Seasonal Changes in Quality Properties of Shiikuwasha (Citrus depressa Hayata) Juice

Abstract

　The seasonal changes in the quality properties of Shiikuwasha (Citrus depressa Hayata) juice were investigated. In juice at from Shiikuwasha the beginning of the extraction season (October), the concentrations of polymethoxylated flavones (PMFs), such as nobiletin, tangeretin and sinensetin, and the synephrine concentration were higher than those in other months. However, the °Brix/acid ratio was low at 2.20 (°Brix : 9.20，acid : 4.18) in October, indicating the inferior quality of the juice as beverage. The °Brix/acid ratio of the juice at the end of the extraction season (late December) was comparatively high at 5.35～6.09 (°Brix : 9.20, acid : 1.51～1.72), showing high sensory quality. However, the PMF concentration is 1/3 that of the juice at the beginning of the Shiikuwasha season. From these results, juice from Shiikuwasha from the end of November to the beginning of December was considered to be [of well balanced quality] in terms of PMF, and synephrine concentrations and °Brix/acid ratio.