A process to preserve a carbohydrate feedstock against contaminant microorganisms comprises contacting the carbohydrate feedstock with a stabilized chlorine dioxide at a pH of at least 2.6. The carbohydrate feedstock preferably comprises a naturally-occurring carbohydrate, particularly a carbohydrate having a reducing end group. The process is particularly suitable to treat feedstocks used in biorefining processes, such as in ethanol fermentation.
