Factors affecting the sulfur dioxide uptake in sulfited pre-peeled potatoes

Summary and Conclusions

A study was made of certain factors that influence the SO₂ uptake of sulfited pre-peeled potatoes. Use of a NaHSO₃-citric acid dip instead of NaHSO₃ alone greatly increased the absorption of SO₂. Upon increasing NaHSO₃ and citric acid in the dip simultaneously from 0.125% to 1%, SO₂ uptake regularly increased from average values of 104 to 274 ppm. With 0.5% each of NaHSO₃ and citric acid in the dip, SO₂ uptake increased regularly from 122 to 222 ppm as dipping time was increased from 1/2 minute to 4 minutes. Temperature apparently has little effect on the quantity of SO₂ absorbed by peeled potatoes within the limits of 40° to 50° F., the range in which it is common to chill the dipping bath in a central peeling plant. At room temperature, i.e. about 75°, somewhat more SO₂ was absorbed during a 2 minute immersion in 0.5% NaHSO₃-0.5% citric acid solution than under the same conditions of time and dip concentration in the lower temperature range.

Whole peeled potatoes absorbed less than one-third as much SO₂ as did French fry slices under comparable conditions. Boiling the whole potatoes reduced the SO₂ content to less than one-half the value in the raw state, and French frying the slices reduced the SO₂ content to less than one-fourth the former value.

During cold storage (37°F.), raw French-fry slices lost SO₂ fairly rapidly for the first few days and then at a slower, nearly constant rate such that an appreciable quantity of SO₂ remained even after 2 weeks.