EFFECT OF HEATING TEMPERATURE AND MICROWAVE PRETREATMENT ON THE FORMATION OF SUGARS AND VOLATILES IN JEWEL SWEET-POTATO

Experiments investigating changes in the concentration of individual s ugars in sweetpotato storage roots with cooking and their relationship to the formation of volatile compounds were conducted. During heat tr eatment maltose concentration increased from 0.03% fresh weight at 25C to 4.33% at 80-C, at which temperature maximum synthesis occurred. Mi crowave pretreatment (2 or 4 min) resulted in a significant decrease i n amounts of maltose and volatiles formed. At 80C, approximately 80% o f maltose synthesis was inhibited when pretreated With microwaves. Add ing maltose into microwave pretreated samples and then cooking in a co nvection oven restored most of the volatile profile with the exception of phenylacetaldehyde. It was concluded that maltose represents a pri mary precursor for many of the volatile compounds emanating from baked 'Jewel' sweetpotatoes and the formation of these volatiles appears to involve both enzymatic and thermal reactions.