Abstract
We investigated the effect of modified atmosphere (MA) packaging on freshness retention; contents of polymethoxylated flavones (nobiletin, tangeretin, and sinensetin), synephrine, and ascorbic acid; and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity in unripe green Shiikuwasha (Citrus depressa Hayata) when it was stored at 5, 10 and 25℃, using sealed micro-perforated polypropylene (PP) film bags (film No.1 : oxygen permeability, 160mℓ・bag－1・day－1・atm－1 ; film No.2 : oxygen permeability, 420 mℓ・bag－1・day－1・atm－1). The appearance (greenness) was used as an index of the freshness of fruit; the freshness of fruit stored for 4 months in film No.1 at 5℃, for 3 months in film No.1 at 10℃, and for 1 month in both films (No.1 and No.2) at 25℃ was compared with that of fruit stored for 2 weeks in holed PP film bag. The chemical contents in the fruits investigated at the beginning of storage, were as follows: nobiletin, 419.4 mg/100 g freeze-dried peel; synephrine, 536.4 mg/100 g freeze-dried peel and 25.6 mg/100 mℓ juice; ascorbic acid, 34.4 mg/100 g fresh peel and 9.6 mg/100 mℓ juice. DPPH radical-scavenging activity was 99.4 μm ol-Trolox equivalent/100 g fresh peel. In the fruits stored for 3 months in film No.1, the decrease rate of chemical content in the peel was 23% for nobiletin and 35% for synephrine. Ascorbic acid in the fresh fruits stored for 3 months at 5℃ decreased by 67% for peel and 39% for juice, while DPPH activity of peel decreased by 20%. These data showed that MA packaging using film No.1 at 5℃ was the most suitable condition for storing unripe green Shiikuwasha in terms of freshness retention; contents of polymethoxylated flavones, synephrine, and ascorbic acid; and radical-scavenging activity.
