Oligosaccharide Profile in Fruits and Vegetables as Sources of Prebiotics and Functional Foods

Low molecular weight carbohydrates including sugar alcohols and mono-, di- and oligosaccharides, in particular fructooligosaccharides and raffinose-family oligosaccharides, were determined in 32 fruits and 41 vegetables. Vegetables generally contained less monosaccharides than fruits. Sorbitol was detected in 18 fruits, xylitol in 15, while mannitol was found only in watermelon. On the other hand, sorbitol was found in 12, xylitol in 16, and mannitol in 14 vegetables. Cluster analysis was applied to categorized fruit and vegetables according to their content. Blueberry, pear, watermelon, and nectarine from the fruits; and garlic, spring garlic, leek, white onion, and scallion from the vegetables formed statistically significant clusters reach in oligosaccharides. Most fruits contained low amounts of fructooligosaccharides. The highest content of fructooligosaccharides was found in nectarine (0.89 ± 0.031 g/100 g fresh weight). The vegetable with the highest quantity of fructooligosaccharides was scallion (3.32 ± 0.108 g/100 g fresh weight). White onion (2.24 ± 0.092 g/100 g fresh weight) and scallion (4.10 ± 0.147 g/100 g fresh weight) were found to have relatively high fractions of fructooligosaccharides and raffinose-family oligosaccharides, while Jerusalem artichoke, chicory root, and garlic distinguished themselves by the highest fructan levels, 8.99 ± 0.238 g/100 g fresh weight, 8.40 ± 0.186 g/100 g fresh weight, and 7.51 ± 0.209 g/100 g fresh weight, respectively. These foods could be exploited as potential sources for commercial extractions of prebiotics which can be used as ingredients for functional food products.