Fig. 2From: Conventional use and sustainable valorization of spent egg-laying hens as functional foods and biomaterials: A reviewProtein extraction from spent hens. Protein extraction protocol 1 was summarized from Wang and Wu (2012) and Fan et al. (2021) with slight modifications; protein extraction protocol 2 was summarized from Zubair (2017) with slight modifications. Supernatants can be freeze-dried to obtain proteins, or be further dialyzed before collecting the retainates for freeze-dryingBack to article page