Investigation of the effects of chemical interestification and adsorption processes on the monoacylglycerol, diacylglycerol (MAG/DAG) content, melting characteristics, and glycidyl ester and 3-monochloropropane-1,2-diol (GE/3-MCPD) levels in refined palm olein

This study aims to investigate the effect of chemical interesterification and adsorption processes on the amounts of monoacylglycerol (MAG), diacylglycerol (DAG), melting characteristics, and levels of 3-MCPD and GE in palm olein oil. For this purpose, an optimization process was carried out using a trial plan with two different types of bleaching earth (natural and acid-activated) and different amounts of bleaching earth (3-6%). To eliminate the hardening effect of the chemical interesterification process, a mixture oil was prepared by adding sunflower oil to palm olein oil, except for the palm olein trial. This trial plan was applied to both palm olein and palm olein-sunflower oil mixtures. As a result of the applied processes, the free fatty acid content, peroxide value, conjugated diene value, p-Anisidine value, fatty acid composition, MAG and DAG contents, solid fat content, and 3-MCPD and GE levels of each sample were determined. Based on all results, the oil samples with the lowest 3-MCPD and GE contents were identified for both palm olein and palm olein-sunflower oil mixtures, and productions were repeated. The oils with the lowest 3-MCPD and GE contents were finally subjected to deodorization, and the free fatty acid content, peroxide value, conjugated diene value, p-anisidine value, fatty acid composition, MAG and DAG contents, solid fat content, and 3-MCPD and GE levels of the samples were determined. In the study conducted on the palm olein group, it was found that the type of bleaching earth had no statistically significant effect on the free fatty acid content, peroxide value, conjugated diene value, and p-Anisidine value (p>0.05). However, the amount of adsorbent used was found to have a significant effect on the peroxide value and conjugated diene value (p<0.05), with the lowest free fatty acid content, peroxide value, conjugated diene value, and p-anisidine value obtained in samples produced with 5.25% bleaching earth. After the chemical interesterification and adsorption processes, the TAG (%) content decreased in all samples, while the DAG (%) and especially MAG (%) contents increased. The 3-MCPD levels of the samples decreased depending on the amount of adsorbent used, with natural adsorbent providing better results compared to acid-activated adsorbent; however, the type of adsorbent did not have a statistically significant effect on the 3-MCPD levels (p>0.05). The amount of adsorbent used had a significant effect on the GE levels of the samples (p<0.05), with GE levels decreasing as the amount of adsorbent increased. The lowest GE level was found to be 6% with acid-activated bleaching earth, and 5.25% with natural bleaching earth. The type of adsorbent did not have a statistically significant effect on the GE levels (p>0.05). The amounts of bleaching earth with the lowest 3-MCPD and GE contents were determined to be 5.25% and 6%, respectively. After production was repeated using both acid-activated and natural bleaching earth, deodorization was applied to the samples. Post-deodorization analyses showed that the type of adsorbent had no statistically significant effect on the free fatty acid content, peroxide value, conjugated diene value, and p-anisidine value (p>0.05). Additionally, the type and amount of adsorbent used had no statistically significant effect on the MAG (%), DAG (%), and TAG (%) values (p>0.05). The amount of adsorbent used did not have a statistically significant effect on the 3-MCPD levels (p>0.05), but the type of adsorbent had a statistically significant effect (p<0.05), with natural bleaching earth reducing the 3-MCPD levels more effectively. The amount of adsorbent used did not have a statistically significant effect on the GE levels (p>0.05), but the type of adsorbent had a statistically significant effect (p<0.05), with lower GE levels observed with acid-activated bleaching earth.