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ความรู้ทั่วไปเกี่ยวกับสิ่งเป็นพิษความรู้ทั่วไปที่นักวิชาการควรทราบพิษวิทยาคลีนิคก้าวทันโลกข้อมูลบริการแหล่งข้อมูลที่เกี่ยวข้อง
 
   
CHANGES IN QUALITY OF REPEATEDLY USED COOKING OILS: TOXICOLOGICAL CONCERNS.

SUPATRA PORASUPHATANA.*, WONGWIWAT TASSANEEYAKUL.*,
YUPAPORN PREECHAGOON.*, AND MAITREE SUTTAJIT.**

*Department of Toxicology, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, Thailand, ** Faculty of Science, Mahasarakam University, Mahasarakam, Thailand

E-mail : psupatra@kku.ac.th

         Deep-frying cooking oil is commonly found in Thailand. The utilization of cooking oils is occasionally found to be misused which may cause toxicity due to oil deterioration and peroxidation. This study aimed to evaluate the changes in quality of refined palm and soybean oils repeatedly used for deep-frying at different period and to determine the cutoff point to discharge the recycled oils. Chicken wings (600 gm) without or with seasoning were daily fried at 180?10oC in palm and soybean oil and oils were continued heating for 2 hours per day. Samples were collected and determined the parameters of oil degradation. Chemical parameters included the total polar compounds (TPCs), peroxide value (PV) and iodine value (IV) as well as physical parameters (viscosity and color) were also determined. Results showed the increase of TPCs in the relation to frying time, reaching 25% TPCs at 10 and 12 hours for palm and soybean oil (with ingred ients), respectively. Interestingly, soybean oil for non-ingredient-containing chicken exhibited higher stability. PV initially started to decline after 2 hours whereas IV constantly reduced. Rancidity and greasy appearance were clearly observed in chicken fried in multi-repeatedly used oils. In conclusion, repeated frying palm and soybean oils exhibited significant degradations as determined by chemical and physical analysis. According to the European regulations which allow 25% TPCs as a cutoff point, it is suggested the discard of frying oil after the period of accumulating frying time approximately 10 hours for palm oil and 12 hours for soybean oil. This should prevent peroxide by-products which may be toxic and mutagenic or carcinogenic compounds by the consumption of oil-frying foods.


ที่มา ABSTRACT นำเสนอที่ การประชุมวิชาการสมาคมพิษวิทยาแห่งประเทศไทย ประจำปี 2547 อาหารกับความปลอดภัย วันศุกร์ที่ 17 ธันวาคม 2547 โรงแรมมิราเคิลแกรนด์ กรุงเทพฯ