Evaluating the feasibility of powder milk production by pulse spray drying: An approach on sensory properties, toxicological assessment, and microbial inactivation

The potential of a new spray drying technology (pulse spray drying, PSD) was explored in drying milk, using two outlet temperatures. Sensory attributes, instrumental color properties, and volatile compounds were examined. Additionally, the effect of PSD on the food's chemical safety was measured by CALUX® bioassays. For these approaches, milk was also dried by conventional spray drying (SD) and lyophilization (LYO). Finally, the impact of PSD on the microbiological load was investigated using Pediococcus acidilactici ATCC 8042, as a non-pathogenic surrogate of enteric pathogens. In sensory analysis, reconstituted PSD samples were scored with higher color, odor, and flavor intensities than LYO and SD. Volatiles like γ-hexalactone, acetic acid, and ethyl acetate could have contributed to these particularities. Accordingly, instrumental color revealed differences between the four treatments, showing a more evident yellowish coloration and higher saturation in PSD milk. Cytotox, PXR, and p53 CALUX® results in PSD samples ranged from 0.11 to 0.21 μg Tributyltin acetate eq./g, 0.30–0.51 μg Nicardipine eq./g, and were under quantification limit, respectively. These findings indicated that PSD does not pose an increased toxicological risk compared to other drying technologies. Viability results of Pediococcus acidilactici during PSD showed that the higher the outlet temperature, the lower the cell viability. In conclusion, all data raised in this study evidenced that PSD could be used in milk drying without compromising its quality and safety.

Industrial relevance

Considering the low energetic consumption described in several works, pulse spray drying could be a promising approach for the food sector. In addition, it may play a relevant role in overcoming the limitations of conventional spray dryers in terms of viscosity. The results obtained in this study are one of the first in this field and show the feasibility of milk powder production without compromising its quality and safety.