Biology subjects

Powell-Palm, M. J.

Publications and source records attributed to Powell-Palm, M. J..

5 recordsLinked to original sources

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↗

bioRxiv2023

Cryopreservation and revival of Hawaiian stony corals via isochoric vitrification

Corals are under siege by both local and global threats, creating a wordwide reef crisis. Cryopreservation is an important intervention measure and a vital component of the modern coral conservation toolkit, but preservation techniques are currently limited to sensitive reproductive materials that can only be obtained a few nights per year during spawning. Here, we report the first successful cryopreservation and revival of cm-scale coral fragments via mL-scale isochoric vitrification. We demonstrate coral viability at 24h post-thaw using a calibrated oxygen-uptake respirometry technique, and further show that the method can be applied in a passive, electronics-free configuration. Finally, we detail a complete prototype coral cryopreservation pipeline, which provides a platform for essential next steps in modulating postthaw stress and initiating long-term growth. These findings pave the way towards an approach that can be rapidly deployed around the world to secure the biological genetic diversity of our vanishing coral reefs.

biophysics↗

bioRxiv2023

Metrics of Coral Microfragment Viability

Coral reefs are being degraded at unprecedented rates and decisive intervention actions are urgently needed to help them. One such intervention in aid of reefs is coral cryopreservation. Although the cryopreservation of coral sperm and larvae has been achieved, preservation of coral fragments including both its tissue and skeleton, has not. The goal of this paper was to understand and assess the physiological stressors that might underlie coral fragment cryopreservation and the long-term consequences of these physiological exposures to continued growth. Therefore, we assessed small fragments ([~]0.5 x0.5 mm2) from the Hawaiian coral, Porites compressa, examining: 1) the sensitivity of the fragments and their algal symbionts to chilling temperatures; 2) the sensitivity of the coral to complex cryoprotectants; 3) methods to safely remove the algal symbionts from the coral fragment for cryopreservation, given the two symbiotic partners may require different cryopreservation protocols; 4) continued growth over time of coral fragments once returned to running seawater after treatment exposures; and, 5) assessment of health and viability of microfragments after treatments examining the distribution of green fluorescent protein and fluorescent symbionts. Technological advances in cryo-technology promise to support successful coral fragment cryopreservation soon, and its success could help secure much of the genetic and biodiversity of reefs in the next decade.

cell biology↗

bioRxiv2021

Isochoric supercooled preservation and revival of human cardiac microtissues

Low-temperature ex vivo preservation and tissue engineering based on human induced pluripotent stem cells (hiPSC) represent two of the most promising routes towards on-demand access to organs for transplantation. While these fields are often considered divergent from one another, advances in both fields present critical new opportunities for crossover. Herein we demonstrate the first-ever sub-zero centigrade preservation and revival of autonomously beating three-dimensional hiPSC-derived cardiac microtissues1 via isochoric supercooling2, without the use of chemical cryoprotectants. We show that these tissues can cease autonomous beating during preservation and resume it after warming, that the supercooling process does not affect sarcomere structural integrity, and that the tissues maintain responsiveness to drug exposure following revival. Our work suggests both that functional three dimensional (3D) engineered tissues may provide an excellent high-content, low-risk testbed to study organ preservation in a genetically human context, and that isochoric supercooling may provide a robust method for preserving and reviving engineered tissues themselves.

bioengineering↗