Edible flowers of Viola tricolor L. as a new functional food: Antioxidant activity, individual phenolics and effects of gamma and electron-beam irradiation

Amanda Koike,João C.M Barreira,Lillian Barros,Celestino Santos-Buelga,Anna L.C.H Villavicencio,Isabel C.F.R Ferreira

doi:10.1016/j.foodchem.2015.01.123

Abstract

Edible flowers are used in food preparations, being also recognized for their beneficial effects on human health. Nevertheless, these species are highly perishable, and irradiation treatment might be applied to ensure food quality and increase their shelf life. Viola tricolor L. is a typical edible flower, with multiple applications and biological properties, mainly provided by the flavonoid content. In the present work, the phenolic compounds were analyzed by HPLC–DAD–ESI/MS, and the antioxidant activity was evaluated using biochemical assays. Linear discriminant analyses (LDA) were performed in order to compare the results obtained with flowers submitted to different irradiation doses and technologies (cobalt-60 and electron-beam). In general, irradiated samples (mostly with 1kGy) showed the highest phenolic content and antioxidant activity. Furthermore, the significant differences observed in the LDA allow determination of which dose and/or technology is suitable to obtain flowers with higher antioxidant potential.

Highlights

Edible flowers have been used in culinary preparations to improve the sensorial and nutritional qualities of food, by adding colour, flavour, taste and visual appeal to culinary preparations
The precise identity and position of the sugar substituents cannot be concluded from the LC-mass spectrometer (MS) data, compound 3 was tentatively assigned as isorhamnetin-3-O-(6-O-rhamosylgalactoside), considering the identification of this compound together with isorhamnetin-3-O-(6-O-rhamosyl-glucoside) in petals of Catharanthus roseus by Ferreres Pereira, Valentão, Andrade, Seabra, & Sottomayor (2008), in both cases with elution and spectral characteristics similar to the ones observed in our study
The mass fragmentation of the compound obtained in our study is coherent with the second structure; in particular the fragment at m/z 343 would not be produced from a quercetin-O-triglycoside structure as proposed by Karioti et al (2011)

Summary

Introduction

Edible flowers have been used in culinary preparations to improve the sensorial and nutritional qualities of food, by adding colour, flavour, taste and visual appeal to culinary preparations. They are used in sauces, jellies, syrups, liquors, vinegars, honey, oils, candied flowers, ice cubes, salads, teas and other beverages, and different desserts. V. tricolor has a refreshing taste and velvety texture which allows its use in sweets, salads, soups, vinegars, drinks, as in the extraction of blue and yellow food colourings (Creasy, 1999; Newman & O’Conner, 2009). The purpose of this study was to characterize the phenolic profile and the antioxidant activity of V. tricolor flowers from Brazilian origin, and to evaluate the effects of different electron-beam and gamma irradiation doses on these two bioactive indicators (i.e., phenolic compounds and antioxidant activity)

Objectives

Methods

Results

Conclusion