Zagazig Journal of Food and Dairy Research 295 INFLUENCE OF ADDITION MODIFIED STARCHES AS STABILIZER ON PHYSICOCHEMICAL AND TEXTURAL PROPERTIES OF CAMEL'S MILK YOGHURT Salah A. Khalifa 1* and Alaa H. Ibrahim 2 1. Food Sci. Dept., Fac. Agric., Zagazig Univ., Egypt 2. Anim. and Poult. Breed. Dept., Desert Res. Cent., Cairo, Egypt ABSTRACT The objective of this study was to estimate the effect of addition of modified starch (1, 2, 3, 4 and 5%, w/w) on camel's milk yoghurt during cold storage. Major component, water holding capacity (WHC), susceptibility to syneresis (STS) and viscosity were determined. Moreover, the changes in microstructure and sensory properties were evaluated. Addition of modified starch significantly (p ≤ 0.05) decreased the syneresis, whereas increased significantly (p ≤ 0.05) viscosity and water holding capacity of camel's milk yoghurt (p ≤ 0.05), in addition, enhanced their sensory acceptability. The addition rate of modified starch had significant effect on acidity and total solids of camel's milk yoghurt. The water holding capacity and susceptibility to syneresis of camel's milk yoghurt were significantly (p ≤ 0.05) affected by the quantity of modified starch. The optimum results were recorded using the addition rate at 3%. Increasing the amount of the modified starch added, resulted in increasing water holding capacity and lower susceptibility to syneresis values. Addition of modified starch caused the lowest acidity and the highest pH value of camel's milk yoghurt compared to control. The modified starch treated camel's milk yoghurt had higher total solids, protein and fat than the control. The images of scanning electron microscopy (SEM) showed that the modified starch occupied the void space within casein particle network. Treated camel's milk yoghurts had more systematically and smoothly distributed proteins with a bit coarse structure as well as less porosity in protein network. As well as the addition of modified starch to camel's milk yoghurt lead to the merger of casein micelles with each other, which increases the cohesion flat casein compared with a control sample. Camel's milk yoghurt with 3% modified starch gained the highest sensory score compared to the corresponding treatments. It could be concluded that the addition of modified starch can improve the chemical, sensory and microstructure properties of set camel's milk yoghurt. Camel's milk yoghurt with 3% modified starches is recommended to improve the body and texture without affecting the overall acceptability of the product. Key words: Modified starch, sensory evaluation, camel's milk yoghurt, microstructure. INTRODUCTION Rheological properties of yoghurt are known to be influenced by several factors during processing, the milk constituency itself (protein content, additives), the type of culture (ropy or non ropy), heat treatment and mechanical processes undergoes after fermentation. The mechanical processes include stirring, pumping through pipes and filling which exposes it to shear resulting in a viscosity decrease. Rheological and stability properties of yoghurt can be modified by fortifying the milk with dairy – based ingredients, non-dairy ingredients or a combination of both prior to heat treatment and acidification (Oh et al., 2007). Non-dairy additives like polysaccharides such as starches can be used in yoghurt in * Corresponding author: Tel. : +201229931517 E-mail address: salahkhalifa2006@yahoo.com http:/www.journals.zu.edu.eg/journalDisplay.aspx?Journalld=1&queryType=Master Zagazig J. Agric. Res., Vol. 42 No. (2) 2015 295-307