The Absorption of Sulfur Dioxide by Fruit Tissue

SUMMARY The influence of many individual factors on the uptake of sulfur dioxide by apricot, peach, and pear tissue before drying was tested in equipment designed to permit accurate control over sulfuring conditions. Exploratory trials showed that estimates of sulfur dioxide uptake were unreliable unless standardized sampling methods were used. Absorption rate was affected appreciably by type of fruit, surface area as influenced by size, and the use of irrigation, and less so by variety and maturity. Sulfur dioxide uptake through the skin was slow. Combinations of gas concentration and exposure time were the most important processing variables affecting absorption. Variation in air speed and temperature had little influence upon absorption. Holding cut fruits for up to 10 hr before sulfuring did not cause a decrease in gas uptake. Excess water on the fruit surface from spraying tended to decrease absorption, while steam‐blanching retarded it appreciably. Any disorganization of tissue, whether from increasing maturation, storage, or processing, retarded sulfur dioxide uptake, probably through sealing, of penetration pathways. The ready desorption of sulfur dioxide from tissue removed from the sulfuring environment indicated low chemical fixation at that stage.