Al-Khusaibi Mohamed, Al-Habsi Nasser Abdullah, Al-Yamani Sara Abdullah, Al-Khamis Adhraa Saif, Al-Shuhaimi Iman, Rahman Mohammed Shafiur
Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod 123, P. O. Box 34, Muscat, Oman.
J Food Sci Technol. 2022 Nov;59(11):4176-4186. doi: 10.1007/s13197-022-05471-8. Epub 2022 Jun 13.
In this work, chemical degradation of oil was determined as a function of frying time during intermittent deep-fat frying (i.e. 185 °C for 5 h per day for 12 days) and was correlated with the thermal characteristics as measured by Differential Scanning Calorimetry (DSC) and proton mobility by Low-Field Nuclear Magnetic Resonance (LF-NMR). Linear increases of FFAs and PV were observed as a function of frying time. FFAs and PV were strongly correlated with the melting enthalpy. The melting enthalpy of oil decreased exponentially, and the melting temperature remained nearly same until 30 h of frying time followed by a sharp increase. The relaxation times of rigid, semi-rigid and mobile protons (i.e. , , and ) decreased with the increase of frying time. The decrease of , and were steeper as compared to the T. A strong correlation was observed between conventional chemical parameters (i.e. PV and FFAs), and and The populations of the three pools of protons as identified by Inverse Laplace Transformation and Gaussian distribution function showed the interchange of the protons with the chemical changes during frying. It is concluded that chemical free DSC and LF-NMR could be potential methods to monitor frying oil degradation.
在本研究中，测定了间歇式深度油炸（即每天185℃油炸5小时，共12天）过程中油的化学降解情况，并将其与通过差示扫描量热法（DSC）测量的热特性以及低场核磁共振（LF-NMR）测定的质子迁移率相关联。观察到游离脂肪酸（FFAs）和过氧化值（PV）随油炸时间呈线性增加。FFAs和PV与熔化焓密切相关。油的熔化焓呈指数下降，在油炸30小时之前熔化温度几乎保持不变，随后急剧上升。刚性、半刚性和可移动质子的弛豫时间（即 、 和 ）随油炸时间的增加而减小。 、 和 的下降比 更陡峭。在传统化学参数（即PV和FFAs）与 和 之间观察到强相关性。通过逆拉普拉斯变换和高斯分布函数确定的三个质子池的数量显示了油炸过程中质子随化学变化的交换。得出的结论是，无化学干扰的DSC和LF-NMR可能是监测油炸油降解的潜在方法。
