Improving quark-type cheese yield and quality by treating semi-skimmed cow milk with microbial transglutaminase

Abstract This work aimed at studying the impact of adding different concentrations of microbial transglutaminase (MTGase) during the making process of quark, a mainly acid coagulated fresh cheese, using re-heated semi-skimmed milk. The results indicated that cheese yield increased linearly with increasing enzyme concentrations, thus reaching values of up to 19% higher than those of control cheeses. This increase resulted from reducing losses during the cheese-making process, both uncontrolled and at the curd-cutting step; all enzyme-assisted treatments exhibited similar behaviours and consequently, similar recovered protein levels. Yield differences among enzymatic treatments were due to changes in the amount of retained water related to variations in the MTGase-promoted protein polymerization level and their effects on cheese microstructure. Moreover, MTGase increased cheese hardness by strengthening protein network, and enhanced the nutritional quality due to the higher protein content; however, in both cases, an enzyme overdose involved a setback in the improvements obtained.