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Microwave-assisted extraction in goji berries: effect on composition and bioactivity, evaluated through conventional and nonconventional methodologies

Publication . Carvalho, Ana P.; Mendes, Marta; Moreira, Manuela M.; Cruz, Diana; Magalhães, Júlia M. C. S.; Barroso, M. Fátima; Ramalhosa, M. J.; Duarte, Abel; Guido, Luís; Gomes, Ana M. P.; Matos, Cristina Delerue

This study aimed to evaluate the effect of microwave-assisted extraction (MAE) parameters on the composition and bioactivity of goji (Lycium barbarum) extracts. Extracts were obtained under a central composite design combination of experimental conditions, and characterised through HPLC-DAD; their bioactive capacity was ascertained for antimicrobial and antioxidant capacity, the later by spectrophotometric [2,2-azinobis (3- ethylbenzothiazoline-6-sulfonic acid) diammonium salt-radical scavenging activity assay – 413–748 mg ascorbic acid equivalents/100 g DW and oxygen radical absorbance capacity – 1901–2292 mg trolox equivalents/ 100 g DW] and electrochemical (DNA-based sensor – 3571–6602 mg ascorbic acid/100 g DW) methods. The quantitative profile of phenolic compounds was strongly dependent on MAE conditions. Significant correlations were found between the presence of several flavonoids and solvent composition, as well as between phenolic acids with methoxy group and the response to DNA-based sensor. Results may improve targeted extractions for specific compounds, leading to the achievement of extracts richer in antioxidant capacity, as well as in the tailoring of the biosensor response sensitivity to the composition of the extracts under analysis.

2016Journal article

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Brazilian fruit pulps as functional foods and additives: evaluation of bioactive compounds

Publication . Paz, Mário; Gúllon, Patricia; Barroso, M. Fátima; Carvalho, Ana P.; Domingues, Valentina F.; Gomes, Ana M.; Becker, Helena; Longhinotti, Elisane; Delerue-Matos, Cristina

Eight tropical fruit pulps from Brazil were simultaneously characterised in terms of their antioxidant and antimicrobial properties. Antioxidant activity was screened by DPPH radical scavenging activity (126-3987 mg TE/100 g DW) and ferric reduction activity power (368-20819 mg AAE/100 g DW), and complemented with total phenolic content (329-12466 mg GAE/100 g DW) and total flavonoid content measurements (46-672 mg EE/100 g DW), whereas antimicrobial activity was tested against the most frequently found food pathogens. Acerola and acai presented the highest values for the antioxidant-related measurements. Direct correlations between these measurements could be observed for some of the fruits. Tamarind exhibited the broadest antimicrobial potential, having revealed growth inhibition of Pseudomonas aeruginosa. Escherichia coli, Listeria monocytogenes, Salmonella sp. and Staphylococcus aureus. Acai and tamarind extracts presented an inverse relationship between antibacterial and antioxidant activities, and therefore, the antibacterial activity cannot be attributed (only) to phenolic compounds.

2015Journal article

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