Bioactive Compounds and Prebiotic Activity in Thailand-Grown Red and White Guava Fruit (Psidium guajava L.)

This research involves the comparison of bioactive compounds, volatile compounds and prebiotic activity of white guava (Psidium guajava L.) cv. Pansithong and red guava cv. Samsi. The antioxidant activity values determined by 2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging and ferric reducing antioxidant power (FRAP) assays were 10.28 mu g fresh weight (fw)/mu g DPPH and 78.56 mu g Trolox equivalent (TE)/g fw for white guava and 7.82 mu g/mu g DPPH, fw and 111.06 mu M TE/g fw for red guava. Ascorbic acid contents were 130 and 112 mg/100 g fw total phenolics contents 145.52 and 163.36 mg gallic acid equivalents (GAE)/100 g fw and total flavonoids contents 19.06 and 35.85 mg catechin equivalents (CE)/100 g fw, in white and red guava, respectively. Volatile compounds in guava were analyzed by the solid-phase microextraction (SPME)/gas chromatography (GC)/mass spectrometry (MS) method. The major constituents identified in white and red guavas were cinnamyl alcohol, ethyl benzoate, beta-caryophyllene, (E)-3-hexenyl acetate and alpha-bisabolene. Prebiotic activity scores for Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12 were 0.12 and 0.28 in white guava, respectively, and 0.13 and 0.29 in red guava, respectively.