Journal of Horticultural Science & Biotechnology (2009) ISAFRUIT Special Issue 89–95
Characterisation of the chemical composition of scab-resistant apple
pomaces
By KRZYSZTOF KOŁODZIEJCZYK1*, MONIKA KOSMALA1, JOANNA MILALA1,
MICHAŁ SÓJKA1, MAŁGORZATA UCZCIWEK1, BOGUSŁAW KRÓL1, JAROSŁAW
MARKOWSKI2 and CATHERINE M.G.C. RENARD3
1
Technical University of Łódź, Institute of Chemical Technology of Food, ul. B. Stefanowskiego 4/10,
90-924 Łódź, Poland
2
Research Institute of Pomology and Floriculture, ul. Pomologiczna 18, 96-100 Skierniewice, Poland
3
UMR 408 Sécurité et Qualité des Produits d’Origine Végétale, INRA, Université d’Avignon, 84000
Avignon, France
(e-mail : kkolodz@p.lodz.pl)
(Accepted 31 August 2009)
SUMMARY
Pomaces obtained during the production of cloudy or clear juice from scab-resistant apple cultivars (28 harvested in
2006, and 23 harvested in 2007) were studied as a source of nutritionally important components. It was shown that the
average yield of pomace during the production of cloudy juice was 6.4% (w/w), and 4.9% (w/w) for clear juice
pressing. The average total dietary fibre (TDF) contents were 48.4% (w/w) and 52.4% (w/w) for cloudy and clear juice
pomaces, respectively. Ten pomaces from cloudy apple juice production, and 12 obtained from clear juice production,
contained ≥ 2,000 mg kg–1 of polyphenols. ‘Ariwa’ and ‘Rajka’ are apple cultivars suitable for juice production and their
pomaces are characterised by having high contents of TDF [50.9% (w/w) and 51.1% (w/w), respectively], with aboveaverage polyphenol and quercetin glycoside concentrations. The mean contents of quercetin glycosides for pomaces
from all apple cultivars was 994 mg kg–1 after clear juice production, and 908.2 mg kg–1 after cloudy juice production.
‘Topaz’, which became a popular commercial apple cultivar in Europe, was the best source of health-promoting
components. Its pomace was the richest source of polyphenols among all 28 cultivars studied. It contained ≥ 2,000 mg
kg–1 quercetin glycosides in both its clear and cloudy juice pomaces.
rowing scab-resistant apple (Malus domestica
Borkh.) cultivars allows for a reduction in pesticides
usage and a decrease in environmental damage (Czynczyk
et al., 2005). Scab-resistant cultivars are heritably immune
to apple scab, a major disease of the fruit and foliage of
apples that requires several applications of fungicide to
control on non-resistant cultivars. Many European
Governments are interested in reducing pesticide use to
limit problems of environmental pollution (Guillino and
Kuijpers, 1994). The consumption of apples, and apple
products (e.g., juices) made from scab-resistant apples, due
to their lower levels of potentially toxic residues, may also
become appealing to consumers.
During the process of apple juice production, pomace
is obtained as a waste product. However, considering
that it is a good source of dietary fibre and polyphenols
(Schieber et al., 2003), it may be regarded as a coproduct. Dietary fibre plays an important role in the
prevention and treatment of obesity, arteriosclerosis,
coronary heart diseases, and cancers of the large
intestine (Jenkins et al., 2004; Galisteo et al., 2008).
Dietary fibre increases the time for glucose absorption,
flattening the glucose profile by which insulin secretion
is decreased, thus helping to prevent diabetes (Giacco
et al., 2002). Dietary fibre binds hydrochloric acid in the
stomach, as well as metal ions and cholesterol, it
increases faecal bulk, improves intestinal peristalsis, and
G
*Author for correspondence.
stimulates the growth of positive microflora in the gut
(Nawirska and Kwaśniewska, 2005). Sub-classes of
polyphenols in apple pomace are: hydroxycinnamates,
dihydrochalcones, and flavonoids (i.e., flavanols and
flavonols; Schieber et al., 2003). It has been claimed that
the consumption of flavonoid-rich food is associated
with lower incidences of heart disease, cancer, and other
chronic diseases connected with increased oxidative
stress, thanks to the high anti-oxidant activity expressed
by polyphenols (Lotito and Frei, 2006; Aldini et al., 2003;
Hollman et al., 1995). The chemical structure of
polyphenols enables them to behave as anti-oxidants,
free radical scavengers, and metal ion chelators that are
more powerful than vitamin C (Łata et al., 2008).
Apple pomace can be considered as a raw material for
the direct production of dietary fibre, or used for the
production of polyphenol concentrates, which could be
used to design new functional food products (Larrauri,
1999; Kołodziejczyk et al., 2007). Pectin production is a
classical use of apple pomace, if pectolytic enzymes were
not used as pressing aids (May, 1990; Voragen et al.,
1986). Other uses which have been proposed for pomace
include: as a fuel (Jewell and Cummings, 1984), an animal
feed (Oltjen et al., 1977), a raw material for citric acid
production (Hang and Woodsams, 1984), a pie filling and
in oatmeal cookies (Carson et al., 1994), as a product for
ethanol fermentation, apple wax production, or ion
exchange resin (Kennedy et al., 1999). Significant
differences in composition between apple cultivars, in
Composition of apple pomace
90
the processes of enzyme treatment (“enzymation”), or in
the pomace liquefaction regime chosen during juice
production, different enzyme activities, and/or
time/temperature profiles, all influence pomace quality
(Kennedy et al., 1999) and the final product, which is
usually a concentrated apple juice, or a clear or cloudy
juice. Cloudy juices are characterised by their turbidity
and are regarded as containing more polyphenols and
higher dietary fibre contents than typical clear juices,
which contain only minor amounts of phytocomponents
(Will et al., 2008; Oszmiański et al., 2007).
The aim of this work was to evaluate pomaces
obtained from scab-resistant apples grown over two
successive seasons, with respect to their contents of
polyphenols, dietary fibre, proteins, and sugars. Another
matter of interest was the production of apple juices that
contained as many biologically-active components as
possible. Therefore, as well as standard juice production
methods using enzymes, the production of cloudy juices
was carried out with no enzymes added, allowing us to
investigate two different kinds of pomace. Special
attention was paid to pomaces obtained from cultivars
yielding the best juices (i.e., ‘Florina’, ‘Ariwa’, ‘Rajka’,
‘Novamac’ and ‘Gold Milenium’).
MATERIALS AND METHODS
Pomaces were collected during juice production from
scab-resistant apple cultivars obtained from the
Research Institute of Pomology and Floriculture,
Skierniewice, Poland. In 2006, pomaces from 28 apple
cultivars (Table I) were investigated; whereas, in 2007,
only 23 cultivars could be used, due to a severe late frost
and lack of experimental material (Table I).
TABLE I
Mean yields of freeze-dried apple pomaces [%(w/w)] obtained from 28
scab-resistant apple cultivars harvested in 2006 and in 2007
Cultivar
‘Ahrista’
‘Anagold’
‘Antonowka’
‘Ariwa’
‘Shampion’
‘Enterprise’
‘Florina’
‘Free Redstar’
‘Freedom’
‘Gerlinde’
‘Gold Milenium’
‘Gold Star’
‘Gold Star’ eco
‘Medea’
‘Melfree’
‘Novamac’
‘Rajka’
‘Rebella’
‘Regina’
‘Reglindis’
‘Renora’
‘Retina’
‘Rewena’
‘Rosana’
‘Rubinola’
‘Sawa’
‘Selena’
‘Topaz ‘
Minimum
Maximum
Mean
Pomace from cloudy
juice production
5.92*
7.20 ± 1.30
5.35*
4.65 ± 0.05
8.35 ± 0.65
6.40 ± 0.10
5.20 ± 0.10
8.10 ± 0.30
6.35 ± 0.05
5.40 ± 0.70
7.10 ± 0.30
8.00*
4.40*
5.92*
6.95 ± 0.05
4.60 ± 0.30
5.40 ± 1.00
5.55 ± 0.35
6.70 ± 1.50
7.55 ± 0.15
8.40 ± 1.00
8.00 ± 0.90
5.70 ± 0.40
5.70 ± 0.60
5.50 ± 1.20
5.80 ± 1.80
4.45 ± 0.35
4.80 ± 0.10
4.50
8.40
6.40 ± 1.30
Pomace from clear
juice production
5.08*
5.00 ± 0.10
4.15*
4.25 ± 0.05
5.35 ± 0.25
5.80 ± 0.20
4.80 ± 0.10
7.00 ± 0.10
5.50 ± 0.10
4.90 ± 0.60
5.10 ± 0.00
6.77*
3.90*
4.73*
5.10 ± 0.00
3.45 ± 0.05
4.70 ± 0.90
5.00 ± 0.50
5.60 ± 0.94
6.80 ± 0.30
7.30 ± 0.30
5.40 ± 0.10
5.20 ± 0.20
4.22 ± 0.02
4.70 ± 0.60
3.85 ± 0.05
3.70 ± 0.10
4.20 ± 0.20
3.50
7.30
4.90 ± 0.90
Average dry matter was 97% (w/w). Mean values marked with an
asterisk are from 2006 only.
Apples were collected at harvest maturity and
delivered to cold storage. Within a few days of storage
under normal atmosphere, fruits were sorted to obtain
representative samples. One 5 kg sample of each fruit
was ground using a Fryma perforated disc (i.e., a screen
with openings 6-mm in diameter was used for
disintegration; BASIS 91/55; Fryma-Maschinen AG,
Rheinfeld, Switzerland). At least two separate samples of
200 g of ground apple were de-pectinised using
100 mg kg–1 Rohapect MA PLUS (AB Enzymes,
Darmstadt, Germany), then pressed using an Instron
4303 Universal Testing Machine (Instron 4303; Instron
Limited, High Wycombe, UK) equipped with a special
attachment for juice pressing of 200 g samples.
Two further 200 g samples of ground material were
pressed directly, yielding cloudy juices. Pomaces
obtained after clear juice production (CL pomace) and
cloudy juice production (CD pomace) were frozen
immediately, then freeze-dried.
Duplicate samples of each pomace were analysed for
total dietary fibre, total protein content, soluble sugars,
and polyphenol contents. In addition, polyphenol
contents were determined in the fruit of four selected
cultivars (‘Ariwa’, ‘Gold Milenium’, ‘Rajka’, and ‘Topaz’)
in order to calculate the proportion of polyphenols
retained in the corresponding pomace. The fruits to be
tested were prepared by grinding in liquid nitrogen, then
extracted and analysed by HPLC, as described below.
Extraction of apple fruit and pomace
Extraction was performed as follows: 0.5 g of each
freeze-dried sample was mixed with 4 ml of solvent [70%
(v/v) methanol] and sonicated for 15 min After
centrifugation at 4,800 g for 5 min, the supernatant was
collected and the residue was re-extracted twice with 3
ml of the same solvent. The pooled extracts were made
up to 10 ml. The methanolic extracts, containing most of
the soluble polyphenols were analysed by HPLC.
HPLC analysis of phenolic compounds
HPLC analyses were carried out using a Dionex
HPLC system with a Diode Array Detector (UVD340U;
Dionex, Germering, Germany) equipped with a 150 mm
2.00 mm Phenomenex® Synergi, 4 µm, Fusion-RP 80A
column (Phenomex, Torrance, CA, USA).
The mobile phase consisted of 0.05% (w/v) phosphoric
acid (solvent A) and 0.05% (w/v) phosphoric acid in
acetonitrile (solvent B). A gradient was applied at a flow
rate of 0.25 ml min–1. After stabilisation for 10 min with
4% (v/v) B, a gradient of 4 – 50% (v/v) B over 0 – 33 min,
from 33 – 34 min of 50% (v/v) B, and from 34 – 35 min of
4% (v/v) B was applied. The column temperature was
kept at 25°C. Chlorogenic acid, epicatechin, hyperoside,
phloridzin and quercetin (all from Extrasynthese, Genay,
France) were used as standards to calculate the
concentrations of hydroxycinnamic acids, procyanidins,
quercetin glycosides, phloridzin, and aglycons,
respectively. Hydroxycinnamic acids, procyanidins, and
phlorizin were detected at 280 nm, while quercetin
glycosides and aglycones were detected at 360 nm. The
results were quoted as the sum of polyphenols and the
sum of quercetin glycosides, which are considered to be
particularly biologically-active groups among all apple
polyphenols (Lu and Fo, 2000).
K. KOŁODZIEJCZYK, M. KOSMALA, J. MILALA, M. SóJKA, M. UCZCIWEK, B. KRóL, J. MARKOWSKI and
C. M. G. C. RENARD
Total dietary fibre (TDF)
TDF was determined according AOAC Official
Method 993.21 (AOAC, 1995b).
HPLC analysis of sugars
Samples were prepared for sugar analysis by HPLC as
follows: 2 g of ground pomace sample, 20 ml water, and
3 g CaCO3 were mixed, boiled for 5 min, chilled, madeup to 50 ml, and filtered. The extract was desalted on an
ion exchange column (two parts of Amberlite IRA 400
anion exchanger to one part of Amberlite IR 120 cation
exchanger). After centrifugation at 4,800 g for 5 min,
the solution was analysed by HPLC. To separate sugars,
a 300 mm 7.6 mm Aminex HPX-87C column
(Bio-Rad, Reinach, Switzerland) was used. The mobile
phase was water, at an isocratic flow rate of 0.5 ml min–1,
and a column temperature of 70°C. Glucose, fructose,
saccharose, and sorbitol (Sigma, St Louis, MO, USA)
91
were used as standards. Quantitative analysis was carried
out using a Knauer system with an RI detector (Knauer,
Berlin, Germany).
Protein was determined by the AOAC 920.152
method.
RESULTS AND DISCUSSION
The average yield of pomace obtained during clear
juice production was 4.9 ± 0.9% (w/w), and was lowest
for ‘Novamac’ [3.5% (w/w)] and highest for ‘Renora’
[7.3% (w/w)]. During cloudy juice production, the
average yield of pomace was 6.4 ± 1.3% (w/w), and was
lowest for ‘Sawa’ 4.5% (w/w) and highest for ‘Renora’
8.4% (w/w) (Table I). Three scab-resistant apple
cultivars: ‘Ariwa’, ‘Rajka’ and ‘Topaz’, yielded ca. 5%
(w/w) of pomace during the production of both clear and
cloudy juices. All three cultivars could be used to
TABLE II
Mean sugar contents (g 100 g–1 DW) in pomaces derived from 28 scab-resistant apple cultivars
Cultivar
‘Ahrista’
Juice
CL
CD
‘Angold’
CL
CD
‘Antonowka’
CL
CD
‘Ariwa’
CL
CD
‘Shampion’
CL
CD
‘Enterprise’
CL
CD
‘Florina’
CL
CD
‘Free Redstar’
CL
CD
‘Freedom’
CL
CD
‘Gerlinde’
CL
CD
‘Gold Milenium’ CL
CD
‘Gold Star’
CL
CD
‘Gold Star’ eco
CL
CD
‘Medea’
CL
CD
‘Melfree’
CL
CD
‘Novamac’
CL
CD
‘Rajka’
CL
CD
‘Rebella’
CL
CD
‘Regina’
CL
CD
‘Reglindis’
CL
CD
‘Renora’
CL
CD
‘Retina’
CL
CD
‘Rewena’
CL
CD
‘Rosana’
CL
CD
‘Rubinola’
CL
CD
‘Sawa’
CL
CD
‘Selena’
CL
CD
‘Topaz’
CL
CD
Sucrose (S)
Glucose (G)
Fructose (F)
Sorbitol
G : F ratio
Total (S+G+F)
0.6*
0.5*
15.2 ± 4.0
10.3 ± 2.0
4.3*
5.6*
1.2 ± 0.1
1.0 ± 0.0
12.0 ± 0.5
8.2 ± 0.5
17.9 ± 6.0
18.6 ± 7.0
14.9 ± 3.0
13.3 ± 2.0
14.3 ± 3.0
11.2 ± 0.5
13.0 ± 3.0
10.9 ± 3.0
12.3 ± 5.0
11.3 ± 5.0
18.3 ± 3.0
12.2 ± 4.0
20.0*
18.4*
10.6*
11.4*
12.6*
10.9*
21.3 ± 8.0
11.2 ± 4.0
17.3 ± 2.0
11.1 ± 4.0
11.5 ± 1.0
11.3 ± 1.5
0.7 ± 0.3
0.4 ± 0.2
17.2 ± 1.5
14.7 ± 2.0
2.1 ± 1.0
2.1 ± 1.0
20.9 ± 1.5
17.0 ± 3.5
22.8 ± 1.0
15.7 ± 0.2
1.0 ± 0.5
1.3 ± 0.7
20.8 ± 1.5
14.6 ± 0.5
16.8 ± 5.0
15.2 ± 3.5
15.7 ± 5.2
11.6 ± 2.0
13.8 ± 1.1
14.3 ± 3.0
18.7 ± 3.0
16.8 ± 2.0
9.8*
7.9*
5.2 ± 2.0
4.2 ± 1.0
4.2*
3.6*
11.1 ± 1.0
10.6 ± 2.0
8.5 ± 3.0
6.2 ± 2.0
3.4 ± 2.0
3.8 ± 3.0
4.5 ± 2.0
4.3 ± 1.0
3.5 ± 2.0
3.3 ± 1.0
3.4 ± 1.0
3.1 ± 0.2
7.6 ± 4.0
7.1 ± 4.0
4.5 ± 1.0
3.3 ± 0.0
11.0*
10.2*
8.0*
8.3*
3.2*
3.1*
2.9 ± 0.7
1.8 ± 0.5
5.4 ± 0.5
4.1 ± 0.1
3.6 ± 0.3
3.7 ± 0.3
9.5 ± 0.5
8.7 ± 0.0
5.1 ± 0.6
4.6 ± 0.5
16.2 ± 5.0
11.0 ± 0.1
2.6 ± 0.5
2.9 ± 0.5
3.4 ± 0.05
2.7 ± 0.3
9.1 ± 2.0
8.3 ± 1.6
4.6 ± 2.0
3.6 ± 1.0
6.2 ± 2.0
6.0 ± 1.5
5.2 ± 1.0
4.4 ± 0.4
5.4 ± 1.8
4.7 ± 1.0
3.1 ± 0.6
2.7 ± 1.0
18.2*
14.5*
25.4 ± 8.0
19.5 ± 4.0
17.2*
14.5*
20.2 ± 1.0
19.0 ± 1.0
28.2 ± 5.0
19.6 ± 3.5
14.9 ± 6.0
15.5 ± 7.0
16.7 ± 6.0
15.1 ± 2.0
17.5 ± 9.0
15.9 ± 5.0
17.0 ± 2.0
14.6 ± 2.2
17.3 ± 6.0
16.2 ± 5.0
19.0 ± 4.0
15.1 ± 2.0
27.7*
25.2*
17.6*
18.4*
17.0*
15.3*
16.7 ± 4.0
10.8 ± 2.0
17.2 ± 0.5
12.2 ± 0.5
14.8 ± 0.5
14.9 ± 1.0
20.1 ± 2.5
18.3 ± 1.0
19.0 ± 4.0
16.5 ± 4.0
30.6 ± 10.0
21.8 ± 0.2
13.1 ± 0.5
13.6 ± 1.0
20.0 ± 1.5
14.5 ± 0.4
16.7 ± 2.0
14.9 ± 2.5
15.7 ± 3.5
11.6 ± 2.0
22.0 ± 8.0
20.3 ± 5.0
25.7 ± 8.0
19.9 ± 2.5
19.0 ± 4.5
15.4 ± 1.0
13.1 ± 0.5
11.8 ± 1.0
0.9*
0.7*
1.3 ± 0.0
1.1 ± 0.0
0.8*
0.7*
1.0 ± 0.0
0.9 ± 0.0
2.1 ± 0.5
1.6 ± 0.3
2.5 ± 1.0
2.6 ± 1.0
1.9 ± 1.0
1.7 ± 0.0
2.0 ± 0.4
1.7 ± 0.1
1.5 ± 0.2
1.4 ± 0.4
1.1 ± 0.1
1.1 ± 0.1
2.3 ± 0.5
1.9 ± 0.2
0.9*
0.8*
1.0*
1.0*
1.5*
1.3*
1.4 ± 0.5
0.8 ± 0.3
1.0 ± 0.0
0.9 ± 0.2
1.4 ± 0.5
1.4 ± 0.4
1.1 ± 0.4
1.0 ± 0.4
0.6 ± 0.0
0.6 ± 0.0
3.4 ± 1.7
2.4 ± 0.3
1.2 ± 0.1
1.0 ± 0.2
3.0 ± 0.2
2.1 ± 0.1
1.8 ± 0.2
1.9 ± 0.4
1.2 ± 0.2
1.0 ± 0.0
1.8 ± 1.0
1.7 ± 0.5
1.6 ± 0.5
1.3 ± 0.3
1.0 ± 0.2
0.9 ± 0.0
1.1 ± 0.1
1.1 ± 0.1
0.54*
0.54*
0.20 ± 0.00
0.20 ± 0.00
0.24*
0.25*
0.55 ± 0.10
0.56 ± 0.10
0.30 ± 0.05
0.31 ± 0.05
0.23 ± 0.10
0.24 ± 0.30
0.27 ± 0.20
0.29 ± 0.10
0.21 ± 0.05
0.21 ± 0.05
0.21 ± 0.05
0.22 ± 0.10
0.39 ± 0.20
0.39 ± 0.15
0.24 ± 0.10
0.22 ± 0.10
0.40*
0.40*
0.45*
0.45*
0.19*
0.20*
0.17 ± 0.01
0.16 ± 0.02
0.31 ± 0.01
0.34 ± 0.01
0.24 ± 0.0
0.25 ± 0.0
0.48 ± 0.3
0.48 ± 0.2
0.29 ± 0.3
0.28 ± 0.30
0.53 ± 0.00
0.53 ± 0.00
0.20 ± 0.30
0.20 ± 0.05
0.17 ± 0.01
0.20 ± 0.30
0.55 ± 0.05
0.56 ± 0.20
0.27 ± 0.05
0.29 ± 0.05
0.28 ± 0.00
0.29 ± 0.01
0.21 ± 0.05
0.22 ± 0.05
0.28 ± 0.02
0.30 ± 0.40
0.23 ± 0.04
0.23 ± 0.05
29.5*
23.6*
47.0 ± 8.0
35.0 ± 7.0
26.5*
24.4*
32.7 ± 2.0
31.5 ± 2.0
50.1 ± 10.0
35.3 ± 6.0
38.9 ± 15.0
40.4 ± 10.0
37.9 ± 3.0
34.3 ± 4.0
37.2 ± 15.0
32.1 ± 5.0
35.0 ± 4.0
30.0 ± 5.0
38.3 ± 6.0
35.7 ± 5.0
44.1 ± 3.0
32.4 ± 4.0
59.6*
54.6*
37.2*
39.1*
34.3*
30.6*
42.3 ± 8.0
24.6 ± 7.0
40.8 ± 0.5
28.2 ± 2.5
31.3 ± 1.0
31.2 ± 2.5
31.4 ± 4.0
28.4 ± 2.0
41.9 ± 5.0
36.3 ± 6.0
52.1 ± 13.0
36.2 ± 2.5
37.8 ± 0.5
34.5 ± 5.0
48.1 ± 1.0
34.9 ± 0.5
28.4 ± 4.0
26.5 ± 5.0
42.0 ± 7.0
30.5 ± 4.0
46.2 ± 15.0
43.1 ± 5.0
48.1 ± 10.0
37.2 ± 5.0
39.1 ± 8.0
35.2 ± 2.0
35.7 ± 2.5
32.3 ± 0.3
Mean values marked with an asterisk are from 2006 only. CL, clear juice pomace, CD, cloudy juice pomace.
92
Composition of apple pomace
ratios of ≤ 0.2, whereas ‘Rewena’, ‘Reglindis’, ‘Rebella’,
‘Gold Star’, ‘Ariwa’, and ‘Ahrista’ had G:F ratios of
≥ 0.55. For apple juice, an acceptable G:F ratio lies
between 0.3 – 0.5. Considering that the distribution of
sugars was similar between pomace and juice, it may be
concluded that some scab-resistant cultivars are unique.
Published data on the sugar contents of apple pomaces
show that saccharose contents range from 1.42% (w/w)
(Hours et al., 1988a) to 11.16% (w/w) (Wang and
Thomas, 1989); fructose from 13.6% (w/w) (Waugh,
1981) to 30.05% (w/w) (Wang and Thomas, 1989); and
glucose from 6.1% (w/w) (Waugh, 1981) to 13.3% (w/w)
(Wang and Thomas, 1989).
Pomaces from ‘Ariwa’, ‘Ahrista’, and ‘Rewena’, which
have low saccharose contents and are rich in fructose, can
be regarded as dietetic or diabetic products. On the other
hand, a high saccharose content in pomace (e.g., ‘Topaz’)
can lead to a lower hygroscopic character of the product.
Content (mg kg–1)
produce either clear or cloudy juices that are both
environment-friendly and healthy.
The sugar compositions of scab-resistant apple
pomaces varied greatly, both quantitatively and
qualitatively (Table II). The total contents of sugars in
CD pomaces was, on average, 38.9 ± 7.9% (w/w), with a
range from 26.5% (‘Antonowka’) to 59.6% (‘Gold Star’).
The average value for CL pomaces was 34.0 ± 6.6%
(w/w), whereas the minimum value was 23.6% (w/w) for
‘Ahrista’ and the maximum was 54.6% (w/w) for ‘Gold
Star’. A few of the pomaces (‘Ahrista’, ‘Reglindis’,
‘Rewena’, ‘Ariwa’, and ‘Rebella’) contained ≤ 1 g 100 g–1
saccharose. ‘Gold Milenium’, ‘Renora’, ‘Rosana’, ‘Topaz’,
and ‘Enterprise’ contained ≥ 17 g 100 g–1 saccharose.
‘Angold’, ‘Gold Star’, ‘Rebella’, ‘Reglindis’, and
‘Rubinola’ contained ≥ 20 g 100 g–1 fructose. The
glucose:fructose ratio (G:F) varied widely, from
0.17 to 0.56. ‘Retina’, ‘Medea’, and ‘Melfree’ had G:F
Content (mg kg–1)
Cultivar
Cultivar
FIG. 1
The mean protein and total dietary fibre (TDF) contents (g 100 g–1) in 2006 and 2007 in CD (Panel A) and CL (Panel B) apple pomaces. Mean values
for cultivars marked with an asterisk in Table II are from the 2006 data only.
K. KOŁODZIEJCZYK, M. KOSMALA, J. MILALA, M. SóJKA, M. UCZCIWEK, B. KRóL, J. MARKOWSKI and
C. M. G. C. RENARD
The total dietary fibre (TDF) content of pomaces
obtained during cloudy apple juice production was, on
average, 48.4 ± 7 g 100 g–1. The lowest was 34.3 g 100 g–1
for ‘Retina’, and the highest was 61.3 g 100 g–1 for
‘Rebella’. In pomace from clear juice production, the
average value was 52.4 ± 5 g 100 g–1 (Figure 1). The
lowest TDF value was 41.7 g 100 g–1 for ‘Gold Milenium’,
and the highest was 62.5 g 100 g–1 for ‘Rebella’. The
average TDF content of both clear and cloudy pomaces
from cultivars ‘Ariwa’, ‘Rajka’, and ‘Topaz’ was close to
50 g 100 g–1 (with 50.9 ± 0.2; 50.4 ± 1.0; and 51.1 ± 0.3 for
93
CL; and 52.6 ± 7.0; 51.9 ± 2.0; and 49.3 ± 0.2 for CD,
respectively). Both CL and CD pomaces from ‘Ariwa’
and ‘Topaz’ were characterised by having a reproducible
composition in 2006 and in 2007 (Table I; Table II). Data
on industrial apple pomaces usually show a TDF content
of ca. 60% (w/w) in the dried pomace (Kołodziejczyk et
al., 2007; Schieber et al., 2003; Renard and Thibault,
1991). In our study, apples were pressed using an Instron
4303 Universal Testing Machine, which uses a pressure
similar to that used in industry (Banaszczyk and
Płocharski, 1990); but, all cultivars were analysed
4,000
3,500
Content (mg kg–1)
QG
3,000
POLYPHENOLS
2,500
2,000
1,500
1,000
500
0
Cultivar
4,000
Content (mg kg–1)
3,500
3,000
2,500
2,000
1,500
1,000
500
0
Cultivar
FIG. 2
Polyphenol contents (mg kg–1) in CD (Panel A) and CL (Panel B) pomaces from 23 scab-resistant apple cultivars. POLYPH, sum of polyphenols.
QG, sum of quercetin glycosides.
Composition of apple pomace
94
TABLE III
Concentrations of polyphenols and quercetin glycosides (mg kg–1) in fruit and in dried pomace obtained from these fruit, retention of quercetin
glycosides and the sum of polyphenols in the pomace
Fruit†
Dried Pomace‡
Cultivar
Quercetin
glycosides
Total
polyphenols
Type of
pomace
Quercetin
glycosides
‘Ariwa’
62.5
390
‘Gold Milenium’
101.4
425
‘Rajka’
88.9
452
‘Topaz’
106.0
460
CL
CD
CL
CD
CL
CD
CL
CD
38.5
44.5
46.6
59.9
60.8
65.2
82.4
92.4
Retention (%)
Total
polyphenols
97.3
114.8
72.0
96.3
105.1
106.8
149.0
156.0
MEAN CL
MEAN CD
Quercetin
glycosides
Total
polyphenols
61.6
72.2
45.9
59.0
68.4
73.3
77.7
87.0
63 ± 13
73 ± 11
24.9
29.4
16.9
22.6
23.3
23.6
32.4
33.9
24 ± 6
27 ± 5
†
Contents of quercetin glycosides and total polyphenols in 1 kg fruit.
Dried pomace, amounts of quercetin glycosides and total polyphenols in pomace derived from 1 kg of apples. Total polyphenols was calculated from
the integrated peaks of the HPLC traces.
‡
separately to allow comparisons of the yields of juice and
pomaces. Figure 1 shows that pomaces from 11 CD and
13 CL juices fulfilled the minimum requirements for
dietary fibre preparations (Larrauri, 1999).
The pomaces also varied in protein content (Figure 1)
from 2.60% (w/w) for ‘Angold’, to 6.36% (w/w) for ‘Gold
Star’ for CD pomaces [the average for all cultivars being
4.38 ± 0.94% (w/w)], and for CL pomaces from 2.47%
(w/w) for ‘Melfree’, to 7.11% (w/w) for ‘Gold Star’, with
an average of 4.89 ± 0.96% (w/w). ‘Anagold’, ‘Freedom’,
‘Regina’, and ‘Melfree’ had ≤ 3.8% (w/w) total protein.
While ‘Gerlinde’, ‘Ariwa’, ‘Gold Star’, ‘Rewena’, and
‘Novamac’ had ≥ 5% (w/w) total protein, and ‘Topaz’ and
‘Ariwa’ had 5% (w/w) total protein. Published data on
total protein contents in apple pomace range from
1.8% (w/w) (Hours et al., 1988b) to 8.0% (w/w) (Nikolic
and Jovanovic, 1986).
Ten of the freeze-dried pomaces from cloudy juice
production, and 12 obtained from clear apple juice
production, contained ≥ 2,000 mg kg–1 polyphenols
(Figure 2). The apple cultivars ‘Sampion’, ‘Sawa’,
‘Rubinola’, and ‘Florina’ belonged to the group with the
highest polyphenols contents. ‘Topaz’, ‘Sawa’, ‘Rewena’,
‘Rajka’, and ‘Novamac’ were rich in quercetin glycosides,
with amounts ≥ 1,000 mg kg–1.
The quercetin glycosides in apple pomaces varied
quantitatively, with mean contents of 994 mg kg–1 for CL,
and 908.2 mg kg–1 for CD. ‘Reglindis’ pomace was
characterised by having the lowest contents of quercetin
glycosides for both methods of processing, (475.2 mg kg–1
for CL and 385 mg kg–1 for CD), while ‘Topaz’ showed
the highest concentrations with 2,202.8 mg kg–1 for CL
and 2,083 mg kg–1 for CD.
On the basis of the yields of pomaces (Table I), and the
concentrations of polyphenols and quercetin glycosides
in fruit and the corresponding pomace, the retention of
polyphenols in the pomaces were calculated (Table III).
The average retention of glycosides was 63 ± 13% for CL
and 73 ± 11% for CD, while the retention of all
polyphenols was 24 ± 6% and 27 ± 5% for CL and CD,
respectively. Pomaces obtained from the selected apple
cultivars ‘Florina’, ‘Ariwa’, ‘Rajka’, and ‘Gold Milenium’
were a good source of dietary fibre and polyphenols,
especially quercetin glycosides, which prevent the
oxidation of low-density lipoproteins in vivo (Hollman,
1995). This did not apply to ‘Novamac’, since it was
characterised by the lowest pomace yield, with an average
polyphenol concentration among the cultivars studied,
and it is a poor source of dietary fibre. ‘Topaz’ pomace
had the highest polyphenol concentration and should be
propagated more widely as it was also characterised by
reliable cropping (Czynczyk, 2005) and its pomace was
the richest source of polyphenols amond all the scabresistant cultivars studied.
CONCLUSIONS
Two years of investigation on freeze-dried scabresistant apple pomaces led to the following conclusions:
• Freeze-dried ground pomace is characterised by
having good stability and a diversity of contents of
phytocomponents, dietary fibre, and nutritional
components such as total protein and sugars.
• On the basis of the results obtained (reproducible
dietary fibre contents in pomaces obtained during clear
or cloudy juice production, and high contents of
polyphenols) ‘Ariwa’ and ‘Rajka’ were considered good
cultivars.
• For their high polyphenol concentrations, especially
quercetin glycosides, ‘Sawa’, ‘Rubinola’, ‘Rewena’,
‘Enterpise’, and ‘Florina’ could also be considered to be
good sources of biologically-active nutritional
components.
The ISAFRUIT Project is funded by the European
Commission under Thematic Priority 5 – Food Quality
and Safety of the 6th Framework Programme of RTD
(Contract No. FP6-FOOD-CT-2006-016279).
Disclaimer: Opinions expressed in this publication
may not be regarded as stating an official position of the
European Commission.
K. KOŁODZIEJCZYK, M. KOSMALA, J. MILALA, M. SóJKA, M. UCZCIWEK, B. KRóL, J. MARKOWSKI and
C. M. G. C. RENARD
95
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