Fourteen tropical fruits from south Florida (red guava, white guava, carambola, red pitaya (red dragon), white pitaya (white dragon), mamey sapote, sapodilla, lychee, longan, green mango, ripe mango, green papaya, and ripe papaya) were evaluated for antioxidant activity, total soluble phenolics (TSP), total ascorbic acid (TAA), total dietary fiber (TDF), and pectin. ORAC (oxygen radical absorbance capacity) and DPPH (1,1-diphenyl-2-picrylhydrazyl, radical scavenging activity) assays were used to determine antioxidant activity. The TSP, ORAC, and DPPH ranged from 205.4 to 2316.7 g gallic acid equiv/g puree, <0.1 to 16.7 micromol Trolox equiv/g puree, and 2.1 to 620.2 microg gallic acid equiv/g puree, respectively. The TAA, TDF, and pectin ranged from 7.5 to 188.8 mg/100 g, 0.9 to 7.2 g/100 g, and 0.20 to 1.04 g/100 g, respectively. The antioxidant activities, TSP, TAA, TDF, and pectin were influenced by cultivar (papaya, guava, and dragon fruit) and ripening stage (papaya and/or mango). Antioxidant activity showed high correlations with levels of TSP compounds (r = 0.96) but low correlations with levels of ascorbic acid (r = 0.35 and 0.23 for ORAC and DPPH data, respectively). The antioxidant activities evaluated by both ORAC and DPPH showed similar trends where red guava and carambola exhibited the highest and sapodilla and green papaya exhibited the lowest levels. Guava and mamey sapote exhibited the highest TDF and pectin levels. Many of the tropical fruits were shown to contain an abundance of hydrolyzable tannins, ellagic acid conjugates, and flavone glycosides. Preliminary descriptions are given of the phenols in red/white pitaya (dragonfruit), lychee, and mamey sapote, these fruit being thus far uncharacterized in the literature.

Four norisoprenoids, alpha-ionone, beta-ionone, beta-cyclocitral, and beta-damascenone, along with their putative carotenoid precursors, were identified in Valencia orange juice using time-intensity GC-O, GC-MS, and photodiode array HPLC. alpha-Ionone and beta-cyclocitral are reported in orange juice for the first time. GC-O aroma peaks were categorized into seven groups with similar sensory qualities: citrus/minty, metallic/mushroom/geranium, roasted/cooked/meaty/spice, fatty/soapy/green, sulfury/solventy/medicine, floral, and sweet fruity. The four norisoprenoids contributed approximately 8% of the total aroma intensity and 78% of the total floral aroma category. The putative carotenoid norisoprenoid precursors, alpha- and beta-carotene, alpha- and beta-cryptoxanthin, and neoxanthin, were identified in the same orange juice using photodiode array HPLC retention times and spectral characteristics.