カツオ・マグロかん詰のかっ変（オレンジミート）防止 ＶＩＩ オレンジミートの発生に及ぼす原料処理および貯蔵条件の影響

Abstract

Skipjack samples were frozen after standing on board for 15min (Na) and 3 hr (Nb), after immersion in iced sea water for 12 hr (Pc), or after instant blow (Kb). Air-blast freezing at about -50°C(A), brine immersion freezing at -17 ?? -20°C (Bi) and -7.5 ?? -14°C (Bii) were used as the freezing methods. The fish frozen on landing was stored at -40, -20, -17 or -13°C for one month and cooked directly or after thawing overnight in still water at 5°C, in running water at 14°C or in air at 13°C. Twenty four groups of sample fish thus prepared were canned as usual and examined for the extent of orange discoloration. The orange discoloration was induced only in the groups stored at -13°C and the group stored at -20°C with a short time temperature rise up to -2°C. The extent of orange discoloration was rather slight in groups Nb-A, -Bi, and -Bii, especially in Nb-Bii, compared with the groups Na-A, -Bi and -Bii and Kb-Bi. No orange discoloration occurred in Pc-Bi. It was concluded from those results that, in the processing of raw skipjack, quick freezing after landing, storage at below -20°C, and speedy thawing in running water are quite essential if the orange discoloration is to be avoided.