A problem of excessive sedimentation was detected in soy and palm biodiesel, preventing the product from complying with requirements on contamination/ filterability. The objective of the study was to determine the nature of the sediment by different analytical techniques and to obtain data on the typical range of its components in industrially produced biodiesel samples. The sediment was investigated and the appearance of haze is linked to the presence of free steryl glucosides (FSG) above a certain concentration. This paper focuses on the original analytical approach, taking into account particular physical properties of FSG. Nuclear magnetic resonance and mass spectrometry were used as fast and reliable identification methods, without the need for a prior hydrolysis of the glucosidic bond. A GC method, including optimised sample preparation, was developed for the quantification of the FSG in biodiesel as well as in filter residues. The FSG concentrations in biodiesel produced by different processes ranged between 55 and 275 mg/kg for palm and from not detectable to 158 mg/kg for soy biodiesel.

Fish oils are well-known sources of nutritionally valuable components such as the n-3 FA EPA and DHA as well as the fat-soluble vitamins A, D, and E. However, some fish oils can be contaminated with considerable amounts of dioxins and dioxin-like PCB. The most important challenge during fish oil refining is to remove these contaminants without altering the levels of nutritionally valuable compounds and the oxidative status and stability of the oil. Treatment with an apolar adsorbent, e.g., activated carbon (AC), seems to be the most efficient process today. Very little information about the adsorption of different dioxin and PCB congeners is available. Four grades of AC were evaluated for their efficiency in removing these compounds. In addition, the effects of the treatment on the nutritional and oxidative quality of the oil were evaluated. After treatment of contaminated cod liver oil [5.4 ppt toxic equivalents (TEQ) polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), 18.1 ppt TEQ dioxin-like PCB] with 0.5% AC, almost all PCDD/F and up to 80% of the dioxin-like PCB could be removed. AC showed low affinity for mono-ortho PCB (<30% removal), which could be explained by their noncoplanar structure. Removal efficiencies were dependent on the grade and percentage of AC used. The treatment of contaminated cod liver oil caused no important effects on oil quality or FA composition in the conditions tested.

Phorbol esters present in Jatropha curcas oil are toxic when consumed and are co-carcinogens. These could be a potential constraint in the widespread acceptance of Jatropha oil as a source of biodiesel. Phorbol esters were quantified in the fractions obtained at different stages of oil pre-treatment and biodiesel production. During degumming some phorbol esters were removed in the acid gums and wash water. This implies that the use of these acid gums in animal feed is not possible and care should be taken when disposing the wash water into the environment. Silica treatment did not decrease the phorbol esters, while stripping/deodorization at 260°C at 3 mbar pressure with 1% steam injection completely degraded phorbol esters. Phorbol esters were not detected in stripped oil, fatty acid distillate, transesterified oil (biodiesel) and glycerine. The presence of possibly toxic phorbol ester degradation products in these fractions could not be ruled out.

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Palm oil is rich in minor components that impart unique nutritional properties and need to be preserved. In this context, refining technologies have been improved, with the dual temperature deodorizer, the double condensing unit and the ice condensing system. The DOBI is a good tool to assess quality of the crude palm oil and its ability to be properly refined. Specially refined oils open a market for new high quality products (golden palm oil, red palm oil, white soaps, etc.). Palm oil is a good candidate for the multi-step dry fractionation process, aiming to the production of commodity oils and specialty fats (cocoa butter replacers). New technological developments allow quality and yield improvements. Palm oil and fractions are also valuable feedstock for enzymatic interesterification in which applications are for commodity oil (low-trans margarines and shortenings) and for special products (cocoa butter equivalents, infant formulation, …).