Post-harvest processes and end product characterization for cultivated meat

Current challenge

After slaughter, oxygen levels drop and cells switch to glycolysis. In animals with low glycogen reserves, the pH level can be too high, leading to meat that is dark, firm, and dry. If the pH drop is too rapid, especially if the meat remains warm, meat becomes pale, soft, and exudative. Glycogen synthesis increases with the concentrations of glucose, insulin, and epidermal growth factor (EGF) and is also influenced by glucosamine levels. Meat texture changes after rigor mortis in a manner dependent on ATP and calcium concentration, the extent of muscle contraction at rigor onset, and the cooling rate. The tenderness from aging meat results, in part, from enzymes such as cathepsins, calpains, and β-glucuronidase that break down connective tissue and myofibrillar proteins. We do not fully understand how these processes will differ in cultivated meat or how to manipulate the culture or harvest conditions to optimize cultivated meat quality.

Proposed solution

Academic research should investigate the rate and extent of pH changes in samples of cultivated meat immediately following harvest, and determine whether the relationship between pH, temperature, concentration of known factors like glucose, insulin, EGF, and glucosamine, and ultimately meat quality is the same as that in conventional meat. The effects of ATP and calcium concentrations and of enzymes produced within the muscle tissue should be investigated for their effects on meat texture over time in order to replicate the processes of rigor mortis under ideal conditions and of meat aging. Startups attempting to produce cultivated meat should consider variables that impact glycolysis, rigor mortis, and proteolysis when formulating strategies for optimizing their processes for growing and harvesting meat. While investigation of these basic principles in the context of cultivated meat will likely fit best in the academic context, some internal R&D work will be required in order to adapt these principles to a particular company’s set of processes and desired products. This research will likely spawn additional innovations in bioprocess design, cell line development, or harvesting methods to optimize cultivated meat quality.

Anticipated impact

A comprehensive understanding of post-harvest processes will enable consistently high-quality cultivated products. Producers may be able to alter texture, color, and flavor by changing the media composition during the final days of maturation, by flushing tissue with pre-harvest solutions to pre-condition cells for harvest, or by adjusting the rate of cooling before or after harvest. While conventional meat suffers from inconsistencies from the conditions in which animals are raised, experiences immediately pre-slaughter, the method of slaughter, and post-mortem handling of the meat, cultivated meat has the potential for unprecedented consistency and fine-tuning. This consistently high quality will lead cultivated meat to become an obvious choice for consumers while also reducing waste associated with sub-par products. Because cultivated meat will be sterile at the point of harvest, further improvements in taste and texture may be achievable via innovations in aging.

Related efforts

Academic papers on glycogen synthesis in cultured muscle cells:

• Control of glycogen synthesis in cultured human muscle cells
• Control of glycogen synthesis by glucose, glycogen, and insulin in cultured human muscle cells
• Glucosamine regulation of glucose metabolism in cultured human skeletal muscle cells: Divergent effects on glucose transport/phosphorylation and glycogen synthase in non-diabetic and type 2 diabetic subjects

References for understanding post-slaughter processes:

• Lawrie and Ledward, 2006. Lawrie’s Meat Science, 7th Edition.
• Gates, 2011. “Handbook of Seafood and Seafood Products Analysis.” Journal of Aquatic Food Product Technology 20 (2): 258–69.

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