ArticlePDF Available

The effect of long-term frozen storage on the nutraceutical compounds, antioxidant properties and color indices of different kinds of berries

Authors:
  • Banat's University of Agricultural Sciences and Veterinary Medicine "King Michael I of Romania" from Timisoara

Abstract and Figures

The effects of the Individual Quick Freezing (IQF) process and frozen storage at -18° C up to 10 months, on the nutraceutical compounds, antioxidant properties and color indices of various berries (blueberry, red raspberry and blackberry) have been evaluated. Samples were extracted and analyzed for their total phenolics content, total monomeric anthocyanins, vitamin C, antioxidant activity and color indices. Total anthocyanins and color indices were evaluated by using pH-differential method, total phenolics content was measured using Folin-Ciocalteu procedure, vitamin C content using 2,6-dichlorophenolindophenol method and antioxidant activity using ferric-reducing antioxidant power (FRAP) assay. Blueberry contains the highest amounts of polyphenols, anthocyanins and antioxidant activity among the berries studied. The highest content of vitamin C was found in fresh raspberry. After freezing, no significant difference was observed for investigated nutraceuticals and color of berries, because the IQF is a rapid and non-destroying preservation method. Results showed that the frozen storage up to 4 months did not significantly affect the bioactive compounds and color indices of berries. The degradation of these characteristics was not recorded more than 23% during six months of storage. After 10 months, the content of polyphenols decreased up to 28-47% of the initial value; the total anthocyanins was found in proportion of 80-91%, and the ascorbic acid content was kept at 62-76%. After 10 months of storage the smallest loss of antioxidant activity was recorded for blueberries (approximately 23%) and the biggest loss for raspberries (approximately 37%). The results showed a positive correlation between antioxidant capacity and polyphenols, vitamin C and anthocyanins content. The correlation coefficient between FRAP and the total phenolics was higher than the correlation coefficient between FRAP and total anthocyanins or FRAP and vitamin C for all investigated berries.
Content may be subject to copyright.
54 Journal of Food, Agriculture & Environment, Vol.8 (1), January 2010
www.world-food.net
Journal of Food, Agriculture & Environment Vol.8 (1) : 54-58. 2010
WFLPublisher
Science and Technology
Meri-Rastilantie 3 B, FI-00980
Helsinki, Finland
e-mail: info@world-food.net
The effect of long-term frozen storage on the nutraceutical compounds, antioxidant
properties and color indices of different kinds of berries
Mariana-Atena Poiana *, Diana Moigradean, Diana Raba, Liana-Maria Alda and Mirela Popa
Banat’s University of Agricultural Sciences and Veterinary Medicine, Food Technology Department, Calea Aradului 119,
300645, Timisoara, Romania. *e-mail: atenapoiana@yahoo.com
Received 23 September 2009, accepted 4 January 2010.
Abstract
The effects of the Individual Quick Freezing (IQF) process and frozen storage at -18°C up to 10 months, on the nutraceutical compounds, antioxidant
properties and color indices of various berries (blueberry, red raspberry and blackberry) have been evaluated. Samples were extracted and analyzed
for their total phenolics content, total monomeric anthocyanins, vitamin C, antioxidant activity and color indices. Total anthocyanins and color
indices were evaluated by using pH-differential method, total phenolics content was measured using Folin-Ciocalteu procedure, vitamin C content
using 2,6-dichlorophenolindophenol method and antioxidant activity using ferric-reducing antioxidant power (FRAP) assay. Blueberry contains the
highest amounts of polyphenols, anthocyanins and antioxidant activity among the berries studied. The highest content of vitamin C was found in
fresh raspberry. After freezing, no significant difference was observed for investigated nutraceuticals and color of berries, because the IQF is a rapid
and non-destroying preservation method. Results showed that the frozen storage up to 4 months did not significantly affect the bioactive compounds
and color indices of berries. The degradation of these characteristics was not recorded more than 23% during six months of storage. After 10 months,
the content of polyphenols decreased up to 28-47% of the initial value; the total anthocyanins was found in proportion of 80-91%, and the ascorbic
acid content was kept at 62-76%. After 10 months of storage the smallest loss of antioxidant activity was recorded for blueberries (approximately
23%) and the biggest loss for raspberries (approximately 37%). The results showed a positive correlation between antioxidant capacity and
polyphenols, vitamin C and anthocyanins content. The correlation coefficient between FRAP and the total phenolics was higher than the correlation
coefficient between FRAP and total anthocyanins or FRAP and vitamin C for all investigated berries.
Key words: Frozen berries, anthocyanins, polyphenols, vitamin C, antioxidant activity, color.
Introduction
Berries are known for their bioactive properties such as antioxidant
activity, cardiovascular protection, antidiabetic properties, vision
improvement properties, and inhibition of carcinogenesis and
mutagenesis 20, 23, 24. Blueberries, raspberries and blackberries are
excellent sources of phytochemicals that are believed to have
significant biological activity 14, 18, 20. During the last decade, much
interest has been focused on berries due to their high levels of
anthocyanins and antioxidant capacity. Prior et al.18 reported a
significant correlation between the antioxidant capacity and the
total content of anthocyanins and phenolics among blueberries.
Many studies 4, 12, 14, 15 evaluated the phenolic content of different
berries and found significant differences in the anthocyanins,
phenolics and antioxidant capacity of phenolic content among
the different species. Anthocyanins have been associated with
the antioxidant properties of many common small fruit crops and
have been characterized as having significant beneficial effects
on various diseases. Anthocyanins had the greatest
antiproliferation effect with an inhibition of greater than 50% as
opposed to the phenolic acids, flavonols and tannins 23. Phenolic
compounds from berry extracts have been reported to exhibit a
broad range of protective health benefits that may reduce the risk
factors associated with certain types of cancer, cardiovascular
disease as well as other degenerative diseases 3. Only a small
percentage of berries reaches the fresh market, and most berries
end up frozen or canned. Frozen berries can be then processed in
jams, purees, jellies and juices 13, 20. Changes in antioxidant content
and color take place in frozen berries as a result of oxidation-
reduction reactions occurring in fruits. These changes are
influenced by the initial quality of berries, raw material processing
prior to freezing, freezing methods, storage conditions (temperature
and relative humidity), storage time of frozen berries and quality
of container 16, 21. Due to the high antioxidant levels found in
blueberries, blueberry processors are seeking effective processing
techniques such as IQF (Individual Quick Freezing) to further
optimize the amount of antioxidants retained in the final product.
Freezing of berries will increase flexibility for consumers by
extending the length of time in which fruits are available. IQF is
one of the simplest and least time-consuming ways to preserve
berries, but the long-term frozen storage might affect
anthocyanins, polyphenols, vitamin C, color quality and
antioxidant effects of berries. The literature provides many studies
about the effects of freezing on the retention of antioxidants in
different berries 1, 11, 13, 16, 21. Little is known, however, about the
effect of long-term frozen storage on color indices, polyphenols
Journal of Food, Agriculture & Environment, Vol.8 (1), January 2010 55
and other antioxidants in different kinds of berries. Because during
the storage of frozen berries the levels of antioxidant compounds
may be altered resulting in a change in antioxidant properties, the
goal of this research was to investigate how freezing and long-
term storage can affect the retention of antioxidant properties and
bioactive compounds in berries.
Material and Methods
Blueberry (Vaccinium myrtillus), red raspberry (Rubus idaeus)
and blackberry (Rubus fruticosus) were harvested in Romania, at
the commercial maturity stage. After harvesting, berries were
refrigerated (3-5°C for 24 h) and frozen by IQF freezing techniques
(Individual Quick Freezing) by passage through a Frigoscandia
freezing tunnel. The frozen samples were stored in polyethylene
bags in freezing box at temperature of -18°C for 10 months. Fresh
and frozen berries were supplied by S.C. LEGOFRUCT S.R.L from
Timisoara (the western part of Romania). The samples were
analyzed fresh (FR), immediately after freezing (0-F) and during
storage in frozen state after 2, 4, 6, 8 and 10 months (2-F, 4-F, 6-F,
8-F and 10-F), respectively.
For total anthocyanins, total polyphenols, vitamin C and
antioxidant activity determination, three replicates of berry extracts
were prepared in accord with Kalt et al. 8. Before the analysis, the
frozen berries were thawed in refrigerator (3-5°C) for 4 h. Berry
extracts for anthocyanin analysis were obtained by grinding berries
(~5 g) in 95% (v/v) ethanol (20 mL) acidified with HCl (0.1%, v/v)
for 2 min. The mixture was stored at room temperature in the dark
for 16 h and then filtered 8. The extracts for phenolics and vitamin
C analysis were obtained by grinding berries (~5 g) in hot 95% (v/
v) ethanol (10 mL) for 2 min. The solution was filtered. The
extraction of the residue was repeated twice following above
mentioned procedure. Three extracts were combined 8.
The extracts for antioxidant activity determination were obtained
by grinding berries (~20 g) in 95% (v/v) ethanol (20 mL) acidified
with HCl (0.1%). After 60 min the solution was filtered. The residue
was extracted again. The extracts were combined and diluted to
volume of 50 ml with methanol acidified with HCl (0.1%) 8.
Determination of total phenolics (P): Total phenolic content was
analyzed spectrophotometrically using an adapted
Folin-Ciocalteu colorimetric method described by Singleton and
Rossi 22. Extract samples were diluted to fall within the range of
the calibration curve. The calibration curve was prepared using
0.05-0.6 mML-1 gallic acid equivalents (GAE). The samples were
incubated for 2 h in the dark at room temperature prior to measuring
the absorbance reading at 750 nm using the UV-VIS
spectrophotometer (Analytic Jena Specord 205). Quantification
of the data was calculated based on the calibration curve generated
using gallic acid as the standard and the results were expressed
as mg of gallic acid equivalents (GAE) per 100 g of berry.
Determination of total monomeric anthocyanins (A): Total
monomeric anthocyanins of berry extracts were determined by
the pH differential method 6. Samples were diluted to the
appropriate concentration with 0.025 M potassium chloride buffer
(pH 1.0) and 0.4 M sodium acetate buffer (pH 4.5). The absorbance
was measured with the UV-VIS spectrophotometer (Analytic Jena
Specord205) using 1 cm path length disposable cells at 520 nm
and 700 nm after 15 min of incubation at room temperature. The
content of total anthocyanins was expressed as mg of cyanidin-3-
glucoside equivalents per 100 g of berry. The total monomeric
anthocyanins content was calculated using cyanidin-3-glucoside
coefficients (molar extinction coefficient ε = 26,900 Lcm-1mol-1
and molecular weight MW = 449.2 gmol-1). Percent of polymeric
color contents of these samples were determined by the bisulfite
bleaching method 6. Berry extract samples were diluted using the
appropriate dilution factor and treated with potassium metabisulfite
solution or distilled water. The samples were incubated at room
temperature for 15 min prior to measuring absorbance at 420, 520
and 700 nm. The percent of polymeric color was based on the
color density of the control sample and the polymeric color of the
bisulfite bleached sample.
Determination of vitamin C (VC): Vitamin C was measured by
titration with a 2,6-dichlorophenolindophenol sodium salt solution,
and chloroform was used for intensely colored extracts 2.
Ferric reducing antioxidant power (FRAP) assay: The ability
to reduce ferric ions was measured using methods of Benzie and
Strain 5. An aliquot (200 µL) of the extract with appropriate dilution
was added to 3 mL of FRAP reagent (10 parts of 300 mM sodium
acetate buffer at pH 3.6, 1 part of 10 mM TPTZ solution and 1 part
of 20 mM FeCl36H2O solution), and the reaction mixture was
incubated in a water bath at 37°C. The increase in absorbance at
593 nm was measured after 30 minutes. The antioxidant capacity
based on the ability to reduce ferric ions of the extract was
expressed as mM Fe2+/kg fresh weight -1 was calculated.
All chemicals and solvents used in this study were of analytical
grade. All tests were run in triplicates. The concentrations of total
phenolics, anthocyanins, ascorbic acid and the results of
antioxidant activity determination were expressed as related to
the fresh weight (FW) basis. Each value is the mean of three (n =
3) independent determinations.
Results and Discussion
The antioxidant activity, vitamin C, total phenolic and total
anthocyanin contents in fresh berries, after freezing and during
the 10 months storage period are shown in Table 1. No significant
changes in vitamin C, total phenolic content and antioxidant
activity of all analyzed berries were found after freezing. In our
study only slight increases of anthocyanins were found
immediately after freezing. It is most probable that the anthocyanins
in frozen fruit become more easily extractable. This might be due
to degradation of cell structures in berries. The losses of bioactive
compounds and antioxidant activity during the storage time are
presented in Fig. 1. It was found that contents of the antioxidant
compounds, ascorbic acid, polyphenols and monomeric
anthocyanins, decreased in frozen storage products. During the
first 4 months there was a slow degradation of antioxidants in
frozen berries stored at -18°C. At a longer storage the bioactive
compounds degradation rate was accelerated. The value of
percentage degradation was depending on berry species and
storage life.
At the end of frozen storage period, total phenol content
decreased up to 28.37% from the 0-F values for blueberry, 42.41%
for blackberry and greatest losses (47.42%) were found for
raspberry. The long storage time affected the vitamin C content:
after 6 months the losses were 16-19% while after 10 months the
56 Journal of Food, Agriculture & Environment, Vol.8 (1), January 2010
losses reached 23-38%. The smallest loss was registered for
blueberry. It can be concluded that storage in frozen state for a
period of more than 8 months significantly affects ascorbic acid
concentration in fruits investigated 17. Probably, significant
decrease of investigated compounds was due to water content in
non-frozen state. Activity and enzymatic reaction rate reached
maximum values in the layers of liquid water in frozen fruits.
Perhaps, this phenomenon contributes to the modification of
chemical compounds, including biologically active substances.
In frozen products the enzymatic reactions are slow, but not
completely blocked. In general, the activity of enzymes in frozen
berries is linked to the presence of non-frozen water. At a
temperature of -18°C in frozen berries water content represents
approximately 89% of total water of berries. Liquid water in these
products will be 11%. At a temperature of -30°C frozen water in
berries will be 91% of total fruit water and liquid water content 9%.
It was found that storage of frozen fruit for 6 months slowed
down anthocyanin degradation (losses in these compounds after
6 months were below 5% for blackberry and blueberry and 10%
for raspberry). After 10 months there was an accelerated
degradation of anthocyanins, so that losses were 9% for
blackberry, 13% for blueberry and 20% for raspberry. These data
are in agreement with other studies 7, 9, 10, 13, 21 showing that a
period of 6 months of freezing does not cause significant loss of
anthocyanin content. This information is important because the
monomeric anthocyanins represent approximately 25% of the total
antioxidant capacity of berries 5. Antioxidant activity decreased
during the frozen storage of berries. In the first 4 months of storage
there was a relatively small decrease in antioxidant capacity, which
was followed by a significant decline in the following months.
During the storage for 10 months, antioxidant capacity decreased
up to 23% of 0-F value for blueberry and up to 34-37% for both
0
5
10
15
20
25
30
35
40
246810
storage time (months)
()
raspberry
blueberry
blackberry
a
0
10
20
30
40
50
246810
storage time (months)
(%)
raspberry
blueberry
blackberry
b
0
10
20
30
40
246810
raspberry
blueberry
blackberry
0
5
10
15
20
246810
tti(th)
(%)
raspberry
blueberry
blackberry
%%
%
%
ab
cd
Storage time (months) Storage time (months)
Storage time (months) Storage time (months)
Figure 1.The losses of vitamin C (a), total phenolics (b), antioxidant activity (c) and total
anthocyanins (d) during the long-term frozen storage of berries.
Frozen fruits
Berries FR
0-F 2-F 4-F 6-F 8-F 10-F
Vitamin C (mg/100 g FW)
Raspberry 31.55 31.41 29.91 27.15 26.22 25.15 22.13
Blueberry 8.20 8.15 7.92 7.68 6.61 6.43 6.22
Blackberry 6.63 6.46 5.81 5.46 5.28 4.39 3.97
Total phenolics (mg GAE/100 g FW)
Raspberry 197.79 197.14 182.23 169.45 153.21 129.75 103.65
Blueberry 641.53 640.11 611.43 589.31 550.4 511.22 458.54
Blackberry 333.60 331.87 322.47 279.07 242.79 224.27 191.12
Antioxidant activity (mM Fe
2+
/kg FW)
Raspberry 40.16 39.21 37.89 35.72 31.38 28.37 24.84
Blueberry 58.31 57.94 55.16 53.10 50.44 47.10 44.82
Blackberry 49.64 48.73 46.02 43.17 38.46 37.32 32.29
Total anthocyanins (mg/100 g FW)
Raspberry 39.71 41.67 39.95 37.85 37.56 34.85 33.51
Blueberry 205.48 207.12 205.14 202.67 198.0 185.12 180.31
Blackberry 193.72 195.89 192.08 191.75 188.4 182.55 178.62
Table 1. Effect of freezing and frozen storage time on the total phenolics, vitamin C, total
anthocyanins and antioxidant activity of different berries.
Journal of Food, Agriculture & Environment, Vol.8 (1), January 2010 57
R
Y=A+B•X raspberry blueberry blackberry
FRAP=f(VC) R=0.96891 R=0.96272 R=0.96239
FRAP=f(P) R=0.99225 R=0.99194 R=0.99146
FRAP=f(A) R=0.96846 R=0.96744 R=0.96317
Table 2. Correlation coefficients obtained after simple regression
model applied for antioxidant activity, vitamin C, total
phenolics and anthocyanins contents.
raspberry and blackberry. Also, at the end of six months of frozen
storage period the losses of antioxidant activity of blueberry were
less than 13% compared with the values measured just after
freezing process while the losses in antioxidant activity for
raspberry and blackberry were in the range of 20-21%.
In this study, the correlations established between total
antioxidant activity and investigated bioactive compounds were
evaluated. Simple regression models were applied using the Origin
4.1 software program. The values of correlation coefficients (R)
are presented in Table 2. It was found a linear dependence between
antioxidant activity and nutraceutical compounds. Antioxidant
activity was strongly correlated with total phenolics, vitamin C
and total anthocyanin contents (R>0.95). The linear correlations
FRAP = f (P), FRAP = f (VC) and FRAP = f (A) for raspberry are
shown in Figs 2-4. For all investigated berries, the best correlation
coefficient (R>0.99) was recorded for FRAP = f(P).
The storage time affects the color quality of berries. The effect
of frozen storage time on berries color was quantified by measuring
the color density, polymeric color and percent polymeric color
(Table 3). The percentage of polymeric color is a result of the
degree of anthocyanins polymerization 19, 25. The color density
showed a similar trend over storage time. The color density
decreased due to destroying of monomeric anthocyanins and
increase in polymeric color. The percentage of polymeric color
from the fresh berries was 9-11%. By freezing, the degree of
pigments degradation was affected in a very small extent (less
than 1%). In the time of long-term frozen storage of berries at -
18°C there was a relative increase in the percent of polymeric
color. For raspberry, the percentage of polymeric color becomes
significant after 10 storage months (22.22%). After 10 months of
frozen storage, the best color stability was registered for blueberries
and blackberries. The IQF process can be used to assurance the
retention of various nutrients that are naturally present in berries.
Because the antioxidant activity of berries is an appealing
characteristic to consumers, we appreciate that the IQF of berries
followed by a six months frozen storage is a very good preservative
process to support almost superior bioactive compounds while
minimizing loss of color.
22 24 26 28 30 32
24
26
28
30
32
34
36
38
40
100 120 140 160 180 200
24
27
30
33
36
39
42
F
RAP (mM Fe2+/kg FW)
34 36 38 40 42
24
27
30
33
36
39
42
FRAP (mM Fe2+/kg FW)
T t l th i ( /100 FW)
FRAP = -11.4980 + 1.6447 VC
R = 0.96891 FRAP = 7.601 + 0.1623 P
R = 0.99225 FRAP = -34.7272 + 1.8003 A
R = 0.96846
Vitamin C
(mg/100 g FW)
FRAP (mM Fe2+/kg FW)
Total anthocyanins
(mg/100 g FW)
Total phenolics
(mg GAE/100 g FW)
FRAP (mM Fe2+/kg FW)
FRAP (mM Fe2+/kg FW)
Figure 2. Linear correlation between
FRAP = f(VC) for raspberry. Figure 3. Linear correlation
between FRAP= f(P) for raspberry. Figure 4. Linear correlation
between FRAP=f(A) for raspberry.
Frozen
Berries FR
0-F 2-F 4-F 6-F 8-F 10-F
Color density index
Raspberry 7.14 7.09 6.90 6.71 6.05 5.27 5.04
Blueberry 11.77 11.68 11.51 11.21 10.85 10.71 10.43
Blackberry 12.28 12.21 12.15 11.96 11.80 11.53 11.58
Polymeric color index
Raspberry 0.78 0.80 0.83 0.87 0.94 1.02 1.12
Blueberry 1.05 1.10 1.17 1.23 1.36 1.44 1.50
Blackberry 1.16 1.19 1.23 1.29 1.34 1.38 1.43
% polymeric color
Raspberry 10.92 11.28 12.03 12.97 15.54 19.35 22.22
Blueberry 8.92 9.42 10.17 10.97 12.53 13.45 14.38
Blackberry 9.45 9.75 10.12 10.79 11.36 11.97 12.35
Table 3. Effect of frozen storage time on the color indices of frozen berries.
58 Journal of Food, Agriculture & Environment, Vol.8 (1), January 2010
References
1Ancos, B., Gonzalez, E.M. and Cano, M.P. 2000. Ellagic acid, vitamin
C, and total phenolic contents and radical scavenging capacity affected
by freezing and frozen storage in raspberry fruit. J. Agric. Food Chem.
48:4565-4570.
2AOAC 1990. Vitamin C (ascorbic acid) in vitamin preparations and
juices. In Helrich, K. (ed.). Official Methods of Analysis. 15th edn.
AOAC, Inc., Arlington, VA, 1058 p.
3Bachgi, D., Sen, C.K., Bagchi, M. and Atalay, M. 2004. Antiangiogenic,
antioxidant and anticarcinogenic properties of a novel anthocyanin-
rich berry extract formula. Biochem. 69(1):95-102.
4Beattie, J., Crozier, A. and Duthie, G. 2005. Potential health benefits of
berries. Curr. Nutr. Food Sci. 1:71-86.
5Benzie, I.F.F. and Strain, L. 1996. Ferric reducing ability of plasma
(FRAP) as a measure of antioxidant power: The FRAP assay. Anal.
Biochem.239:70-76.
6Giusti, M.M. and Wrolstad, R.E. 2001. Unit F1.2: Anthocyanins.
Characterization and measurement with UV-visible spectroscopy. In
Wrolstad, R. (ed.). Current Protocols in Food Analytical Chemistry.
John Wiley & Sons, New York, pp. 1-13.
7Gonzalez, E.M., de Ancos, B. and Cano, M.P. 2003. Relation between
bioactive compounds and free radical-scavenging capacity in berry
fruits during frozen storage. J. Sci. Food Agric. 83:722-726.
8Kalt, W., Forney, C.F., Martin, A. and Prior, R.L. 1999. Antioxidant
capacity, vitamin C, phenolics and anthocyanins after fresh storage of
small fruits. J. Agric. Food Chem. 47:4638-4644.
9Kalt, W., McDonald, J.E. and Donner, H. 2000. Anthocyanins, phenolics,
and antioxidant capacity of processed lowbush blueberry products. J.
Food Sci. 65(3):390-393.
10Kalt, W. 2005. Effects of production and processing factors on major
fruit and vegetable antioxidants. J. Food Sci. 70(1):R11-R18.
11Kampuse, S., Kampuss, K. and Pizika, L. 2002. Stability of
anthocyanins and ascorbic acid in raspberry and blackcurrant cultivars
during frozen storage. Acta Horticulturae 585:507-600.
Conclusions
Bioactive compounds content is not affected by the IQF process.
Long-term frozen storage had a significant impact on the
nutraceutical compounds and color stability of berries, depending
on the kind of berries. In the first 4 months of frozen berries storage
there was a slight decrease in content of bioactive compounds,
after which the rate of degradation increased. The highest degree
of bioactive compounds degradation was recorded after 10 months
of frozen storage. Investigated berries can be presented in the
following order depending on the antioxidant characteristics:
blueberries>blackberries>raspberries. The highest degree of
antioxidant compounds stability during frozen berries storage was
registered for blueberries. Total polyphenols content has a special
importance in evaluating of the antioxidant quality of berries. After
10 months of storage the polyphenols content decreased up to
47% of initial value for raspberries. A strong correlation (R>0.95)
was found between antioxidant activity and bioactive compounds.
The raspberry color is very sensitive to long-term frozen storage:
the content of anthocyanins decreased after 10 months up 20%
of initial value, while the percent of polymeric color reached 22%.
For IQF blueberries and blackberries the best color stability was
recorded during long-term storage at -18°C. The quality of frozen
fruits is affected by oxidative degradation of bioactive
compounds. In a storage temperature of -18°C, we can recommend
the storage life of frozen fruits, packed in polyethylene bags or
plastic boxes for 6 months as optimal for obtaining of products
with superior antioxidant properties and to minimize loss of color.
12Koca, I., Sule Ustun, N., Koca, A.F. and Karadeniz, B. 2008. Chemical
composition, antioxidant activity and anthocyanin profiles of purple
mulberry (Morus rubra) fruits. J. Food Agric. Environ. 6(2):39-42.
13Lohachoompol, V., Srzednicki, G. and Craske, J. 2004. The change of
total anthocyanins in blueberries and their antioxidant effect after drying
and freezing. J. Biomed. Biotechnol. 5:248-252.
14Mainland, C.M., Tucker, J.W. and Hepp, R.F. 2002. Blueberry health
information - some new mostly review. Acta Hort. 574:39-43.
15Moyer, R.A., Hummer, K.E., Finn, C.E., Frei, B. and Wrolstad, R.E.
2002. Anthocyanins, phenolics, and antioxidant capacity in diverse
small fruits: Vaccinium, Rubus, and Ribes. J. Agric. Food Chem. 50(3):
519-525.
16Mullen, W., Stewart, A.J., Lean, M.E., Gardner, P., Duthie, G.G. and
Crozier, A. 2002. Effect of freezing and storage on the phenolics,
ellagitannins, flavonoids and antioxidant capacity of red raspberries. J.
Agric. Food Chem. 50:5197-5201.
17Noormets, M., Karp, K., Starast, M., Leis, L. and Muru, K. 2006. The
influence of freezing on the content of ascorbic acid in Vaccinium
species berries. Acta Hort. 715:539-544.
18Prior, R.L., Cao, G., Martin, A., Sofic, E., Ewen Mc, J., O’Brien, C.,
Lischner, N., Ehlenfeldt, M., Kalt Krewer, W.G. and Mainland, C.M.
1998. Antioxidant capacity as influenced by total phenolic and
anthocyanin content, maturity and variety of Vaccinium species. J.
Agric. Food Chem. 46(7):2686-2693.
19Rommel, A., Wrolstad, R.E. and Heatherbell, D.A. 1992. Blackberry
juice and wine: Effect of processing and storage effects on anthocyanin
composition, color and appearance. J. Food Sci. 57:385-391.
20Schmidt, B.M., Erdman, J.R.J.W. and Lila, M.A. 2005. Effects of food
processing on blueberry antiproliferation and antioxidant activity. J.
Food Sci. 70(6):19-26.
21Scibisz, I. and Mitek, M. 2007. The changes of antioxidant properties
in highbush blueberries (Vaccinium corymbosum L.) during freezing
and long-term frozen storage. Acta Sci. Pol. Technol. Aliment. 6(4):
75-82.
22Singleton, V.L. and Rossi, J.A. 1965. Colorimetry of total phenolics
with phosphomolybdic-phosphotungstic acid reagents. Am. J. Enol.
Vitic. 16:1644-1658.
23Smith, M.A.L., Marley, K.A., Seigler, D., Singletary, K.W. and Meline,
B. 2000. Bioactive properties of wild blueberry fruits. J. Food Sci.
65(2):352-356.
24Yi, W., Fischer, J., Krewer, G. and Akoh, C. 2005. Phenolic compounds
from blueberries can inhibit colon cancer cell proliferation and induce
apoptosis. J. Agr. Food Chem. 53:7320-7329.
25Yuksel, S. and Koka, I. 2008. Color stability of blackberry nectars
during storage. J. Food Technol. 6(4):166-169.
... La mora conservada en congelación puede ser empleada posteriormente para la elaboración de mermeladas, gelatinas, salsas, pulpas y jugos (Poiana et al., 2010;Wu, Frei, Kennedy y Zhao, 2010). Esto hace que el colapso estructural que presenta el producto descongelado no sea un problema para las compañías procesadoras o para el consumidor final. ...
... Se ha encontrado que el contenido de compuestos bioactivos no se afecta significativamente durante la congelación y el almacenamiento, especialmente cuando se realiza por un método de congelación rápida. De acuerdo con Poiana et al. (2010), el contenido de vitamina C, compuestos fenólicos totales y antocianinas disminuyeron en cerca 10 % después de dos meses de almacenamiento en congelación. Los cambios provocados en la congelación están influenciados por la variedad de la fruta, el tipo de suelo, el tiempo de cosecha, la calidad inicial de la fruta, el manejo previo a la congelación, el método de congelación, las condiciones de almacenamiento (temperatura, humedad relativa y tiempo) y la calidad del empaque (Poiana et al., 2010;Wu, Frei, Kennedy y Zhao, 2010;Veberic et al., 2014). ...
... De acuerdo con Poiana et al. (2010), el contenido de vitamina C, compuestos fenólicos totales y antocianinas disminuyeron en cerca 10 % después de dos meses de almacenamiento en congelación. Los cambios provocados en la congelación están influenciados por la variedad de la fruta, el tipo de suelo, el tiempo de cosecha, la calidad inicial de la fruta, el manejo previo a la congelación, el método de congelación, las condiciones de almacenamiento (temperatura, humedad relativa y tiempo) y la calidad del empaque (Poiana et al., 2010;Wu, Frei, Kennedy y Zhao, 2010;Veberic et al., 2014). ...
Book
Full-text available
Dentro del proyecto BPIN 2014000100010 “Incremento de la competitividad sostenible en la agricultura de ladera en todo el departamento, Valle del Cauca, Occidente”, la Universidad del Valle propuso la actividad 2: diseñar e implementar procesos agroindustriales que generen, con base en estándares internacionales, valor agregado a los productos seleccionados, así como desarrollar y/o evaluar empaques innovadores apropiados para los productos seleccionados en fresco y procesados. Esta actividad incluye las siguientes acciones específicas: 1) vigilancia tecnológica sobre procesos agroindustriales y productos; 2) selección de productos procesados a desarrollar y 3) selección de los procesos, entre otras. Este documento corresponde al entregable de las actividades específicas 1, 2 y 3. Se incluyen los resultados de los productos y los procesos seleccionados de acuerdo con las brechas identificadas en mora de Castilla, tanto en fresco como procesada, tras un análisis comparativo de los resultados. La vigilancia tecnológica se llevó a cabo incluyendo cuatro tipos de vigilancias (competitiva, comercial, científico-tecnológica y estratégica). Con base en estas, se seleccionaron los productos y procesos correspondientes a la fruta objeto de este estudio. A partir de lo anterior, se evidenció que aumentar la vida útil del producto fresco es un reto para la exportación. En el caso de mora de Castilla, se presentan problemas como el carácter altamente perecedero de esta fruta, con altas pérdidas poscosecha a causa de la escasa tecnología de conservación y transformación en las zonas de producción. El transporte del producto fresco es difícil, debido a que las zonas de producción generalmente están en regiones de ladera con malas vías de comunicación. Para responder a las situaciones presentadas, es necesario buscar alternativas de conservación y transformación que permitan aumentar la productividad y competitividad de los sectores mencionados. Se definieron los siguientes productos y procesos: • Mora fresca: mora refrigerada y congelada. • Mora procesada: mora en polvo obtenida por secado en bandejas.
... However, the loss of ascorbic acid was observed in all the varieties during storage, whereas, bruno variety has been showed the most significant decrease in the ascorbic acid i.e. 37% (Cano et al., 1993) [10] . Similar results found by Myojin et al., (2008) [50] , Lee et al., (1946) [36] and Poiana et al., (2010) [53] . All the authors observed a decrease in ascorbic acid content during frozen storage. ...
... However, the loss of ascorbic acid was observed in all the varieties during storage, whereas, bruno variety has been showed the most significant decrease in the ascorbic acid i.e. 37% (Cano et al., 1993) [10] . Similar results found by Myojin et al., (2008) [50] , Lee et al., (1946) [36] and Poiana et al., (2010) [53] . All the authors observed a decrease in ascorbic acid content during frozen storage. ...
... ascorbic acid degradation by a factor of 6 to 20 times, whereas in fruits such as peaches, boysenberries, and strawberries, rate of degradation is raised by a factor of 30 to 70 times. The total phenolic contents in fresh berries, after freezing and during the 10 months storage period was studied by Poiana et al., (2010) [53] . At the end of frozen storage period, total phenol content decreased up to 28.37% for blueberry, 42.41% for blackberry and greatest losses (47.42%) were found for raspberry. ...
Article
Full-text available
Freezing is a very well-established food preservation process that produces high quality nutritious foods with a long storage life. However, freezing isn't appropriate for all types of the food materials, as it may cause physical, biochemical and sensory changes in some foods that are perceived as reducing the quality of the final product especially after thawing. The food industry employs both chilling and freezing processes where the food is cooled from ambient to temperatures above 0 °C in the former and between −18 °C and −35 °C in the latter to slow the physical, microbiological and chemical activities that cause deterioration in foods. This paper provides a brief review of freezing systems used in food processing industries for preservation of perishable food commodities. There are different types of freezers used in food industries for different commodities like air blast freezer, plate freezer, contact freezer, immersion freezer, cryogenic freezer, individual quick freezer etc. Selection of freezer and refrigerant depends on the type, moisture content, nature and pretreatments given to particular food commodity before freezing. Freezing may also causes damage to cells of fruit and vegetable by ice crystal growth. However, freezing retains most of the pigments, aroma, flavors, characteristic taste and other nutritional components in most of the perishable food commodities.
... Freezing had the same effect on catechin hydrate content, which also increased significantly, especially in conventionally frozen horseradish roots. However, phenolic compounds can be de-graded during freezing and frozen storage (Chaovanalikit and Wrolstad, 2004;Poiana et al., 2010). In the current study, increase of TFlC was observed after freezing. ...
... This can be explained by the presence of phenolic compounds in plants in free forms or covalently bound with macromolecules, or packed in cellular organs or cell wall components (Palermo et al., 2014). In addition, other studies have discussed similar tendencies, where content and quality of bioactive compounds depended on many factors, including initial quality, freezing rate, storage conditions, temperature, and time (Olivera et al., 2008;Poiana et al., 2010;Mazzeo et al., 2015). ...
... Similar trends were observed by Puupponen-Pimiä et al. (2003) for frozen carrots. The reduction of phenolic compounds during storage may be associated with enzyme, especially polyphenol oxidase, activity (Chaovanalikit and Wrolstad, 2004;Poiana et al., 2010). Prabhu and Barrett (2009) reported an increase between 3 and 5% in TPC of African leafy vegetables after 90 days in Cassia tora leaves, and between 8-9% in Corchorus tridens leaves. ...
Article
Full-text available
Freezing is one of the ways to preserve plant products, because it allows inhibiting natural degradation and transformation processes of the bioactive compounds. The aim of this study was to evaluate the effect of freezing on bioactive compounds of horseradish roots and their dynamics in long-term frozen storage. Horseradish roots were frozen at two different conditions (–18±2°C and –40 ± 2 °C) and further stored at –18 ± 2 °C for 12 months. Total phenolic content (TPC), total flavonoid content (TFC), total flavonol content (TFlC), total flavan-3-ol content (TF3C), total phenolic acid content (TPAC), and radical scavenging activity (RedPow, DPPHÿ, ABTSÿ+) were determined spectrophotometrically. Individual phenolic compounds were deremined by liquid chromatography. The dominant individual phenolic compounds were phenolic acids (gallic and sinapic) and flavonoids (kaempferol, luteolin, and rutin). Because of freezing, TPC, TFC, and DPPHÿ as well as RedPow increased in horseradish roots. During storage, the content of analysed bioactive compounds mainly decreased. After 12-month storage, it was not possible to say unambiguously which of the freezing methods turned out to be better in general.
... For example, Beekwiler et al. [38] reported a relatively low contribution of vitamin C to the antioxidant activity in raspberries, about 20%, while for anthocyanins, about 25% of the antioxidant capacity of red raspberry fruits was reported. Poiana et al. [17] and Viskelis et al. [28] found highly correlated antioxidant activity with total phenolics content. According to the obtained results, the analyzed berry species differ significantly in terms of antioxidant capacity, the highest being found for blackberry (1764 µmol TE/kg) and the lowest for raspberry (1742 µmol TE/L). ...
... It is for these reasons that the right choice of freezing method can successfully influence the quality of the final product. Many studies prove the advantages of using modern freezing methods (use of cryogenics, IQF method, etc.) in preserving the quality of the final product [1,8,9,17,39]. However, above all, it is important to optimize the choice of the method itself, i.e., to adapt it to the type of fruit and the properties and conditions that significantly affect the preservation of each nutrient. ...
... The most significant decrease during storage was observed in frozen blackberry fruits, about 10% in frozen samples and about 7% in classically frozen samples. The obtained results are as expected and in agreement with other literature data, where a significant decrease in antioxidant activity during storage time was found [17,60]. ...
Article
Full-text available
Cryoprotective freezing methods are increasingly being developed and used as an effective means of protecting valuable bioactive compounds in processed berry fruits. The quick-freezing method allows the bioactive compounds in the plant material to be preserved over a longer period of time, thus providing a high-quality product with significant antioxidant capacity. The aim of this study was to determine the effects of the quick-freezing method on physico-chemical properties and bioactive compounds content of fruits in three soft fruit species: tayberry, raspberry, and blackberry, and to evaluate the stability of specific phytochemicals during the three-month storage period. The freezing method had a significant effect on the physicochemical properties with a significantly less drip loss observed after thawing in fruit frozen by quick-freezing (at −34 ◦C for 25 min) compared to fruit frozen classically (−18 ◦C to 24 h). The color of quick-frozen fruits also changed significantly less compared to fresh fruits. Of the bioactive compounds analyzed, it should be noted that there was a significantly lower loss of ascorbic acid recorded during quick-freezing. On average, the quick-frozen fruits contained 28% more ascorbic acid than the classical frozen fruits. In general, the quick-freezing procedure contributed to a better preservation of total polyphenolic compounds and anthocyanins, and thus berry fruits also showed higher values of antioxidant capacity during quick freezing than during the classical procedure. During the storage period of three months, a decrease in the content of all the bioactive compounds studied was observed, although it should be emphasized that this loss during storage was not as pronounced in fruits frozen by the quick-freezing method as in classically frozen fruits. It can be concluded that the quick-freezing contributes significantly to the preservation of valuable bioactive compounds of berries and that this processing method can be considered important for maintaining the nutritional properties of berry fruits.
... The freezing rate determines the size and form of ice crystals, which in turn determines the degree of damage that produces a change in the tissue (Alvarez & Canet, 1997) and results in excessive softening. The freezing rate is a variable recognized as the one responsible for tissue damage (Fuchigami et al., 1997;Semenov et al., 2015); the fast freezing rates positively affect the texture and quality of fruits (Delgado & Rubiolo, 2005;Poiana et al., 2010). The freezing velocity and formation of small ice crystals during freezing are critical in minimizing tissue damage and a drip loss after thawing (Li & Sun, 2002). ...
... The literature data provide many results of the effects of freezing and frozen storage on the quality and AO activity of the various cultivars of strawberry and raspberry (Delgado & Rubiolo, 2005;Gonzales et al., 2002Gonzales et al., , 2003Moraga et al., 2006;Mullen et al., 2002;Poiana et al., 2010;Šamec & Piljac Žegarac, 2015;Sousa et al., 2005;Sousa et al., 2007). However, according to our knowledge, there are no data about the effect of different freezing methods and freezing velocities on the quality and AO activity of strawberry and raspberry fruits. ...
... The obtained results indicate that physicochemical characteristics were more affected by the long-term frozen storage than processes of freezing itself; in addition, their better retention was determined after IQF, where fruits were frozen with higher rate of freezing, less water migration, formation of smaller crystals, and resulted in minor tissue changes. Also, the results indicated that chemical and biochemical changes had been slowed down, but not entirely terminated at the temperatures below zero (Neri et al., 2020;Poiana et al., 2010). A similar tendency of changes in the physicochemical properties after the freezing of strawberry fruits was also obtained by Moraga et al. (2006). ...
Article
The effects of different freezing methods and long‐term frozen storage on quality of strawberry and raspberry were investigated, i.e. the retention of initial property and free radical scavenging (AO) activity after Individual Quick Freezing (IQF) and conventional (discontinuous) freezing. The physicochemical properties, vitamin C and AO activity were more affected by long‐term frozen storage than by freezing itself; however, their better retention was obtained after IQF. Moreover, AO activity was found to be higher in frozen samples compared to fresh fruits, but significant decrease was detected after 8 months of frozen storage. Despite the significantly higher initial content of vitamin C in strawberry, it demonstrated a lower AO activity than raspberry. Sensory attributes were significantly affected by the freezing; the most considerable changes were recorded on their texture/firmness, especially after conventional (slow) freezing. Therefore, IQF can generally be suggested as a more suitable method of preserving these delicate fruits than slow freezing.
... In contrast, other studies report decreased total phenolic changes during frozen storage. After 10 mo. at − 20°C, total phenols decreased by 28% for blueberries, 42% for blackberries, and 47% for raspberries (Poiana et al. 2010). However, results are inconsistent between different studies as polyphenol content of various berries may decrease (Chaovanalikit & Wrolstad 2004), increase (de Ancos et al. 2000;Urbanyi & Horti 1992), or remain unchanged (Cocetta et al. 2015;Khattab et al. 2015). ...
... When the berries were in the freezer, not all the water was frozen due to the sugar content in aronia berries (Allan-Wojtas et al. 2006). In Poiana et al. 2010, berries stored at − 18°C included 89% of total water frozen, and at − 30°C, 91% were completely frozen. The unfrozen water migrates to outer cells, containing less water, generating larger ice crystals and recrystallization (Allan-Wojtas et al. 2006). ...
Article
Full-text available
Postharvest storage of many freshly picked berries affects polyphenol and sugar content. However, little is known about the impact of refrigerated and frozen storage on aronia berry composition. Therefore, the objective of this study was to characterize how storage at 4 ± 2 °C and − 20 ± 2 °C, and temperature cycles affect aronia berry polyphenols, total solid content, pH, titratable acidity, polyphenol oxidase (PPO) activity, sugar content, acid content, color, and cell structure. Refrigerated storage reduced proanthocyanidins (21%), anthocyanins (36%), and total phenols (21%) after 12 weeks. Frozen storage increased polyphenols in the first 6 mo. of frozen storage but then decreased polyphenols at mo. 8 to levels similar to initial values. Frozen temperature cycling reduced anthocyanins 18% but did not affect total phenols or proanthocyanidins. Scanning electron microscopy analysis indicated temperature cycling induced cell damage, shrinking, and fusion. This disruption led to the release of anthocyanins inside the berry tissue. PPO activity did not significantly correlate with the decrease in polyphenol content during storage. °Brix did not significantly change during refrigeration and frozen storage but did during the 12th temperature cycle. Aronia berries’ pH and titratable acidity were affected more by refrigeration than frozen and temperature storage. The pH increased by 4% during refrigeration, and titratable acidity decreased by 17% at 12 weeks. In conclusion, refrigerated storage results in a modest reduction of aronia berry polyphenols, but absolute extractable polyphenols are stable for up to 8 months of frozen storage. Graphical abstract
... For example, total anthocyanin content increased in both cultivated and wild black currants by 10.7% and 51.6%, respectively, during storage for seven months at −18 °C (Oancea, Cotinghiu, and Oprean 2011). This may be due to the degradation of cell structure during cold storage, which increases the extractability of phenolics during subsequent analyses (Poiana et al. 2010). Meanwhile, total anthocyanins remain constant in blueberries and blackberries when stored at −20 °C for three and six months, respectively (Hager, Howard, and Prior 2008;Lohachoompol, Srzednicki, and Craske 2004). ...
Article
Full-text available
The consumption of small fruits has increased in recent years. Besides their appealing flavor, the commercial success of small fruits has been partially attributed to their high contents of phenolic compounds with multiple health benefits. The phenolic profiles and contents in small fruits vary based on the genetic background, climate, growing conditions, and post-harvest handling techniques. In this review, we critically compare the profiles and contents of phenolics such as anthocyanins, flavonols, flavan-3-ols, and phenolic acids that have been reported in bilberries, blackberries, blueberries, cranberries, black and red currants, raspberries, and strawberries during fruit development and post-harvest storage. This review offers researchers and breeders a general guideline for the improvement of phenolic composition in small fruits while considering the critical factors that affect berry phenolics from cultivation to harvest and to final consumption.
... The peels of blueberry and watermelon were used as positive and negative controls. 49 The TAOC data for the cryogels were further expressed as vitamin C equivalent antioxidant capacity (VCEAC) by using the following equation 50 = + VCEAC (FRAP 11.498)/1.6447 (4) where the unit for FRAP is μmol Fe(II)/g, and the unit for VCEAC is mg. ...
... One of the most important factors that affect the degree of dietary polyphenol preservation during food freezing is the freezing rate, as observed in a study that reported that slow-frozen strawberries had lower levels of monomeric anthocyanins than quickfrozen ones [93]. Similarly, Poiana et al. observed that individual quick freezing had no significant effect on polyphenolic compounds (total phenolic content, total monomeric anthocyanins) in three berries: blueberry, red raspberry, and blackberry [94]. The proposed mechanism is based on the nature of crystal formation. ...
Article
Full-text available
Dietary plant polyphenols are natural bioactive compounds that are increasingly attracting the attention of food scientists and nutritionists because of their nutraceutical properties. In fact, many studies have shown that polyphenol-rich diets have protective effects against most chronic diseases. However, these health benefits are strongly related to both polyphenol content and bioavailability, which in turn depend on their origin, food matrix, processing, digestion, and cellular metabolism. Although most fruits and vegetables are valuable sources of polyphenols, they are not usually consumed raw. Instead, they go through some processing steps, either industrially or domestically (e.g., cooling, heating, drying, fermentation, etc.), that affect their content, bioaccessibility, and bioavailability. This review summarizes the status of knowledge on the possible (positive or negative) effects of commonly used food-processing techniques on phenolic compound content and bioavailability in fruits and vegetables. These effects depend on the plant type and applied processing parameters (type, duration, media, and intensity). This review attempts to shed light on the importance of more comprehensive dietary guidelines that consider the recommendations of processing parameters to take full advantage of phenolic compounds toward healthier foods.
Article
Recent studies have found that blueberry supplementation can improve parameters related to metabolic syndrome (MetS); however, there is no definitive consensus. Analysis of several randomized controlled trials can demonstrate whether a reduced effect of MetS risk factors is more pronounced in individuals who received supplementation with blueberry than in individuals who did not receive this supplementation. This systematic review and meta-analysis aimed to investigate the effect of blueberry intervention on MetS risk factors, including blood pressure, anthropometric measurements, and glycemic and lipid profiles. PubMed, Scopus, Web of Science, and SciELO were systematically searched to identify relevant studies published before July 2020. To compare the effects of blueberry supplements (powder, extract, fruit, juice, or frozen) with placebo, the mean differences with 95 % confidence intervals (CI) were pooled based on the random-effects model. We classified the quality of evidence according to the GRADE approach. In total, 18 randomized controlled trials (RCTs) were included in this systematic review, and 12 studies were selected for meta-analysis. Based on the Cochrane Collaboration risk-of-bias tool, all studies were of good quality. These trials differed with regards to blueberry dosage and forms, recruited subjects, and trial duration. Meta-analyses of the data showed that blueberry intervention had a significant effect on lipid levels, decreasing total cholesterol and low-density lipoprotein (LDL) levels. We found no significant differences in the glycemic status markers and anthropometric measurements. Blueberry supplementation significantly decreased diastolic blood pressure. In conclusion, the meta-analysis showed that blueberry may be efficacious in the treatment of MetS, due to its beneficial effects on lipid and blood pressure markers.
Article
Full-text available
Fruit and vegetable consumption is inversely related to the incidence of heart disease and several cancers. However, many people in countries in Northern latitudes do not eat the recommended “5-a-day” of fruit and vegetables. For such populations, a potentially important source of fruit may be locally grown soft fruits (eg. raspberries, blackberries, blueberries, blackcurrants). Such berries contain micronutrients such as vitamin C and folic acid which are essential for health. However, berries may have additional health benefits as they are also rich in phytochemicals such as anthocyanins which are glycosidic-linked flavonoids responsible for their red, violet, purple and blue colours. In vitro studies indicate that anthocyanins and other polyphenols in berries have a range of potential anti-cancer and heart disease properties including antioxidant, anti-inflammatory, and cell regulatory effects. Such experimental data has lead to numerous health claims on the internet implying that “berries are edible superstars that may protect against heart disease, cancers and ageing”. However, the bioavailabilty of polyphenols such as anthocyanins would appear to be limited, thus compromising their nutritional relevance. Consequently the aim of the article is to assess the current scientific evidence for claims that berries may have additional health benefits to those normally associated with consuming fruit and vegetables.
Article
Full-text available
Three types of mulberry; white (M. alba), black (M. nigra) and red-purple (M. rubra) are grown in Turkey. It is widely consumed fresh as well as dried, processed into jam, marmelade, pekmez (a traditional Turkish food), wine, juices, paste and ice cream. In this study, anthocyanin composition, chemical composition and antioxidant activity of wild purple mulberry grown naturally was determined. The color of the samples differed from red to purple. Brightness, redness and blueness values were found as 33.07, +7.64 and -4.30, respectively. Average composition of the samples were 173.10 g kg-1 dry matter, 13.50°Bx soluble solids, 4.92 pH, 4.0 g kg-1 total acidity, 127.18 g kg-1 total sugar, 120.95 g kg-1 reducing sugar, 5.92 g kg-1 non-reducing sugar, 12.60 g kg-1 crude protein, 2107.47 mg kg-1 potassium, 889.04 mg kg-1 calcium, 194.04 mg kg-1 magnesium, 118.94 mg kg-1 sodium, 28.50 mg kg-1 iron, 5.20 mg kg-1 zinc, 3.49 mg kg -1 manganese and 3.09 mg kg-1 copper. Average values for the natural antioxidants were found as 28.42 mg kg-1 ascorbic acid, 193.85 mg kg-1 total anthocyanins and 1308.07 mg kg-1 total phenolics. The ferric reducing/antioxidant power (FRAP) assay was used to measure the total antioxidant activity of purple mulberry and the average value was obtained as 33.90 μmol g-1. The anthocyanin pigments in purple mulberry samples were isolated and identified by high performance liquid chromatography (HPLC) with UV-Visible detection. The ratios of individual anthocyanins in the purple mulberries varied markedly. Cyanidin 3-glucoside was the predominant anthocyanin in the samples.
Article
In this work the correlation between the free radical-scavenging capacity and bioactive compounds (anthocyanins, ellagic acid, total phenolics and vitamin C) in four Spanish raspberry cultivars (Heritage, Autumn Bliss, Zeva and Rubi) and Spanish wild blackberry as affected by freezing and frozen storage was evaluated. From this mathematical study a significant correlation was obtained between the radical-scavenging capacity and the anthocyanin and total phenolic contents in both raspberry (r = 0.85 and 0.83 respectively) and blackberry (r = 0.84 and 0.68 respectively) fruits, but no correlation was found between this parameter and the ellagic acid and vitamin C contents. A key objective of this study was to select the raspberry cultivar most suitable for freezing preservation in terms of the stability of its health-promoting constituents. A two-dimensional principal component analysis (PCA) of the raspberry cultivars explained 82% of the total variance of the factors mentioned above. The early raspberry cultivars (Heritage and Autumn Bliss) showed a lower content of bioactive compounds and lower radical-scavenging capacity, while the late cultivars (Zeva and Rubi) showed higher values, and these differences were clearly displayed by the PCA.© 2003 Society of Chemical Industry
Article
Blackberry wine was made from thawed fruit (Evergreen variety) by fermentation of pulp, depectinized juice, and high-temperature short-time (HTST)-treated and depectinized juice. The effects of fining and storage on pigment composition, color and appearance were investigated. Seven anthocyanin pigments (cyanidin-3-glucoside, cyanidin-3-rutinoside, a xylose-cyanidin derivative, two acylated cyanidin derivatives, cyanidin and a polymeric derivative) were detected in the juices and wines by HPLC. Cyanidin-3-glucoside was highly unstable during fermentation. Haze development and sediment formation occurred, and 85 to 100% of total anthocyanins degraded. Blackberry juice that had been HTST-pasteurized, depectinized and fined produced wine with the most stable color and best appearance after storage.