Synthesizing mechanically robust natural pea protein hydrogels via deep cryogenic treatment: State of the art in bioactive compound delivery system

Abstract

The current study focused on the production of pea protein-based natural hydrogels without the need for a poly/cross linker, thanks to cryogenic application. Cryogenic process was applied to hydrogels in three different stages. PHB sample was obtained by directly applying this process to the pea protein isolate before gelation step, PHA sample was exposed to cryogenic process after hydrogel formation, and treatment for PHD sample was applied to both the pea protein isolate and after the hydrogel formation. Hydrogels containing non-cryogenic-treated pea protein alone and the mixture of untreated protein and locust bean gum were selected as negative (NC) and positive control (PC), respectively. Shifts in essential and non-essential amino acid profiles of samples were not notable. Losses/shortenings in bonds were observed in FTIR spectra of PHB, PHA, and PHD compared to NC. More porous structures were seen in SEM images of cryogels. Cryogenic process led to the development of water holding capacity (NC: 51.84%, PHA: 76.89%, PHB: 82.76%, PHD: 83.70%) and swelling ratio (NC: 14.62%, PHA: 21.47%, PHB: 22.89%, PHD: 28.38%). Protein leachability was 26.65, 20.04, 19.79, 16.77, and 15.67% for NC, PHB, PHA, PHD, and PC, respectively. More effective findings in terms of textural properties were obtained in PHB and PHD. Hydrogels displayed elasticity behavior rather than viscous property but elasticity levels were not the same. PHB and PHD as bioactive compound delivery systems in sodium phosphate buffer and in vitro gastrointestinal tract were prominent. Ultimately, cryogenic application, a sustainable green technology, is promising in this field.