RESEARCH is showing that quantifying the presence of nitrogenous compounds in beef is a more precise and accurate way of determining if it is fresh compared to the more common spoilage parameters based on microbial load.
Total volatile basic nitrogen, known as TVB-N, is associated with measures for colour, microbial load, tenderness and moisture content and therefore a useful biomarker of beef freshness, studies run by the NSW Department of Primary Industries in Cowra indicate.
The work is important to safeguard Australian beef exports and market access, with the potential for TVB-N standards to be used as an entry requirement, particularly to China.
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Meat scientist with NSW DPI Benjamin Holman said the association between TVB-N and freshness was first established using fish products and this threshold was then transferred to red meat, but the biochemical pathways for TVB-N and its relationship to red meat freshness biomarkers were, at present, ill-defined.
Without this information, the Australian red meat sector is unprepared and vulnerable to terms in trade discussions that could constrict export access and market share, he said.
Speaking at a recent Graham Centre Livestock forum, held virtually, Dr Holman explained TVB-N was generated from the degradation of proteins by endogenous enzymes and microbial activity in meat.
As meat ages post mortem, protein breaks down and it can be measured as TVB-N to provide an indication of whether the meat is spoilt.
"Different markets have used TVB-N to define a threshold at which meat is fresh and thus whether it is accepted. That threshold is inconsistent across markets and often it is informed by research into fish," Dr Holman said.
"This has highlighted that we need to investigate to ensure thresholds applied are appropriate to determine if the beef is indeed fresh or spoiled."
Researchers tested beef loins that had been aged up to 14 weeks.
The results showed TVB-N follows similar trends to microbial loads but there is some variation.
It found a TVB-N level of about 5 milligrams per 100 grams is equal to a microbial load log 7, which corresponds with Australian guidelines for spoilage.
This is much lower than recommended by other authorities in export markets.
TVB-N was not related to intramuscular fat or antioxidant parameters, however these contribute to beef rancidity, so there is potential it is missing this element of beef spoilage.
TVB-N is higher when beef is more tender. How this could penalise more tender beef is something to consider, Dr Holman said.