Gum Arabic (GA), a natural plant extract, is frequently used for the preparation and stabilization of flavor emulsions that is commonly used in soft drink and flavored beverage industry. This study aimed to reduce the amount of GA in some flavor model emulsions for cost effectiveness and studying the effect of that on the stability of these emulsions against gravitational separation during storage. Five flavor model emulsions were formulated using pure citral and cinnamic aldehyde and their mixtures at different weight ratios. Results indicated that a flavor/gum ratio 1:1 or 1:0.5 was not able to stabilize the particle size of all emulsions which is manifested by increase in size by many folds during storage. Similarly, four of the flavor model emulsions showed instability behavior (creaming or sedimentation) toward gravitational separation at the same flavor/gum ratios. However, only one flavor model emulsion out of the five models showed a high stability against gravitational separation at flavor/gum ratio 1:1 or even 1:0.5. That emulsion model was characterized by having a density matching (similarity) between its dispersed flavor phase and its continuous water phase. This indicates the possibility of formulating some flavor emulsions with reduced amounts of gum Arabic only by matching the density between the flavor phase and the continuous phase of the emulsion.

Two successive field experiments were carried out during two seasons (2006 and 2007) at three Agricultural Experimental stations of Desert Research Center (DRC) in three locations: El-Maghara, El-Wadi El-Gedeed and Maryout to evaluate variation, mean performance and stability parameters of four diverse sesame cultivars. Also, study the oil content, physical and chemical properties, fatty acids composition of oil and proteins patterns in seeds of the tested cultivars (Shandaweel 3, Toushki 1, Giza 32 and Taka 3). The results obtained could be summarized in the following categories:- Wide range of variability between locations and high genotypic differences were detected. The genotype x environment interaction was significant and a major portion of this was accounted by the deviation among source of variations. Hence, the genotypes tested had a wide diversity and ranked differently among locations and seasons. The average plant height, number of branches/plant, number of capsules/plant, 1000-seed weight, grain yield/plant, grain yield/feddan and oil yield/feddan were recorded under El-Wadi El-Gedeed, El-Maghara and Maryout locations. Toushki 1 recorded the highest values across different locations for Number of capsules/plant (46.21), number of seeds/plant (47.27), seed yield/plant (14.76 g.), seed yield/feddan (333.84 kg.) and oil yield/feddan (168.56 kg.). El-Wadi El-Gedeed location is considered the best location for most studied traits except for number of branches/ plant. On the other hand, Maryout location (calcareous 34% CaCo3) recorded the lowest values for all traits under study; such findings may be due to the differences between soil and irrigation water types. Stability parameters were fitting together in determining the stable genotypes Toushki1, Shandaweel 3, Giza32 and Taka3 overall tested environments. Genotypes varied in their calculated bi values as well as S2di . Toushki 1 is the most stable genotype across different environments and for all traits under study except for number of capsules/plant. However, genotypes produced higher yield such as Toushki 1 and Shandaweel 3 showed below average stability and were well adapted for El-Wadi El-Gedeed conditions.   Oil content was increased while protein content was decreased significantly in seeds of Shandaweel3 and Toushki1 under El-Wadi El-Gedeed location. However, acid value was decreased for all cultivars except Taka 3 under El-Wadi El-Gedeed location at zero and 6 months of storage. On the other hand, the oil of all sesame cultivars which grown under El-Wadi El-Gedeed location had a higher iodine value than oil of the same cultivars under El-Maghara location. In