Influence of different light conditions and time of sprouting on harmful and beneficial aspects of rutabaga sprouts in comparison to their roots and seeds.

BACKGROUND: This study aimed to evaluate the presence and content of selected phytochemicals, namely glucosinolates, fatty acids and phenolic compounds, in rutabaga (Brassica napus L. var. napobrassica) sprouts grown under various light conditions, in comparison to rutabaga seeds and roots. As rutabaga sprouts are likely to become new functional food, special emphasis was placed on the related risks of progoitrin and erucic acid presence - compounds with proven antinutritive properties. RESULTS: Time of sprouting significantly decreased progoitrin content, especially after 10 days (by 91.5%) and 12 days (by 97.5%), as compared to 8 days. In addition, sprouts grown under dark conditions showed 27%, 60% and 17% reduction in progoitrin level in 8, 10 and 12 days after sowing, respectively, as compared to sprouts grown under natural conditions. Progoitrin was found to be the predominant glucosinolate in rutabaga seeds (804.07 ± 60.89 mg 100 g-1 dry weight (DW)), accompanied by glucoerucin (157.82 ± 21.04 mg 100 g-1 DW), also found in the roots (82.20 ± 16.53 mg 100 g-1 DW). Among the unsaturated fatty acids in rutabaga sprouts, erucic, linoleic, linolenic and gondoic acids decreased significantly, and only oleic acid increased as germination days progressed. The amount of harmful erucic acid in rutabaga sprouts was found to vary between 1.8% and 7%, depending on the day of seeding or light conditions, as compared to 42.5% in the seeds. CONCLUSION: The evaluated rutabaga products showed a wide content range of potentially antinutritive compounds, sprouts having the lowest amounts of erucic acid and progoitrin. © 2018 Society of Chemical Industry.