Author
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Widmer, Wilbur |
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Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings Publication Acceptance Date: 12/20/2002 Publication Date: 2/1/2003 Citation: Widmer, W.W. Dietary fiber content in fresh citrus. Proceedings of the Florida State Horticultural Society. 2002. v. 115. p. 301-303. Interpretive Summary: There is a wide variation in the dietary fiber content of the edible parts of fresh orange and grapefruit. The Produce Marketing Association (1990) report there to be 4.0 g dietary fiber / 100 g edible grapefruit and 4.4 g dietary fiber / 100 g fresh edible orange. Other studies report much lower fiber values in fresh citrus. Some difference in reported values is to be expected and can be explained by several factors including: how the edible fruit portion is defined, definition of what constitutes dietary fiber, how the samples are prepared for analysis, and content differences due to seasonal and varietal variation. After reviewing the available literature and results of fiber analyses on samples collected by the author, realistic total fiber content, based on The Food and Drug Administration definition of 154 g serving size, for orange and grapefruit are 2.3 - 3.4 g and 1.5 - 2.3 g, respectively. These values assume the segment membranes are included in the edible portion. If segment membranes are not considered part of the edible portion, the dietary fiber content is approximately half the above values. Examining all available data from the Produce Marketing Association reports, the low values reported for total carbohydrate and the very high proportion of total fiber reported as soluble fiber, indicate sugars were not completely removed from the soluble fiber extract preparation. Technical Abstract: There is a wide variation in the reported values for pectin and dietary fiber content in the edible portions of fresh orange and grapefruit. Two studies done by the Produce Marketing Association in 1990 reported 4.0 g dietary fiber/ 100 g of fresh edible grapefruit and 4.4 g dietary fiber / 100 g fresh edible orange. Other studies report fiber values in fresh citrus as being much less. Differences can largely be explained by several factors and include how the edible fruit portion is defined, definition of what constitutes dietary fiber, how the sample is prepared for analysis, and the analytical method used. How well the peel is removed from fruit segments will have a dramatic effect on dietary fiber measurements as citrus peel contains a large amount of fiber. For grapefruit the edible portion may be defined as whole peeled fruit segments including the segment membranes, or only as the juice sacs removed from the segment membranes. After reviewing the available literature and results of fiber analyses on samples collected by our laboratory, realistic total fiber contents for orange and grapefruit, based on a 154 g serving size are 2.3 - 3.7 g and 1.5 - 2.3 g, respectively. Some variation is to be expected with season, maturity and variety. These values assume the segment membranes are included in the edible portion. If segment membranes are not considered part of the edible portion, the dietary fiber content is approximately half the above values. |
