**1. Introduction**

The date palm, the tree and the fruit alike, enjoys a high place in the hearts and minds of the people of the Arab region, in particular, and the Middle East in general and of the three major regional religions (Islam, Christianity, Judaism). A place where the mythological and the cognitive are highly intertwining and intersecting, culturally, religiously, and historically, in a clear indication of the depth of this tree's roots in the soul and civilization of this part of the world. The foundations on which this status is based may be lacking in validity and may be somehow exaggerated but cannot be ignored.

This tree, which enjoys a status of sanctity, due to many religious verses, conversations, and curses, was a staple food for the farmers in their ranches, the divers looking for pearls in the deep sea away from land for several months, and for the mobile

#### *Antioxidants*

Bedouin in the deserts in the cold winter and in the high heat during their winter/ summer traveling trips. With respect to common food consumption, the lives of people, in this area, were centered around few simple things, and their day may begin and end with eating dates supplemented with few additional foods such as milk, meat, and fish. The temporal and spatial presence of dates in the residences was overwhelming in the Arabian Peninsula and, archeologically, very well documented in many locales [1].

At present, global production statistics show increasing interest in dates as an economic commodity with a good financial return [2]. Scientifically, researchers have also increased their academic interest in studying different aspects of the date tree and its fruit using recent approaches and methodologies. The phytochemicals, antioxidant efficacies, and health of common dried fruits, including dates, have recently been reviewed [3]. The phenolic antioxidant properties and benefits in date fruits have recently been reviewed [4]. The biochemistry of the ripening process in dates as the main deriving source of metabolic variation has been recently reported [5].

Nutritionally, date fruits provide quick and high energy (~280–330 kcal/100 g) due to its high content of simple carbohydrates, mainly glucose, fructose, and sucrose [6]. They are also rich sources of fibers and potassium, among other nutrients. In recent years, there have been several reviews of the nutritional attributes of dates [6, 7]. The health and therapeutical attributes of dates have also been recently reviewed by [8–10]. These attributes include anticancer, anti-inflammatory, antimicrobial, antioxidant, antimutagenic, gastroprotective, hepatoprotective, immunostimulant, and nephroprotective activities. Of these, the antioxidant property appears to be of a high interest and, currently, is being explored at different levels using different methodological approaches including the metabolomics studies [11].

Because of this scientific activity, knowledge of the antioxidant properties of dates and the importance of dates as a good source of antioxidants has substantially increased. This knowledge, however, has been accompanied by claims and misconceptions, mostly are unsubstantiated and/or justified, rather, unfortunately confusing and questionable. Such claims include, but not limited to (1) claims of country-wise (or regional-wise) superiority of dates, (2) claims of antioxidant superiority of certain cultivars, and (3) claims of high ranking of dates among other dried fruits and natural products.

The main aim of this chapter is to review the current state of knowledge of the antioxidants in date fruits, with emphasis on dry stage (Tamer), and the issues pertinent to the huge quantitative discrepancy of total phenolic (TP) content in an attempt to find answers to questions that directly address the abovementioned issues/claims. This chapter singles out TP content as the only antioxidant parameter understudy due to space and time limitation; hence the analysis is a preliminary. Further analysis of TP content in relation to other related parameters and factors is highly needed and is to be seen.

### **2. The date palm**

#### **2.1 The tree and cultivars**

The date palm (*Phoenix dactylifera* L.) is among the first domesticated perennial plants with some fossil records showing that the tree has existed for about 50 million years [12]. It has been growing in the Arabian Peninsula, the Middle East, North Africa, and South Asia for about 5000 years [12]. Generally, it is characterized by its ability to tolerate relatively high temperatures, salinity, and drought [13]. To produce dates, the date palm tree has a strict requirement to relatively a hot and lengthily summer. The date palm belongs to the family Arecaceae and is a dioecious

**103**

*b*

**Table 1.**

*antioxidant properties.*

**Figure 1.**

Duration (weeks)

Maturation and growth rate

*Antioxidants in Date Fruits and the Extent of the Variability of the Total Phenolic Content…*

flowering plant which can live for 100 years [13, 14]. Usually, artificial pollination of the date palm starts late February to early March [15]. Fruit development and ripening stages are cultivar-dependent (see next section). It is a common practice to classify cultivars into early, mid, and late cultivars where fruit maturation takes place in June, August, and late September, respectively. Worldwide, the number of date cultivars is large (2000–3000) [16], and at the country level, the number may range between 300 and 600 cultivars in the known major country producers [16]. Within each country, the number of cultivars with significant commercial importance is very limited (10–30). Generally, names of cultivars are, country (or regional)-dependent, with some names of cultivars being traded widely. The same

*DOI: http://dx.doi.org/10.5772/intechopen.83851*

cultivar may have different names in different countries.

*Stages of maturation of date palm fruits. Re-drawn from Al-Mssallem et al. [17].*

Edibility Inedible Inedible Inedible with

*TN = tannins, TP = total phenolics, TF = total flavonoids, CT = condensed tanninsa*

*percentages were calculated from a limited number of published studies.*

*Few published studies reported rather higher values in Tamer than Rutab.*

Very early slow

**Parameter Developmental (maturation) stages of date fruits**

Fast fruit enlargement

Moisture (%) 85 50–60 35–45 20–25

Color Green Green, unripe Yellow or red Varies Golden grown

Texture Hard Hard Soft Soft, semihard,

TN (%)a 100 58–64 28–36 TP (%)a 100 45–57 40–51b TF (%)a 100 40–88 22–70b FRAP (%)a 100 30–72 25–55b DPPH (%)a 100 55–76 39–60b

*percent since data points of the included parameters vary greatly, with values of Khalal stage taken as 100%. These* 

*Chemical and physical characteristics of the developmental (maturation) stages of date fruits in relation to* 

**Hababouk Kimri Khalal Rutab Tamar**

5 weeks 9–14 3–5 Varies Stable

Full size, crunchy

exceptions

Ripe, soft

Ripe, sun-dried

to dark blue

hard

Edible Edible

*All values are expressed as* 

*Antioxidants in Date Fruits and the Extent of the Variability of the Total Phenolic Content… DOI: http://dx.doi.org/10.5772/intechopen.83851*

flowering plant which can live for 100 years [13, 14]. Usually, artificial pollination of the date palm starts late February to early March [15]. Fruit development and ripening stages are cultivar-dependent (see next section). It is a common practice to classify cultivars into early, mid, and late cultivars where fruit maturation takes place in June, August, and late September, respectively. Worldwide, the number of date cultivars is large (2000–3000) [16], and at the country level, the number may range between 300 and 600 cultivars in the known major country producers [16]. Within each country, the number of cultivars with significant commercial importance is very limited (10–30). Generally, names of cultivars are, country (or regional)-dependent, with some names of cultivars being traded widely. The same cultivar may have different names in different countries.

#### **Figure 1.**

*Antioxidants*

Bedouin in the deserts in the cold winter and in the high heat during their winter/ summer traveling trips. With respect to common food consumption, the lives of people, in this area, were centered around few simple things, and their day may begin and end with eating dates supplemented with few additional foods such as milk, meat, and fish. The temporal and spatial presence of dates in the residences was overwhelming in the Arabian Peninsula and, archeologically, very well documented in many locales [1]. At present, global production statistics show increasing interest in dates as an economic commodity with a good financial return [2]. Scientifically, researchers have also increased their academic interest in studying different aspects of the date tree and its fruit using recent approaches and methodologies. The phytochemicals, antioxidant efficacies, and health of common dried fruits, including dates, have recently been reviewed [3]. The phenolic antioxidant properties and benefits in date fruits have recently been reviewed [4]. The biochemistry of the ripening process in dates as the main deriving source of metabolic variation has been recently reported [5].

Nutritionally, date fruits provide quick and high energy (~280–330 kcal/100 g)

The main aim of this chapter is to review the current state of knowledge of the antioxidants in date fruits, with emphasis on dry stage (Tamer), and the issues pertinent to the huge quantitative discrepancy of total phenolic (TP) content in an attempt to find answers to questions that directly address the abovementioned issues/claims. This chapter singles out TP content as the only antioxidant parameter understudy due to space and time limitation; hence the analysis is a preliminary. Further analysis of TP content in relation to other related parameters and factors is

The date palm (*Phoenix dactylifera* L.) is among the first domesticated perennial plants with some fossil records showing that the tree has existed for about 50 million years [12]. It has been growing in the Arabian Peninsula, the Middle East, North Africa, and South Asia for about 5000 years [12]. Generally, it is characterized by its ability to tolerate relatively high temperatures, salinity, and drought [13]. To produce dates, the date palm tree has a strict requirement to relatively a hot and lengthily summer. The date palm belongs to the family Arecaceae and is a dioecious

due to its high content of simple carbohydrates, mainly glucose, fructose, and sucrose [6]. They are also rich sources of fibers and potassium, among other nutrients. In recent years, there have been several reviews of the nutritional attributes of dates [6, 7]. The health and therapeutical attributes of dates have also been recently reviewed by [8–10]. These attributes include anticancer, anti-inflammatory, antimicrobial, antioxidant, antimutagenic, gastroprotective, hepatoprotective, immunostimulant, and nephroprotective activities. Of these, the antioxidant property appears to be of a high interest and, currently, is being explored at different levels using different methodological approaches including the metabolomics studies [11]. Because of this scientific activity, knowledge of the antioxidant properties of dates and the importance of dates as a good source of antioxidants has substantially increased. This knowledge, however, has been accompanied by claims and misconceptions, mostly are unsubstantiated and/or justified, rather, unfortunately confusing and questionable. Such claims include, but not limited to (1) claims of country-wise (or regional-wise) superiority of dates, (2) claims of antioxidant superiority of certain cultivars, and (3) claims of high ranking of dates among other

**102**

dried fruits and natural products.

highly needed and is to be seen.

**2. The date palm**

**2.1 The tree and cultivars**

*Stages of maturation of date palm fruits. Re-drawn from Al-Mssallem et al. [17].*


*TN = tannins, TP = total phenolics, TF = total flavonoids, CT = condensed tanninsa All values are expressed as percent since data points of the included parameters vary greatly, with values of Khalal stage taken as 100%. These percentages were calculated from a limited number of published studies. b Few published studies reported rather higher values in Tamer than Rutab.*

#### **Table 1.**

*Chemical and physical characteristics of the developmental (maturation) stages of date fruits in relation to antioxidant properties.*

#### **2.2 The date palm fruit**

The date palm fruit, the date, is a berry or drupe consisting of a single inedible seed (pit) surrounded by a fibrous, parchment-like endocarp, a fleshy mesocarp, and the fruit skin (pericarp) [13, 15]. Usually, the fruit is oblong, though great variation exists in shape, size, color, as well as in quality and texture. Weight of dates ranges between 4 and 36 g; length, 2–7.5 cm; diameter, 1.3–4 cm; and volume, 5–19 cm. The edible part of the date represents 85–92% of the total fruit weight. The development of the date passes through five distinct morphological stages, widely known by their Arabic names: Hababouk (Habanbo), Kimri, Khalal (Besser), Rutab, and Tamer (**Figure 1**, **Table 1**). At full size, Khalal, the color of dates is either yellow or red, with different shading and hues, with the yellow-colored dates representing the majority (> 80%). Date maturation starts 10–15 weeks after pollination and takes place over an extended period lasting for about 6–8 months. This process requires developmental competence and high heat. Dates of some cultivars can be eaten starting from the Khalal stage; others can only be eaten during or after attaining some degree of ripening. Antioxidant properties of dates are directly and indirectly influenced by the physiological aspects and developmental stages (**Table 1**).
