Ultra high temperature (UHT) processability of high protein dispersions prepared from milk protein-soy protein hydrolysate mixtures

Abstract

This study investigated the effect of addition of soy protein hydrolysates on Ultra high temperature (UHT) processability of milk protein beverages. There is also a lack of reported data on UHT processability of soy protein hydrolysates. UHT processability of 80 g/kg protein reconstituted milk protein concentrate (8-RMPC), 80 g/kg protein soy protein hydrolysate (8-RSPH) and 8-RMPC with added 10, 20 and 30 g/kg protein RSPH (e.g. 8-RMPC+1-RSPH) was studied on a bench-top UHT equipment. Both 8-RMPC and 8-RSPH showed very high UHT processability (UHT plant run-time > 120 min). Inclusion of 1-RSPH in 8-RMPC did not affect UHT run-time (>120 min) and overall heat transfer coefficient (OHTC). Significant drop in OHTC was observed in 8-RMPC+2-RSPH without reducing the UHT run-time below 120 min mark and required UHT processing temperatures could be maintained (143–146 °C) throughout the UHT run. 8-RMPC+3-RSPH showed markedly reduced UHT processability both shorter UHT run-time (61 min) and very low OHTC values were observed which can be attributed to formation of larger protein aggregates. An increase in apparent viscosity (42.0 ± 0.6 and 11.8 ± 0.3 mPa s) for 8-RSMP+3-RSPH and 8-RSMP+2-RSPH, respectively) of UHT processed samples would have also induced severe fouling during UHT.