preparation and handling fresh-cut root vegetablesfresh-cut2015.ucdavis.edu/files/220788.pdf ·...
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PREPARATION AND
HANDLING FRESH-CUT
ROOT VEGETABLES
MERETE EDELENBOS
DEPT. OF FOOD SCIENCE
AARHUS UNIVERSITY
DENMARK
Production Handling and Storage
Processing and Packaging
Distribution and Market
Consumption
Preparation and handling fresh-cut root vegetables
Pre-harvest Post-harvest Processing Post-processing
CONTENT
Characteristics of root vegetables
The unit operation
Peeling and cutting
Washing
Pre-packaging treatments
Packaging
Research needs
Conclusions
Root vegetables are mostly underground storage organs containing soil
Roots Tubers
C
Root vegetables
True taproots Includes a swollen hypocotyl
Seed Termination of
root growth Dormancy Growth
Seed Sprouting and
flowering Re-growth
Harvest Cold storage
Nov Jan May March
Root vegetables
Root vegetables are biennial crops
Chemical constituents vary between cultivars
Root vegetables
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
Purple
Haze
Soprano Yellow
Stone
Nottingham Tornado White Satin Mello Yello Nairobi Nebula Line 1 Bolero
ng
/g
fre
sh w
eig
ht
Genotype
Total terpene content in carrots
Adapted from Kreutzmann et al. 2008
Chioggia
Touchstone Golden
Sensory quality vary between cultivars Root vegetables
Taunus
Rocket
Pablo
f:
a:
t:
Mikkelsen 2012
CHARACTERISTICS OF ROOT VEGETABLES
Belong to many different plant families
Are biennial crops
Continue to grow after harvest
Can be stored for up to 12 months
Store mainly sugars
Vary considerably in quality depending on
family, species, cultivar and time of usage
The unit operation for root vegetables
Unit operation
Peeling Cutting ± Washing Centrifugat.
±Pre-packaging treatment
Packaging
An example with processing of carrot sticks Unit operation
‘Bolero’ carrots
Fine abrasion peeling + rinsing
Cutting
Centrifugation
‘Bolero’ carrots
Cutting
Centrifugation
Washing in tap water
Household box
with ventilation
‘Bolero’ carrots
Hand peeling
knife
Trimming
+ rinsing
Cutting into 2 x 2 mm sticks
Cool room overnight
Coarse fine
abrasion peeling
+ rinsing
Cold air cooling
on conveyer belt
Centrifugation
Packaging
Trimming
Household Factory A Factory B Factory C
Effect of processing on visual quality
Factory A
Unit operation
Trimming Peeling Cutting
Trimmed
5 cm
Factory C
Peeled
Cut
Factory A
Trimmed
5 cm
Factory C
Peeled
Cut
Factory A
Trimmed
5 cm
Factory C
Peeled
Cut
Factory A
Trimmed
5 cm
Factory C
Peeled
Cut
Factory A
Trimmed
5 cm
Factory C
Peeled
Cut
Factory A
Trimmed
5 cm
Factory C
Peeled
Cut
Factory A
Factory C
5 mm
5 mm 5 cm
Fractures
log
CF
U/g
afte
r 1
day
in M
AP
at 5
o C
0
1
2
3
4
5
6
7
Factory A
Factory B
Factory C
Coliforms Lacticacid bacteria
Yeast& Mold
Effect of processing on microbial load
Unit operation
Effect of processing on sensory quality
Unit operation
Se
nso
ry s
co
res f
rom
lo
w t
o h
igh
0
2
4
6
8
10
12
14 Household
Factory A
Factory B
Factory C
c
a
b
a
c
a
b
ab
Orange colour Wet surface
0
2
4
6
8
10
12
14
a
aa
b
a
bb
c
Carrot flavour Sweetness Juiciness
aa a
b
pinene
Vo
lati
le c
on
ten
t (n
g/g
fre
sh w
eig
ht)
1
10
100
1000
Control (cut)
Cut
Cut+spin
Cut+wash+spin
terpinolene caryophyllene
Effect of processing on aroma volatiles and sensory quality
Edelenbos et al. (2010) Acta Hort 876
Washing to reduce total microbial load Washing
Storage days at 4 oC
0 2 4 6 8 10
Mic
rob
ial l
oad
(lo
g C
FU
/g)
0
1
2
3
4
5
6
7
8
9
Control
Pre-wash water
Pre-wash chlorine
Pre-wash ozone
Washed sticks chlorine
Adapted from Klaiber et al. 2004
Total sugars
Control/pre-wash 6.3%
Washed sticks 5.2%
Washing to reduce microbial load
A B C
A
C B
Washing
Phytochemicals in carrots
Polyacetylenes
Isocoumarins
Phenolic acids
Some phytochemicals are simply removed in the peeling process
Peeling
Effect of processing on polyacetylenes
Parsnip discs
Peeling
Knife hand
Fine abrasion machine
Coarse abrasion machine
Carrot discs
Effect of peeling on phenolic acids
‘White blush’ in root vegetables
Trimmed
5 cm
Factory C
Peeled
Cut
Factory A
Chitosan-based coating to overcome ‘white blush’
Pre-packaging
6 mm carrot sticks
Packaging to maintain the initial sensory profile Packaging
Edelenbos et al. (2010) Acta Hort 876 Storage time (days)
Ga
s c
om
po
siti
on
(%
)
0
1
2
3
4
5
Carrot odor (**)
Sour odor (***)
Carrot flavor (*)
Sweetness (ns)
Fermented/sour flavor**
Juiciness (ns)
Day 0 8 days in perf film 8 days in non-perf film
Packaging
Packaging to prolong shelf-life Swede cubes
a
cb
b
aa
b ba b b
a
Days
Sw
eetn
es
s f
ra l
ow
to
hig
h
0
1
2
3
4
5
6
7
8
9
10
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a
cb
b
aa
b ba b b
a
Days
To
tal su
gars (
g/1
00 g
FW
)
4.5
5.0
5.5
6.0
6.5
7.0
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a aa
b bb
b
AB
AB
AAB
Packaging
Effect of time, temperature and packaging on quality
a
cb
b
aa
b ba b b
a
Days
To
tal
su
gars
(g
/10
0 g
FW
)
4.5
5.0
5.5
6.0
6.5
7.0
5 d
10 d
5 oC
10 oC
MA1
MA2
MA2-5%
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a aa
b bb
b
AB
AB
AAB
a
cb
b
aa
b ba b b
a
Days
To
tal su
gars
(g
/100 g
FW
)
4.5
5.0
5.5
6.0
6.5
7.0
5 d
10 d
5 oC
10 oC
MA1
MA2
MA2-5%
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a aa
b bb
b
AB
AB
AAB
a
cb
b
aa
b ba b b
a
Days
To
tal
su
gars
(g
/10
0 g
FW
)
4.5
5.0
5.5
6.0
6.5
7.0
5 d
10 d
5 oC
10 oC
MA1
MA2
MA2-5%
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a aa
b bb
b
AB
AB
AAB
Adapted from:
Sugars Sweetness
Sc
ore
fro
m lo
w t
o h
igh
Packaging
a
cb
b
aa
b ba b b
a
Whiteness
Days
Sc
ore
fra
lo
w t
o h
igh
0
1
2
3
4
5
6
7
8
9
10
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
ab
A
a a aaa
B B
AABAB
a
cb
b
aa
b ba b b
a
Days
To
tal
su
gars
(g
/10
0 g
FW
)
4.5
5.0
5.5
6.0
6.5
7.0
5 d
10 d
5 oC
10 oC
MA1
MA2
MA2-5%
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a aa
b bb
b
AB
AB
AAB
a
cb
b
aa
b ba b b
a
Days
To
tal su
gars
(g
/100 g
FW
)
4.5
5.0
5.5
6.0
6.5
7.0
5 d
10 d
5 oC
10 oC
MA1
MA2
MA2-5%
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a aa
b bb
b
AB
AB
AAB
a
cb
b
aa
b ba b b
a
Days
To
tal
su
gars
(g
/10
0 g
FW
)
4.5
5.0
5.5
6.0
6.5
7.0
5 d
10 d
5 oC
10 oC
MA1
MA2
MA2-5%
Temperature Packaging
Swede Turnip Swede Turnip Swede Turnip
a aa
b bb
b
AB
AB
AAB
Whiteness (the higher the score the less enzymatic browning)
Sc
ore
fro
m lo
w t
o h
igh
Effect of time, temperature and packaging on quality
PROCESSING OF ROOT VEGETABLES
Peeling Cutting ± Washing Centrifugat.
±Pre-packaging treatment
Packaging
Effects on:
•The physical properties
•Wounding & oxidation
•Vapor exchange
•Constituents & microbial load
•Leakage
•Enzymatic
browning
•Microbial load
•Moisture
retention
•Quality
retention
Variation in the unit operation
•Abrasion peeling
•Knife peeling
•Knife cutting,
slicing,
dicing &
shredding
•Chemical
treatments
•Physical
•treatments
•Gas
transmission
rates
•Edible coatings
RESEARCH NEEDS
Appropriateness of cultivars/colored
types/tissue age at processing.
Gentle processing/efficient
decontamination to maintain sensory
quality and safety.
Better methods to evaluate the direct
effects of processing on quality.
CONCLUSIONS
Root vegetables contain dietary fibers, sugars and
phytochemicals. Are low in vitamin C.
Peeling removes the protective skin so
microorganisms can enter. Specific phytochemicals
are removed.
‘White blush’ develops in wounded tissue due to
loss of moisture from the surface.
Harsh handling/abiotic stress enhance phenolic
metabolism.
CONCLUSIONS
Fresh-cut root vegetables are prone to:
- enzymatic browning in white/light-colored tissue
- white blush in dark-colored tissue
- loss of aroma and flavor especially in carrots,
parsnips, root parsley and celeriac if finely cut and
washed
- loss of sweet taste if finely cut and washed
- fermentation if oxygen get too low in the package
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