RELATIONSHIPS BETWEEN QUALITY OF CRUDE AND REFINED EDIBLE OILS BASED ON QUANTITATION OF MINOR GLYCERIDIC COMPOUNDS

The relationships between crude and refined oils are examined by quant itation of minor glyceridic compounds, namely, oxidized triglyceride m onomers, dimers and diglycerides, associated with oil quality. Particu larly, two groups of compounds, i.e. oxidized triglyceride monomers an d diglycerides, are of especial interest as they are indicative of oxi dative and hydrolytic alterations, respectively. Olive, sunflower and soybean oils differing in initial quality, as evaluated by classical i ndices and levels of undesirable minor compounds, were subjected to ph ysical and alkali refining in a laboratory system. In all assays, resu lts indicated that amounts of oxidized triglyceride monomers and digly cerides in refined oils remained close to those found in the starting crude oils. Triglyceride dimers were the only group of compounds showi ng a significant increase, which was dependent on fatty acid compositi on and initial quality of crude oils. The main conclusion is that quan titation of minor glyceridic compounds in refined oils not only offers a new possibility for quality evalution but also allows the crude oil s to be characterised by the presence of markers of oxidative and hydr olytic alterations. (C) 1997 Elsevier Science Ltd.