title: Changes in caffeic acid derivatives in sweet potato (Ipomoea batatas L.) during cooking and processing.
abstract: There was an obvious decrease in caffeic acid derivatives during the boiling of cube-shaped blocks of sweet potatoes. They also decreased in a mixture of freeze-dried sweet-potato powder and water maintained at room temperature. Ascorbic acid prevented the decrease, supporting the occurrence of an enzyme reaction with polyphenol oxidase (PPO). 5-O-Caffeoylquinic acid (5-CQA, "3-O-caffeoylquinic acid" as a trivial name) and 3,5-di-O-caffeoylquinic acid (3,5-CQA), major phenolic compounds of sweet potato, did not change when they were separately heated in boiling water. When the mixture of powdered sweet potato and water was heated at 100 degrees C, there was only a negligible decrease in the total amount of phenolic compounds, and portions of 5-CQA and 3,5-CQA were found to be isomerized to 3-CQA, 4-CQA, 3,4-CQA, and 4,5-CQA. The content and composition of the phenolic compounds in sweet potatoes differed between fresh and long-stored ones, as did their response to heating.
authors.affiliation: Food Engineering Division, National Food Research Institute, Ibaraki, Japan. tknk1221@nfri.affrc.go.jp
authors.forename: Makiko
authors.initials: M
authors.lastname: Takenaka
authors.forename: Kazuko
authors.initials: K
authors.lastname: Nanayama
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Isobe
authors.forename: Masatsune
authors.initials: M
authors.lastname: Murata
mesh_terms: D002109:Caffeic Acids / Q000737:chemistry*; D003296:Cooking; D005511:Food Handling; D005612:Freeze Drying; D006358:Hot Temperature; D027723:Ipomoea batatas / Q000737:chemistry*; D015394:Molecular Structure; D019800:Phenol / Q000737:chemistry
chemical_list: D002109:Caffeic Acids; D019800:Phenol; C040048:caffeic acid