INFLUENCE OF GRADED LEVELS OF GUM ARABIC ON YOGHURT STABILITY UNDER STORAGE

Abstract

The study was carried out to evaluate the effect of Arabic Gum (AG) on the physical properties of yoghurt made from powdered milk. Reconstituted powdered milk was pasteurized at 85oC for 30 minutes and then fast-cooled to 42oC. Starter culture MIX505LYODCU (Streptococcus thermophiles and Lactobacillus bulgaricus SSP.) was added at 3% inclusion level, and the mixtures were incubated at 42oC for four hours. Yoghurt samples were formulated with 0%, 5%, 10% and 15% Arabic Gum in a Completely Randomized Design (CRD). After setting, the yoghurt was kept refrigerated at 10oC for 24hrs. Standard analytical procedures were used to determine the physicochemical properties of the product. . Results showed that, powdered milk contained 3.5% moisture, 24.43% protein, 25.66% fat, 28.45% lactose, 3.65% ash, 6.57 pH and acidity of 0.14. Gum Arabic had moisture, protein, ash, and fibre contents of 7.00%, 2.55%, 1.38%, and 1.26% respectively. Increasing the gum level, led to a significant (P≤0.05) decrease in the pH values of the yoghurt, while wheying-offWheyingwas significantly (P<0.05) affected by the gum arabic level. All treated samples were synerisis free. Viscosity increased as gum concentration increasedwith the control sample having the the lowest viscosity of 1213cp, and samples stabilized with 5%, 10% and 15% Gum Arabic (GA) had viscosities of 1260.42. 1326.25 and 1402.50cp respectively. Regarding storage period, the pH- value of yoghurt was significantly (P<0.05)as well as wheying-off of yoghurt and there was significant (P<0.05) reduction in viscosity during storage period.