Processing of Japanese Apricot (Prunus mume) Jam by Constant-temperature Preheating - Studies on Internal Pectic Change and Physical Properties of Jam -

摘要

In this study, effects of constant-temperature preheating (40, 50, 60, 70, 80 degrees C) on physical properties of Japanese apricot (Prunus mume) jam were investigated. Breaking stress of jam was temperature-dependently increased by preheating, and this value reached maximum with preheating at 60 degrees C for 30 min. Shape retention of jam in a 200 degrees C oven was strongly correlated with breaking stress; that is, the jam prepared from fruit treated at 60 degrees C for 30 min was the most stable against heating (200 degrees C, 10 min). During constant-temperature preheating, soluble pectin in fruit was temperature-dependently increased by heating, whereas the molecular size of soluble pectin was gradually decreased. Pectin solubilized by preheating at 60 degrees C for 30 min would be the most favorable for gelation, as the definite quantity of solubilized pectin was above the specified molecular size. Acid hydrolysis during preheating is suggested to play a role in solubilization of pectin. Constant-temperature preheating is expected to be a new technique for controlling and utilizing internal constituents in food materials.