Nutritional composition and antioxidant capacity in edible flowers: characterisation of phenolic compounds by HPLC-DAD-ESI/MSn.

Inmaculada Navarro-González,María Jesús Periago,Rocío González-Barrio,Verónica García-Valverde,Ana Belén Bautista-Ortín

doi:10.3390/ijms16010805

Inmaculada Navarro-González, María Jesús Periago + Show 3 more

Open Access

https://doi.org/10.3390/ijms16010805

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Abstract

Edible flowers are commonly used in human nutrition and their consumption has increased in recent years. The aim of this study was to ascertain the nutritional composition and the content and profile of phenolic compounds of three edible flowers, monks cress (Tropaeolum majus), marigold (Tagetes erecta) and paracress (Spilanthes oleracea), and to determine the relationship between the presence of phenolic compounds and the antioxidant capacity. Proximate composition, total dietary fibre (TDF) and minerals were analysed according to official methods: total phenolic compounds (TPC) were determined with Folin-Ciocalteu’s reagent, whereas antioxidant capacity was evaluated using Trolox Equivalent Antioxidant Capacity (TEAC) and Oxygen Radical Absorbance Capacity (ORAC) assays. In addition, phenolic compounds were characterised by HPLC-DAD-MSn. In relation to the nutritional value, the edible flowers had a composition similar to that of other plant foods, with a high water and TDF content, low protein content and very low proportion of total fat—showing significant differences among samples. The levels of TPC compounds and the antioxidant capacity were significantly higher in T. erecta, followed by S. oleracea and T. majus. Thirty-nine different phenolic compounds were tentatively identified, with flavonols being the major compounds detected in all samples, followed by anthocyanins and hydroxycynnamic acid derivatives. In T. erecta small proportions of gallotannin and ellagic acid were also identified.

Highlights

Edible flowers have been eaten as part of human nutrition since ancient times, as they are considered plant foods with medicinal properties and beneficial effects for human health
Total carbohydrates were the most abundant macronutrient, with significant differences (p < 0.05) among samples. They were comprised of digestible carbohydrates, simple sugars and indigestible carbohydrates, the latter mainly represented by total dietary fibre (TDF)
TDF was the main component of the total carbohydrates, as simple sugars ranged from 2.63% to 4.95% and TDF from 4.51% to 10.11%, with significant differences (p < 0.05) among the three species

Summary

Introduction

Edible flowers have been eaten as part of human nutrition since ancient times, as they are considered plant foods with medicinal properties and beneficial effects for human health. Their consumption has been reported for centuries and includes flowers of different species—like rose, violet, jasmine, monks cress, Prunus and flower of Jamaica—that are consumed as ingredients in different meals, salads, foodstuffs and drinks. Not all flowers are edible; to be included in a human diet, flowers have to be non-toxic and innocuous (considering the presence of biological and chemical hazards) and have nutritional properties [3,4]. Some flower species have toxic substances that could affect their nutritional properties, such as trypsin inhibitors, or—even worse—cause severe damage to consumers; for example, those that contain hemaglutinnins, oxalic acid, cyanogenic glycosides or alkaloids [2,3,5]

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