Total antioxidant activity of yacon tubers cultivated in Brazil

Abstract

Yacon (Smallanthus sonchifolius) is a tuberous root from the Andean region in the South America rich em water, fructooligosaccharides and phenolic compounds, some of which are natural antioxidants and may help prevent the deleterious action of free radicals in the body. The yacon has attracted much attention due to their potential health benefits to humans. In this study the levels of total phenolics, tannins, phenolic acids, and total antioxidant activity were measured in the peel and pulp of yacon tubers both in the fresh and flour forms. The flours of yacon presented higher concentrations of total phenolics and tannins, especially peel flour. The yacon pulp flour stood out as the main source of phenolic acids, mainly caffeic and chlorogenic acid. The total antioxidant activity assessed by DPPH (2,2-Diphenyl-1-picrylhydrazyl) and ABTS (2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) assays was higher in the yacon peel flour. The total antioxidant activity was correlated with the total phenolic content and tannins by the DPPH and ABTS assays. These results suggest that yacon can be used as an alternative food source of phenolic compounds that help prevent degenerative processes caused by oxidative stress, especially in the flours form.Index terms: Smallanthus sonchifolius; total phenolics; tannins; phenolic acids. RESUMOYacon (Smallanthus sonchifolius) é uma raiz tuberosa da região andina na América do Sul, rica em água, frutooligossacarídeos e compostos fenólicos, alguns dos quais são antioxidantes naturais e podem auxiliar a prevenir a ação deletéria dos radicais livres no organismo. O yacon tem atraído muita atenção devido a seus potenciais benefícios de saúde para os seres humanos. Neste estudo, os níveis de fenólicos totais, taninos, ácidos fenólicos e atividade antioxidante total foram mensurados na casca e polpa de túberas de yacon ambas nas formas fresca e de farinha. As farinhas de yacon apresentaram altas concentrações de fenólicos totais e taninos, especialmente a farinha da casca. A farinha da polpa de yacon destacou-se como a principal fonte de ácidos fenólicos, principalmente caféico e ácido clorogênico. A atividade antioxidante total avaliada pelos métodos DPPH (2,2-Difenil-1-picril-hidrazil) and ABTS (2,2′-Azino-bis (3-etilbenzotiazolina-6-ácido sulfônico)) foi maior na farinha de casca de yacon. A atividade antioxidante total foi correlacionada com o conteúdo de fenólicos totais e taninos pelos métodos DPPH e ABTS. Estes resultados sugerem que yacon pode ser usado como uma fonte alimentar alternativa de compostos fenólicos que auxiliam a prevenir processos degenerativos causados pelo estresse oxidativo, especialmente na forma de farinhas.

Evaluation of nutritional and chemical composition of yacon syrup using 1H NMR and UPLC-ESI-Q-TOF-MSE

“…The authors concluded that yacon exhibit an important antioxidant activity due its phenolic compounds, such as CGA. Recently, Pereira et al (2016) measured the total antioxidant activity of yacon in natura by the DPPH and ABTS assays. The authors correlated its antioxidant activity with the total phenolic content and tannins, and suggest that yacon can be used as an alternative food source of phenolic compounds that help prevent degenerative processes caused by oxidative stress.…”

Total Phenolic Content and Antioxidant Activity of Yacon (Smallanthus Sonchifolius Poepp. and Endl.) Chips: Effect of Cultivar, Pre-Treatment and Drying

“…Castro et al showed that drying of yacon slices at 50 • C in a cabinet dryer results in yacon chips with a higher total phenolic content (TPC) and antioxidant activity compared to those which were dried at 40 • C and 60 • C [18]. Moreover, yacon slices dried at 55 • C in a forced air oven with and without soaking of them in a solution of sodium hypochlrorite (20 mg L −1 ) and 0.1% sodium disulfide to produce yacon flour, showed that retention of TPC and individual phenolic compounds namely, chlorogenic acid, ferulic acid and caffeic acid, were better when pre-treatment was applied before drying [20]. On the other hand, the quality of yacon dried products can be influenced by the quality of the fresh yacon tubers.…”

“…In particular, preservation of yacon using drying has been investigated before, and the production of certain dried products from yacon tubers including yacon chips, whole yacon flour, yacon juice powder, yacon peel flour and yacon pulp flour have been studied [18][19][20][21][22]. Most of these studies have evaluated the effects of various drying processes on the quality of final dried yacon products regarding their sugar and FOS content [19,22,23].…”

Yacon (Smallanthus sonchifolius Poepp. & Endl.) as a Novel Source of Health Promoting Compounds: Antioxidant Activity, Phytochemicals and Sugar Content in Flesh, Peel, and Whole Tubers of Seven Cultivars

“…In respect to novel food product developments using yacon tubers, the flesh of tubers has been the focus of several recent studies, but yacon peels and recovery of their valuable compounds for potential applications has not been considered in detail yet [ 19 , 26 , 27 , 28 ]. A study of Pereira et al (2016) investigated the phytochemical content in the peels and flesh of one yellow yacon cultivar cultivated in Brazil [ 29 ]. It was reported that these yacon peels had a TPC and ABTS radical scavenging activity of 2500.0 ± 23.1 (mg gallic acid equivalent kg −1 ) and 372.5 ± 15.9 (µmole trolox equivalent g −1 DW) [ 29 ].…”

“…A study of Pereira et al (2016) investigated the phytochemical content in the peels and flesh of one yellow yacon cultivar cultivated in Brazil [ 29 ]. It was reported that these yacon peels had a TPC and ABTS radical scavenging activity of 2500.0 ± 23.1 (mg gallic acid equivalent kg −1 ) and 372.5 ± 15.9 (µmole trolox equivalent g −1 DW) [ 29 ]. Thus, differentiation between phyto/chemical content of flesh, peel, and whole yacon tuber is required to facilitate the selection of suitable raw material for specific food products to insure the aimed phyto/chemical quality of the final product.…”