科研之友
微信
新浪微博
Facebook
分享链接
摘要
Identification of volatile compounds formed when frying food represents an important tool to identify markers of oil thermal degradation, and can help to elucidate the chemical reactions occurring during deep frying. In particular, in this study the heat-induced degradation of edible oil has been evaluated by analyzing the composition of volatile organic compounds (VOCs) and fatty acids formed during intermittent frying with the aim of finding new possible markers to correlate with the total polar compounds (TPC) fraction. The frying was realized using a thermostatically temperature-controlled fryer at a temperature of 1805 degrees C. A mixed oil constituted by palm, sunflower, and soybean frying oil and commercially available frozen potatoes have been used. The intermittent frying (4h per day) with the same oil was repeated at 24h intervals for a total of 40h. VOCs were identification has been obtained by dynamic head space analysis combined with high resolution GC-MS. Among the VOCs, two compounds, namely (E,E)-2,4-decadienal, and (E)-2-undecenal, showed good correlations with the TPC values. NMR spectra (H-1 NMR) confirmed that 2-alkenals and alka-2,4-dienals are the major compounds formed during the deep frying. Practical applications: The analysis of volatile compounds during intermittent deep frying using mixed oil allowed to show a good correlation of C18:2 (cis-9, cis-12), (E,E)-2,4-decadienal and (E)-2-undecenal, and of the ratio C16:0/C18:2 (cis-9, cis-12) with total polar compounds in both frying oils and thermo-oxidized oils. In particular, the results obtained from the analytical evaluation of the thermo-oxidized and fried oils subjected to prolonged intermittent heating for deep frying led to the conclusion that these data could be used as an alternative way for monitoring the thermal degradation of frying oils. This contributes with other resource to try to answer the question: when should frying oil be discarded? Many variables can affect the thermal degradation of frying oil, and the presence/absence of volatile compounds is a marker of frying oil thermal degradation. A specific analysis detection method and data correlation as reported could lead to assess the key point for discarding the frying oil.
- 出版日期2013-7
