Sterilization of dehydrated potato granules with propylene oxide.

Results were provided for propylene oxide "cold sterilization" of dehydrated mashed potato granules that contained 7% moisture and 0.044% chloride. Treatment with an optimum concentration of 0.1% w/w sterilant for 6 days at 22 degrees C gave a bacterial count reduction from 3.4 X 10(5) to less than 5 X 10(3), a low glycol residue of 29 ppm, and 12 ppm of chlorohydrin, with the 1-chloro-2-propanol isomer constituting 94% of the total. This indicated that, in spite of the granule pH of 5.62, nucleophilic attack in dehydrated granules involves nonprotonated propylene oxide. Based on NMR analysis, evidence was given that such sterilization does not result in detectable etherification of starch, even though its content of 83% on a dry basis places it as the major potentially reactive constituent.