Thermal Stability of Chlorophyll Pigments in Virgin Olive Oil

Yıl 2014, Cilt: 17 Sayı: 2, 34 - 40, 26.12.2014

Holem Rasul , Ahmet İnanç

https://doi.org/10.18016/ksujns.55749

Cited By: 5

Öz

Abstract: The aim of the present study was to determine the changes in the chlorophyll content and the K₂₃₂ and K₂₇₀ specific extinction coefficient values in virgin olive oil (VOO) subjected to high temperatures for 24 h. VOO, was obtained from Kahramanmaraş city, Turkey, and subjected to 150, 160, 170, 180. 190 and 200ºC for 2, 4, 6, 8, 10, 12 and 24 h, and the chlorophyll content and the K₂₃₂ and K₂₇₀ specific extinction coefficient values were determined. The chlorophyll content of VOO decreased significantly as the treatment temperature and the extent of heat treatment increased (P<0.05) Especially, the temperature above 180ºC, the chlorophyll content decreased below 3% after 24 h. The K₂₃₂ and K₂₇₀ specific extinction coefficient values of VOO increased significantly with increasing the treatment temperature and time (P<0.05). The values of K₂₃₂ and K₂₇₀ specific extinction coefficients reached to 9.12 and 5.28 (1%, 1 cm), respectively, at 200ºC after 24 h. However, the rates of the increase in these values did not change with respect to different temperature and time. A significant inverse relationship was found between the chlorophyll content and the K₂₃₂ and K₂₇₀ specific extinction coefficient values (P<0.05). This study showed that chlorophyll, as one of the major quality criteria for olive oils, is heat-liable, and decomposes at high temperatures and long treatment times. In addition, increases in the conjugated diene and triene contents of VOO indicate the accelerated oxidation reactions at high temperatures; therefore VOO is no longer classified as “virgin olive oil” according to the official standards.

Keywords: Virgin olive oil, chlorophyll, conjugated diene and triene, thermal stability

 

Natürel Zeytin Yağındaki Klorofil Renk Maddelerinin Isısal Kararlılığı

 

Özet: Bu çalışmanın amacı, yüksek sıcaklıklara maruz bırakılan natürel zeytinyağında klorofil ve konjuge bağların miktarlarındaki değişimi 24 saat süresince belirlemektir. Kahramanmaraş, Türkiye’den temin edilen natürel zeytinyağı, 150, 160, 170, 180. 190 ve 200ºC sıcaklıklarda 2, 4, 6, 8, 10, 12 ve 24 saat bekletilmiş ve natürel zeytinyağının klorofil miktarı ve 232 ve 270 nm’deki absorbans değerleri ölçülmüştür. Natürel zeytinyağının klorofil miktarı sıcaklık ve süre arttıkça istatistiksel olarak önemli oranda düşüş göstermiştir (P<0,05). Özelikle, 180ºC üzeri sıcaklıklarda 24 saat işlem gören sızma zeytinyağında klorofil miktarı %3’ün altına düşmüştür. Natürel zeytinyağının K₂₃₂ ve K₂₇₀ absorbans değerleri, sıcaklık ve sürenin artışına paralel istatistiksel olarak önemli oranda artmıştır (P<0,05). 200ºC sıcaklıkta ve 24 saat sonunda natürel zeytinyağının K₂₃₂ absorbans değeri 9,12 (1%, 1cm) ve K₂₇₀ absorbans değeri 5,28 (1%, 1 cm)’ye ulaşmıştır. Ancak, farklı sıcaklık ve süreler sonunda K₂₃₂ ve K₂₇₀ absorbans değerlerindeki artış hızı hemen hemen sabit kalmıştır. Lineer regresyon analizinde, klorofil miktarındaki düşüş ile K₂₃₂ ve K₂₇₀ absorbans değerlerindeki artış arasında istatistiksel olarak önemli negatif bir ilişki bulunmuştur (P<0,05).Sonuç olarak, natürel zeytinyağının kalite göstergelerinden olan klorofilin ısıya karşı duyarlı olduğu ve uzun süre sıcaklık uygulamalarından olumsuz etkilendiği görülmüştür. Ayrıca, yüksek sıcaklıkla meydana gelen oksidasyon reaksiyonları zeytinyağında konjuge bağların artışına neden olmuştur. Bulunan K₂₃₂ ve K₂₇₀ absorbans değerleri, resmi standartlarda verilen değerleri aştığı için natürel zeytinyağı vasfını yitirmiştir.

Anahtar kelimeler: Natürel zeytinyağı, klorofil, konjuge bağ, ısı kararlığı

Anahtar Kelimeler

Virgin olive oil, chlorophyll, conjugated diene and triene, thermal stability

Kaynakça

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