An Investigation into the Characteristics of Super-Healthy Doogh: Application of Microbial Transglutaminase and Lipase Enzymes

Iran has a long history in the production of a wide variety of dairy products. Doogh is one of the traditional Iranian drinks which is made by mixing yogurt and water and a little salt. This beverage has a special place in the Iranian markets. During its storage, the main problem with doogh is the two phases that results from low pH and caseins accumulation. Doogh preparation, which has not been serum separation, is considered by researchers and industries. The transglutaminase enzyme has positive effect on the serum storage capacity and the strength of the food in the gel by creating cross linking at the proteins. Therefore, in the present study, the effect of using the transglutaminase and lipase enzymes was studied in order to improve the rheological properties and durability of doogh. The transglutaminase enzyme in doses of 10, 15 and 20 ppm and lipase enzyme in doses of 30, 45 and 60 ppm were added to doogh with fat 1.5% and 3%. Then, physicochemical, microbial, rheology properties, stability and microstructure were investigated. The results showed that treatment with these enzymes improved the stability. The treated samples showed a particulate accumulation, and casein clusters were more regular than the control sample. Added enzymes changed the flow behavior of all treatments and their behavior led to a behavior non-Newtonian shear-thinning. It also increased viscosity and decreased serum separation amount in two phases. This study showed that the combination of transglutaminase and lipase enzymes had a good potential for use in doogh as a stabilizing and viscosity improvement factor.