2009 Volume 35 Issue 1 Pages 3-9
The stability of chemical components including polymethoxylated flavones (PMFs) such as nobiletin,tangeretin and sinensetin, and synephrine in shiikuwasha ( Citrus depressa Hayata) fruit juice was investigated for four months. The juice tested was prepared from whole fruits by using three types of extractor, namely, a belt-press extractor, a centrifugal extractor and a screw-press extractor, and then stored at temperatures of 5, 20 and 25 °C. The juice yield obtained using the screw-press extractor was higher than those obtained using the other two extractors. Storage temperature had a significant effect on the stability of PMFs and synephrine during 4 month storage, compared with the effect of the extractors. The amounts of PMFs remaining in the fruit juice obtained using the extractors after storage for 4 months at 35 °C, were as follows: 95.1-97.3% of nobiletin, 94.6-97.8% of tangeretin,and 70.2-96.2% of sinensetin. Little change in the amounts of PMFs was observed at 5 and 20 °C. This means that nobiletin and tangeretin are stable. On the other hand, 73.9-87.4% of synephrine remained after 4 months storage at 35 °C , while 41.5-46.7% of vitamin C remained. In sensory evaluation, a marked change in appearance (browning) was observed. From the overall palatability, shelf life of bottled juice prepared using the centrifugal extractor was estimated to be approximately 1 month at 35 °C, 3 months at 20 °C, or 4 months at 5 °C.