Effect of enzymatic treatment of milk by transglutaminase on physical properties of low fat milk powder

Converting milk from liquid state into its powder form increases its shelf life. Milk powder can be stored even at ambient temperatures for about one year without considerable loss of its quality. Different kinds of milk powders have specific applications in food production. By improving quality parameters of milk powder, manufacturers are able to produce foods with more functional properties and higher quality. Microbial transglutaminase (MTGases) by intra- and intermolecular cross-linking of molecules between various primary amines, peptides and proteins is capable to modify food structure contain proteins. The aim of this study was to assay the effect of MTGases treatment of low fat milk (1.5 per cent fat) on flowability of milk powder. For this purpose, five levels of enzyme concentration (0, 0.005, 0.01, 0.015 and 0.02 per cent) at three time-temperature conditions (35°C for 8 h, 40°C for 4 h and 45°C for 2 h) were applied. Results showed that enzymatic treatment of the milk led to a decrease in bulk and tapped density of the milk powder. Furthermore, as enzyme concentration increased, amounts of cohesiveness and compressibility of the milk powder were decreased. These condition resulted in a product with higher flowability and quality. Based on results obtained from statistical analysis, the best flowability with respect to the lower adhesiveness and compressibility of the product was achieved by enzymatic treatment of the milk at 45°C along with 0.02% enzyme concentration.