1996 Volume 22 Issue 4 Pages 205-208
The occurrence of bitterness, changes in the production of bitter compounds, and sugar contents were measured to determine the effects of ethylene (C2H4) treatment and/or cutting on different tissues (different part of phloem or xylem) of partially processed carrot (PPC) during storage. Carrots (Daucus carota L. var. sativa DC, cv : unknown) were sliced with 1 cm thickness and stored at 20°C with or without C2H4 (100ppm) in air. Phloem or xylem of PPC were divided into three portions (A : part located at 0-1.5mm from cut surface, B : 1.5-3.0 mm, and C : 3.0-5.0), respectively, and the occurrence of bitterness and contents of phenols and sugar in these portions were determined. Neither C2H4-treated nor un-treated PPC showed apparent decay during 3 days of storage, but brown pitting injury on the surface of phloem was markedly associated with C2H4 treatment. This was not so for xylem tissue. The occurrence of bitterness increased apparently in phloem treated with CO2H4 and the xylem was less sensitive than phloem. Bitterness in A was significant and moderate in B and C of phloem. The contents of isocoumarin and phenols, bitter compounds, did not show apparent changes in phloem and xylem of un-treated PPC. The accumulation of these compounds were induced significantly in phloem and moderately in xylem by C2H4 treatment. This increase was greatest in A, followed by B and C in both tissues. An increase in reducing sugar content and a decrease in total sugar content were observed in phloem but not in xylem of C2H4 treated PPC, while neither phloem nor xylem in un-treated PPC showed apparent changes during storage. We conclude that the occurrence of bitterness and the accumulation of bitter compounds in PPC are induced by C2H and cutting and propose the importance of PPC storage without C2H4.
