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Biltong is a dry-cured meat product from Southern Africa, typically made from beef or antelope. It is prepared through a series of steps: first making the cut, then salting, acidifying, spicing, massaging and, finally, drying. Rising demand and changing foodways (for biltong that is softer, not as dry, and contains less salt) are now moving production practice towards a more industrial method that employs a tumbling process. However, these industrially-processed products have a shorter shelf-life than traditional biltong and require better control to stabilize the microbial load of the end-product. Our research sets out to investigate the tumbling process and its impacts on the mass transfer mechanisms (salt, water and acetic acid) in small beef meat pieces.

Here we profiled salt, water and acetic acid transfers 25 mm deep into meat samples. The results showed that tumbling increases salt and acid diffusion deeper into the meat. The driving process factor was the mechanical action tied to size of the tumbler, followed by tumbling time and, to lesser extent, whether vacuum was used. This study also showed that tumbling conditions did not significantly impact water content profiles but did significantly impact salt and acetic acid concentration profiles. The most intensive tumbling conditions produced high concentration gradients with a high salt concentration and low pH at the meat surface, which may help keep the meat safe at the later drying step.

The next step is to study how the drying step shapes the food safety and sensory properties of the biltong so as to secure the best post-drying trade-off between good meat hygiene and a sufficiently tender and organoleptically acceptable end-product.

This work materialized through PhD research led by INRAE–CIRAD under the wider GloFoodS metaprogramme, leading out from a research collaboration between INRAE–QuaPA, the CIRAD, the QualiSud joint research unit in Montpellier, and Stellenbosch University in South Africa.