MATERIALS AND METHODS

Fruit materials: Dates palm trees were selected to collect dates fruit properly from dates palm field from June to October, 2014, Hail, Saudi Arabia. A total of 5 dates fruit trees were selected from the field in the season the dates were harvested on the 15th August, 2014.

Data collection: First of all fruits were harvested randomly from all of the selected trees and tagged them properly and finally was brought to the Biotechnology Laboratory, Department of Biology, University of Hail, for measurement. Ten fruit weight and diameter were measured by electric balance of fresh fruit then fresh fruit were ground by grinder and then juice was extracted by cheese cloth net and extracted juice was kept in the freeze for short time for analysis of fructose, glucose and inverted sugar 1st time.

Fresh fruit preservation for full ripen: The remaining fruit were kept in the room temperature until the full ripened. In full ripen condition, juices were extracted and analyzed the fructose, glucose and inverted sugar 2nd time after 15 days (Fig. 1a).

Hot water treatment and sun drying of fruit: The fruit were pinched the skin by nip and kept for 30 min in a water bath with hot water at 45°C then the fruit were taken out until the stop of water drop. Afterward, the fruit were put in the expose sun drying (40°C) for 8 h and finally kept in the room temperature. The same procedure was followed 3rd, 4th and 5th time at every 15 days interval (Fig. 1b).

Fig. 1(a-f):	Structure of date fruit and sugar and nutrient determination procedures, (a) Fresh date fruit water treatment, (b) Sundry fruit, (c) Fructose meter (showing 18.7%), (d) Glucose meter (showing 16.7%), (e) Calcium measurement by calcium meter and (f) Potassium measurement by potassium meter

Data analysis
Fructose content determination: Fructose was determined by using fructose refractometer, Atago-Japan. Three drops of juice sample were put on the disc of the meter and data was displayed and recorded (Fig. 1c).

Glucose content determination: Glucose was determined by using glucose refractometer, Atago-Japan. Three drops of juice sample were put on the disc of the meter and data was displayed and recorded (Fig. 1d).

Inverted sugar determination: Inverted sugar (combination of glucose, fructose and sucrose) was determined by using inverted sugar refractometer, Atago-Japan. Three drops of juice sample were put on the disc of the meter using small syringe dropper and data was displayed and recorded.

Nutrient content determination: Nutrient content [N (as NO₃¯), K⁺ and Ca⁺⁺, Na] was determined by using the nitrate, potassium and calcium digital meter, model: Horiba NO₃ Meter (USA), Horiba K meter (USA) and Horiba Ca meter (USA). Five drops of juice sample were put on the disc sensor of the meter using small dropper and data was displayed and recorded (Fig. 1e-f).

Statistical analysis: Data was analyzed statistically. Standard Error (SE) was done.

RESULTS

Figure 1 shows the fruit structure and procedure done in the experiment. Table 1 shows the dates fruit weight and diameter measurement. The lower fruit weight and diameter were found (3.5 g and 1.7 cm) in the dried fruit (having hot water treatment and sun drying) than in fresh fruit. In Table 2, it had been seen that mineral content like nitrogen, potassium, calcium and sodium was found lower in the dried fruit than in fresh fruit. In Fig. 2-4, it had been seen that fructose, glucose and inverted sugar content were found initially higher in the week 0 and 1 in the case of both treatments. Afterward it was found that decreasing trend was occurred in the dried fruit (having hot water treatment and sun drying) than in fresh fruit at different months after the fruit harvested (Fig. 2-4). It had been observed that hot water treatment and sun drying treated fruit had the lowest sugar (fructose, glucose and inverted sugar) and nutrient content (Fig. 2-4).

Table 1:	Measurement of fruit weight and diameter.
SE: Standard error, Values are given as Mean±SE (n = 10)

Table 2:	Determination of nutrient contents
SE: Standard error, Values are given as Mean±SE (n = 10)

Fig. 2:	Fructose content of fresh and dried fruit at different weeks

Fig. 3:	Glucose content of fresh and dried fruit at different weeks

Fig. 4:	Inverted sugar content of fresh and dried fruit at different weeks

DISCUSSION

In the results it has been seen that fruit weight and diameter were reduced in the dried fruit (having hot water treatment and sun drying). It might be due to the water dehydration and osmosis factor in the fruit. Kannall (2013) reported that dried fruit and fresh fruit contain many of the same health benefits but differ slightly in vitamin and mineral content. Both dried and fresh fruits supply with antioxidants and fiber, which are beneficial for the health, however dried fruit has lost a small percentage of its vitamins during the dehydration process.

Overall sugar content like fructose, glucose and inverted sugar were found higher initially it was due to the conversion of sugar from hard ripe stage to soft or full ripe stage. It was found lower trend in the dried fruit (having hot water treatment and sun drying) than fresh fruit at room temperature after 2 weeks. It might be due to the dehydration process by sun drying. Mineral content like nitrogen, potassium, calcium and sodium was found lower in the dried fruit than in fresh fruit. These results were supported by Kannall (2013). USDA (2009) reported that dates contain 696 mg potassium, 64 mg calcium and 10 mg sodium. So, our results are supported by the results of USDA (2009). Polynapas (2015) stated that dehydrated jackfruit contained lower sugar content than non-dehydrated jackfruit. Hossain et al. (2009) reported that the sugar content represented by Total Soluble Solids (TSS) of the harvested elephant apple fruit was bit higher in exposed sunlight (35°C) treated fruit than in room temperature (28°C). After a certain period, TSS content was slightly reduced. Initially, there was an increasing trend in TSS values and then decreasing slow and steady.

CONCLUSION

From the results it can be concluded that hot water and sundry treatment was the best technique for reducing the sugar content from date fruit. It can be recommended that it may be an important diet for the diabetic patient due to the reduction of overall sugar content compared to the fresh fruit having higher sugar content.