RT Journal Article SR Electronic T1 Factors Influencing Sulfite Residues in Table Grapes After Sulfur Dioxide Fumigation JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 131 OP 136 DO 10.5344/ajev.1990.41.2.131 VO 41 IS 2 A1 Joseph L. Smilanick A1 John M. Harvey A1 Preston L. Hartsell A1 Delmer J. Hensen A1 C. Max Harris A1 David C. Fouse A1 Mitra Assemi YR 1990 UL http://www.ajevonline.org/content/41/2/131.abstract AB Sulfur dioxide (SO2) content of fresh table grapes after SO2 fumigation was determined by ion exchange chromatography (IC) and pararosaniline colorimetry (PRAC). Results of these methods were not significantly different when residues of five lots of fumigated Thompson Seedless grapes were compared. The coefficient of variation for PRAC (28.7%) was higher than IC (17.1%). Table grapes contained 5 to 20 µg/g total SO2 immediately after fumigation for 30 minutes with 0.5% SO2. Residues decreased rapidly after fumigation; the SO2 half-life was 24 to 36 hours at 0°C. Grapes fumigated at warmer temperatures accumulated more SO2, but residues were less persistent. Immature grapes accumulated more SO2 than mature grapes in three of four cultivars evaluated. Grapes injured by cuts or infected with Botrytis cinerea accumulated up to seven times more sulfite than sound grapes. Sulfur dust applied preharvest left no detectable sulfite residues. Residues can be minimized by the selection of mature grapes free from rot and injuries, use of minimal SO2 fumigant doses, and post-fumigation storage of several days duration so that residue can diminish before marketing.