From top to bottom: agar plate, slurries and meatpacks
New Zealand is one of the world’s largest lamb exporting nations and produces some of the finest quality lamb in the world. The key challenge for NZ industry is to get sufficient “fresh” product of a superior eating quality to distant markets.
Major economic losses can be caused by microbial spoilage or through reduced retail shelf-life due to unacceptable colour changes. In addition, due to the differences in time-to-market, inappropriate overseas microbiological criteria designed for local product may lead to scientifically unjustified rejection or downgrades.
Prolonging the shelf-life of export meat
New Zealand has one of the strictest meat safety regimes and some of the best hygiene standards in the world. New packaging technologies have not only helped New Zealand chilled meat last longer and reach overseas markets, but they have also helped to improve meat safety.
Current meat microbiology research is focusing on bio-preserving meat using good bacteria that will grow in the conditions inside meat vacuum-packs and kill the bacteria that cause spoilage. The lactic acid bacteria (LAB) chosen for bio-preservation are able to grow at below 0 degrees celcius, in order to be effective in frozen packed meat.
Phase contrast micrograph showing the termination spore stage of Clostridium esthertheticum
AgResearch is also looking at a group of spore-forming bacteria, known as Clostridium Spp., that also grow at low temperatures in the absence of oxygen – conditions typically found in vacuum-packed meat. Clostridia produce a foul smelling gas in vacuum-packed chilled meat and result in what is called 'blown pack spoilage,' where the gas causes the packaging to blow up like a balloon. Researchers are investigating ways to trigger germination of the spore form of the bacteria, which would make it easier to kill the Clostridia.
Blown meatpack spoilage
Our research focuses on understanding the impact of varying environmental and biological factors on the interactions of meat pack microflora and identification of those factors that promote competitive exclusion of major spoilage-causing microorganisms.
Much of the current understanding of meat spoilage has been derived from experiments conducted with pure cultures, however this is not a realistic model. To understand the intricate nature of the interactions of multiple competitive bacteria, a more complex model is required.
Experimental data on the interactions of a number of different spoilage organisms within a meat matrix, at different storage temperatures, has been incorporated into a commercial program FoodQSM™. It is anticipated that uptake of this technology will contribute to the mitigation of premature spoilage incidents, science based support for appropriate microbial regulations and optimised product performance in our high value overseas markets.
Some of our “industry good” projects funded through MSI, MPI-NZFSA, MIA, Beef + Lamb NZ and MIRINZ Inc:
- Best practice guidelines for storage of chilled lamb
- Biopreservation technology for extending the shelf life of NZ chilled lamb
- Improving the quality of chilled beef and extending the shelf life of NZ chilled lamb
- Development and validation of a real-time PCR assay for Clostridium estertheticum
- Veal Carcass Antimicrobial Interventions
- Evaluating procedures for validating cleaning processes in boning rooms
- NZ Beef and Lamb: Value from Quality (AgResearch Limited).