**9. Nonfood applications**

As commented previously, soybean deodorizer distillate represent good source of valuable compounds such as phytosterols, tocopherols and squalene, which can be recovered and further used as food additives, in pharmaceutical industry and cosmetics. Alternatively, deodorizer distillates have nonfood applications, such as biodiesel or can be used mixed with the fuel oil to fire the steam boilers (Svensson, 1976).

Refined vegetable oils are the predominant feedstocks used for the production of biodiesel. However, their relatively high cost renders the resulting fuels unable to compete with petroleum-derived fuel and makes the use of side-stream refining products (soapstock, acid oil and deodorizer distillate) important alternatives as a feedstock for biodiesel production.

Biodiesel is produced from deodorizer distillates by direct esterification of the FFA or by conversion of FFA to acylglycerols prior transesterification (Figure 2). Esterification of the FFA is also performed as a preliminary step in the purification of the tocopherols and sterols in order to reduce their boiling points, thereby facilitating their separation.

deodorization has been studied under various process conditions. The presence of oxidation products has no influence on the loss of tocopherols during deodorization based on the fact

Experiments using spiked triolein with 2000 ppm of α-tocopherol showed that the addition of tertbutylhydroquinone (TBHQ) as a strong antioxidant reduces the loss of tocopherols with more than 50% in comparison with the reference procedure. α- Tocopherol (2000 ppm) was dissolved in triolein and heated to 254 °C, 5-6 mbar, for 80 min, with no steam injection. 9% of tocopherol loss was observed in the control sample and 3% for the sample with 1500 ppm TBHQ. The more active TBHQ will compete with tocopherols to scavenge radicals and consequently the tocopherol loss in the mass balance is reduced as more natural tocopherols

In vegetable oils, the addition of TBHQ from 0 to 1500 ppm establishes a gradual reduction in tocopherol loss from 26.7% to 17.6% while the concentration of tocopherols in the distillate rises from 1.85% to 2.35%. Performing deodorization with nitrogen as stripping agent showed an important reduction in the tocopherol loss (Verleyen, 2002a). In the model study with triolein no reduction of α-tocopherol was observed while using corn oil a reduction of 30%-50% was observed. The highest reduction was detected at severe deodorization conditions (260 °C, 3 mbar) (Verleyen, 2002a). These experiments show that tocopherols are thermally stable compounds and probably the loss of tocopherols is due to oxidation reactions, which leads to compounds such as α- tocopherol dimer quinone, 4α, 5 epoxytocopherolquinone, 7, 8-epoxy tocopherol quinone, tocopherol dimer quinone, tocopherol spirotrimer and ditocopherol ethers (Verleyen, 2001a). These compounds can be

In a model experiment using 3500 ppm α- tocopherol in triolein and heating at 240 °C for 90 min at a reduced pressure of 6-7 mbar 4α, 5-epoxytocopherolquinone, 7, 8-epoxy tocopherolquinone and α-tocopherol quinone were identified as oxidation products supporting that the tocopherol loss during deodorization is mainly due to oxidative

As commented previously, soybean deodorizer distillate represent good source of valuable compounds such as phytosterols, tocopherols and squalene, which can be recovered and further used as food additives, in pharmaceutical industry and cosmetics. Alternatively, deodorizer distillates have nonfood applications, such as biodiesel or can be used mixed

Refined vegetable oils are the predominant feedstocks used for the production of biodiesel. However, their relatively high cost renders the resulting fuels unable to compete with petroleum-derived fuel and makes the use of side-stream refining products (soapstock, acid oil and deodorizer distillate) important alternatives as a feedstock for

Biodiesel is produced from deodorizer distillates by direct esterification of the FFA or by conversion of FFA to acylglycerols prior transesterification (Figure 2). Esterification of the FFA is also performed as a preliminary step in the purification of the tocopherols and sterols

in order to reduce their boiling points, thereby facilitating their separation.

that two successive deodorization steps yielded identical loss of tocopherols.

stay in the oil or in the distillate (Verleyen *et al.*, 2002a, Verleyen *et al.*, 2003).

found in the finished oil and in the distillate.

with the fuel oil to fire the steam boilers (Svensson, 1976).

degradation (Verleyen, 2002a).

**9. Nonfood applications** 

biodiesel production.

Fig. 2. Production of biodiesel from deodorizer distillates by direct conversion (A) and *via*  acylglycerols route (B).
