Abstract
This study addresses the effects of gamma irradiation (1, 5 and 8 kGy) on color, organic acids, total phenolics, total flavonoids, and antioxidant activity of dwarf mallow (Malva neglecta Wallr.). Organic acids were analyzed by ultra fast liquid chromatography (UFLC) coupled to a photodiode array (PDA) detector. Total phenolics and flavonoids were measured by the Folin-Ciocalteu and aluminium chloride colorimetric methods, respectively. The antioxidant activity was evaluated based on the DPPH• scavenging activity, reducing power, β-carotene bleaching inhibition and thiobarbituric acid reactive substances (TBARS) formation inhibition. Analyses were performed in the non-irradiated and irradiated plant material, as well as in decoctions obtained from the same samples. The total amounts of organic acids and phenolics recorded in decocted extracts were always higher than those found in the plant material or hydromethanolic extracts, respectively. The DPPH• scavenging activity and reducing power were also higher in decocted extracts. The assayed irradiation doses affected differently the organic acids profile. The levels of total phenolics and flavonoids were lower in the hydromethanolic extracts prepared from samples irradiated at 1 kGy (dose that induced color changes) and in decocted extracts prepared from those irradiated at 8 kGy. The last samples also showed a lower antioxidant activity. In turn, irradiation at 5 kGy favored the amounts of total phenolics and flavonoids. Overall, this study contributes to the understanding of the effects of irradiation in indicators of dwarf mallow quality, and highlighted the decoctions for its antioxidant properties.
Highlights
Organic acids are primary metabolites widely spread throughout the plant kingdom
Organic acids were analyzed by ultra fast liquid chromatography (UFLC) coupled with photodiode array (PDA) detection according to the procedures previously described by Pereira et al [28]
This study demonstrated the adequacy of gamma irradiation at 5 and 8 kGy to preserve the color parameters of M. neglecta dry material
Summary
Organic acids are primary metabolites widely spread throughout the plant kingdom They are low weight molecules and are considered to be any organic carboxylic acid with a general structure R-COOH. They are weak acids, these water-soluble compounds may confer acidic properties to foods containing them and influence its organoleptic properties (flavor, color and aroma) and consequent acceptability by the consumers [1]. From a practical point of view, the organic acids profile (levels and relative ratios) is important for food quality control. Qualitative and quantitative analyses of these ingredients are of great importance
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