Abstract
The relationship between the softening of yuzu and the extraction of pectin during soaking in citric acid, heating or pressurization was investigated. Firmness of peel was greatest to least; pressurized>soaked for 24 hrs at pH 2.7>heated, respectively. The cell walls did not loosen after pressurization. However, after heating, the middle lamella of albedo separated but flavedo did not. The amount of pectin was greatest to least in albedo>flavedo>segment walls>juice sacs, and in flavedo, raw>pressurized>heated>soaked at pH 2.7>boiled flavedo. About 24% of pectin was extracted by soaking at pH 2.7. By soaking, peel softened due to the removal of Ca2+. The pH values of peel and cooked water were 3-4 and 4.02, respectively. Therefore, it was found that degradation of pectin by heating was mainly from hydrolysis and not by trans-elimination.
