Improved freeze drying efficiency by ice nucleation proteins with ice morphology modification

This study aims to use ice nucleation proteins (INPs) as a novel approach to improve the efficiency of freeze drying process and investigate the related mechanism of ice morphology. Our results show that INPs can significantly improve freeze drying efficiency with increased primary drying rate under the increase of INP concentration from 0 to 10−2mg/mL. Moreover, such improvement was more significant at higher subzero freezing temperatures with the addition of INPs, when the control samples were unable to freeze. Those improvements further lead to reduced total drying time, which suggests an estimated total energy saving of 28.5% by INPs. Our ice morphology results indicate the ability of INPs to alter ice morphology with lamellar ice structure and larger crystal size, which both show linear relationships with primary drying rate. The results further suggest that these ice morphology characteristics induced by INPs are very likely to facilitate the water vapor flow and improve the sublimation rate. Additionally, the increase of freeze drying efficiency can also be achieved by INPs in other food systems like coffee and milk with elevated primary drying rate. The results of this study suggest great potential of using INPs to improve the efficiency of freeze drying process for a wide range of food products and other related applications. This study also provides new insights into the relationship between process efficiency and ice morphology. [Display omitted] •INPs can be used as a novel approach to improve the efficiency of freeze drying process.•The application of INPs in freeze drying of different food systems suggests significant energy savings.•The imaging analysis by X-ray CT provides new evidence of 3D ice structures in frozen samples before sublimation.•The modification of ice morphology by INPs is very likely to be the major reason for efficiency improvement.•The morphology study emphasizes the importance of controlling the freezing step and related ice morphology.