Crocin and β-Carotene bleaching assays as analytical tools in the optimization of the extraction of hydrophilic and lipophilic antioxidants from tomato


Autoria(s): Pinela, José; Prieto, M.A.; Barreiro, M.F.; Carvalho, Ana Maria; Oliveira, M.B.P.P.; Vásquez, J.A.; Ferreira, Isabel C.F.R.
Data(s)

16/09/2016

16/09/2016

2016

Resumo

Tomato (Lycopersicon esculentum Mill.) is the second most important vegetable crop worldwide and a rich source of hydrophilic (H) and lipophilic (L) antioxidants. The H fraction is constituted mainly by ascorbic acid and soluble phenolic compounds, while the L fraction contains carotenoids (mostly lycopene), tocopherols, sterols and lipophilic phenolics [1,2]. To obtain these antioxidants it is necessary to follow appropriate extraction methods and processing conditions. In this regard, this study aimed at determining the optimal extraction conditions for H and L antioxidants from a tomato surplus. A 5-level full factorial design with 4 factors (extraction time (I, 0-20 min), temperature (T, 60-180 •c), ethanol percentage (Et, 0-100%) and solid/liquid ratio (S/L, 5-45 g!L)) was implemented and the response surface methodology used for analysis. Extractions were carried out in a Biotage Initiator Microwave apparatus. The concentration-time response methods of crocin and P-carotene bleaching were applied (using 96-well microplates), since they are suitable in vitro assays to evaluate the antioxidant activity of H and L matrices, respectively [3]. Measurements were carried out at intervals of 3, 5 and 10 min (initiation, propagation and asymptotic phases), during a time frame of 200 min. The parameters Pm (maximum protected substrate) and V m (amount of protected substrate per g of extract) and the so called IC50 were used to quantify the response. The optimum extraction conditions were as follows: r~2.25 min, 7'=149.2 •c, Et=99.1 %and SIL=l5.0 giL for H antioxidants; and t=l5.4 min, 7'=60.0 •c, Et=33.0% and S/L~l5.0 g/L for L antioxidants. The proposed model was validated based on the high values of the adjusted coefficient of determination (R2.wi>0.91) and on the non-siguificant differences between predicted and experimental values. It was also found that the antioxidant capacity of the H fraction was much higher than the L one.

Identificador

Pinela, José; Prieto, M.A.; Barreiro, M.F.; Carvalho, Ana Maria; Oliveira, M.B.P.P.; Vásquez, J.A.; Ferreira, Isabel C.F.R. (2016) - Crocin and β-Carotene bleaching assays as analytical tools in the optimization of the extraction of hydrophilic and lipophilic antioxidants from tomato. In 5° Encontro Português de Jovens Químicos (PYCheM) e o 1° Encontro Europeu de Jovens Químicos (EYCHeM). Guimarães

http://hdl.handle.net/10198/13239

Idioma(s)

eng

Relação

info:eu-repo/grantAgreement/FCT/5876/135938/PT

info:eu-repo/grantAgreement/FCT/5876/147218/PT

SFRH/BD/92994/2013

info:eu-repo/grantAgreement/FCT/5876/147286/PT

Direitos

openAccess

http://creativecommons.org/licenses/by/4.0/

Tipo

conferenceObject