Multielementar/centesimal composition and determination of bioactive phenolics in dried fruits and capsules containing Goji berries (Lycium barbarum L.)

The elemental/centesimal composition of dried fruits and capsules containing Goji berries (Lycium barbarum L.) was evaluated by ICP OES after two digestion procedures. Furthermore, phenolic acid compounds and flavonoids were quantified by HPLC-UV-DAD. Precision, accuracy, LOD and LOQ were evaluated. The samples showed similar contents of proteins, lipids and carbohydrates. The metal contents in the samples were found at different levels (minimum-maximum, in mg kg−1), as follows: Ca (181.1-200.2); Cu (1.703-2.145); Fe (7.420-7.852); K (81.78-83.59); Mg (92.58-95.12); Mn (1.630-2.570); Na (587.9-590.7); P (3.124-3.360); Se (2.812-3.345); V (0.055-0.062) and Zn (2.325-2.610). Al, As, Ba Cd, Co, Ni, P, Pb, Sb, Sn and Sr showed values below the LOD. Accuracy was assessed by analysis of tomato leaves (NIST 1573a). Eight bioactive phenolic compounds (caffeic, chlorogenic, ellagic, ferulic, gallic, p-coumaric, syringic and vanillic acids) and two flavonoids [(+)-catequin and rutin] were determined, in levels of 55.5-83.700 and 172.3-2982.4 mg kg−1, respectively.