الفهرس 
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Abstract
This study was carried out on three fish species namely: Bolti (Tilapia nilotica), Karmout (Claries lazera) and Kannome (Mormyrus kannume). Fish of medium size were chosen, each kilogram 2-3 fishes.
The fish samples were obtained immediately after catching from the local markets of Assiut Governorate and transferred directly to the laboratory of Food Science and Technology Department, Faculty of Agriculture , Assiut University and then were divided each type of fish into two groups: the first group, whole with guts and scale and the second group cleaned without guts and scale has been salting the fish whole and cleaned with salt dry and then put them in containers plastic containing brine concentration of 16% this method is called salting mixed. After that samples were taken from the whole salted fish and cleaned salted fish after each 10, 20 and 30 days salting and after storage at 4ºC for 1, 2 and 3 months for conducting chemical analysis.
The study tried to identify the effect of salting and storage on 4ºC for 3 months on some chemical analysis of fish used.
Some chemical analysis were used in this study to determine:
Chemical composition ( moisture , protein , lipid, and ash contents ) , sodium chloride , pH value , chemical properties of lipid ( acid value , iodine value , saponification value and thiobarbituric acid).
On the other hand, extraction and separation of total lipid and fraction of these lipids by using thin Layer chromatography(T.L.C) was carried out.
Meanwhile, the gas chromatographic (G.L.C) separation of the methyl esters of lipids was performed. The identification of the methyl esters of the straight chain saturated and unsaturated fatty acids of even and odd number carbon atoms was made.
In addition, organoleptic tests were carried out for the evaluation on the quality of the fish species used in this study.
The results led to following conclusions:
1. The result showed that moisture and protein contents of fresh Bolti were higher than Karmout and Kannome, while lipid and ash contents of fresh Kannome were higher than Karmout and Bolti. During salting and storage the moisture and protein contents were decreased , while ash content was increased in each of whole and cleaned of three fish species. Meanwhile, lipid content was increased after 10 days salting in cleaned of three fish species , after that lipid content decreased at the end storage time. On the other hand, the results revealed that lipid content was increased during salting and storage in whole of three fish species.
2. The results of this study indicated that there was a relationship between moisture and total lipids in the three fish species. This relationship was that the decrease in moisture was accompanied by increase in total lipid content of whole three fish species. While relationship was that the decrease in moisture was accompanied by decrease in total lipid content of cleaned three fish species.
3. The sodium chloride content increased in each of whole and cleaned of three fish species during salting and storage. This increase may be due to that the brine solution was higher in salt concentration than the fish tissue fluid during the salting process. Also the loss of moisture during salting and storage may be due to an additional cause for the increment in sodium chloride content.
4. The pH value decreased in each of whole and cleaned of three fish species during salting and storage. This changes of pH values may be related to the breakdown of protein fraction and formation of lactic acid as a result of glycogen breakdown in muscle tissues.
5. Variations in the type and the percentage of lipids fraction were observed in the three fish species.
6. Five fractions of lipids were separated from Bolti. These were: phospholipids, cholesterol, diglycerides, free fatty acids and triglycerides.
7. Seven fractions of lipids were isolated from Karmout and Kannome. These were: phospholipids, monoglycerides, cholesterol, diglycerides, free fatty acids, triglycerides and hydrocarbons.
8. However , the percentage of lipid fractions was variable after the different process, as follows:
A. The phospholipids decreased in each of whole and cleaned of three fish species during salting and storage. The decreasing rate of phospholipids was less in whole fish species from cleaned of fish species. Also the decreasing rate of phospholipids content in the muscles of cleaned Karmout was more than in muscles cleaned Bolti and Kannome.
B. The monoglycerides decreased in each of whole and cleaned of Karmout and Kannome fish during salting and storage. The decreasing rate of monoglycerides was less in whole Karmout and Kannome fish from cleaned of Karmout and Kannome fish. Also the decreasing monoglycerides in the muscles of Kannome fish was more than in muscles Karmout.
C. The cholesterol increased in each of whole and cleaned of three fish species during salting and storage. The increasing rate of cholesterol was less in whole fish species from cleaned fish species, Also the increasing rate of cholesterol content in the muscles of whole and cleaned Kannome fish was more than in muscles whole and cleaned Karmout and Bolti.
D. The diglycerides was increased in each of whole and cleaned of three fish species during salting and storage .The increasing rate of diglycerides was less in whole fish species from cleaned fish species. Also the increasing rate of diglycerides content in the muscles of whole Kannome fish was more than in muscles whole Karmout and Bolti, while in cleaned Bolti was more than in muscles cleaned Kannome and Karmout.
E. The free fatty acids increased in each of whole and cleaned of three fish species during salting and storage. The increasing rate of the free fatty acids was less in whole fish species from cleaned fish species, Also the increasing rate of the free fatty acids in the muscles of whole Kannome fish was more than in muscles whole Karmout and Bolti, while in cleaned bolti was more than in muscles cleaned karmout and Kannome.
F. The triglycerides decreased in each of whole and cleaned of three fish species during salting and storage. The decreasing rate of triglycerides was less in whole fish species from cleaned of fish species. The decreasing rate of triglycerides in the muscles of whole and cleaned Kannome fish was more than in muscles whole and cleaned Karmout and Bolti.
G. The hydrocarbons increased in each of whole and cleaned of Karmout and Kannome fish during salting and storage. The increasing rate of hydrocarbons was less in whole Karmout and Kannome fish from cleaned of Karmout and Kannome fish. Also the increasing hydrocarbons in the muscles of Kannome fish were more than in muscles Karmout.
9. The results reported that the lipids of the fresh Bolti , Karmout and Kannome contained 21,19 and 21 total fatty acids, respectively. where Karmout recorded the highest percentage of the saturated fatty acids, while Kannome contained the least percentage. Also Bolti recorded the highest percentage of the essential fatty acids, while Kannome contained the least percentage. The saturated fatty acid increased of whole and cleaned in three fish species during salting and storage, while unsaturated fatty acids decreased of whole and cleaned in three fish species during salting and storage .The increasing rate of saturated fatty acid was less in whole fish species from cleaned fish species, while the decreasing rate of unsaturated fatty acids was less in whole fish species from cleaned fish species. Thus the unsaturated fatty acids in whole fish species were higher than cleaned fish species. Also the essential fatty acids in whole fish species was higher than cleaned fish species during salting then lower during storage.
10. The result showed that acid value, iodine value and thiobarbituric acid value of fresh Kannome were higher than Karmout and Bolti , while saponification value of fresh Karmout were higher than Kannome and Bolti. During salting and storage the acid value, saponification value and thiobarbituric acid increased of whole and cleaned in three fish species. While iodine value decreased during salting and storage. Increasing rate of acid value, saponification value and thiobarbituric acid value were less in whole fish species from cleaned fish species, while the decreased rate of iodine value was less in whole fish species from cleaned fish species. The changes in chemical properties of lipids in three studies fish species during salting and storage are parallel to that of lipid fractions content and the fatty acids composition.
11. The organoleptic properties of the three studies fish species were very good after salting and 2 months storage in whole Bolti, Karmout and Kannome fish. While these organoleptic properties were good after 3months storage in whole Bolti, Karmout and Kannome. The organoleptic properties were very good after salting and 1 month storage in cleaned Bolti, Karmout and Kannome fish. While these organoleptic properties were good after 2months storage in cleaned Bolti, Karmout and Kannome fish.
As a conclusion of these investigation, salting was a suitable method for the preservation of the three studies fish species. These products were preserved after salting for three months at 4ºC.
Results also revealed that the salting of whole fish was better than cleaned fish, (therefore) So, it was recommended for salting the whole fish.