The combination of HPP and natural additives ensures safety and extends the shelf life of plant-based burgers. A recent study shows that this synergy improves pathogen control, prolongs freshness, and allows for lower pressure levels, resulting in energy savings. Thanks to these benefits, HPP stands out as one of the most promising technologies for the gentle preservation of plant-based meats.
The Growing Need
Plant-based meat alternatives are booming, but like traditional beef burgers, they face food safety and shelf-life challenges. Both matrices are vulnerable to Listeria monocytogenes and spoilage organisms during extended refrigerated storage. Consumers demand clean-label solutions, making innovative preservation strategies essential.
The Approach
Researchers from the University of Reading (UK) and the University of Burgos (Spain) recently investigated the use of High Pressure Processing (HPP) combined with nisin (500 IU/g) or blueberry powder (4%) to improve safety and shelf life in beef and plant-based burgers. Both additives are clean-label solutions. Nisin is a GRAS-approved bacteriocin (i.e. a natural antimicrobial peptide produced by probiotics such as Lactococcus lactis). The blueberry powder is derived from juice industry byproducts, aligning with sustainability standards.
- Pressure levels studied: 300 to 600 MPa (43.5 to 87 kpsi) for 3 min
- Storage: 7 °C (44.6 °F)
- Goal: Control monocytogenes and spoilage organisms while maintaining quality
Key Findings: Plant-Based Burgers Outperform
Listeria monocytogenes control:
- In plant-based burgers, HPP at 600 MPa (87 kpsi) combined with nisin or blueberry powder reduced monocytogenes to below detection limits (<1 log CFU/g) immediately after treatment, performing better than HPP alone. In both cases, the overall reduction exceeded 5 log.
- During storage, both additives delayed pathogen regrowth in plant-based burgers for 104 days, far longer than in beef burgers, where regrowth occurred within 27–34 days.
Shelf-Life Extension:
- Plant-based burgers maintained overall microbial counts below 3 log CFU/g for 83 days, regardless of additive.
- Beef burgers showed faster spoilage: aerobic plate counts exceeded 6 log CFU/g by day 27 (HPP alone and HPP + nisin) or day 69 (HPP + blueberry).
Synergistic Effect of Additives:
- At lower pressures (300–500 MPa / 43.5–72.5 kpsi), combining HPP with nisin or blueberry achieved up to 1.4 log additional reduction compared to HPP alone.
- Nisin showed stronger synergism in plant-based burgers, while blueberry powder provided better long-term antimicrobial activity in beef.
- This synergy suggests that processors could lower pressure levels, reducing costs and energy use without compromising safety.
Physicochemical Impact
- Blueberry powder lowered pH and darkened color in both matrices, which may help mask HPP-induced lightening in beef but could affect consumer perception in plant-based products.
- Nisin had no noticeable effect on pH or color.
- Water activity remained stable across treatments.
Why Plant-Based Products Benefit Most
- Higher synergistic effect between HPP and nisin in plant-based burgers compared to beef.
- More homogeneous composition of plant-based matrix likely improves antimicrobial diffusion and activity.
- Lower initial microbial load and absence of myoglobin reduce quality changes after HPP and during shelf-life.
Industry Takeaways
- HPP at 600 MPa (87 kpsi) for 3 min ensures safety for both matrices, but plant-based burgers achieve exceptional shelf life.
- Combining HPP with nisin or blueberry powder could enable lower pressure treatments, reducing costs and energy use.
- Plant-based burgers are ideal candidates for this hurdle technology, supporting clean-label and sustainability goals.
Collaboration and Funding
This research was the result of a collaboration between Hiperbaric, the University of Burgos, and the EU-funded TRANSIT project (Marie Skłodowska-Curie grant agreement No. 955431), with additional support from the Spanish Ministry of Science and Innovation (Project PID2021-125400OB-I00).
