Chemical, Mineral and Phytochemical Screening

International Journal of Bioengineering & Biotechnology
2017; 2(2): 6-12
http://www.openscienceonline.com/journal/ijbb
Chemical, Mineral and Phytochemical Screening
Assay of Date Palm Seeds for the Development of
Date Palm Seed Coffee
Sobia Niazi1, 2, *, Seemab Rasheed2, *, Imran Mahmood Khan1, 2, Ayesha Safdar4, Fozia Niazi3
1
School of Food Science and Technology, Jiangnan University, Wuxi, China
2
National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan
3
Faculty of Sciences, Gomal University, Dera Ismail Khan, Pakistan
4
Department of Chemistry, Government College Women University, Sailkot, Pakistan
Email address
sobianiazi47@yahoo.com (S. Niazi), seemabrasheed2241@gmail.com (S. Rasheed)
*
Corresponding author
To cite this article
Sobia Niazi, Seemab Rasheed, Imran Mahmood Khan. Chemical, Mineral and Phytochemical Screening Assay of Date Palm Seeds for the
Development of Date Palm Seed Coffee. International Journal of Bioengineering & Biotechnology. Vol. 2, No. 2, 2017, pp. 6-12.
Received: August 13, 2017; Accepted: September 9, 2017; Published: October 25, 2017
Abstract
Date palm fruits possess high nutritional and therapeutic value with significant antioxidant, properties. The inedible parts of
date palm (date seeds) are often discarded as waste however these are rich source of dietary fiber, phenolics and antioxidants.
Present study is an attempt to explore the nutritional and phytochemical profile of date seeds and their utilization in food
product development. Purposely, date seeds were analyzed for their proximate and mineral contents. Afterwards, date seeds
extracts was obtained using methanol as extraction solvent. The extract was analyzed for total phenolic and flavonoids
contents. Finally roasted date seed powder was used for the development of date seed coffee and analyzed for its sensory. The
proximate composition of date seed powder showed that it contained 5.65±0.17% moisture, 1.17±0.04% ash, 5.85±0.23%
crude protein, 7.95±0.39% crude fat, 64.75±2.59% crude fiber and 14.63±0.44% nitrogen free extracts. Amongst the minerals,
potassium is present in maximum amount 375.87±11.7 mg/100g followed by phosphorus 125.58±5.02 mg/100g, magnesium
77.55±2.33 mg/100g, calcium 18.73±0.93 mg/100g and sodium 15.23±0.6 mg/100g. Moreover, the antioxidant profiling of
date seed showed that the value of TPC 31.2±0.93 mg GAE/g of dry weight and flavonoids 29.5 mg/g dry weight. The
developed date seed coffee was also sensory evaluated.
Keywords
Date Seeds, Chemical Composition, Mineral Contents, Antioxidant, Date Seed Coffee
1. Introduction
Date palm (Phoenix dactylifera L.) is considered as one of
the oldest and staple crops in Southwest Asia and North
Africa. Besides, dates can be grown in Australia, Southern
Africa, Mexico, South America and the United States,
especially in southern California, Texas and Arizona [1, 2].
Egypt is largest producer of dates while, Pakistan is the 5th
largest date producing country [3].
The most significant quality attributes to grade dates are
color, flavor, moisture content and absence of defects i.e
insect, damage, cracks and surface damage. Date fruit is good
source of high nutritional value. It is rich in carbohydrates,
dietary fibers, proteins, minerals and vitamin B complex [4,
5]. In more details, carbohydrates forms 70% of date fruit
and date proteins are rich in amino acids. Minerals in date
fruits are calcium, iron, magnesium, selenium, copper,
phosphorus, potassium, zinc, sulfur, cobalt, fluorine,
manganese, and boron [1, 6].
The protective effects of fruits against chronic diseases are
ascribed to bioactive non-nutrients called phytochemicals.
Phytochemicals have gained increased interest among several
investigators, including clinicians due to their antioxidant
7
Sobia Niazi et al.: Chemical, Mineral and Phytochemical Screening Assay of Date Palm Seeds for the
Development of Date Palm Seed Coffee
activity, cholesterol-lowering properties, and many other
potential health benefits such as cardiovascular diseases,
prevention of diabetes and chemoprevention of cancer [1, 7].
Date seed, an agro-waste encompasses a number of
bioactive components that are helpful in mitigating various
physiological threats. Ample amount of waste is produced
from date processing industries mainly date pit and tip. Date
pits are usually discarded as a waste material having merely
no use. It considered waste product of date fruit. Rarely, in
the Middle East, date seeds are used in animal feed, such as;
for camel, sheep, poultry and cattle industries [8]. Seeds are
often used in foods, pharmaceuticals and also having
ornamental benefit like making beads for decoration [9].
These are rich source of dietary fiber, phenolics and
antioxidants and no health use of these by product results in
nutritional as well as economic loss [10].
The aim of the current research was to explore the
antioxidant potential and nutraceutic worth of date seeds due to
its phytochemistry. In low income countries, the development
of cost effective natural products is the need of time as
numerous researches have yet been reported in this field. Date
industries produces large amount of waste in the form of date
pit, therefore need of the day is to utilize these agro wastes
because of its high antioxidants potential. In this context,
conventional solvent extract were prepared and analyzed for
their in vitro antioxidant potential through phytochemical
screening assays. During product development module, date
seeds coffee powder and ready to drink date seeds coffee were
prepared to assess consumer acceptance using 9-point hedonic
scale. The date seeds extracts were further used during storage
for their antioxidant profiling through TPC and DPPH assay.
The collected data was finally subjected to statistical analysis
in order to determine the level of significance.
2. Materials and Methods
The present research was conducted in the Functional and
Nutraceutical Food Research Section, National Institute of
Food Science and Technology, University of Agriculture,
Faisalabad Pakistan. For the purpose, date seed powder was
used for the extraction and characterization of its bioactive
molecules. Afterwards, roasted date seeds were used for the
development of caffeine free coffee to explore its sensory
characteristics.
ambient temperature prior to analysis.
2.3. Proximate Analyses
The date seed samples were analyzed for moisture, ash,
crude protein, crude fat and crude fiber according to their
respective methods as described in Association of Official
Analytical Chemists (AOAC) [11].
2.3.1. Moisture Content
The moisture content of date seeds powder were
determined following method mentioned by AOAC Method
No. 934-01 [11]. Accordingly, 10 g sample was dried in hot
air oven (Model: DO-1-30/02, PCSIR, Pakistan) at a room
temperature of 105±5°C for the duration until weight was
constant. Moisture percent was found according to the
following equation;
Moisture(%) =
2.2. Preparation of Date Seed Powder
Date flesh and pit was separated. Seeds were washed to
remove adherent fruit material. After washing and drying,
seeds were roasted and grounded to obtain fine roasted date
seeds powder. The powder was stored in plastic jars at
100
2.3.2. Total Ash
The ash content of date seeds powder was estimated
according to the procedure outlined in AOAC Method No.
942-05 [11]. Briefly, 5 g of sample was directly charred on
flame in crucible until there were no fumes coming out.
Afterwards sample was ignited in muffle furnace (MF-1/02,
PCSIR, Pakistan) at 550-600°C for 5-6 hours or until grayish
white residues were obtained.
Ash (%) =
100
2.3.3. Crude Protein
The percentage of nitrogen in the sample was determined
by following AOAC Kjeldahl’s Method No. 984-13 [11]. The
sample was first digested with concentrated H2SO4 in the
presence of digestion mixture (K2SO4: FeSO4: CuSO4 100: 5:
10) for 2-3 hours or until the digested material attained light
greenish or transparent color. This material was diluted (250
mL using distilled water) and distillation was done by taking
10 mL of diluted material and 10 mL of 40% NaOH solution
in the distillation apparatus. Liberated ammonia was
collected in 2% boric acid solution containing methyl red as
an indicator. Finally the distillate was titrated against 0.1 N
H2SO4 till golden brown end point. The crude protein
percentage was calculated by multiplying nitrogen (N) with
factor as described below:
2.1. Procurement of Raw Material
The dates were procured from local market. The analytical
reagents were purchased from Merck (Merck KGaA,
Darmstadt, Germany) and Sigma-Aldrich (Sigma-Aldrich
Tokyo, Japan).
N (%) =
! "
#.%&'( )*+ ! "
( ) ! "
, "
#.##%-
,
100
Crude Protein = N (%) x 6.25
2.3.4. Crude Fat
The crude fat content in date seeds powder was calculated
following guidelines of Method No. 920-39 in AOAC [11].
Briefly, 3 g sample was refluxed in soxhlet apparatus (Model:
H-2 1045 Extraction Unit, Hoganas, Sweden) using n-hexane
as a solvent.
International Journal of Bioengineering & Biotechnology 2017; 2(2): 6-12
Crude fat (%) =
100
2.3.5. Crude Fiber
The crude fiber was estimated by digesting fat free sample
using 1.25% H2SO4, followed by 1.25% NaOH solutions.
The residue was weighed and ignited in a muffle furnace at
550°C till white residue left. Fiber percentage was calculated
according to the AOAC Method No. 978-10 [11]. The crude
fiber was calculated by using following expression.
Crude fiber (%) =
( )
( )
100
2.3.6. Nitrogen Free Extracts (NFE)
The NFE was calculated through subtraction method
following the expression:
NFE% = 100–(Moisture + Crudeprotein
+ Crudefat + CrudeFiber + Ash)%
2.4. Mineral Analysis
For mineral determination, wet digestion of all samples
was carried out according to the method of AOAC [11]. The
sample 0.5 g was taken in a conical flask and was digested
with 10 mL HNO3 at a temperature of 60-70°C for 20
minutes and then digested with 5 mL HClO4 at a temperature
of 60-70°C for 20 minutes and subsequently increasing the
temperature to 195°C till the volume of the content was
reduced to 1-2 mL. The digested sample was transferred to
100 mL volumetric flask and volume was made up to the
mark using distilled water and then filtered. After filtration,
the digested samples were stored for different mineral
determination according to their respective methods.
2.5. Phytochemical Screening Assay
2.5.1. Preparation of Date Seed Extracts
The solvent extraction was carried out using aqueous
methanol by following the protocol of Al- Farsi et al [12].
Briefly, 50 g of date seeds powder was added in 149 mL of
aqueous methanol in 250 mL conical flask, 1 mL of acetic
acid and 40 mL of distilled water were added in flask. The
mixture of solvent and date seeds powder was placed in
orbital shaker for 3-4 hours at 280 rpm with controlled
temperature at 20°C. The mixture was filtered through
Whatman filter paper No. 2. The solvent was evaporated
using rotary evaporator under reduced pressure at 40°C. The
final extract was stored at -40°C.
2.5.2. Total Phenolic Contents
The total phenolic contents in date seeds extracts were
determined by the Folin-Ciocalteu method [13]. The
principle is based on the oxidation of phenolic compounds
under alkaline conditions that result in reduction of
phosphotungstic acids contained in Folin-Ciocalteu reagent
to phosphotungstic blue or blue colored tungsten oxides. The
absorbance of phosphotungstic blue is directly proportional
to the number of aromatic phenolic groups. Briefly, 1 mL of
8
appropriately diluted samples or a standard solution of gallic
acid was added to a 25 mL volumetric flask containing 9 mL
of distilled water. A reagent blank was prepared using
distilled water. One milliliter of Folin–Ciocalteu phenol
reagent was added to the mixture and mixed by shaking.
After 5 min, 10 mL of 7% Na2CO3 solution were added under
shaking. The solution was then immediately diluted to 25 mL
with distilled H2O and mixed thoroughly. After incubation
for 90 min at 23°C, the absorbance was read at 750 nm using
a spectrophotometer. The total phenolic contents are
expressed as milligrams of gallic acid equivalents (GAE) per
100 g of powder. All measurements were performed in
triplicate using gallic acid as standard, expressing the results
as mg/g of gallic acid equivalent (GAE). The total
polyphenols in each extract were measured by using the
mentioned formula:
C=c×V/m
C = Total phenolic contents (mg/g plant extract, in GAE)
c = Concentration of gallic acid (mg/mL)
V = Volume of extract (mL)
m = Weight of lemongrass extract (g)
2.5.3. Total Flavonoids
The flavonoid content was measured using the procedure
of Al- Farsi and Lee [14]. Briefly, 1 mL of the extracts or
standard solutions of catechin was added to a 10 mL
volumetric flask. Distilled water was added to make a
volume of 5 mL. At zero time, 0.3 mL of 5% (w/v) sodium
nitrite was added to the flask. After 5 min, 0.6 ml of 10%
(w/v) AlCl3 was added and, then 6 min, 2 mL of 1 M NaOH
were also added to the mixture, followed by the addition of
2.1 mL distilled water. Absorbance was read at 510 nm
against the blank (water) and flavonoid content was
expressed as mg catechin equivalents per 100 g of fresh herb.
Samples were analyzed in triplicate.
2.6. Product Development
In the product development module, roasted date seeds
powder was utilized for the preparation of date seed coffee
powder and ready to drink date seed coffee. According to the
treatment plan mentioned in Table 1, T0 was formulated to
have 100% date seed powder, While T1 and T2 had date seed
coffee powder
traditional coffee in 70:30% and 50:50%
respectively. To assess the technological characteristics of
date seed coffee, ready to drink date seed coffee was also
prepared and analyzed.
Table 1. Product Development Plan.
Treatments
T0
T1
T2
Date Seed Coffee Powder
Date seed coffee
Date seed coffee + traditional coffee
Date seed coffee + traditional coffee
%
100
70:30
50:50
2.7. Sensory Evaluation
The sensory evaluation attributes; color, taste, flavor,
sweetness and overall acceptability were analyzed. Sensory
assessment of prepared product was scored using nine point
9
Sobia Niazi et al.: Chemical, Mineral and Phytochemical Screening Assay of Date Palm Seeds for the
Development of Date Palm Seed Coffee
hedonic scale system ranging from extremely like to dislike
(9 = like extremely; 1 = dislike extremely) in the sensory
evaluation laboratory of the NIFSAT, University Of
Agriculture, Faisalabad, Pakistan. Various sensory attributes
like taste, color, flavor, sweetness and overall acceptability of
the prepared products were evaluated during storage by
following the protocol of Meilgaard et al [15].
3. Results and Discussion
3.1. Proximate Composition
Proximate composition is essential parameter to assess the
quality of raw material. The proximate characteristics of date
seeds powder which were found during instant research
indicated that the roasted date seeds powder contained
5.65±0.17% moisture, 1.17±0.04% ash, 5.85±0.23% crude
protein, 7.95±0.39% crude fat, 64.75±2.59% crude fiber and
14.63±0.44% nitrogen free extracts (Figure 1).
The present finding are in line with the previous work of
El Sheikh et al who analyzed the roasted date seeds powder
and results revealed that date seeds contains 5.59% moisture
content, 1.21% ash, 5.90% crude protein, 63.81% crude fiber
and 7.5% crude fat. The results are similar and in the range of
current findings. The results showed the average fat content
of date seed powder was 7.95% which is reasonably high.
This is an indication that date seeds has a reasonable amount
of fat content and allows for high oil recovery from date
seeds through various extraction techniques. The high fiber
content of the date seeds shows that it is a good source of
energy and necessary for digestion of food [16]. Simillarly, it
was reported that 75-80% fiber content in date seeds
depending upon variety and ripeness [17].
In another investigation, Al Farsi and Lee (2008)
compared the comparative study of date pulp by comparing
with date seeds and results revealed that date pulp contain
1.5% ash, 10.2% moisture content, 1.2% lipid and 10.9%
fiber. While date seeds contains reasonable high value of
dietary fiber required for balanced diet and can be considered
a good source of fiber. These results also support the present
study because values are close to the current investigation
regarding all the proximate values [14]. Earlier, Akasha et al
(2012) also found that date seeds powder contain crude fat,
carbohydrates and moisture content 8.14%, 62.71% and
5.39% respectively, which support the findings of present
study. The carbohydrate content is high (62.71%). This
shows that date seeds are a good source of energy. The food
energy of date seeds sample (360.55 cal/100g) is moderate
compared with those of other plants [18].
Moreover, Elleuch et al (2008) have also revealed that the
date seed powder contained moisture content 6.5%, crude
protein 5.8% and crude fiber 68.7%, however differ in
carbohydrates contents from the previous investigations. But
crude protein, crude fiber and moisture content were also in
the same range as the present results. The high moisture
content indicates that date seeds may be susceptible to
microbial growth but the reasonable amount of carbohydrate
and fiber shows that it can be part of human diet and also
considered as a good source of dietary fiber [19].
The present results regarding chemical composition of date
seeds powder are also in strong harmony with findings of
Rehman et al (2007) who reported that moisture content,
protein, lipids and ash are 1.6%, 6.96%, 7.95% and ash
0.97% respectively. However, the difference in carbohydrate
and fat content may be attributed to varietal difference and
environmental conditions [20].
Figure 1. Proximate Composition of Date Seeds.
3.2. Mineral Profile
Minerals play an imperious part to evaluate quality
characteristics of raw material i.e. date seeds. Mineral
content (Figure 2) analysis of seeds powder has exhibited
that potassium is present in maximum amount 375.87±11.7
mg/100g, followed by phosphorus 125.58±5.02 mg/100g,
magnesium 77.55±2.33 mg/100g and calcium 18.73±0.93
International Journal of Bioengineering & Biotechnology 2017; 2(2): 6-12
mg/100g, sodium 15.23±0.6 mg/100g, while iron, zinc,
copper and manganese is also found in considerable amounts.
Owing to the rich mineral profile of date seeds powder,
extensive research has been carried out to estimate the
amount of mineral elements present. Data obtained was
comparable to the research findings, with potassium being
the most abundant element in green tea. El sheikh et al
(2014) reported minerals in roasted date seeds samples and
estimated the concentrations ranges of potassium,
phosphorus, magnesium, calcium, sodium and iron as 375379, 120-122.5, 75.5-77.5, 18.2-18.4, 14.9-15.9 and 3.583.60 mg/100g, respectively [16].
10
Previously, Besbes et al (2004) determined the amount of
minerals in date seeds as potassium 229 mg/100g followed
by posphorous, magnesium, calcium and sodium as 68.3,
51.7, 38.8 and 10.4 mg/100g, respectively. Date seeds
mineral profile varies widely with varieties and growing
regions. However, studies concluded that the concentration of
potassium in all date seeds sample was higher than
phosphorus while magnesium was higher than calcium. [21].
Ali-Mohamed and Khamis, (2004) reported that comparison
of mineral content of date seeds and barley seeds revealed
that date seed was the good source of minerals and can also
be used in the food products in place of barley [22].
Figure 2. Mineral Profile of Date Seeds.
3.3. Phytochemical Screening Assay
3.3.1. Total Phenolic Content (TPC)
Health associated benefits of polyphenols have
necessitated their quantification in various food products.
The values of TPC acquired from date seeds thorough
solvent extraction are represented in table 2 which are
31.2±0.93 mg GAE/g of dry weight.
Earlier, it was measured the total polyphenols extracted
through solvent extraction of 14 different varieties of date
seed extracts. They measured the polyphenol contents on
(mg/100g) basis using dry plant which is 3541 mg/100g in
Zahedi variety and 1260 mg/100g in Shahabi variety
respectively, ultimately they concluded that the on dry basis
different varieties show different range of phenolics contents
[23]. Antioxidant effectiveness in largely depends on the
bioavailability of responsible compounds and phenolic
contents. Besbes et al (2004) determined total polyphenols in
Maktab and Kabkab dalaki 2 varieties were 3284±10.14 to
2548±75.71 mg/100g [21]. This difference in the result was
due to different extraction method.
3.3.2. Flavonoids
The value of total flavonoids observed during the current
investigation assimilated from date seed through solvent
extraction were as 29.5 mg/g dry weight (Table 2). This is the
amount which obtained through methanol extraction. AlFarsi and Lee carried out the flavonoids compound analysis
by comparing aqueous, butanol and acetone extracts. They
concluded that maximum value were observed in butanole
50% extract 15.75±0.81 g/100g followed by acetone 50%
15.93±0.98 g/100g and least amount in aqueous extract
8.13±0.70 to 6.39±0.30 g/100g of flavonoids content [14].
Table 2. Phytochemical Screening and Antioxidant Activity of Date Seeds.
TPC (mg/g)
TFC (mg/g)
31.23±1.24
29.54±0.88
3.4. Sensory Evaluation of Date Seed Ready
to Drink Coffee
The mean squares for sensory evaluation of date seed cold
coffee (Table 3) revealed the momentous variation on flavor,
11
Sobia Niazi et al.: Chemical, Mineral and Phytochemical Screening Assay of Date Palm Seeds for the
Development of Date Palm Seed Coffee
taste, color, sweetness& overall acceptability as a function of
storage and treatments. While, non-significant variation was
observed on color, flavor, taste, sweetness and overall
acceptability regarding their interaction throughout the study.
The highest score (Table 4) for overall acceptability of
date seed cold coffee were assigned to T0 (7.4±0.29), T2
(7.3±0.26) and T1 (7.2±0.28), although, the variation was
significant. A momentous decrease in overall acceptability
(8.1±0.32 to 6.4±0.26) was shown during storage at initiation
and termination of study respectively.
Lee and Chamber found that the flavor of coffee or tea
changed with different brewing methods. Green flavor of
green tea was overtaken by brown flavor due to increase
brewing temperature and time [24]. Simillarly, Baggenstoss
et al (2007) another researcher exhibited the same trend of
sensory attributes during storage of cold coffee. [25]
Table 3. Mean Square for Sensory Evaluation of Ready to Drink Date Seed Coffee.
SOV
Treatments (A)
Time (B)
Ax B
Error
df
2
2
4
18
Color
1.979**
1.989**
0.358NS
0.292
Flavor
0.6770*
18.6620**
0.2345NS
0.2322
Taste
1.541**
1.208*
0.244NS
0.215
Sweetness
6.583**
2.083*
0.083NS
0.362
Overall acceptabilility
4.616**
0.366*
0.153NS
0.188
**
= Highly significant, * =Significant, NS=Non significant
T0 = Date seed coffee 100%
T1 = Date seed coffee 70% + traditional coffee 30%
T2 = Date seed coffee 50% + traditional coffee 50%
Table 4. Mean Values for the Effect of Storage Time and Treatments on Overall Acceptability of Ready to Drink Date Seed Coffee.
Storage (Days)
0
15
30
Means
Treatments
T0
8.2±0.32
7.7±0.30
6.5±0.26
7.4±0.29
T1
7.9±0.31
7.4±0.28
6.5±0.26
7.2±0.28
T2
7.8±0.32
7.1±0.27
6.4±0.26
7.3±0.26
Means
8.1±0.32a
7.4±0.28b
6.4±0.26c
T0 = Date seed coffee 100%
T1 = Date seed coffee 70% + 30% traditional coffee
T2 = Date seed coffee 50% + 50% traditional coffee
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U. Rosas, G. M. Pham, R. S. Meyer, C. K. Johansen, Z. A.
Fresquez, K. Masmoudi, Whole genome re-sequencing of date
palms yields insights into diversification of a fruit tree crop,
Nature communications, 6 (2015).
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M. K. Elashry, M. S. GHEBLAWI, S. A. SHERIF, Analysis of
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processing technology and health benefits, John Wiley & Sons
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4. Conclusion
Date seed, an agro-waste contains a number of bioactive
components that are helpful in mitigating various
physiological threats. The inedible parts of fruits and
vegetables are often discarded as waste. However, these are
rich source of dietary fiber, phenolic and antioxidants. In
modern era consumers are more conscious about their diet
and demand low caloric foods with better health improving
properties. Intake of coffee is one of the most common trends
in world, because to support our daily activities. Drinking
coffee is considered as a sign of friendship and socialization.
As date seeds are source of dietary fiber, phenolic and
antioxidants and no health use of these by product results in
nutritional as well as economic loss. In low income countries,
the development of cost effective natural products is the need
of time. Therefore, more research work is needed for further
evaluations of its potential and utilization for the
development of novel functional foods.
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