الفهرس 
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Abstract
Sample6 of Bolti-fish of’ Nasser’s lake from local market were obtained to study its keeping quality during frozen storage at -4°0 and 10’°C. The effect of wrapping, the fish in polyethylene bags during storage was also
studies. The fo11o’l-ling factors were determined.: Moisture content (A.O.A.C 1965). actomyosin solubility (Soloviev 1966), total soluble nitrogen (SoloViev 1966), soluble protein nitrogen (Soloviov 1966), non-protein nitrogen~ tota.l nitrogen (A.O.A.e. 1965), thiobarbituric acid (value
(Yu and Sinnhvber 1957) acid value (A.O.P..C. 1965), total volatile nitrogen (Winton and Winton 1958), trimethylamine nitrogen (Winton and Winton 1958), amino nitrogen (Pope and Stevens 1939), refractive index of the fish eye fluids (Proctor ~ a1 1959) t tenderness using Warner Bratzler apparatus, drip content (Awad 1967), histological changes (Diord 1962), and organoleptic tests were carried. out.
The results revealed the following:
(1) The 108s of moisture content at _4°0 after 120 days of storage re ached as high ~s 6.04 %, v:hi1e at _10°C for the same time of storage reached only 4.6) %, wrapping fish tissues in polyethylene bags at –l0 ͦC showed the lowest loss of moisture content.
(2) According to the results of actomyosin solubility and total soluble protein it was found that denaturation at -4°C was more evident a8 compared with –l0 ͦC. Storage in polyethylene bags slightly decreased protein denaturation.
(3) The increase of non-protein nitrogen and amino nitrogen content was higher during frozen storage at -4°C, showing more proteolysis as compared with storage at –10ͦ C.
(4) A decrease of total nitrogen content was higher during storage at .4°C, compared with storage a t -10ͦ C. This loss was due to drip and volatile compounds losses. Storage ill polyethylene bags, slightly decreased the loss in total nitrogen.
(5,) Fat oxidation as well as fat hydrolysis took place at a higher degree during storage at -4°0, compared with storage at -10°C. as shown from the determination 0f Thiobarbituric acid-value and acid value.