In the research study, the effect was analyzed of conventional and freeze-drying processes on the content and antioxidant properties of some selected bioactive components contained in Rosa rugosa rosehips. The conventional drying (air chilling) process was conducted at a temperature of 72±1 °C during a 37 h period, and the freeze-drying process was carried out at a temperature of 33 °C for 22.5 h (including a predrying process in a nitrogen atmosphere at a temperature of -20 °C). The fruits dried were characterized by a low content of the lipid fraction (0.67 and 0.88 %), in which 19 fatty acids (FA) were determined. The following FA prevailed quantitatively: C18:2 9c12c; C18:3 9c12c15c; and C16:0. The biggest differences were found in the content of PUFA: 56.55g/100g contained in the lyophilisate and 48.35 g/100g contained in the conventionally dried fruits. As regards the content of C18:3 9c12c15c acid in the lyophilized dried fruits, the content thereof was as much as 16 % higher compared to the conventionally dried fruits. Both the lyophilized and the conventionally dried fruits contained beneficial carotenoids (lycopene, β-carotene, ζ-carotene, lutein, zeaxanthin, rubixanthin, and β-cryptoxanthin). A lower content of lycopene and rubixanthin in the rosehips dried using the conventional method was caused by the sensitivity of those compounds to a high temperature conditioned by the presence of unsaturated bindings. Regardless of the drying method applied to dry Rosa rugosa fruits, the levels of polyphenolic compounds determined in the fruits were high: 245.5 GAE/1 g of dry matter in the lyophilisate and 224.55 mg GAE/1 g of dry matter in the conventionally dried fruits. A higher ability to neutralize the free DPPH• radical, expressed as a percent rate of inhibition, was found in the freeze-dried fruits (averagely: 72 %), whereas in the conventionally dehydrated fruits, the inhibition rate was lower and amounted to 49 % on average.
Rosa rugosa rosehips, drying, carotenoids, fatty acids, polyphenols, DPPH•