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Egypt. J. Food. Sci. Vol. 48, No.1, pp. 27-40 (2020)
OLIVE oil pomace is produced as by-product with a large quantity during olive oil
processing. It is a promising source for polyphenolic compounds and fibers which could
be used in food industry. In this work proximate chemical analysis of olive pomace (two-phase
olive oil extraction) was studied. Also, seven extracting solvents were tested in extracting the
phenolic compounds from the olive pomace (OP). Total phenolic, flavonoids, and flavonols
contents of the different extracts were determined. In addition to, the antioxidant activity of
the phenolic extracts was investigated using 2, 2-diphenyl-1-picrihydrazyl (DPPH) to assess
the extracting efficiency of solvents. The obtained data rivaled that protein, fat, ash and fiber
contents of OP were 2.48, 2.33, 1.33 and 20.37% (FW), respectively. It is clear that the OP
contains a large quantity of fibers and it had cellulose content about 40.7% of the fiber content.
Furthermore, the total phenolic content was varied in the various extracts and ranged from
8.29 to 36.24 mg GAE g -1. While, total flavonoids were ranged from 2.23 to 12.52 mg QE g-1.
Methanol and water (80:20) recorded the highest antioxidant activity with EC50 of 1.373µg/µg
DPPH while, the acetone extract recorded the lowest antioxidant activity with EC50 of 8.052µg
/µg DPPH. Toast bread was fortified with the cellulose isolated from OP at three replacement
levels of 2, 4, and 6% and the results showed no significant differences between control sample
and the sample fortified with 2% cellulose in most of sensory characteristics tested. Addition
of pomace cellulose at replacement level of 2% enhanced the texture of the bead and was more
acceptable than the control. The results concluded that olive pomace is a good source for dietary
fibers and polyphenolic compound which could be used in the food industry.
Keywords: Olive pomace, Bioactive compounds and Toast bread.
3
Utilization of Olive Pomace As A Source of Bioactive Compounds
in Quality Improving of Toast Bread
Khaled A. Sleim1*, Waleed Z. Badawy2 and I. Smetanska3
1Food science and technology Department, Faculty of Agriculture, Fayoum University,
Egypt
2Food Technology Department, Faculty of Agriculture, Kaferelsheikh University,
Egypt
3Department of Plant Food Processing, Agricultural Faculty, University of Applied
Science Weihenstephan-Triesdorf, Weidenbach, Germany
Egyptian Journal of Food Science
http://ejfs.journals.ekb.eg/
*Corresponding author email: kas00@fayoum.edu.eg.
Received:22/1/2020; accepted:27/2/2020
DOI: 10.21608/EJFS.2020.22871.1038
©2020 National Information and Documentation Centre (NIDOC)
Introduction
Olive oil showed very interested nutritional
and sensorial properties due to its contents
of unsaturated fatty acids and polyphenolic
compounds which act as natural antioxidants to
protect human body (Paz Aguilera et al., 2005). In
addition to antioxidant activity of olive phenolic
compounds, it was found to have antifungal
activity (Winkelhausen et al., 2005). Extraction
process of the olive oil production generates a
considerable quantity of by-products which could
cause serious environmental problems due to its
very high organic loads (Roig et al., 2006). Those
by-products found to consist of sugars, pectin,
lipid, tannins and polyphenolic compounds.
Utilization of it as a raw material for producing
a high value compounds is particularly attractive
way to reuse it (Niaomakis and Halvadakis, 2004).
Three different kinds of by-products are
produced during the olive oil production
depending on the production method used.
(Fenandyez-Bolanos et al., 2006). The traditional
28
Egypt. J. Food Sci. 48, No.1 (2020)
KHALED A. SLEIM et al.
press method generates three phase and two by-
products: olive oil about (20%), solid by-product
(olive cake) around (30%) and waste water
about (50%) of the olive fruits (Jerman Klen and
Mozetic Vodopivec, 2012). On the other hand,
the two-phase extraction system generates olive
oil and one by-product which is a combination
of liquid and solid. This by-product contains
about 80% of the olive fruit which include pulp,
skin, seeds and pieces of stones (Vlyssides et al.,
2004). The by-product in this production method
(olive pomace) differs in its chemical properties
compared to olive cake from the traditional
three-phase extraction method. It has higher
moisture content ranged from 65-75% compared
to 22-25% for the olive cake (Alburquerque et
al., 2004). OP is the major output from the two-
phase extraction method it is a good source for
bioactive compounds which could be used in
food manufacturing as well as pharmaceutical
fields. Because of the high-water content of olive
pomace, the concentration of water soluble salts
and phenolic compounds in it were higher than
that of the olive cake produced by the three-phase
extraction system (Dermeche et al., 2013). Those
bioactive compounds could have new application
in foods and cosmetic industries (Rodrigues et al.,
2017).
The quantity of olive pomace generated
during production of olive oil is ranged from 2.75
to 4 tons for each ton of oil depending on fruit
quality, and extraction technology (Rorja et al.,
2006 and Conterno et al., 2017). OP was found
to have a considerable amount of polyphenoilc
compound. It was reported that about 89% of
olive fruit phenolic compounds remains in olive
pomace for which the functional properties of
olive oil and olive pomace are related (Ghanbari
et al., 2012). Olive pomace phenolic profile has
been studied and found to be fared according to
many factors including, fruit ripening, climatic
condition, cultivar, origin, and the extraction
system (Obied et al., 2008). Some authors found
oleuropein and oleuropein derivatives as major
compounds (Cioffi et al., 2010). Other researchers
reported different major compounds, namely
hydroxytyrosol as the main phenolic compounds
in olive pomace. (Alu’datt et al., 2010; Rubio-
Senen et al., 2012 and Nunes et al., 2018). The
major components in the olive pomace are
dietary fiber (including cellulose, hemicellulose,
lignin and pectin), protein, lipids, pigment, and
polyphenolic compounds (Di Gioia et al., 2002).
The inclusions of fibre in the food’s formulation
will inevitably bring about certain changes to
the product. Utilization of OP to obtain natural
ingredients like phenolic compounds and dietary
fibers to develop new food products is a proms
subject (Nunes et al., 2018).
Cellulose is insoluble in cold or hot water
and in hot dilute acids or alkalis. (Singanuson et
al., 2014). Powdered cellulose used in many food
applications, essentially in functional bread, to
increase fibre content and to decrease nutritional
value of the bread. Addition of cellulose to the
bread formulation, results in many changes in the
quality properties of the bread (Poran et al., 2008).
It is increasing the viscosity of the liquid mixture
of flour because its insolubility in water. This leads
to form a stronger gas holding structure. Thus, the
air bubbles will remain in small sizes and will not
float on the surface of the liquid, which results
in the product having accurate air bubbles, larger
foam size and better stability (Wongsonsarim et al.,
2001).. cellulose powder was announced to use as
a bulking agent in drink products, meat products,
salads, and especially baked and cereal products.
In this current work, various extracting
solvents were tested for extracting the phenolic
compounds from tow-phase extraction olive
pomace. Total phenolic, flavonoids, flavonols
contents were also determined and identified
using HPLC/DAD- MS. The antioxidant activity
of the different phenolic extracts was investigated
using DPPH method. Cellulose was isolated from
the OP as functional food ingredient and used at
different concentrations in toast bread formulation
to investigate its effects in the quality proprieties
of the produced toast.
Materials and Methods
Materials and reagents
Olive pomace (4 kg) from tow-phase
extraction olive oil unit was acquired from
olive production factory in Fayoum, Egypt. The
sample was homogenized and stored at -20º C
until analysis. All chemicals used were analytical
grade and purchased from sigma-Aldrich, Berlin,
Germany
Proximate chemical analysis
Moisture content was determined using oven
at 50°C under vacuum for 48 hr and the dried
sample was ground to fine powder for using
in farther analysis. Fat, total protein, ash, and
fiber of OP and toast bread were determined
according to (AOAC, 2012). Total protein
content was calculated using 6.25 as the nitrogen
conversion factor (Nunes et al., 2018). Available
carbohydrates were calculated by difference.
29
Egypt. J. Food Sci. 48, No.1 (2020)
UTILIZATION OF OLIVE POMACE AS A SOURCE OF BIOACTIVE COMPOUNDS ...
Extraction of phenolic compounds from olive
pomace
The dried Olive pomace was first extracted
which n-hexane in at ratio (1: 4 W/V) three times
successively to remove the residuals of fats and
pigments. Then, the polyphenols were extracted
from the OP using varies extracting solvents
including acetone, ethanol, ethanol and water
(50:50), methanol, methanol and water (80: 20),
ethyl acetate, and water at solvent to pomace ratio
(10: 1). The extraction process was cured out in a
shaker at room temperature for 24 hr followed by
filtration. The residues were re-extracted under the
seam conditions. The total extracts were filtered
(0.45 µm) and the solvents were evaporated at
35°C. in a Speed Vacuum Concentrator, SPD111V
230 (Thermo scientific, USA). The yield was
calculated and stored in dark at -20 oC until used
(Alu’datt et al., 2010).
Determination of total phenolic content
Total phenolic content of the extracts was
determined spectro-photometrcally with Folin–
Ciocalteu assay (Vergani et al., 2014). A 20 µL
aliquot of extracts solutions were mixed with 100
µL of Folin–Ciocalteu’s reagent followed by 1.586
mL of distilled water and followed by 300 µL of
20% Na2CO3 solution. The obtained mixtures
were incubated in a shaking incubator at 40 °C
for 30 min and the absorbance was measured at
765 nm. The results were expressed as mg gallic
acid equivalent (GAE) using the following liner
equation based on gallic acid calibration curve.
Y = 0.0248x + 0.237 (R² = 0.997)
Where A is the absorbance and C is the
Determination of total flavonoids and flavonols
Total flavonoids content was determined
as described by Mohdaly et al. (2009). Using
AlCl3 ethanolic solution and the absorbance was
measured at 420 nm. Total flavonoids content
calculated and expressed as quercetin equivalent
(QE) using the following equation based on the
calibration curve:
Y = 0.0035x + 0.0258 ((R² = 0.9929)
Where Y is the concentration (mg QE/100
g extract) and X is the absorbance and Total
flavonols content was determined according to the
method described by Kumaran and Joel (2007). 2
mL of 20 g/L AlCl3 ethanolic solution and 3 mL
of 50 g/L sodium acetate solution were added
to 2 mL of extract solution. The absorption was
recorded after 2.5 hr at 440 nm. Total flavonols
content expressed as QE was calculated using the
quercetin calibration curve:
Antioxidant activity of olive pomace extracts
The antioxidant capacity pomace extracts were
determined using 2,2-diphenyl-1-picrihydrazyl
(DPPH) assay according the method of Brand-
Williams et al., (1995) with some modifications.
Extracts and synthetic antioxidants (BHA, BHT
and TBHQ in ethanol) solutions of different
concentrations (100µL of each) were vortexed
for 30 s with 1.8 mL of DPPH solution and left
to react for 30 min, after which the absorbency
of the remaining DPPH was recorded at 515
nm. A control sample was prepared at the same
conditions without extract. The measurements
were performed in triplicate. Scavenging activity
was calculated as follows:
scavenging (%) = [(A. control – A. sample) /A.
control] × 100
Where : A is the absorbance at 515 nm.
Antiradical Efficiency = 1/EC50
EC50 is extraction concentration providing 50%
inhibition of DPPH.
High performance liquid chromatography
(HPLC/DAD)
HPLC was performed in LC10 AD HPLC
eluent pump (Shimadzo, Kyoto, Japan), DAD
SPDM10 AVP, UV-Vis SPD 10AVP detectors
(Shimadzo, Kyoto, Japan). phenolic compounds
were separated on a C18 analytical column, 250
.46 mm i.d. (Shimadzo, Kyoto, Japan) packed
with Luna C18 stationary phase, particle size
3µm and connected to C18 precolumn. The time
of HPLC run was over 40 min. UV-Vis detector
was operating at 290 nm wavelength. Phenolic
compounds were identified by comparison of
chromatographic retention times and area of
the peak in the extract with that of the standard
phenolic acids and reference compounds using
Mass Lynx 4.0 software (Micromas UR Ltd., UK)
and the available literature data (Gheldof et al.,
2002).
Determination of cellulose content
This was achieved by delignification of the
sample with chlorous acid followed by elimination
of hemicellulose by treatment of the resulting
holocellulose with 10 % NaOH at 80°C for 3
hours as reported by Chen et al. (1988) as follows:
The lignocelluloses material was first subjected to
Soxhlet extraction with a mixture of methanol and
benzene (1:1) for 8 hr lignin was then eliminated
30
Egypt. J. Food Sci. 48, No.1 (2020)
KHALED A. SLEIM et al.
treating 5.0 grams (oven dry) of olive cake with
sodium chlorite solution (sodium chloride 1.5
gram in 160 mls. of water containing 10 drops
of glacial acetic acid). The mixture was left
in water bath at 70°C for one hour then after,
ten drops of glacial acetic acid and 1.5 gram
of sodium chlorite were again added and this
was repeated twice. After filtration the residual
material was washed successively with water
and ethyl alcohol to give the holocellulose.
For the removal of hemicellulose, the obtained
holocellulose was treated 10 % NaOH solution
(1:20 W/V) and heated at 80°C in a water bath
for 1.5 – 3.0 hour. After filtration, the residue
was washed with water, ethanol and ether and
then dried at 105°C to constant weight.
Determination of hemicellulose content
Hemicellulose content was estimated,
gravimetrically, after extraction, as reported
by Chen et al. (1988) 10 grams of olive cake
with 14 % NaOH (100ml) at 90ºC for 3 hr, and
precipitated with HCl at PH 5. The precipitated
hemicellulose was separated by centrifugation,
washed with ethanol, then dried and weighted.
Determination of lignin content
Lignin content in the investigated materials
was also determined according to the method
described by Fahmi (1984) as follows: One
gram olive cake extracted using a mixture of
methanol and benzene (1:1). In a wide mouthed
bottle of 150 ml capacity, 50 ml of 38% pure
HCL (not less than 38%) was added. The
mixture was left for two min, and then 50 ml
of concentrated sulfuric acid was added. After
shaking for one hour the mixture was left for 24
of one-liter capacity. The bottle was washed
with 415 ml of distilled water and filtered.
weighted.
Cellulose isolation
The isolation of cellulose was cured out
using the methods described by Brendel et al.
(2000) as follows: 500 gram of dried olive cake
was extracted with aqueous acetic acid 80%
(w/w) and nitric acid 70% (w/w). The residue
was then thoroughly washed with distilled
water and ethanol 95% to remove the nitric
acid and extraction breakdown products. The
residue was then dried in an oven at 60 ºC for
16 hr and was labeled as cellulose.
Determination of dough rheological properties
The effect of powdered cellulose on
rheological properties of dough during mixing
was determined by the Brabender Farinograph,
following the AACC Approved methods (54
– 21, 1983) and the Brabender Extensigraph
following the AACC Approved methods (54 –
10, 1983).
Bread making
The Straight Dough (Bulk Fermentation)
method was used for bread making as described
by Pourabedin et al. (2017), the amount of
added water was calculated from Table 6. The
control sample was consisted of 100 g flour, 1.5
g salt, 1g yeast. Three treatments ware prepared
with three different replacement levels 0, 2, 4
and 6 % of the flour. Dough pieces (100 ± 0.1
25 min.
Sensory evaluation
Toast bread containing different cellulose
powders and control bread were sensory tested
in Food Technology Department, Faculty of
Agriculture, Kaferelsheikh University, Egypt.
For their color, appearance, odor, texture, taste
and overall acceptability on a 1 to 10 hedonic
scale as described by Meilgaard et al. (2007).
Statistical analysis
Statistical analysis of the data obtained
from the study was performed using the SPSS
v statistical program SPSS v. 16 for windows
(SPSS, Chicago, II., USA) The ANOVA method
was used to analyze the results. Multiple range
tests from Duncan were used at a level of 5% of
significance for comparison of means. All trials
were conducted in triplicate.
Results and Discussion
Proximate chemical composition of olive pomace
The main values obtained for the proximate
composition of OP are presented in Table 1.
The results showed that the sample presented
a moisture content of 64.58% (FW) and protein
content of 2.48%. The data rivaled that ash
and fiber content of OP was 1.33 and 20.37%
(FW) respectively. The total lipid of the
analysed sample was 2.33g/100g (FW) which
could be used in food and cosmetics industry
(Rodrigues et al., 2017). Di Giovacchino and
Prezioso, (2006) reported that ash content of
OP ranged from 1.42 to 4% (FW). It is clear
31
Egypt. J. Food Sci. 48, No.1 (2020)
UTILIZATION OF OLIVE POMACE AS A SOURCE OF BIOACTIVE COMPOUNDS ...
that the OP contains a large quantity of fibers
and it had cellulose content about 40.7% of the
fiber content. Several studies have focused on
isolation of dietary fibers from olive pomace
and reported cellulose, hemicellulos and lignin
as the main carbohydrates in olive by-products
(Jimenez et al., 1994). In another study, Vlyssides
et al., (1998) found that OP contains cellulose,
hemicellulos and lignin of 14.54, 6.68, and 8.54%
(DW) respectively. These compounds could be
used in many food products as gelling agents,
fiber source and fat substitute. It was found that
the proximate composition of OP is influences by
many factors including ripening stage, cultivar,
and agriculture practices (Portarena et al., 2017).
Our results agreed with that stated by Roselló-
Soto et al. (2015) and Nunes et al. (2018).
TABLE 1. chemical composition of olive pomace.
Olive pomace g /100g (FW)
64.58± 2.51
Total lipids 2.33± 0.06
Protein 2.48±0.04
Ash 1.13±0.02
Total carbohydrates 29.48± 2.41
20.37± 1.65
Cellulose* 40.77 ± 2.44
Hemicelluloses* 33.63±2.28
Lignin* 19.50± 1.79
dry weight basis)
TABLE.
Solvents Extract yield (g/
kg-1 DW)
Total phenolic
(mg GAE g-1 DW)
EC50
µg/µg DPPH
Antiradical
Methanol 115.85±0.22 24.64±0.05 2.337 0.428
Ethanol 98.68±0.21 18.22±0.04 4.416 0.226
Methanol: water (80:20) 141.27±0.28 36.24±0.10 1.373 0.728
Ethanol: water (50:50) 118.61±0.34 26.22±0.08 1.733 0.577
Ethyl acetate 80.51±0.17 9.04±0.02 5.821 0.172
Acetone 66.92±0.13 8.29±0.03 8.052 0.124
Water 94.58±0.19 19.50±0.07 2.795 0.358
Extraction of phenolic compounds from olive
pomace by different solvents
The majority of polyphenolic compounds
(98%) remain in the olive pomace and a small
fraction passes into the oil about (2%). (Chanioti
and Tzia, 2017). To extract the phenolic compounds
from OP, suitable solvents must be used according
to their extraction efficiency and according to the
uses of the compounds to be extracted. The effect
of various solvents was assessed to determine the
most appropriate one for yield, total phenoilc,
flavonoids, and flavonol content of the extracts
obtained. Polyphenolic yields were found to
increase with increasing the polarity of the solvents.
The extract yield was varied from 141.27 to 66.92
g / kg -1 (DW) (Table 2). The obtained results
proved that using methanol and water showed
highest yield , while acetone scored the minimal
polyphenol production (66.92 g / kg DW).
Referring to polyphenols from different
extracts, the results showed that the polyphenols
content varied from 36.24 to 8.29 mg/g-1.
Methanolic extract recorded the highest total
polyphenolic content higher than the other solvents
While, hand, acetone extract presented the less
polyphenolic contents. This because of the high
polarity of methanol. The obtained findings similar
to those obtained from other researchers who used
several solvents to extract phenolic compounds
from olive and olive pomac. (Cioffi et al, 2010,
Lafka et al, 2011, Vergani et al, 2016, Araújo , 2015
and Albahari et al., 2018). Cedola et al. (2019)
found that dry olive paste had phenols content,
equal to 45.09 mg GAE/g dw, and high amount of
flavonoids (36.11 mg QE/g dw).
32
Egypt. J. Food Sci. 48, No.1 (2020)
KHALED A. SLEIM et al.
Total flavonoids and flavonols content of olive
pomace extracts
Total flavonoids and flavonols content
of olive pomace extracts were determined to
identify the quality and the structure of the OP
phenolic compounds. Because of the antioxidant
efficiency dose not correlate with the quantity of
the phenolic compounds in all cases. The results
are presented in Fig. 1. The results indicated that
flavonoids and flavonols content were varied with
the different extracts. Total flavonoid contents
ranged from 12.52 mg/g-1 (DW) for methanol +
water extract to 2.23 mg/g-1 (DW) for acetone
extract. Regarding to the flavonols contents,
methanol + water and ethanol+ water recorded the
highest content with values of 6.73 and 5.72 mg/
g-1 (DW) respectively. On the other hand, aceton
and ethyl acetate recorded the lowest flavonoids
and flavonol contents of the olive pomace.
Identification of polyphenolic compounds from
methanol: water extract of olive pomace
The phenolic compounds and derivatives
of olive pomace methnolic extract in this study
were fractionated an identified by HPLC/DAD.
The protective chromatogram obtained at 290nm
along with the corresponding retention time,
peaks number and beak relative area are presented
in Fig. 2 and Table 3. The prime polyphenolic
found in the studied extract are phenolic-acids,
phenolic-alcohols, secoiridoid derivatives, and
flavonoids. The major phenolic acids were galic,
acid showed the highest concentration, while
galic acid and cinnamic acid recorded the lowest
concentration in the methanolic pomace extract.
Many factors were found to affect the phenolic
compounds concentrations including the cultivar,
agronomic, geographic origin of olive, olive tree
irrigation, and technological conditions of oil
production (Servili and Montendoro, 2002). These
results agree with those reported by Vincenzo
(2016) and Cioffi et al. (2010).
The chromatogram of olive pomace brings to
light the presence of hydroxytyrosol and tyrosol
as phenolic alcohols and oleuropein, ligstroside
aglycone, and oleuropein aglycone as secoiridoid
derivatives. Hdroxytyrosol have been revealed
to be one of the most interesting phenolic
compounds in the olive pomace, because of its
strong antioxidant activity, anti-inflammatory
and antimicrobial properties (Robles-Almazan,
2018). Moreover, this compound affects the
quality properties (sensory and chemical) of food
products was explored (Nunes et al., 20180).
Oleuropein and oleuropein aglycone were found
in olive oil and olive pomace (Fernendez-Bolanes
et al., 2006, Goldsmith et al., 2014, Leouifoudi
et al., 2014. and Sicari, 2016). Oleuropein also
works as natural anti-oxidant in the body (Visioli
et al., 2006). The results showed the presence
Rutin and luteolin as flavonoids derivatives in the
olive pomace. According to the literature data,
these compounds were detected in olive oil and
olive by-products (Dermeche et al., 2013).
Antioxidant activity of olive pomace extracts
Because of the undesirable effects of the
synthetic antioxidants on human health and
enzymes systems, the natural antioxidants
can replace the synthetic one (Monica et al.,
2007 and Baydar et al., 2007). The results
of scavenging effects of the OP extracts are
summarized in Fig. 3. It could be notice that
inhibition ratio is increases by increasing the
concentrations of extracts for all tested extracts.
when low concentration 50µg/mL was used,
the remaining DPPH hanged from 93.63% for
acetone extract to 60.38% for methanol+water
extract. Meanwhile, when the concentration was
increased to 300 µg/mL the remaining of DPPH
was decreased to 64.72, 8.38, and 6.65% for
acetone, ethanol +water, and methanol+water
extracts respectively. These results may be
due to the elevated polyphenolic content in
methanol and ethanol extracts. Our findings
are compatible with that stated by (Silva et al,
2006, Obied et al., 2007, and Leouifoudi et al.,
2014).
The results in the same figure illustrate
the scavenging activity of the OP extracts
at different concentrations compared to the
synthetic antioxidants (BHA, BHT, and BHTQ).
Scavenging activity of OP was found to be
concentration dependent. The results showed
that methanol+water and ethanol+water had
high scavenging activity as strong as BHA and
BHT and recorded EC50 values of 1.373 and
1.728µg/ µg DPPH and antiradical efficiency
values of 0.728 and 0.577, respectively. The
results also proved that acetone extract showed
the lowest scavenging antioxidant activity with
EC50 value of 8.052µg/µg DPPH. The strong
scavenging activity could be related to the high
concentration of the antioxidant compounds
in OP such as hydroxytyrosol, oleuropein, and
oleuropein aglycon (Suarez et al., 2009 and
Leouifoudi et al., 2014).
33
Egypt. J. Food Sci. 48, No.1 (2020)
UTILIZATION OF OLIVE POMACE AS A SOURCE OF BIOACTIVE COMPOUNDS ...
5,0 10,0 15,0 20,0 25,0 30,0 35,0
-20
50
100
150
200
120330 #55
K87
UV_ VIS_ 1
m AU
min
1 - 8,327
2 - 11,403
3 -Caffeic Acid
4 - 13,923
5 - 14,973
6 - 15,637
7 - 16,390
8 - 16,983
9 - 17,423
10 - 18,473
11 - 18,807
12 -Cinnamic Acid
13 - 21,677
14 - 22,757
15 - 23,167
16 - 23,927
17 - 24,863
18 - 25,273
19 - 25,650
20 - 26,473
21 - 27,610
22 - 28,007
23 - 28,883
WVL:290 nm
Fig.2. HPLC–DAD chromatogram of olive pomace methanolic extract.
TABLE 3. Phenolic components of olive pomace methanolic extract.
No. R. T.
Min. Peak Name Height mAU Area
mAU*min
Relative Area
%
1 8.33 Gallic acid 2.893 1.390 1.22
2 11.4 Hydroxytyrosol 10.090 3.342 2.93
3 12.65 10.873 3.706 3.25
4 13.92 Cumaric acid 9.062 2.684 2.36
5 14.97 Tyrosol 84.547 23.963 21.03
6 15.64 Vanillic acid 6.272 1.652 1.45
7 16.39 Oleuropein 27.784 7.064 6.20
8 16.98 NA 8.605 1.999 1.75
9 17.42 6.360 2.967 2.60
10 18.47 NA 14.712 8.113 7.12
11 18.81 oleuropein aglycone 20.897 9.379 8.23
12 20.7 Cinnamic acid 4.391 0.691 0.61
13 21.68 NA 17.878 3.555 3.12
14 22.76 Ferulic acid 13.727 2.074 1.82
15 23.17 NA 4.207 0.748 0.66
16 23.93 NA 2.932 0.552 0.48
17 24.86 Oleuropein glucoside 48.869 12.416 10.90
18 25.27 Luteolin 40.621 8.189 7.19
19 25.65 Luteolin-7-glucoside 13.812 2.484 2.18
20 26.61 NA 4.130 0.688 0.60
21 27.61 Rutin 10.918 1.886 1.65
22 28.01 NA 6.671 1.217 1.07
23 28.88 NA 53.992 13.190 11.58
34
Egypt. J. Food Sci. 48, No.1 (2020)
KHALED A. SLEIM et al.
Sensory evaluation of toast bread samples
fortified with olive pomace cellulose
Cellulose is one of the main olive cell wall
polysaccharides recovered from olive pomace
(Catanakis et al., 2010). In food industry, the
valorization of native dietary fibers appears to be
have role in prevention of several diseases such
as cancer (Rodríguez et al., 2006). There are less
publications on the utilization of olive pomace
in foods especially its effects on the rheological
properties of the dough when used as a substitute
for wheat flour in bread making. In this part of
the study, isolated cellulose from olive pomace
was used in fortification of toast bread and its
effects on the rheological and sensory properties
of the bread was investigated.Results of sensory
evaluation of produced bread with different added
levels of OP cellulose are given in Table 4. It
indicated no significant differences between the
control and the sample fortified by 2% cellulose
in all the tested parameters. The results showed
that increasing the fortification ratio to 4% led to
no significant differences (p < 0.05) between the
control and the sample in color, taste and texture
and significant differences in, odour, appearance
and overall acceptability.
The bread with 2% substitution level was
superior in all sensory characteristics evaluated
compared to other replacement ratios. Moreover,
it recorded higher scores in texture, appearance
and overall acceptability than the control
sample. When 6% of the flour were replaced
with cellulose,significant drops in the values
of all the sensory characteristics were observed
in the resulting bread. Our results are similar
radical and comparing with synthetic antioxidants .
to that presented by Cecchi, et al. (2019) for
pasta, bread, and granola bar fortified with olive
pomace. Cedola et al. (2019) found that addition
of dry olive paste flour to the bread also slightly
interfered with the network formation, thus
influencing the final bread bubbles that were
considered more acceptable in the control samples
than in the enriched bread. The Sensory evaluation
of cellulose-enriched baked rolls indicated that
addition of cellulose by up to 1% was identical to
the control rolls. It was also found that increasing
the addition levels of cellulose significantly
reduced the crus, taste, porosity and color of the
produced rolls (Lauková et al. (2017). Likewise,
Gómez et al. (2003) mentioned that it is possible
to add dietary fibers to the flour while making
bread by up to 2% without. Ang and Miller (1989)
used cellulose powder in the cake manufacture
with different addition ratios and measured the
texture of the cake. They found that the low
levels of cellulose addition led to the cake being
produced more harder texture than those with a
high level of cellulose. This can be because long
fibers contribute to a soft cake. They also noticed
that these ratios from adding up to 4% improve
the overall appearance and reduce moisture loss
from the surface cracking as well as extending the
shelf life of the cake (Kamel and Stauffeer, 1993
and Prakongpan et al, 2002).
Quality characteristics of toast bread
Regarding to the effect of adding cellulose in
the bread formula in the chemical composition
of the produced bread, the results in Table 5
showed that moisture content of the bead was
increased with increasing the fortification level.
There were no significant differences between
35
Egypt. J. Food Sci. 48, No.1 (2020)
UTILIZATION OF OLIVE POMACE AS A SOURCE OF BIOACTIVE COMPOUNDS ...
the control sample and the sample fortified with
2% olive cellulose. As prospective, it was noted
that the bread samples to which cellulose was
added contained higher fibers than those made
without adding cellulose. Besides, the results
also demonstrated no significantly differences
among the control and the bread samples with 2%
and 4% added olive cellulose powder in protein,
lipid and ash contents. Our results were similar
to that obtained by Lin et al. (2017). For olive
pomace based high fiber biscuit. Sodchit et al.
(2013) added banana peel cellulose powder to
butter cake at three levels and found that addition
cellulose to the cake improved the fiber content of
the product. They also observed that sample with
1.5 % added cellulose recorded no significant
differences compared with the control in protein,
moisture, total lipid and ash contents.
Effect of addition of olive pomace cellulose on the
rheological properties of the dough
Farinograph characteristics
It was found that adding dietary fibers to the
bread improves the nutritional value, but at the
same time it may lead to a change in some of the
rheological properties of the dough, and this may
lead to an effect on the quality of the bread and the
sensory properties of bread (Rosell et al., 2005).
Farinographic properties of doughs with several
levels of olive pomace cellulose are given in Table
(6). Water is an important component of baking
dough because it takes part in hydration of gluten,
thus ensuring that the dough maintained carbon
dioxide. Also, the ability of dough to absorb water
(WA) is of great importance in bread industry.
The water absorption of dough with 2% olive
pomace cellulose substitution was 54.5% and it is
higher than that of control dough. When the olive
TABLE
Samples
Sensory characteristics
Color Odour Texture Appearance Overall
acceptability
Control 9.20 ±0.15a9.23 ±0.37a9.04 ±0.34a8.20 ±0.39ab 9.11 ±0.22a8.23 ±0.27a
2 % OPC*8.8 ±0.38a8.92 ±0.54a8.91±0.12a8.90 ±0.18a8.95 ±0.32a8.53 ±0.44a
4 % OPC 8.75 ±0.29a8.85 ±0.42a8.17 ±0.19b8.10 ±0.32b8.38 ±0.17b8.16 ±0.14b
6 % OPC 7.94 ±0.41b6.81±0.22b6.90 ±0.71c7.43 ±0.54c6.82 ±0.27c7.14 ±0.19c
OPC= olive pomace cellulose
Extensograph properties
According to the results of extensographic
properties of doughs with added olive pomace
cellulose (Table 6), the controls sample recorded
the highest extensibility while the sample
substituted with 6 % cellulose showed the lowest
extensibility value. Thus, it can be observed that
addition of olive pomace cellulose caused the
extensibility of the dough samples to decrease.
Similar findings were reported by Koca and
Anil (2007) for replacement of wheat flour with
flaxseed flour in bread. Likewise, Poran et al.
(2008) found that addition of cellulose to the
wheat flour reduced the extensibility of dough.
This finding could be attributed to the protein
content decreases when flour is substituted by
powdered cellulose and as a result, the dough
loses portion of its expandability property.
A consequence, the dough loses part of its
extensibility property. Also, the dough demand
for water increased when fibre was added
and these led to dilution of gluten and reduce
extensibility of the dough. The resistances to
extension of dough samples are presented in
Table 6. The results indicated that there was a
highly significant increase in the resistance
of dough, when the flour was substituted with
powdered cellulose. The resistance of the dough
increased from for the control to for 6% cellulose
flour sample. Such increment in the resistance
could be due to the interaction between the olive
cellulose and gluten in wheat flour. Many studies
declared negative effect of adding insoluble fiber
on the formation of gluten network (Pourabedin
et al., 2017, and Ahmed et al., 2013). The energy
value of dough with 2% olive pomace cellulose
substitution was analogous to the control.
However, the energy values of doughs made
with 4% and 6% olive pomace cellulose were
36
Egypt. J. Food Sci. 48, No.1 (2020)
KHALED A. SLEIM et al.
TABLE
Samples
Chemical composition (%)
Moisture Protein Ash Total lipids Fiber Carbohydrates
Control 11.20±0.23b10.95±0.33b1.79±0.14a3.80±0.43a3.22±0.32d80.66±1.40a
2 % OPC 11.44±0.40b10.71±0.27b1.78±0.19a3.79 ±0.23a3.90±0.41c79.92±1.55a
4 % OPC 11.98±0.64a10.22±0.29ab 1.77±0.09a3.78±0.28a4.38±0.50b79.55±1.70a
6 % OPC 12.09±0.92a9.69±0.74a1.75±0.11a3.76±0.33a5.14±0.40a79.26±1.60a
OPC= olive pomace cellulose
Conclusion
This research confirmed that the quantity of
polyphenolic compoundst in the olive pomace
were ranged between 36.24 to 8.29 mg/g-1 DW
depending on the extraction solvent used. The
major polyphenolic compounds in the olive
pomace were tyrosol, hydroxytyrosol, oleuropein,
and oleuropein aglycon, luteolin and rutin. The
results showed that olive pomace methanolic
extracts had high scavenging activity as strong
as BHA and BHT which could be related to the
high concentration of the antioxidant compounds
in OP such as hydroxytyrosol, oleuropein,
and oleuropein aglycon. Adding olive pomace
cellulose powder to wheat flour led to significant
alters in farinograph parameters. Addition of 2%
cellulose powder enhanced the texture and the
acceptability of the toast bread compared with
the control sample, . It can be concluded that
TABLE
(82% extraction).
Farinogragh parameters
parameters
Samples
Water absorption
%Arrival time (min) Developing
time (min)
Stability time
(min)
Weakening
value (BU)
Control 53.6c0.5c1.0c4.50a70c
2% 54.5b1.5b2.0b3.52b80b
4% 56.9b1.5b2.25b3.51b80.5b
6% 66.8a2.2a3.1a3.04c90.7a
Extensograph parameters
Extensibility (mm) proportional number Energy (cm2)
Control 125 445 3.65 63
2% 110 462 4.21 58
4% 101 468 4.63 48
6% 95 484 5.09 40
olive pomace cellulose could be used as wheat
replacer in toast making at the level of 2% with no
impairment on quality characteristics of the bread.
Acknowledgment
This study was financial propped by Cultural
Affairs and Missions Sector, Egypt and University
of Applied Science Weihenstephan-Triesdorf,
Weidenbach, Germany.
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Special problems.
two phase extraction
.2,2-diphenyl-1-picrihydrazyl (DPPH)
:
