Guava Fruit (Psidium guajava L.) as a New Source of Antioxidant Dietary Fiber

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Abstract
Guava (Psidium guajava L.) is a tropical fruit, widely consumed fresh and also processed (beverages, syrup, ice cream, and jams). Pulp and peel fractions were tested, and both showed high content of dietary fiber (48.55−49.42%) and extractable polyphenols (2.62−7.79%). The antioxidant activity of polyphenol compounds was studied, using three complementary methods: (i) free radical DPPH• scavenging, (ii) ferric reducing antioxidant power assay (FRAP), and (iii) inhibition of copper-catalyzed in vitro human low-density lipoprotein (LDL) oxidation. All fractions tested showed a remarkable antioxidant capacity, and this activity was correlated with the corresponding total phenolic content. A 1-g (dry matter) portion of peel contained DPPH• activity, FRAP activity, and inhibition of copper-induced in vitro LDL oxidation, equivalent to 43 mg, 116 mg, and 176 mg of Trolox, respectively. These results indicate that guava could be a suitable source of natural antioxidants. Peel and pulp could also be used to obtain antioxidant dietary fiber (AODF), a new item which combines in a single natural product the properties of dietary fiber and antioxidant compounds. Keywords: Guava; Psidium; tropical fruits; dietary fiber; polyphenols; antioxidant dietary fiber; radical scavenging; reducing ability; low-density lipoprotein oxidation