This study compared the Texas commercially grown conventional and certified organic Rio Red grapefruit (C. paradisiMacf.).Whole grapefruit from each system were harvested in November for the early season, mid-January for the middle harvest and in March for the late season over three consecutive years. Grapefruit within the production orchard and harvest season were selected for uniform color, firmness, roundness, and minimal defects, and harvested from inside the mid-canopy.
A randomly selected set of 10 trees from each production system were re-sampled at each harvest. For each harvest season, 40 fruits (four fruits from each tree) from each orchard were immediately transported to the Agricultural Research Service, U.S. Department of Agriculture Research Center in Weslaco, Texas. Ten fruits from each production orchard, per harvest season, per year, were reselected for uniform size, washed in reverse osmosis H2O, and immediately processed.
Within each harvest season, conventional and organic whole fruits were compared for marketable qualities (fruit weight, specific gravity, peel thickness, and peel color), and juices were compared for marketable qualities (specific gravity, % juice, and color), human health-bioactive compounds (minerals, ascorbic acid, lycopene, sugars, pectin, phenols, and nitrates), and consumer taste intensity and overall acceptance. Conventional fruit was better-colored and higher in lycopene, and the juice was less tart, lower in the bitter principle naringin, and better accepted by the consumer panel than the organic fruit. The organic fruit had a commercially-preferred thinner peel, and the juice was higher in ascorbic acid and sugars and lower in the drug interactive bergamottin compounds and the negative health factor nitrate.
Lester, G. E., Manthey, J. A., & Buslig, B. S. (2007. Organic vs conventionally grown Rio Red whole grapefruit and juice: Comparison of production inputs, market quality, consumer acceptance, and human health-bioactive compounds. Journal of Agricultural and Food Chemistry, 55(11), 4474-4480. Available on-line at: http://dx.doi.org/10.1021/jf070901s.