Monitoring lipase-catalyzed interesterification for bulky fats modification with FT-IR/NIR spectroscopy

This work demonstrates the application of FT-IR and FT-NIR spectroscopy to monitor the enzymatic interesterification process for bulky fat modification. The reaction was conducted between palm stearin and coconut oil (70/30, w/w) with the catalysis of Lipozyme TL IM at 70°C in a batch reactor. The blends and interesterified fats samples in liquid form were measured by attenuated total reflectance (ATR) based FT-IR (spectra region: 1516-781 cm-1) and transmission mode based FT-NIR (spectra region: 5369-4752 cm-1) with temperature both controlled at 70°C. The samples in solid form were also measured by reflectance based FT-NIR (spectra region: 7037-6039 & 5995-5612 cm-1) at room temperature. Calibrations of FT-IR and FT-NIR for conversion degrees (evaluated by triglyceride profile), solid fat contents (SFC), and dropping points (DP) of interesterified products were carried out by using partial least squares (PLS) regression. High correlations (r > 0.96) were obtained from cross validations of the data estimated by FT-IR, FT-NIRand above-mentioned conventional analytical methods, except for correlations (r = 0.90-0,95) between FT-IR and SFC profiles. Overall, FT-NIR spectroscopy coupled with transmission mode measured at 70 °C had the highest correlations which also had the most close conditions to the sampled products in the process, indicating a big potential to implement as online control for monitoring enzymatic interesterification process.