Nutritional Characterization and Total Phenolic Content of Arbutus andrachne L. (Fam. Ericaceae) fruit Collected from Syria

 

Diana Hmaidosh¹*, Mahmoud Ali², Rim Salame³

¹Ecological Sciences, Faculty of Agriculture, Tishreen University, Latakia, Syria.

²Department of Forestry and Ecology, Faculty of Agriculture, Tishreen University, Latakia, Syria.

³Department of Pharmacognosy, Faculty of Pharmacy, Tishreen University, Latakia, Syria.

 

ABSTRACT:

The Eastern strawberry tree, Arbutus andrachne L., is a medicinal evergreen small tree naturally distributed from Eastern Mediterranean to the Northern Black Sea region. In this study, We determined several characteristics of four Arbutus andrachne accessions collected from different parts of Latakia province (Syria). The physic-chemical properties of ripe fruits of Arbutus andrachne were determined. Fruits contain 3.33 g/100g of ash, 58.67% of water and 16.2 % of soluble solids. Among nutritionally important components found in fruits were: 0.85 g/100g proteins, fibers (18 g/100g fw) of which 14.45 g/100g was insoluble fibers and 3.55 g/100g soluble fibers. All the element concentrations that were tested varied considerably. The average for total sugars of the Arbutus andrachne accessions was 20.65 g/100g fruit, fructose was the main sugar (average of 12.16 g/100g fruit) followed by glucose (6.25 g/100g fruit) and sucrose (2.24 g/100g fruit). Among the Arbutus andrachne accessions tested, the total phenolics ranged from 14.5 (Height 3) to 15.95 (Height2) mg GAE/100g (fw) with an average of 15.39 mg GAE/100g (fw), and Ascorbic acid with an average of 244.5 mg GAE/100g (fw).

 

 

 

1.      INTRODUCTION:

During the last decade, highly colored fruits have emerged as a natural alternative to modern medicine. Natural plant pigments such as carotenoids, anthocyanins, chlorophylls, and betalains are considered to have bioactive (Functional Food) value, because they can help maintain human health by protecting against chronic diseases, or by restoring wellness by repairing damaged tissues [1-2-3]. The consumption of locally grown, wild or semi-wild edible plants have been important for most human cultures and especially in the Mediterranean region, making an important contribution to the health of local communities [4]. Food industries are demanding new food ingredients for developing commercial foods.

 

The Greek strawberry tree fruits, may have great potential as a source of unusual colors and flavors, as well as bioactive compounds for dietary supplements or functional foods [5-6]. The use of wild plants as a food source is well known in all countries of the word [7].

 

Arbutus andrachne L. is one of the Syrian medicinal species called the Greek Strawberry-tree. A. andrachne can reach a high of about 12 m. Arbutus andrachne is native to the Mediterranean countries and Southwestern Asia [8]. The reddish stems and evergreen foliage make the tree very attractive with high ornamental value. There are a few studies on the Arbutus andrachne compounds [9-10]. Syria¢s flora is very rich and people from ancient times have used different fruits for consumption as well as preparation of medicines, because of the mild climate prevailing there.

 

 

 

Historically, Arbutus andrachne fruit has been used medicinally by many indigenous cultures, it has been used as astringent, urinary antiseptic treatments, treatment for aching joints, wounds and against some cancer types [10-11].

 

The fruit has been traditionally eaten in Spain and other Mediterranean countries (e.g. [12-13-14]). The ripe fresh fruit gets a tasty flavor if taken in an advanced stage of maturity. The combination of their sugar and organic acid contents is responsible for their food sensory characteristics. Due to their high fermentable sugar contents, they have been traditionally used to obtain alcoholic beverages, their pectin content makes them appropriated for the production of gels, as jellies and jams, also they are rich in numerous nutrients especially Calcium, Phosphorus and Potassium [15].

 

The fruit has also antiseptic, diuretic and laxative effects, where the leaves have astringent, urinary tract antiseptic, anti-diarrheal, hypertension, thrombosis and depurative properties [16-17-18-19-20].

 

The objectives of the present study were to determine nutritional characterization and total phenolic content of the fruit of several Arbutus andrachne accessions sampled from the province of Latakia in Syria, investigate the variability among the accessions and compare these characteristics with previously published results for Arbutus unedo and Arbutus andrachne in other countries.

 

2. MATERIALS AND METHOD:

2.1. Sampling (plant material):

Greek strawberry tree (Arbutus andrachne) berries were gathered in their optimal ripening status, which took place in November-December (2016), from Latakia province in Syria, with different environmental conditions. The sampling locations are presented in Table (1).

 

Each sample had at least 500g of fruit that was gathered from different trees. They were packed in plastic bags and carried to the laboratories in a cold system within the day (stored at -20C° until analysis). All the selected berries presented a healthy external appearance. The analyses of fruits characteristics were carried out in three replicates.

 

Table 1. Arbutus andrachne accessions and sampling locations evaluated in the study (Latakia).

 

2.2. Analytical methods:

Fresh fruits were homogenized in a laboratory blender, Aliquots were taken to analyze dry matter, pH and acidity.

 

Other determinations were performed on freeze-dried samples. Triplicate subsample was taken for each analytical procedure.

 

Dry matter (DM) was determined by desiccation to constant weight at 100+2C° following AOAC Official Methods [21].

 

pH was measured by polentiometer (Micro pH-2000, CrisonIstrument) over a homogenized sample 1/10 (w/v) in distilled water [21]; and used slurries to determine total soluble solids (TSS) contents by refract meter (Atago) and levels of titratable acidity (TA) was determined using standard methodology (AOAC, 942.15) [21].

 

Determination of water content according to method AOAC 950,46; and Ash according to method AOAC 920,153 [21].

 

2.2.1. Soluble and insoluble dietary Fiber analysis:

AOAC enzymatic-gravimetric methods (993,19 and 991,42) were used for soluble fibers (SDF) and insoluble fibers (IDF) analysis [21]. Total fibers are the sum of soluble and insoluble fibers.

 

2.2.2. Total Proteins Analysis:

Total proteins were determined as nitrogen content by the Kjeldahl method. An amount of 0.7g of the freeze-dried sample was digested in sulfuric acid, NH₃ was distilled over N/10 H₂SO₄ and the excess of sulfuric acid was titrated against N/10 NaOH. By using the conversion factor 6.25, total nitrogen content was converted to protein content [21].

 

2.2.3. Ash content and Minerals composition:

The method 930.05 of AOAC procedures was used [21]. A sample of 500g was incinerated with high pressure in the microwave oven for 24h at550^°C. With HCL (50%v/v) and HNO₃ (50%v/v), the residue of incineration was extracted and made up to an appropriate volume with distilled water. All measurements were performed in Atomic Absorption Spectrophotometer.

 

2.2.4. Soluble Sugars analysis:

Analysis of sugars was performed using a refractive index (RI) detector (PerkinElmer) [22].

 

 

 

2.2.5. Lipids analysis:

A Soxtec System HT 1043 Extraction Unit Tecator was used. The crude fat was determined by extracting 0.5g of the freeze-dried sample with petroleum ether. Containers were removed and dried at 105C°, cooled and weighed.

 

2.2.6. Total phenolic content:

The total phenolic content was determined as described by Fonseca et al. (2015) [23] by Spectrophotometer at 750nm. The determination was performed according to the Folin-Ciocalteu procedure. The total phenolic content was calculated gallic acid equivalents from the calibration curve, and expressed as mg of gallic acid (GAE) in 100g fresh weight.

 

Statistical analysis:

Analysis of variance (ANOVA) was performed to compare the moral differences between the averages. We used )Genstate 12( program.

3. RESULTS AND DISCUSSION:

Fruit characteristics of the A. andrachne accessions are presented in Table 2. The range of ash was 3-3.58 g/100g with an average of 3.33 g/100g, which is higher than ash in A. unedo fruit (0.86g/100g) [4]. According to Celikel et al. (2008) [24], A. unedo sample had lower soluble solid (11.9% vs 16.2%) and pH (5.57 vs 8.56) but higher acidity (0.67 % vs 0.47%). Results in this study similar to that of Serce et al. (2010) on A.andrachne fruit [10].

 

Statistical differences were between altitudes and nutritional compounds (Ash, PH, soluble solids, dry matter) (P<0.05), were not found significantly different between altitudes and acidity (p>0.05).

 

 

 

 

Table 2. Several characteristics of Arbutus andrachne L. fruit (Latakia) (n=3).

Height 1 (0-300m), Height 2 (300-600m), Height 3 (600-900m), Height 4 >900m Values with different letters (a-d) are significantly different at p<0.05

 

The average content of water in Arbutus andrachne fruit was 58.67% (w/w) (Table 3), a similar value of this was described by Özcan and Haciseferoğullari (2007) [25] and Barros et al. (2010) [26] on Arbutus unedo fruits (53 and 59%) respectively.

 

Table 3. Macronutrient composition (g/100 g on fresh weight, n=3) of Arbutus andrachne L. fruit (Latakia).

Height 1 (0-300m), Height 2 (300-600m), Height 3 (600-900m), Height 4 >900m

Values with different letters (a-d) are significantly different at p<0.05

 

As can be seen in Table 3, Greek Strawberry-tree fruit can be considered a source of dietary fiber, as a 100g serving can provide 42.6% of the daily amount required for men and 64.8% of the daily amount required for women [27]. As far as we know, no data have previously been reported on the distribution of the fiber fraction in these fruits.

 

Insoluble fibers show a wider range (13.1-16.1g/100g) than soluble fibers fraction (3.2-3.9g/100g) in the samples coming from different locations (Table3). The distribution of fiber fractions agrees with the contents found in other wild and cultivated fruits such as Arbutus unedo [4-28]. Proteins represented minor components, their content, are ranging from 0.77 g/100g to 0.95g/100g (an average of 0.85 g/100g).

Compared with the studies on A. unedo fruits, concentration for proteins are ranging from 0.58 to 1.19 g/100g [4] , and (0.82 g/100g) in Croatia [28]. On the other hand, other study found a much higher content of proteins (3.36%) [25], also study on A. unedo fruits in Portugal determined proteins (3.09 g/100g) [26].

 

Study in Spain determined Lipids in the range from 0.55 to 0.61 g/100g f.w. which is similar to the results of this study (0.47-0.61g/100g f.w.) [4], but there were differences among Lipids in A. unedo sample, which was in their study higher than this study (1.71g/100g vs 0.55g/100g) [26].

 

Statistical differences for nutritional compounds (proteins, lipids, insoluble fiber, moisture) (P<0.05), and soluble fiber (p>0.05) were not found significantly different between altitudes. The averages of all specific sugars are presented in Table4. The overall average for total sugars of all A. andrachne accessions was (20.65g/100g fruit). Fructose was the main sugar in these samples (average of 12.16g/100g fruit) followed by glucose (6.25g/100g fruit) and sucrose (2.24g/100g fruit).

 

Table 4. Soluble sugars content (g/100 g on fresh weight, n=3) in Arbutus andrachne L. fruit (Latakia).

accession	Fructose	Glucose	Sucrose	Total
Height 1	11.52+0.54a	4.7+1.21a	2.68+0.45a	18.9
Height 2	11.93+0.54b	7.9+1.21b	1.94+0.45b	21.77
Height 3	12.47+0.54c	6.8+1.21c	2.57+0.45c	21.84
Height 4	12.73+0.54d	5.6+1.21d	1.76+0.45d	20.09
Mean	12.16+0.54	6.25+1.21	2.24+0.45	20.65
C.V. %	0.0	0.3	2.0

Height 1 (0-300m), Height 2 (300-600m), Height 3 (600-900m), Height 4 >900m Values with different letters (a-d) are significantly different at p<0.05

 

The lowest and highest levels of sugars were found in different accessions. For example, the highest fructose average was measured from Height 4 (12.73g/100g fruit) while Height 2 (7.9 g/100g fruit) and Height 1 (2.68g/100g fruit) had the highest average of glucose and sucrose, respectively.

 

Study in Turkey found 9.75 g/100g of fructose, 6.25 g/100g of glucose and 2.23 g/100g of sucrose in A.andrachne fruits, which accordance with results in this study[10].

 

The A.unedo sample had less total sugars than A.andrachne accessions (9.83g/100g vs 20.65g/100g). However, distribution of the specific sugars were similar in both species [29].

 

All the Greek strawberry-tree samples analyzed in this study showed an inverse behavior, with a ratio glucose / fructose 0.5, which is similar to the results on the A.unedo fruits (between 0.4 and 0.6) [4], which means that fructose represented about double than glucose, with independence of the total soluble sugar content. This means that other factors different from the hydrolysis of sucrose may be involved in soluble sugars contents in strawberry-tree fruit. Moreover, this profile can be related to the intense and pleasant sweet taste of strawberry-tree fruits when they are completely ripe since fructose is the sweetest of all the naturally occurring carbohydrates [30]. Statistical differences between altitudes and sugars content (Fructose, Glucose, Sucrose) (P<0.05).

 

Some nutrient element concentrations of Arbutus andrachne accessions are presented in Table5. Among macro elements, K was the main mineral element, showing the highest values ranging from 77.54 mg/100g (Height4) to 226.48 mg/100g (Height1), also N values ranged from 0.33% (Height 4) to 0.55% (Height1) with an average of 0.43%.

 

Table 5. Mineral and trace elements (mg/100g on fresh weight, n=3) in Arbutus andrachne L. fruit (Latakia).

Height 1 (0-300m), Height 2 (300-600m), Height 3 (600-900m), Height 4 >900m Values with different letters (a-d) are significantly different at p<0.05

 

Regarding the microelements, as can be seen in Table 5, the highest values for Fe were (1.62-2.11mg/100g) and Zn (1.39-2.31mg/100g). Manganese and Copper appeared as the minor microelements with values of 0.35-0.77 mg/100g and 0.173-0.464mg/100g, respectively.

 

Microelements, also called "trace elements", include a wide number of compounds with physiological activity and some of them accomplish decisive functions to maintain human health [31].

 

The biological activities of Cu, Mn, Fe and Zn are strongly associated with the presence of unpaired electrons that allow their participation in redox reactions. It is assumed that these trace metals play a key role in the protection mechanisms by scavenging free radicals. The mineral profile of Greek strawberry-tree fruits (Fe, Zn, Mn, Cu) was similar to other wild berries described by previous authors [32] and [4].

 

Contents of phosphor, nitrogen and potassium in this study are in accordance with results on A.andrachne fruits in Turkey (0.59% of N and 119.17 g/Kg potassium) [10], but differs from Arbutus unedo fruits for phosphor content (19.99 mg/100g v 0.32mg/100g) [28].

 

There were differences among phosphor of A. unedo samples in Turkey, compared with this study (1.79 g/kg vs 0.32 mg/100g) [24]. Statistical differences were found between altitudes and mineral and trace elements (P<0.05).

 

Phenolic acids and their derivatives are widely distributed in plants, and many of them are essential metabolites [33]. They occur naturally in combination with other compounds, usually in the form of esters. The quantity and the composition of phenolic compounds present in foods are influenced by the genotype, extraction procedure, and environmental conditions. Since phenolic compounds are known to play an important role as antioxidants in human nutrition, subtle differences in phenolic composition may be of considerable importance from a nutritional stand point.

The total phenolic content in the analyzed Greek strawberry-tree fruits was calculated from the calibration curve (y = 0.009 x+ 0.020, R²=0.998), ranged between 14.5 mg GAE/100g (Height 3) and 15.95 mg GAE/100g (Height 2), with the average of 15.39 mg GAE/100g, while (Height 3) has the lowest total phenolics (14.5 mg GAE/100g) (Table 6).

 

Table 6. Antioxidant compounds (mg GAE/100g on fresh weight; n=3) in Arbutus andrachne L. fruit.

Accessions	Total phenolics (mg GAE/100g fw)	Ascorbic acid (mg GAE/100g fw)
Height 1	15.49+0.62a	222+18.73a
Height 2	15.95+0.62a	237+18.73b
Height 3	14.5+0.62a	225+18.73a
Height 4	15.62+0.62a	264+18.73c
Mean	15.39+0.62	244.5+18.73
C.V.%	5.3	2.6

Height 1 (0-300m), Height 2 (300-600m), Height 3 (600-900m), Height 4 >900m Values with different letters (a-c) are significantly different at p<0.05

 

 

This study showed higher total phenolics (15.39 mg GAE/100g), by comparison with another study on Arbutus andrachne (2422-4102 µg GAE/g ) with an average (3343 µg GAE/g) [10].

 

Study on Arbutus unedo fruits determined total phenols in range from 951 to 1973 mg/100g fw [4], which is more than in this study.

 

Some researchers found total phenols expressed as mg catechin/g dry weight in range from 10.7 to 15.5 mg/g dry weight, their content being related to maturity stage [5-29].

 

Greek Strawberry-tree fruits are a very good source of ascorbic acid. As seen in Table 6, fruits contained 222 mg/100g (Height 1) and 264 mg/g (Height 4), with an average 244.5 mg/100g.

 

Results in this study of ascorbic acid are higher than found in Arbutus andrachne fruits in Spain (111.8 mg/100g of ascorbic acid) [4], but agree with study on Arbutus andrachne fruits in Croatia (255.29 mg/100g of ascorbic acid) [28].

 

Total ascorbic acid content was 270 mg/100g f.w [34]. Due to its high content of ascorbic acid, it can be stated that vitamin C is the most interesting contributor to nutrient intake of strawberry tree fruits.

 

4. CONCLUSIONS:

We determined the fruit characteristics, chemical composition, total phenolic content of A. andrachne sampled from four accessions at different altitudes in Latakia province in Syria.

 

From the nutritional point of view, strawberry fruits are very interesting even though they have a reputation not to be delicious at all. Strawberry tree fruits are a very rich source of ascorbic acid, its content being 244.5 mg/100g f.w. only a few fruits or vegetable species contain more ascorbic acid.

 

Fruits of Greek strawberry tree contain an average amount of total phenolic content (15.39 mg GAE/100g fw) as compared to other fruits species.

 

Greek Strawberry tree fruits is a good source of another nutritionally important constituent, dietary fiber. Most other fruits contain around 10g of dietary fiber/100g, while strawberry fruits contain 18g/100g total dietary fiber.

 

Among minor nutritionally important components, Greek Strawberry fruits contains an amount of potassium comparable to other fruits.

 

In general, results in this work are in good agreement with results of otherretated works, although we found exceptions like the content of ascorbic acid, dietary fibers and potassium.

 

 

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Accepted on 04.10.2017        © RJPT All right reserved

Research J. Pharm. and Tech 2018; 11(2):553-558.