 cm2 yüzey, 16 cm derinlik, 26 cm çap) gerçekleştirilmiştir. Patates dilimleri, her defasında 200 g, 2 litre yağ içerisinde 4 dakikalık süreyle 175±5oC'de aralıklı olarak kızartılmıştır. Patates dilimlerinin konulması öncesi bu sıcaklığa erişim için gerekli süre yaklaşık 6?7 dakikadır. Kızartma işlemleri, 60 dakikalık aralarla her defasında yeni patates dilimleri kullanılarak tekrar yağ ilave etmeksizin 10 defa gerçekleştirilmiştir. Kızartma işlemi öncesi yağlardan ve bu yağlarla arka arkaya gerçekleştirilen 1., 3., 5., 7., 9 ve 10. kızartma işlemlerinden örneklemeler yapılmıştır. Örnekler analiz edilinceye kadar ?18oC'de bekletilmiştir.Kızartma işlemlerinde kullanılan yağların durumlarının değerlendirilmesi amacıyla % serbest yağ asitliği, peroksit sayısı ve yağ asiti bileşimi analizleri uygulanmıştır. Ayrıca, Ransimat cihazı kullanılarak 110oC'de indüksiyon periyodu ölçülmüştür. Elde edilen sonuçlar kızartma işlemleri süresince % serbest yağ asitliği, peroksit sayısı ve Ransimat indüksiyon zamanlarında önemli (P<0,01) değişimlerin olduğunu göstermiştir. Kızartma periyodunda, bütün yağ çeşitlerinde % serbest yağ asitliği sürekli artışlar göstererek kızartma işlemi sonunda en üst seviyeye ulaşmıştır. Peroksit değerleri, rafine ayçiçeği, rafine mısırözü ve rafine soya yağlarında 9. kızartma işlemine kadar sürekli artışlar gösterirken, 10. kızartmada düşüşler görülmüştür. Buna karşın, rafine fındık yağı ve riviera zeytinyağında ise kızartma periyodunun sonuna kadar sürekli artışlar belirlenmiştir. Diğer taraftan, Ransimat indüksiyon zamanları, bütün yağ çeşitlerinde kızartma periyodunun sonuna kadar sürekli olarak azalmıştır. Yağ asiti bileşimlerinde, bütün yağ çeşitlerinin ortalamaları olarak, kızartma periyodunda palmitik asitte önemli artış ve linoleik asitte önemli azalış görülmüştür (P<0,01). İlave olarak, kızartma işlemleri toplam doymuş, toplam çoklu doymamış ve toplam doymamış yağ asiti içeriklerini önemli ölçüde etkilemiştir (P<0,01). Kızartma işlemleri, linoleik ve linolenik asitlerin trans izomerlerinde artışa neden olmamıştır. Trans oleik asit içeriği ise az miktarda ancak istatistiksel açıdan (P<0,01) önemli artış göstermiştir.Anahtar kelimeler: derin yağda kızartma, yağ asiti bileşimi, oksidatif stabilite, patates dilimleri, trans izomer
The objective of this study was to determine the changes in oxidative stability and fatty acid composition of selected vegetable oils during the domestic deep-frying conditions of French fries. Deep-frying experiments were performed in a domestic covered electric deep fryer (530.7 cm2 surface, 16 cm high, diameter 26 cm), with automated thermostat control, by using French fries, in different vegetable oils (riviera olive oil, refined sunflower, refined soybean, refined hazelnut and refined corn oils). The French fries, each weighing 200 g, were intermittently fried each time in 2.0 L of oil, for 4 min at 175±5oC. Time required to bring the oil to 175±5oC before introduction of potato slices was about 6-7 min. The deep-frying experiments were repeated 10 times at intervals of 60 min using new French fries in the same oil without oil replenishment. Samples of the fresh oils together with those sampled at the end of successive frying operations (1, 3, 5, 7, 9 and 10) were removed and maintained at ?18oC until analyses.Free fatty acidities (FFA), peroxide values (PV), and fatty acid compositions were determined during the frying operations in order to evaluate the status of the frying oils. Induction period (IP) was also measured by Rancimat at 110oC. The results showed the free fatty acidities, the peroxide values, and the Rancimat induction times changed significantly (P<0.01) in all samples during the frying operations. The free fatty acid levels increased permanently for each type of oil throughout the frying period. All the oils had reached their maximum levels of free fatty acid by the end of frying operations. The peroxide values for refined sunflower, refined corn and refined soybean oils increased constantly until 9 times of the frying operations. After at that point, nevertheless, their peroxide values declined during the rest of the frying period. But, the peroxide values for refined hazelnut oil and riviera olive oil increased constantly throughout the frying period. On the other hand, the Rancimat induction times for all the oils decreased gradually throughout the frying period. The obtained the fatty acid compositions, as mean values of all the oils, showed a significant increase in palmitic acid and a significant decrease in linoleic acid (P<0.01) during the frying period. In addition, the frying operations had significant effect on the contents of total saturated fatty acid, total polyunsaturated fatty acid, and total unsaturated fatty acid (P<0.01). The frying operations did not cause an increase in the trans isomers of linoleic and linolenic acids. The content of trans oleic acid showed a small but statistically significant increased (P<0.01).Keywords: deep-frying, fatty acid composition, oxidative stability, French fries, trans isomer
The objective of this study was to determine the changes in oxidative stability and fatty acid composition of selected vegetable oils during the domestic deep-frying conditions of French fries. Deep-frying experiments were performed in a domestic covered electric deep fryer (530.7 cm2 surface, 16 cm high, diameter 26 cm), with automated thermostat control, by using French fries, in different vegetable oils (riviera olive oil, refined sunflower, refined soybean, refined hazelnut and refined corn oils). The French fries, each weighing 200 g, were intermittently fried each time in 2.0 L of oil, for 4 min at 175±5oC. Time required to bring the oil to 175±5oC before introduction of potato slices was about 6-7 min. The deep-frying experiments were repeated 10 times at intervals of 60 min using new French fries in the same oil without oil replenishment. Samples of the fresh oils together with those sampled at the end of successive frying operations (1, 3, 5, 7, 9 and 10) were removed and maintained at ?18oC until analyses.Free fatty acidities (FFA), peroxide values (PV), and fatty acid compositions were determined during the frying operations in order to evaluate the status of the frying oils. Induction period (IP) was also measured by Rancimat at 110oC. The results showed the free fatty acidities, the peroxide values, and the Rancimat induction times changed significantly (P<0.01) in all samples during the frying operations. The free fatty acid levels increased permanently for each type of oil throughout the frying period. All the oils had reached their maximum levels of free fatty acid by the end of frying operations. The peroxide values for refined sunflower, refined corn and refined soybean oils increased constantly until 9 times of the frying operations. After at that point, nevertheless, their peroxide values declined during the rest of the frying period. But, the peroxide values for refined hazelnut oil and riviera olive oil increased constantly throughout the frying period. On the other hand, the Rancimat induction times for all the oils decreased gradually throughout the frying period. The obtained the fatty acid compositions, as mean values of all the oils, showed a significant increase in palmitic acid and a significant decrease in linoleic acid (P<0.01) during the frying period. In addition, the frying operations had significant effect on the contents of total saturated fatty acid, total polyunsaturated fatty acid, and total unsaturated fatty acid (P<0.01). The frying operations did not cause an increase in the trans isomers of linoleic and linolenic acids. The content of trans oleic acid showed a small but statistically significant increased (P<0.01).Keywords: deep-frying, fatty acid composition, oxidative stability, French fries, trans isomer
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Yüksek Lisans
Anahtar Kelimeler
Gıda Mühendisliği, Food Engineering
