4.Method

	- 1.Preparation of the separation gel: Separation gel 7.5% acrylamide was prepared by mixing 14.55 ml of distilled water, 7.5 ml of acrylamide solution, 7.5 ml of buffer solution for separation gel, 0.3 ml of SDS solution, 150 μl of ammonium persulfate solution, and 15 μl of TEMED, leave to harden for an hour and a half.

Finally, removal of the gel: Carefully remove the gel from the two glass plates by adding a little water with a syringe to avoid tearing the gel. Then, the dyeing solution was added and left for a whole day. After that, the gel was removed from the dyeing basin and the dye

removal solution was added to it, and the process of washing the gel continued until the bands appeared. It was photographed with an English-origin Gel Documentation Device.


#### **2.3 Statistical analysis**

A completely randomized design (CRD) was used for a factorial storage experiment with three factors: the first factor is field-treated with chitosan, the second factor is storage treatments with three concentrations for each treatment, and the third factor is different storage periods that include six months at 10°C. The analysis was done using the statistical program (SPSS), and the mean values were compared using the least significant difference test (R.L.S.D) at the level of significance (5%) [27].

#### **3. Results and discussion**

#### **3.1 The protein pattern**

As shown in **Figure 1**, the electrophoresis in acrylamide gel of fruits proteins of Berhi and Breim cultivars field-treated with 2% chitosan and postharvest treated with UV rays for 10 minutes, 1-MCP at a concentration of 1 ppm, ozone for 1 hour, and chitosan at a concentration of 2% in addition to control treatment, respectively.

Breim cultivar treated with chitosan recorded the highest height of bundle (180) for the second bundle, while Berhi cultivar treated with the compound (1-MCP) recorded the lowest bundle height of (104) for the first bundle. Berhi cultivar treated with the compound (1-MCP) recorded the largest bundle area of (14,112) for the fourth bundle, while Breim cultivar treated with ultraviolet rays recorded the smallest bundle area of (48) for the first bundle (**Figure 2 a**–**d**).

As shown in **Figure 3**, the number and sites of protein bundles and **Table 2** showed the changes in the number of protein bundles and their molecular weights (kilodalton). It is clear that Breim cultivar fruits treated with chitosan recorded the highest number of bundles of seven bundles, while the control treatments of the two cultivars as well as Breim cultivar fruits treated with ultraviolet rays recorded five bundles each, while all treatments of Berhi cultivar except the control treatment recorded four bundles, as well as the ozone-treated Breim cv. fruits, while the Breim cv. fruits treated with the compound (1-MCP) recorded the lowest number of bundles, which amounted to only three bundles.

The Breim cultivar treated with chitosan recorded the highest molecular weight of (173.857) kDa for the first bundle, while the lowest molecular weight was (32.00) kDa for the Breim dipped in chitosan for the seventh bundle, see **Table 1**.

*The Role of Some Pre and Postharvest Applications on Storage Behavior and Protein Pattern… DOI: http://dx.doi.org/10.5772/intechopen.109899*

**Figure 1.** *The electrophoresis.*

Through the results obtained from the gel-electrophoresis of the proteins of the date palm fruits of the Berhi and Breim cultivars, it is noted that there are significant differences in the number of protein bundles as well as the sites of their appearance between the control treatment and other treatments. There is no doubt that the dependence on the physical and chemical characteristics of the fruits is no longer sufficient to identify and distinguish among date cultivars and to detect commercial fraud for dates, especially after the processes of pressing them. Therefore, the recent trend is to use techniques such as electrophoresis to identify the protein patterns of dates and determine their behavior during storage. These differences in the protein pattern of the fruits mean that the fruits have differed in the process of gene expression.

It is well known in recent years that changes in the process of gene expression played an important role in regulating the process of fruit growth and ripening, and scientific development in the field of molecular biology has led to a significant increase in our knowledge of the mechanisms in which the genes responsible for the ripening of fruits are regulated, and thus, there may be gene expression of heat shock proteins made fruits to bear low temperatures when freezing [28].
