Blanching Effects on the Chemical Composition and the Cellular Distribution of Pectins in Carrots

Carrots were blanched using 4 time‐temperature combinations. Galacturonic acid and sugar contents of pectin extracts were determined, and immunocytochemistry experiments elucidated changes in the cell membrane. Blanching decreased galacturonic acid and total sugar contents for all treatments. Carrots subjected to high‐temperature short‐time (HTST) blanching contained more total galacturonic acid and total sugars in pectins than carrots blanched for a long time at low temperatures (LTLT). Similar trends were observed for methylated pectin and neutral sugars. Immunocytochemistries showed separation of the 3‐way junction of cell walls, and LTLT‐blanched carrots showed higher levels of JIM 7‐labeled pectin (1.6 × 10 −4 particles/nm 2 ) than HTST‐treated carrots (5.9 × 10 −5 particles/nm 2 ).