Residual sulfite levels in retail and food service potato products

Sulfiting agents (sulfites) may be added to peeled potatoes to prevent enzymatic and/or non-enzymatic browning during preparation and processing. Addition of these agents results in products with residual levels of total SO₂ that may, in some cases, be hazardous to the 100,000-200,000 sulfite-sensitive individuals in the United States. Whole, peeled potatoes treated with a potato whitener according to the manufacturer's directions resulted in a cooked product with low residual SO₂. French fry cuts and hash brown style potatoes treated in the same way resulted in products with substantially higher levels of residual SO₂. Increasing the concentration of the whitener in the treatment solution increased the level of residual sulfite as did increases in treatment time. A 1985-1987 survey of potato products at the retail level revealed that only a portion of the potato products had been treated with sulfites and that a wide range of residual SO₂ levels existed in these potato products. Mashed and hash brown potatoes obtained from restaurants frequently contained detectable levels of residual SO₂ Samples from supermarkets with detectable levels of residual SO₂ frequently were dehydrated potatoes or products that contained dehydrated potatoes.