Analytical profiling of selected antioxidants and total antioxidant capacity of goji (Lycium spp.) berries

Analytical profiling of selected antioxidants and total antioxidant capacity of goji (Lycium spp.) berries

Highlights
•The nutritional features of goji berries were assessed.
•An original SPE-LC–MS/MS method was developed and validated to determine 23 antioxidants.
•Goji berries antioxidant activity was tested by using multiple antioxidant assay strategies.
•Modified electrochemical sensor detecting radicals by degradation of a polyphenol film deposited on a glassy carbon electrode was implemented.
•A relationship between antioxidant capacity and content of antioxidants has been investigated.

Abstract
Goji berries and derived products represent a relevant source of micronutrients, most of which are natural antioxidants and contribute to the high nutritional quality of these fruits. Three brands of dried goji berries have been analysed by a multidisciplinary approach to get an insight into both their content of selected antioxidants and their antioxidant capacity (AC).

The former goal has been achieved by developing a liquid chromatographic method coupled to mass spectrometry and combined to a fast solid phase extraction. Several significant representative antioxidant compounds belonging to the following classes: flavonoids, flavan-3-ols, phenolic acids, amino acids and derivatives, and carotenoids have been taken into account. Quercetin and rutin were found to be the predominant flavonoids, chlorogenic acid was the most abundant phenolic acid and zeaxanthin was the major carotenoid.

The AC of the goji berries has been evaluated by four analytical methods in order to estimate the contributions of different reactions involved in radicals scavenging. In particular, AC has been determined using 3 standardised methods (DPPH, ABTS, ORAC) and a recently proposed electrochemical method, which measures the scavenging activity of antioxidants towards OH radicals generated both by hydrogen peroxide photolysis and the Fenton reaction.

The results obtained from chemical composition and antioxidant capacity assays confirm the high nutritional and commercial value of goji berries and highlight that the three brands do not exhibit significant differences.

Author information
1 Pharmaco-Toxicological Analysis Laboratory (PTA Lab), Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy.
2 Department of Industrial Chemistry "Toso Montanari", INSTM, UdR Bologna, Alma Mater Studiorum - University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy.
3 Department for Life Quality Studies (QuVi), Alma Mater Studiorum - University of Bologna, Corso d'Augusto 237, 47921 Rimini, Italy.
4 Pharmaco-Toxicological Analysis Laboratory (PTA Lab), Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy. Electronic address: laura.mercolini@unibo.it.

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