Effect of gum arabic and guar gum as stablizers on yoghurt quality [Sudan]

This study was undertaken to determine the possibility of using Gum Arabic, Guar gum and their mixture as stabilizer in order to improve the quality of yoghurt. Yoghurt was made from skim milk powder (two concentrations 8.5 and 10.5) reconstituted with 1.5 butteroil, with the addition of starter culture at the rate of 3 v/v (1:1 combination of Streptococcus thermophilus and Lactobacillus bulgaricus). Gum Arabic and Guar gum were added to yoghurt as stabilizer at the above mentioned concentrations. Yoghurt was manufactured and stored for 9 days at 10 Daraja C. Sensory evaliation (color, flavour and consistency) was carried out using tenuntrained panelists as well as pH, wheying-off and viscosity were determined at 0,3 and 9 day intervals. The results showed that yoghurt with Gum Arabic gave the best sensory characteristics (P0.001), followed by yoghurt made from the mixture of the two stabilizers. Yoghurt made from Gum Arabic was best in terms of the amount of whey separated from yoghurt (P0.001), but the viscosity did not show any significant difference. The concentration of the stabilizers did not affect the sensory attributes of the yoghurt expcept for pH (P0.05), wheying-off (P0.001) and viscosity (P0.05). The solids non-fat content did not significantly affect (P0.05) the sensory attributes of yoghurt. The storage period affected the color (P0.05), consistency, (P0.05) the pH (P0.05) and the viscosity (P0.05) of yoghurt whatever the stabilizer used. Consistency, color and flavor, wheying-off and viscosity of the product containing Gum Arabic were not affected by storage time, while pH showed slight decrease with time. However the product containing guar gum and the mixture of the two stabilizers showed significant increase in wheying-off and acidity as time passed. Storage time significantly affected the viscosity of the product after 3 days and 9 days (P0.01). So as has been indicated, yoghurt containing Gum Arabic was found to be the best and therefore it is highly recommended to be used for the manutacture of yoghurt.