Antifreeze Proteins from Cold Yeast Protect Food During Freezing

Jenn Hoskins
9th March, 2025

Antifreeze Proteins from Cold Yeast Protect Food During Freezing

Microscopic analysis of carrot, kohlrabi, and blueberry demonstrates that pre-treatment with recombinant antifreeze protein GaAFP (d) preserves cellular integrity after freezing comparably to glycerol (c), whereas untreated samples (b) show visible structural damage compared to fresh tissue (a), supporting the cryoprotective potential of yeast-derived antifreeze proteins in frozen food storage.

Image adapted from: Majewska et al. / CC BY (Source)

Key Findings

  • Scientists at the University of Tennessee discovered an Antarctic yeast that produces antifreeze proteins to stop ice damage
  • They enhanced protein production in the lab and applied it to frozen fruits and vegetables, reducing water loss during thawing
  • The antifreeze proteins also helped yeast cells survive freezing better, showing potential for improved food preservation
Antifreeze proteins (AFPs) are crucial for organisms living in cold environments, helping them survive by preventing ice formation and growth. Extremophiles, such as certain yeasts, have evolved unique AFPs that enable them to thrive under extreme conditions[2]. A recent study conducted by researchers at the University of Tennessee Health Science Center[1] has advanced our understanding of AFPs by focusing on a specific psychrophilic yeast, Glaciozyma martinii. Glaciozyma martinii, an Antarctic yeast strain identified as strain 186, was discovered to produce an extracellular, glycosylated ice-binding protein (GmAFP) with a molecular weight of approximately 27 kDa. This protein exhibits ice recrystallization inhibition (IRI) activity, which is essential for maintaining the quality of frozen products by preventing the growth of large ice crystals that can damage cellular structures. This study is the first to provide evidence of AFP secretion by Glaciozyma martinii, highlighting its potential for biotechnological applications. To enhance the production of AFPs, the research team utilized a synthetic gene from a closely related cold-adapted species, Glaciozyma antarctica, which had been previously studied for its antifreeze properties[3]. By expressing this gene in the Pichia pastoris GS115 strain, they successfully produced a recombinant AFP (GaAFP) with a molecular weight of approximately 26.57 kDa. The recombinant GaAFP retained IRI activity and demonstrated a cryoprotective effect when applied to food storage. The application of GaAFP to frozen vegetables and fruits, including carrots, kohlrabi, and blueberries, significantly reduced drip loss during thawing. Drip loss refers to the loss of water from tissues as ice melts, which can negatively impact the texture and quality of frozen foods. The effectiveness of GaAFP was comparable to that of glycerol, a commonly used cryoprotectant, indicating its potential as a viable alternative. Additionally, GaAFP enhanced the survival of Saccharomyces cerevisiae cells after freezing, suggesting broader applications in preserving various types of cells and biological materials. This study builds on previous research that has explored the diversity and functionality of AFPs in different organisms. For instance, the psychrophilic yeast Glaciozyma antarctica was shown to produce AFPs with significant thermal hysteresis (TH) activity, which prevents ice formation[3]. Similarly, studies on AFPs from the snow mold fungus Typhula ishikariensis revealed the structural basis for their ice-binding properties[4]. These earlier findings underscore the importance of understanding the molecular mechanisms of AFPs to harness their potential effectively. Moreover, the review of marine-derived AFPs highlighted their various functions, including TH, IRI, and dynamic ice shaping (DIS), and discussed their potential applications in the food industry[5]. The current study by the University of Tennessee Health Science Center aligns with these insights by demonstrating that AFPs can be produced in large quantities using biotechnological methods and applied to improve the quality of frozen foods. The use of recombinant GaAFP addresses previous limitations related to the availability and production of bulk AFPs, making them more accessible for commercial use. The methods employed in this study involved cloning the AFP gene from Glaciozyma antarctica into a Pichia pastoris expression system, which is known for its ability to produce high levels of recombinant proteins. The researchers then purified the GaAFP and evaluated its IRI activity and cryoprotective effects through various assays. By demonstrating that GaAFP can effectively reduce ice damage in frozen foods and enhance cell survival, the study provides a practical solution for the food industry to maintain the quality and extend the shelf-life of frozen products without relying on traditional cryoprotectants, which may have environmental or health drawbacks. In summary, the synthesis and application of AFPs from psychrophilic yeasts like Glaciozyma martinii represent a promising advancement in cryoprotection technologies. This research not only validates the potential of AFPs as eco-friendly and biocompatible alternatives to conventional cryoprotectants but also paves the way for their broader implementation in food preservation and other industries where maintaining frozen integrity is essential[2][3][4][5].

BiotechBiochemMycology

References

Main Study

1) Antifreeze proteins produced by Antarctic yeast from the genus Glaciozyma as cryoprotectants in food storage

Published 6th March, 2025

https://doi.org/10.1371/journal.pone.0318459

Related Studies

2) Extremophiles: the species that evolve and survive under hostile conditions.

https://doi.org/10.1007/s13205-023-03733-6

3) Characterization of Afp1, an antifreeze protein from the psychrophilic yeast Glaciozyma antarctica PI12.

https://doi.org/10.1007/s00792-012-0494-4

4) Characterization of microbial antifreeze protein with intermediate activity suggests that a bound-water network is essential for hyperactivity.

https://doi.org/10.1038/s41598-021-85559-x

5) Structural diversity of marine anti-freezing proteins, properties and potential applications: a review.

https://doi.org/10.1186/s40643-022-00494-7


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