Chemical, rheological and surface morphologic characterisation of spent hen proteins extracted by pH-shift processing with or without the presence of cryoprotectants

► The pH-shifting process has been used to isolate proteins from spent hens. ► Addition of cryoprotectants (CP) prevented freezing-induced denaturation. ► CP had protective effect on the secondary structure of the isolated proteins. ► CP formed a protective shield around isolated proteins during freezing. The chemical and rheological properties of spent hen proteins recovered by acid and alkaline extraction have been studied with/without cryoprotectants (CP) after 3weeks of frozen storage. Four pH values (2.0, 2.5, 11.5, and 12.0) were used for extraction. CP addition prevented freeze-induced denaturation and oxidation in all extracted proteins, as revealed by significant increases in reactive sulphydryl groups (p