EFFECT OF PACKAGING AND STORAGE PERIOD ON SOME PHYSICAL, CHEMICAL CHARACTERISTICS ,FATTY ACID COMPOSITION ,STABILITY AND KEEPING QUALITY OF SUNFLOWER OIL .

Abstract

This investigation was carried out to study effect of packaging and storage period on the specific gravity at 25°C ( Sp. Gr) , refractive index(R.I.),color intensity; acid value, peroxide value(P .V), thiobarbituric acid (TBA) ,iodine value (IV) ,fatty acid composition , and keeping quality of Sunflower oil . The obtained results revealed that the storage of sunflower oil at ambient temperature for nine months did not seem to have any appreciable effect on the specific gravity, while the refractive index was decreased gradually .In contrast the color intensity increased as the storage period increased. The rate of change( either increase or decrease) was depended on the storage period as well as type of container. The obtained results showed that the acid value, peroxide value and TBA increased gradually in all oil samples during storage. The highest increase in acid value was recorded in the colorless glass containers while the lowest increase was observed in plastic and brown glass containers. Also, the results showed that the I.V. decreased gradually in all oil samples. The extent of decrease was affected by storage period and type of container. The results revealed that the saponification value (S.V.) increased gradually in all oil samples as storage period increased. The highest increase in S.V. was recorded in oil samples stored in colorless glass containers,. In contrast, the lowest increase in the S.V. due to prolonged storage was observed in oil samples stored in brown glass containers . The unsaponifiable matter percentage decreased gradually in all oil samples during storage. The results obtained reveald that the values of fatty acids C18:2, C18:3, TPUFA, TUFA and ratio of TUFA: TSFA, C18:2: C18:1 as well as iodine value were decreased with increasing the storage period., while the values of fatty acids C18:2, C18:3, TPUFA, TUFA and ratio of TUFA: TSFA, C18:2: C18:1 as well as iodine value were decreased with increasing the storage period. The rate of change in the values of fatty acids was depended on the storage period and types container. The oil samples packed in colorless glass containers showed the highest value of changes in comparison with other oil samples packed in plastic and brown glass containers. It could be mention that the decrease in C18:2 and C18:3 was accompanied by the decreased in the I.V.