ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Curvature of carrot (Daucus carota L.) sticks is related to number and distribution of xylem vessels

Moritz Knoche, Manfred Schutze, Stefanie Peschel and Matthias Hinz

Postharvest Biology and Technology Vol: 22 Issue: 2 Pages: 133-139

2001

บทคัดย่อ

Carrot sticks, marketed as vegetable snacks, often develop significant curvature which is considered to be undesirable. Factors affecting curvature of sticks were investigated following incubation under defined conditions. Curvature was quantified by determining the angle between two tangents fitted to projections of a carrot stick. Curvature of commercially produced sticks following a 3 day-incubation period (5°C, 75% RH) was highly variable and weakly related to segment angle (r=0.23*) or the volume ratio of xylem to phloem tissue (r=-0.24*), but not affected by fresh mass of sticks (r=-0.08), loss of fresh mass during incubation (r=0.11) or volume of xylem (r=-0.02) or phloem (r=0.22). Since geometry and mass of commercially produced sticks were variable, standardized sticks (80 mm length, 45° segment angle, 5.5±0.5 g fresh mass and with a volume ratio of phloem to xylem of 1:0.33) were used in subsequent experiments. Curvature increased with increasing water vapor pressure deficit (range 20_¯566 Pa) at constant temperature (6°C), but temperature (range 6_¯20°C) at constant water vapor pressure deficit (560 Pa) had no effect on curvature. Variation in curvature was larger for sticks prepared from different roots than for sticks from the same root. Proximal xylem vessels were arranged at high density in radial rays adjacent to the cambium (0_¯0.6 mm inwards from cambium), but distal vessels (0.6_¯5 mm inwards from cambium) were more randomly distributed at markedly lower density. Curvature was related to the number of distal xylem vessels (r²=0.43**) or to the ratio of number of distal to proximal xylem vessels (r²=0.66***), but only weakly to mass loss (r²=0.22*). Our data suggest that number and distribution of xylem vessels were key factors determining curvature of carrot sticks.