DEGRADATION OF TOCOPHEROLS DURING NEAR-AMBIENT RAPESEED DRYING

ABSTRACT

Increased interest manifested by consumers in products rich in biologically active components makes it necessary to minimize their loss during drying and storage of raw materials for food production. In this study, the effect of drying conditions and further storage of rapeseed on changes in contents of tocopherols (T) and plastochromanol-8 (PC-8) was examined. Seeds of rape cv. Californium, Elektra and Livius, dried after harvest using the near-ambient drying method in a bed of 2-m thickness and air heated to a temperature of 60, 80 and 100C, were used. Contents of T and PC-8 were determined immediately after drying and after 6 and 12 months of storage at 10 ± 2C. Quality and quantity of antioxidants in seeds were determined using high-performance liquid chromatography. The near-ambient seed drying method resulted in a decrease in T content by 6–11%, while that for hot air drying was 4–8%. Seed storage reduced the level of T by a further 23–30%. Similar dependences were found for PC-8. The analyzed results demonstrated the effect of varietal differences, drying conditions and storage time on the contents of T and PC-8 in rapeseed.

PRACTICAL APLICATIONS

Drying of rapeseed is one of the most energy-intensive stages of its production. At the same time, one needs to consider that these seeds, as biological material, are highly sensitive to thermal treatment. Thus, search for best drying conditions with special emphasis on the preservation of bioactive components that affect human health is necessary. The analyses carried out compared the range of loss of natural antioxidants, tocochromanols, during drying and further storage of rapeseed dried using an energy-saving near-ambient drying and dried using hot air.