Study of bioaccessibility of cobalt species in berries and seeds by mass spectrometry techniques

In recent years, acai berries (Euterpe Oleracea M.), goji berries (Lycium barbarum L.), bilberries (Vaccinium myrtillus L.), and chia seeds (Salvia hispanica L.) have increased interest worldwide due to their nutritional value and health benefits. In the present study, SEC-ICP-MS and μ-HPLC-ESI-MS/MS were used for the investigation of cobalt speciation and evaluation of its bioaccessibility in these products. Total cobalt content was determined, and acai berries (0.348 ± 0.042 μg g−1) and chia seeds (0.352 ± 0.036 μg g−1) were found as the best sources of this element. Different elution profiles of the extracts of examined berries and seeds obtained with the use of ammonium acetate, Tris-HCl, and SDS suggested that cobalt is bound by different bioligands in each biomatrix. The bioaccessibility of cobalt species was evaluated by SEC-ICP-MS. On the chromatograms of extracts obtained after simulation of gastrointestinal digestion, peaks corresponding to low molecular mass (17.00–1.35 kDa) cobalt complexes were observed. In the case of goji berries, their intensities were significantly higher on chromatograms of gastrointestinal than gastric extract. In enzymatic extracts, different forms of vitamin B12 were identified by μ-HPLC-ESI-MS, including its natural forms—methylcobalamin (Me-Cbl) and adenosylcobalamin (Ado-Cbl).