Reference
Cold Extraction
**Cold extraction** is a protein isolation method that avoids high temperatures so the protein retains its native, undenatured three-dimensional shape, preserving solubility and other functional properties that heat would otherwise damage.
How cold extraction works
Rather than relying on heat to drive proteins out of solution, cold (or low-heat) extraction uses physical and chemical separations that operate at or near ambient temperature. Common steps include membrane filtration, controlled pH adjustment, and gentle precipitation, each chosen to concentrate protein without unfolding it. The goal is to remove water, starch, fiber, and small molecules while leaving the protein’s folded structure intact.
This contrasts with older industrial routes that combined heat and acid. High-temperature acid treatment, historically used on potato fruit juice, denatures and aggregates the protein, which lowers solubility and limits its use in beverages, foams, and emulsions.
Why heat matters
Heat causes protein denaturation: the molecule loses its folded conformation and the polypeptide chain unravels. Denaturation does not destroy the amino acids themselves, so nutritional value as measured by amino acid content is largely unchanged, but it does alter techno-functional behavior — solubility, gelling, whipping, and emulsification all depend on the intact native fold. Cold extraction is therefore valued where functional performance, not just amino acid delivery, is the objective.
Relevance to potato protein
Potato protein is recovered from potato fruit juice (PFJ), also called potato fruit water, a byproduct of starch manufacturing (Food and Bioprocess Technology, 2012). The two principal fractions, patatin and protease inhibitors, are heat-sensitive, so producing a soluble, native-state isolate required developing a dedicated low-heat industrial process rather than reusing the older heat-and-acid method. The resulting isolate keeps the solubility behavior characteristic of native potato protein, which is soluble at neutral and strongly acidic pH (Journal of Agricultural and Food Chemistry, 2001, PMID:11600040). For more on the source material and how the isolate is produced, see What Is Potato Protein?
Cold extraction is one reason a single-ingredient potato protein isolate can disperse into liquids and foods without the chalky, insoluble texture associated with heavily heat-treated plant proteins. The native fold preserved by the process is what carries that functionality forward into the finished powder.
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