Chemometric Evaluation on Profiles of Lard and Selected Edible Fats After Heating-Process Using Spectroscopy and Chromatography Techniques

This research aims to evaluate the profile of lard using the chemometric method to discriminate lard from other types of fat after the heating-process and determination of biomarkers in lard. In this research, two types of samples were conducted. First, a total of 270 lard were collected from belly fats (BL), back fats (BK), and shoulder fats (SF) from northern, southern, and central regions of Peninsular Malaysia, which were measured using FTIR. PCA utilised the chemometrics evaluation on lard profiles using PCA and extended Hotelling T2. The scores vectors were found inside Hotelling T2 eclipses at first 3 PCs (99.5% confidence interval) and successfully validated by PCA projection. This indicates that the FTIR profile for lard is undifferentiated for all regions and body parts. Second, for discrimination purposes, a total of 60 fats, lard, chicken, beef, mutton, and plant have undergone twelve heating-process protocols (at 120 °C, 180 °C, 240 °C for 0.5. 1, 2 &3 hrs). In addition, each species without any heating was included in this study. After the heating-process, fat samples were analysed using FTIR, 1H-NMR, 13C-NMR, GC-FID, and LC-MS/MS. The classification was performed using multivariate classification (LDA, MDA, QDA & SVMDA) and multivariate regression (OSC-PLSR, PCR & PLSR) on FTIR and 1H-NMR. Multivariate classification found MDA, QDA, and SVMDA on 1H-NMR provided the best results for classifying lard from other fats. In the multivariate regression, the result of OSC-PLSR on FTIR (R2, adj. R2, RMSEC, RMSEV & MSEP; 0.985, 0.984, 0.049, 0.051 & 0.056) was found to outperform than the OSC-PLSR on 1H-NMR. Finally, profiling lard by 13C-NMR, GC-FID, and LC-MS/MS combined with the PCA were conducted to determine the biomarker of lard. The 13C-NMR-PCA data found that the lard differed against the chicken fats at C-2 of the TAG isomer, denoted by δ 34.21 and δ 62.10 resonances. Meanwhile, the GC-FID-PCA data found that animal fats and plant fats can differ after fatty acids )FAs( degradation of the cis into trans isomers. The lard heated at 180 °C (at 0.5, 1 & 2 hrs.) was found to differ significantly from others by LC-MS/MS-PCA, contributed by saturated fatty acids (SFA) of the diacylglycerol (DAG) and phosphatidic acids (PA) lipid classes. The application of chemometrics was found to discriminate lard against other fats after the heating-process successfully, and FAs were tentatively identified as biomarkers.