New Zealand’s red meat industry exports billions of dollars’ worth of products each year, with consumers around the world relying on the country’s reputation for high-quality, safe meat products. In 2025 alone, the industry exported $5 billion in beef, $4.7 billion in sheep meat and a further $2 billion in co-products derived from carcasses, reaching more than 110 international markets.
Behind that reputation is a strong focus on food safety, and one of the industry’s most important tools is being further modernised.
Why cooling matters
Good hygiene practices inside meat processing plants ensure there are few bacteria on carcasses and co-products after de-hiding and evisceration. Rapid cooling helps prevent any bacteria present from growing to levels that could affect food safety or product quality.
To manage this risk, the meat industry uses the New Zealand Process Hygiene Index (PHI), a model that assesses the potential for bacterial growth during cooling. Electronic data loggers record product temperatures throughout the cooling process, and the resulting data is analysed through PHI to confirm cooling profiles meet performance criteria designed to minimise bacterial growth during cooling.
Updating the model
PHI was originally developed in 1997 and later expanded in 2007 with the introduction of PHI Plus, which allowed processors to incorporate plant-specific microbiological data into calculations. Although the industry remained confident in the effectiveness of PHI, the model had not been substantially updated since 2007. Some of the original assumptions were considered conservative, creating an opportunity to improve the science underpinning the system and provide processors with greater flexibility while maintaining food safety standards.
Collaborative industry effort
In 2017, a collaborative project to review and modernise PHI was initiated with joint funding from the New Zealand Food Safety Science & Research Centre (NZFSSRC) and the Meat Industry Association (MIA). PHF Science partnered with MIA, the Ministry for Primary Industries (MPI), and the Bioeconomy Science Institute to advance this initiative.
The first stage involved an intelligence-gathering project. Researchers and industry representatives from MPI, AgResearch, Massey University and the meat sector reviewed the original PHI assumptions, examined whether microbiological processing data had changed since the late 1990s, and explored opportunities for improvement.
The conclusion was clear: updating PHI would provide significant value to the industry.
Building the new PHI Toolbox
PHF Science played a central role in developing a new PHI Toolbox, including an updated version of the PHI approach. Key contributions included:
- Updating the microbiological growth model to include bacterial growth lag phases and supporting MPI in reviewing performance targets.
- Creating plain-English factsheets explaining PHI and PHI Plus for processors, regulators and international customers.
- Supporting updates to the MPI Red Meat Code of Practice.
- Developing and hosting a web-based PHI Toolbox dashboard that allows processors to calculate PHI results, assess performance targets and access the latest PHI information.
- Evaluating whether PHI Plus methods could also be applied to offal products. Delivering industry training on both the PHI process and use of the PHI Toolbox.
Industry engagement throughout the project was strong, with processors actively supporting with provision of data, software user testing and implementation guidance.
The next phase
Work is continuing to refresh the PHI Plus model for hot-boned beef and red-offal products. Modelling has been completed, and the current focus is on establishing suitable performance criteria, integrating the updated PHI Plus models into the PHI Toolbox software, and preparing a journal paper documenting the lessons learned through the PHI refresh journey.