Polyphenols and Antioxidant Capacity of Vegetables under Fresh and Frozen Conditions

Abstract

The phenolic and oxygen radical absorbance capacity (ORAC) values have been measured in six fresh and frozen vegetables (beet green, spinach, broccoli, carrot, onion, and celery) from the same cultivar by analyzing the whole juice (WJ) and the acetonic extract of the squeezed pulp. To exploit the effect of the acid environment on the stability and recovery of the phenolics, perchloric acid (PCA) was added directly to WJ and to the pulp before the extraction with acetone. In both fresh and frozen vegetables, PCA markedly increased the recovery of phenolics extracted from the pulp, but PCA had no effect on the WJ. Four of six frozen vegetables showed lower phenolic and ORAC values than the fresh vegetables, whereas in the other two cases, values were significantly higher compared to fresh samples. Among the fresh vegetables, beet green showed the highest ORAC and phenolic values; however, when measured in two different cultivars of beet green, the ORAC value showed as much as 4.5-fold variation, whereas total phenolics and flavonoids showed 1.2- and 3.5-fold variations, respectively. The results show that total phenolics and ORAC, compared in fresh and frozen vegetables, represent an index of the mildness of blanching in the industry of frozen vegetables and provide a measure of the gap in antioxidants in the diet of people who consume frozen instead of fresh vegetables. The plant genotype is an important source of variability in the ORAC value, which can be conveniently used to increase the intake of antioxidants from vegetables.

Tronchuda cabbage (Brassica oleracea L. var. costata DC) seeds: Phytochemical characterization and antioxidant potential

“…This is ascribed to the fact that different plants have distinct compound contents, with several structures, thus offering different protective mechanisms at different levels (Chu, Sun, Wu, and Liu, 2002;Ninfali and Bacchiocca, 2003). Among phtyochemicals, phenolic compounds and organic acids may exert a protective role against various diseases, due to their antioxidant potential (Silva et al, 2004).…”

Antioxidative properties of tronchuda cabbage (Brassica oleracea L. var. costata DC) external leaves against DPPH, superoxide radical, hydroxyl radical and hypochlorous acid

“…Cauliflower has been assayed for the ability to scavenge DPPH Å and ABTS Å+ , as well as for ferric reducing efficiency and ability to inhibit lipid peroxidation (Llorach, Espín, Tomás-Barberán, & Ferreres, 2003). The oxygen radical absorbance capacity values have been measured in broccoli (Kurilich, Jeffery, Juvik, Wallig, & Klein, 2002;Ninfali & Bacchiocca, 2003). To find the antiradical activity of white cabbage, hydroxyl radical was used (Racchi et al, 2002).…”

Optimisation of microwave-assisted extraction of flavonoids and phenolics from celery (Apium graveolens L.) leaves by response surface methodology

“…In traditional medicine, celery has been used to treat asthma, bronchitis, spleen, and liver diseases (Singh & Handa 1995). Recently, there has been a growing interest in the plant for its healthbeneficial activities, such as antioxidant activities (Ninfali & Bacchiocca 2003), anti-inflammatory activity (Ovodova et al 2009), anticancer activities (Sultana et al 2005), anti-hyperlipidaemic effect (Tsi & Tan 2000;Iyer & Patil 2011), and so on. Numerous studies have confirmed that flavonoids consist of a common basic structure comprising two aromatic rings linked by three carbons that form an oxygenated heterocyclic compound, and phenol compounds are the main antioxidant substance which can promote the human health through reducing oxidative damage (Wang & Stoner 2008;Mousavinejad et al 2009).…”