Effect of Fortification of Camel’s Milk with Cow’s Milk and Gum Arabic on Physicochemical and Sensory Characteristics of Set Yoghurt During Storage

Abstract

This research was conducted to study the effect of added cow´s milk to camel milk with different levels and Gum Arabic on yoghurt quality during storage period. The present study was carried out during April – May 2017 at the laboratory of Dairy, Department of Dairy Science and Technology, College of Animal Production Science and Technology, Sudan University of Science and Technology. Camel´s milk was purchased from Alarabi shop at Hillat Kuku, Khartoum North and cow´s milk was purchased from Farm of College of Animal Production Science and Technology, Khartoum North. Four liters of raw cow´s milk and three liters of camel´s milk were pasteurized at 90°C for 30 minutes, and then milk was cooled to 40°C and divided into three equal portions: the first portion is pure cow´s milk as control; the second one was a mixture of 50% camel´s milk and 50% cow´s milk. The third portion was a mixture of 75% camel´s milk with 25% cow´s milk, Gum Arabic of 0.5% was added to each of the second and the third portion respectively. Three percent of starter culture were added to each treatment, then packed in plastic packs (size 200 g) and incubated at 45°C until coagulation. Samples were in triplicates for each treatment. Samples were stored in a refrigerator at 4° C for 10 days, then chemical and organoleptic evaluations were carried out in day one, day five and day ten. The results showed that the effect of storage period and treatments have highly significant differences (P<0.01) in chemical characteristics and organoleptic evaluation. The results indicated that significant variations (P<0.01) were observed in the protein, fat, titratable acidity and ash, while no significant (P˃0.01) effect was found in total solids and pH, although the storage period showed significant (P<0.05) effect in protein, pH, titratable acidity and ash instead of no effect (P˃0.05) in fat and total solids. The sensory characteristics of the yoghurt samples found to be not affect (P>0.05) in texture, flavor and body by the storage period, however, the storage had significant difference (P<0.05) in color, taste and overall acceptability. Addition of cow’s milk with Gum Arabic had significant variations on color, taste, texture, flavor, body and overall acceptability. The best value for color, taste, texture, flavor, body and overall acceptability were obtained in yoghurt made from pure cow milk followed by the 50% camel’s milk +50% cow’s milk and the least one was found in 75% camel’s milk + 25% cow’s milk. The study showed that the percentage of Gum Arabic has a significant effect in terms of color, texture, flavor and general acceptance, while the taste was not affected. It would be concluded that mixing camel milk with cow’s milk improved the quality characteristics of yoghurt also Gum Arabic significantly improved the quality of set yoghurt.