Abstract: The objective of this study was to investigate, the changes in physicochemical characteristics of date fruit (Phoenix dactyliferaL.) cultivars at Kimri, Khalal, Rutab and Tamar state by two different propagation methods. Weight and length of whole fruit and seeds were significantly higher in vitro cultivars (16.74±0.38, 4343±0.15) as compare to offshoot cultivars (1.53±0.02, 2.93±0.15), could be the result of older productivity. Ash (1.77±0.44), protein (3.23±0.08) and Carbohydrate (8.48±0.49) were recorded maximum at Tamar stage. Significant amount of fructose and glucose were calculated higher at Tamar stage from in vitro cultivars. Higher percentage of Potassium (419.64±12.12) and Iron (2.3±0.04) among micro nutrients were detected in date fruits, which is considered a front contributor in Saudi Arabian diet.

INTRODUCTION

Date fruits (Phoenix dactyifera L.) are an important commercial crop in Middle East. It is estimated 6.7 millions tons production world wide (www.FAO.org.) and 734000 tons year^-1 in kingdom of Saudi Arabia. Climate condition in the various date producing region are not always same cause’s low production of the date cultivars. Some fruit ripen early whilst others are not until the last of the season. Different time ripen fruit can be vary in the orgenleptic and physico chemical changes (Dowson, 1982). Limited production through off shoots as compared to the demand, researchers propagated in vitro technique, which has been revolutionized as the growing industry with genetically superior products (Al-Ghamdi, 1989; Martin, 1980; Tisserat, 1981; Mahdia and Tisserat, 1985). In spite of socio-economic changes in the kingdom, date fruits are considered a good source of energy, due to their high percentage of sugars and significant amount of fiber (Kulkarni et al., 2008; Swaya et al., 1982; Husain et al., 1993). Date fruit are also, a good source of vitamin and macro nutrient such as potassium, magnesium, iron and calcium (Hafid et al., 2007; Gamil et al., 1980; Al-Shahib and Marshal, 2003; Elleuch et al., 2008). All edible varieties of date have four distinct stages of ripening as Kimri (immature), Khalal (turning to color), Rutab (mature ripe) and Tamar (ripe) states.

Although, the potential in vitro propagation of date is well documented (Mahdia and Tisserat, 1985; Booji et al., 1993). A little information has been published of date fruit about the changes in chemical composition and comparative study between off shoot and in vitro date fruits at different maturation stages. Therefore, it was subjected to judge the physico chemical changes in culture and offshoot fruit at stages of ripening for the benefit of national interest.

MATERIALS AND METHODS

Experimental design and method: The Experiment of cultured and the offshoots propagated khlass date palm was conducted in the experimental station at research center in Riyadh, Saudi Arabia.

Each plant were subjected to the normal culture practice at all location. During flowering season the plants was pollinated with pollen from the same date palm to eliminate effects of metaxinia. Date fruit were collected at each stage of development i.e., Kemri (immature), Khalal (turning of color), Rutab (mature-ripenning) and Tamar (ripe). The samples collected at random from three palms and picked at random from strands located at different parts of three randomly chosen bunches. On the day of harvesting, the fruits were transferred to the laboratory in King Saud University and stored at 4°C for experimental purpose.

Physical characteristics: Physical properties were calculated in 15 fruits of each replicates as follows:

Chemical analysis: Date fruits were cut, deseeded and the pulp portion was homogenized in blender for analysis. Moisture, protein, fat, crude fiber, pH, carbohydrate was determined according to AOAC (2000). Brix was determined using ABBE mark 11-digital refractrometer (Cambridge Instrument Inc., Buffalo, NY, USA). Mineral analysis carried as, 5 g portion of each sample was ignited and ashed at about 750°C in a muffle furnace for overnight.

The total ash was weight and calculated as percentage. The ash was then dissolved in 5 mL of fuming nitric acid and transferred to 100 mL volumetric flask using double distilled demonized water. The solution analyzed by ICP-Integra (GBC Co., Australia). Glucose, fructose and sucrose were determined by HPLC (Scimadzu LC-10AD, Shimadzu Corporation, Japan). All sugars were separated using LC-NH₂ column (Bellefonte, PA, USA).

The mobile phase was acetonitrile 80% in distill water, setting flow rate 1.5 mL min^-1. Data were recorded and analyzed using chromatopack-CR7-A and compare with standard of glucose, fructose and sucrose (Sigma, chemicals, ST, Louis, MO, USA). Data Analysis statistically (ANNOVA) using analysis of variance (Steel and Torrie, 1980) and difference among the means were determined for significance at p<0.05.

RESULTS AND DISCUSSION

Morphological comparisons for offshoots and in vitro plants and significant difference were observed at all stages of whole fruit in weight, length and width, respectively (Table 1). The weight of individual fruit ranged from (8.65±1.12) in offshoot at Tamar stage to (16.74±0.38 g) in vitro at Khalal stage. The length and diameter of whole date fruits varies from 2.50±0.03-4.43±0.15 and 1.86±0.20-2.50±0.10 cm among the samples. Seed weight, length and width were calibrated in range as (0.79±0.09-1.53±0.02), (2.16±0.05-2.93±0.15) and (0.73±0.05-1.06±0.05), respectively. The pattern followed in whole date fruits and seed as well. The weight and size in seeds were found higher in vitro as compare to offshoot particularly at Kimri stage, which could be due to the older productivity. The overall difference in physical properties certainly a cause of environmental effects, which is also supported by the finding of Booji et al. (1993), Ferry et al. (1988). Proximate composition at each stage of date fruit as Kimir, Khalal, Rutab and Tamar are presented (Table 2). The moisture content was calculated higher in Kimir (84.27±0.21), which was lost 85.87% at Tamar stage (11.90±0.26). Unripe contain excess water follows the same pattern, reported by Swaya (1986) and Imad et al. (1995). Significant differences in crude fiber was observed in all samples between tissue culture and offshoots plant fruits (Table 3). Crude fiber were higher in offshoot range (1.41±0.06-2.08±0.06) as compare to tissue culture fruits (1.16±0.00-1.56±0.56). Significantly changes in chemical properties were observed such as, fat, which was extracted more at kimri stage in off shoot fruits, while the percentage of Ash (1.77±0.04), protein (3.23±0.08) and carbohydrate (81.48±0.49) analyzed in cultured fruit were higher as compare of in vitro plants at mature stage.

Table 1:	Physical characteristic at different stages of ripening in vitro culture and Off shoot date fruit (Phoenix dactylifera L.) mg element/100 g wet weight
*Means of replicated raw followed by different letters are significantly different (p = 0.05) ±SD; Wt: Weight; Lth: Length; Wth: Width; O: Offshoot; T: in vitro

Table 2:	Proximate composition at different stages of ripening in vitro culture and off shoot date fruit (Phoenix dactylifera L.) (g/100 g wet weight)
Means of replicated raw followed by different letters are significantly different (p = 0.05) ±SD; O: Offshoot; T: in vitro

Table 3:	Sugar composition at different stages of ripening in vitro culture and off shoot date fruit (Phoenix dactylifera L.) (g/100 g wet weight)

Table 4:	Ash percent and minerals at different stages of ripenning in vitro culture and offshoot date fruit (Phoenix dactylifera L.) (mg/100 g wet weight)
Means of replicated raw followed by different letters are significantly different (p = 0.05) ±SD. Offshoot (O); in vitro (T)

This difference could be due to evaporation of moisture and excess of nutrients provided at the time of culture. The rapid build up fructose and glucose at Rutab and Tamar stage is an excellent source of carbohydrate, which contributes approx. 100 g person^-1 in Saudi Arabian diet (El-Sharawy et al., 1989). Intake of similar amount of fructose as compare the glucose play a role to lower the hyperglycemia is maximum at ripe-Tamar stage (33.24±0.2) as compare to offshoot (22.82±0.29) in cultured fruit (Table 4). The concentration of reducing sugar ratio 2:1 at early stage of the development decreases slowly during maturation in both the cultivars and reaches its ration 1:1 at Tamar stage. This ratio is the same as reported early (Swya et al., 1982; Melgarejo et al., 2000). The result of minerals at all stages of in vitro and offshoots are shown in Table 4. Potassium was present in the largest amount at all stage in offshoot cultivars but maximum values were found at Tamar stage (419.62±12.42) as compare to tissue culture (336.76±12.14), followed by calcium (45.38-50.81), magnesium (21.15-24.70), sodium (7.47-8.35), respectively. Among micro nutrients Iron (2.3-2.15) was calculated higher as compared to zinc (0.78-.92) and copper (0.32-0.40). The overall composition of minerals is markedly varied among various stages at Kimri, Khalal, Rutab and Tamar state, respectively. The amount of potassium, calcium and magnesium were calculated higher at Tamar stage in offshoot fruit cultivars as compare to in vitro cultivars. The other elements in descending order (mg/100g) were sodium, iron, zinc and copper. Their respective values of nutrients at maturation stages in both the cultivars were comparable as reported (Imad et al., 1995). These variations could be due to agro climatic changes. Higher level of potassium and iron an essential minerals as in many fruits like pomegranate and grape (Salah and Ahmad, 2002) are a front contributor in Arabian diet for controlling salt balance.

CONCLUSION

This study provide an important data as a reference to compare the physicochemical changes at four different stages (Kimri, Rutab, Khalal and Tamar) of dates fruits harvested on tree by in vitro culture and traditional propagation methods. More study on physico chemical characteristics at different stages is needed, especially in different agro system in relation with in vitro and off shoot cultivars.

ACKNOWLEDGEMENT

I am indebted to Dr. Dilshad Ahmad for his help through the preparation of the manuscript.