Smart Farming Technology Center, Dept. of Biological and Agricultural Engineering, Faculty of Engineering, Univ. Putra Malaysia, 43400, UPM Serdang, Malaysia.
J Food Sci. 2019 Apr;84(4):792-797. doi: 10.1111/1750-3841.14436. Epub 2019 Mar 12.
Total polar compounds (TPC) and free fatty acids (FFA) are important indicators in evaluating the quality of frying oil. Conventional methods to determine TPC and FFA are often time consuming, involved laboratory analyses which required skilled personnel and used substantial amount of harmful solvent. In this study, dielectric spectroscopy technique was used to investigate the relation between dielectric property of refined, bleached and deodorized palm olein (RBDPO) during deep frying with TPC and FFA. In total, 150 batches of French fries were intermittently fried at 185 ± 5 °C for 7 hr a day over 5 consecutive days. A total of 30 frying oil samples were collected. The dielectric property of frying oil samples were measured using impedance analyzer with frequencies ranging from 100 Hz to 10 MHz. The TPC of frying oil samples were measured with a Testo 270, while the FFA analysis was done using Malaysian Palm Oil Board (MPOB) test method. Results showed that dielectric constant, TPC and FFA of RBDPO increased as the frying time increased. Dielectric constant increased from 3.09 to 3.17, while TPC and FFA increased from 9.96 to 19.52 and from 0.08% to 0.36%, respectively. Partial least square (PLS) analysis produced good prediction of TPC and FFA with the application of genetic algorithm (GA). Model developed for prediction of TPC and FFA yielded highly significant correlation with R of 0.91 and 0.95, respectively and both had root mean square error in cross-validation (RMSECV) of 1.06%. This study demonstrates the potential of dielectric spectroscopy in monitoring palm olein degradation during frying. PRACTICAL APPLICATION: The application of dielectric spectroscopy to detect degradation of palm olein during frying was studied. The dielectric property of palm olein during frying has successfully correlated with TPC and FFA. The model developed in this study could be used for the development of a sensing system for palm olein degradation monitoring.
总极性化合物（TPC）和游离脂肪酸（FFA）是评估煎炸油质量的重要指标。传统的 TPC 和 FFA 测定方法通常耗时耗力，需要实验室分析，需要熟练的人员操作，并使用大量有害溶剂。在这项研究中，介电谱技术被用于研究精炼、漂白和除臭棕榈油（RBDPO）在 185±5°C 下深度煎炸过程中介电特性与 TPC 和 FFA 的关系。总共在连续 5 天内每天 7 小时用 185±5°C 间歇性地煎炸了 150 批薯条。共收集了 30 个煎炸油样品。使用阻抗分析仪在 100 Hz 至 10 MHz 的频率范围内测量煎炸油样品的介电特性。使用 Testo 270 测量煎炸油样品的 TPC，而 FFA 分析则使用马来西亚棕榈油委员会（MPOB）测试方法进行。结果表明，随着煎炸时间的增加，RBDPO 的介电常数、TPC 和 FFA 都增加了。介电常数从 3.09 增加到 3.17，而 TPC 和 FFA 分别从 9.96 增加到 19.52 和从 0.08%增加到 0.36%。应用遗传算法（GA）的偏最小二乘法（PLS）分析对 TPC 和 FFA 进行了很好的预测。为预测 TPC 和 FFA 而建立的模型与 R 分别具有 0.91 和 0.95 的高度显著相关性，两者在交叉验证中的均方根误差（RMSECV）均为 1.06%。本研究表明介电谱在监测煎炸过程中棕榈油降解方面具有潜力。实际应用：研究了介电光谱法在检测煎炸过程中棕榈油降解方面的应用。成功地将棕榈油在煎炸过程中的介电特性与 TPC 和 FFA 相关联。本研究中建立的模型可用于开发用于监测棕榈油降解的传感系统。
