Karman, A. | Search bioRxiv

bioRxiv2024

Low-pressure Isochoric Freezing as a scalable technique for fresh food preservation

Efficient means of reducing food waste are critically needed to meet the demands of a growing global population, while mounting consumer interest in minimally-processed food products has simultaneously driven renewed interest in non-chemical preservation modalities. Here, we investigate the potential of low-pressure isochoric freezing (LPIF) at -1.5{degrees}C / 15 MPa to simultaneously inhibit microbial growth and preserve fresh-like physiochemical and bioactive properties during storage. Using raw cows milk as a model product, we demonstrate synergistic effects of mild low temperature and mild enhanced pressure that significantly improve preservation for storage periods up to 5 weeks. Given the passive nature of the technique and the compatibility of the employed pressures with standard industrial compressed gas containers, these results suggest a route towards a scalable new cold storage modality.

bioengineering↗

bioRxiv2023

Effects of isochoric freezing on quality characteristics of raw bovine milk

This study investigated the effects of isochoric freezing (IF) on the shelf-life and quality of raw bovine milk over a 5-week period. The results were compared with conventional refrigeration (RF) and refrigeration after pasteurization (HTST). The IF treatment process entailed storing liquid raw milk in isochoric chambers in thermodynamic equilibrium at -5{degrees}C /77MPa and -10{degrees}C /96MPa. Several parameters were analyzed, including microbiology count, physicochemical properties, indigenous enzyme activity, protein content, volatile organic compounds profile, and lipid degradation. Both raw and pasteurized milk experienced microbial level increases past the acceptable threshold ([≥]5.5 log CFU/mL) after 2 weeks and 5 weeks, respectively, leading to the deterioration of other parameters during storage. In comparison, microbiology count decreased significantly during storage for both IF treatment conditions but was more pronounced for the higher pressure (96MPa) treatment, leading to undetectable levels of microorganism after 5 weeks. IF treatment maintained stable pH, titratable acidity, viscosity, lipid oxidation, volatile profiles, total protein content, and lactoperoxidase activity throughout the storage period. Color was preserved during IF treatment at -5{degrees}C/77MPa; however, color was impacted during IF treatment at -10{degrees}C/96MPa. Protein structures were also modified during pressurized storage in both IF treatments. Overall, the study demonstrated that isochoric freezing could significantly increase the shelf-life of milk by reducing microbiology activity, whilst maintaining its nutritional content. These results underscore the potential role of isochoric freezing as a valuable tool in eliminating pathogens while maintaining quality characteristics similar to raw milk over long storage periods.

biochemistry↗