Proceedings of the 7th Internaiumal
Working Conference on Stored-product Protection - Volume 2
Cell wall chemistry of carrots (Daucus carota cv Amstrong) during maturation and storage Ng Annie", Srruth Andrew C. 1, and Waldron Kerth W.
1
Abstract
Carrots,
Carrots are a biannual dicotyledon plant, of which is an over-winter post-harvest
storage
architecture
storage
the edible portion
organ.
Maturation
which may affect the textural
aim of this work was to investigate chemistry of carrots
(Daucus
properties.
residues
carota cv Amstrong)
extracted
sequentially
residue.
These
(AIRs) analyzed
of carrots resulted
for
their
methylesterified
)
pectic
carbohydrate
there was no significant
decrease increase
Maturation
storage
in the level of water-soluble in the level of CDTA-soluble
(DM).
pectic
polymers
carrots resulted
(1984)
may
in an increase
and Ng
that most of
be solubilized
Recently,
by
investigations
in cell wall chemistry
and storage
of
et al ,
of cell walls of carrots has
and CDTA.
the changes
source
Robertson
of carrots
showed that maturation m less branched
pectic polysaccharides,
ThIS
carrots resulted m a decrease in total pectic polysacchandes
was
of water-soluble increase
implications.
resulted
polymers polymers.
(Ng
and storage of
polymers and this was accompanied
in total
polymers
change in the
and both maturation
of
cell wall
in (highly
induced firmness of carrots at higher temperature the tissue firmness during subsequent
1979a;
They have demonstrated
in water
during maturation
pectic
et al.
polysacchandes 1998a).
changes during maturation
by an
of CDTA-soluble the physiological
Hence,
of carrots may play an important
role m the quality control of stored carrots.
ferulic acid of AIRs of carrots dunng and post-harvest
extractable
extraction
the edible
organ (root).
as an important
et al.,
A detailed fractionation
concernmg
the DM of the pectic moieties and
composition,
the level of estenfied storage.
the
ferulic acid cross-
linking which may have significant structural Unlike maturation,
1979b).
and were
in the relative
polysacchandes.
accompanied by an increase m estenfied
identified
and Waldron (1997).
carbohydrate
and an increase
have been
storage
been carried out by Steven and Selvendran
and CDTA to leave a
in a decrease
proportion of cell wall xylose,
The during
composition and the degree of methylestenficanon Maturation
Carrots
dietary fibre (Robertson
properties.
were prepared
WIth water
were
portion of which is an over-winter
the changes of cell wall
maturation and storage m relation to textural Alcohol-msoluble
and
the modification of cell wall
involve
a biannual dicotyledon plant, are among the most
ancient of the vegetable crops grown in Europe,
There IS growing interest
m a
and an
meals
in the demand for ready-made
high- fiber
containmg
Storage-
often
enhanced
processing.
One of the most important
during processmg
processing.
undergo
processed
Vegetables
treatment
vegetables. dunng
food
changes occurnng
is heat-induced tissue softening.
to reduce an undesirable carrots
heat
In order
degree of softness during cooking,
can be pre-cooked
at moderate
temperature
for a
period of time and followed by cooking (Ng and Waldron, 1997).
Introduction
ThIS results in greater
probably due to an increase The state important
of maturity
can be manipulated development
are
which
Most aspects
of plant growth
and
involving the modification of cell wall structure
(Waldron
during storage may affect textural
and Selvendran,
1992).
of pectic polysaccharides
Maturation-
and storage-related
of Food Research,
Norwich
Norwich NR4 7UA, Umted Kmgdom
Research
(Ng et al. , 1998a).
increase
final texture
and cell wall composition
processing,
particularly
in CDTA-soluble
the
during subsequent
precooking-induction
of
firmness.
Effect of Maturation on Carrot Cell Wall Chemistry
and
Maturation Institute
m thermal stability of calcium
cross-hnking
Conventional
storage of carrots often results in loss of firmness deterioration m quality (Burton, 1982).
1
compared to those
This firrrung effect IS
polymers of carrots might have significant influence on their
in order to meet the continuous market
1979).
and continued maturation properties
and the conditions of storage
factors affecting the quality of vegetables
supply (Avon,
firmness
directly cooked WIthout precooking.
Park,
Colney,
weight,
of carrots
This was accompanied
1693
resulted
in an increase
of fresh
dry weight and total root length (Ng et al. , 1998). by an mcrease
in cell-wall
pectic
Proceedings of the 7th International polysaccharides, arabinose,
m other
decrease xylose
as indicated
galactose
and glucose
Worktng Conference on Stored-product Protection - Volume 2
by the levels of rhamnose,
and uronic cell-wall
acid,
and a concomitant
polysacchandes
(Table
1).
These
particularly
changes
can be
explained by the lateral growth of the carrot resulting relatively
lower
irutial root.
contribution
of thin
highly
The ratio of uronic acid (UA):
galactose (NS) increased pectic
to the breakdown of the galactan and arabman side
chams
in
polysacchandes
asparagus
(Table
during ~ ~
1).
maturation
This
cell
deposition
of methylesterified
probably pectic-rich
polysaccharides
the
uronide
involves
the
polysaccharides decrease m the
The maturation-related
of water-soluble
reduced
synthesis
and/or
turnover
(WSP)
of
(WSP) dunng maturation
polysaccharides
and
an
(CSP)
water-soluble
(FIgure
1; Ng et
al. , 1998a).
and
30
I-wspl
"E~
a ~ -5 -5
extension
of
could be due to continued synthesis and insertion of CSP and
bears
(Waldron
that
increase in the
(DM)
increase in the level of CDTA-soluble polysacchandes
+
mdicating less-
branched
The maturation-related
suggested
level
vascularised
similarity
1992).
methylesterification
of
(Ng et al. , 1998a).
m a
arabinose
during maturation
Sel vendran, degree
~CSP
25
~ g
..o~
8. a
~~ Co)
20
Co)
8. 8. :E
