studying on the effect of arabic gum, milk protein concentrate and whey protein concentrate on the quality indices of synbiotic yoghurt supplemented with transglutaminase

introduction : yoghurt is one of the most popular dairy products in all over the world.nowadays due to the tendency of consumers to use the products with healthy effects, probiotic and synbiotic products are considered. yoghurt by itself is a healthy food; because of its high levels of protein and calciumcontents.consumption ofprobiotic bacteria via food products is a way to reestablishthe intestinal microflora balance. several studies have been done to improve the growth and viability of probiotic bacteria by adding supplements to milk.the objective of this study was to investigate the effect of three component mixture (arabic gum, whey protein concentrate and milk protein concentrate) on quality indices of synbiotic yoghurt containing transglutaminaseenzyme. the content of theseprotein component, the amount of enzyme, enzyme addition time to the yoghurt samples and storage time were variable materials and methods:yoghurt samples were prepared with milk which contained 2.5 percent fat.milk was heated around 40 ̊c. wpc, mpc and arabic gum were added to samples according to the research design and increasing the solid none-fat content of the milk up to 1.5%. samples were pasteurized at 90 ̊c for 10 minutes in a water bath and were cooled rapidly to 43 ̊c for inoculation starter culture and probiotic bacteria. also enzyme was added to samples before or after pasteurization (according to the research design).in this study microbial test was done to investigateviability of probiotics (bb-12) by differential culture medium (mrs-lp agar). the titratable acidity was determined using 0.1 n naoh until accessing the constant pink colour for 30secondes. water holding capacity (whc) was determined due to measure the protein quality of keeping water inside. syneresis is expressed as the weight percentage of serum released by centrifugation. viscosity was measured using a brookfield viscometer.viscosity measurementswere made using 250 ml ofyoghurt samples at 10 _c discussion & results: the effect of wpc, mpc, arabic gum, enzyme concentration and theaddition time of enzyme on viability of b. lactis (bb-12) for 21 days of cold storage at 4 ̊c were monitored. the results indicatedthat the effect of arabic gum, wpc and mpc on viability of probiotic was significant (p<0.05). the effect of storage time and addition time of transglutaminase were significant on titratable acidity (ta) of samples (α< 0.05). by mixingenzyme after pasteurization, acidity developed more rapidly.storage time and protein mixture had significant effect on whc (α≤ 0.05). linearly stage of storage time effect of wpc was higher than other components while at the end of storage period mpc increased whc more than other factors. as time goes on syneresis was decreased and mpc was more effective than other constitutes in the reduction of synersis of the samples. mpc was more effective than other factors on improving viscosity too.by using 3 components mixture (arabic gum, wpc and mpc) and transglutaminasecould improve quality of synbiotic yoghurt and viability of probiotics.