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Structural modification in album (Chenopodium album) protein isolates due to controlled thermal modification and its relationship with protein digestibility and functionality

2020; Elsevier BV; Volume: 103; Linguagem: Inglês

10.1016/j.foodhyd.2020.105708

1873-7137

Nisar A. Mir, Charanjit S. Riar, Sukhcharn Singh,

Phytase and its Applications

Native pseudo-cereals protein has low gelling characteristics even though they are rich in essential amino acids. It is therefore desirable to find the suitable modification approach which can manipulate their structure with an overall improvement in the functional characteristics. Accordingly, the impact of controlled heat treatment of album protein isolates (93% protein, db), on its structural and conformational changes have been investigated in order to study their impact on physicochemical, rheological, and thermal properties. Fluorescence intensity of native and heat-treated APIs occurred at 350 nm and the highest peak were obtained for the APIs heated at 100 °C for 30 min, depicting conformational changes due to thermal modification. FTIR results showed absorption peaks in amide-I, amide-II, and amide-III zones for the heat-treated APIs which confirms the presence of structural modifications. Molecular weight of heat-treated APIs was reduced to 31 kDa indicated splitting of bands. Surface hydrophobicity of heat-treated APIs was higher indicating maximum unfolding of protein structure, whereas, the available lysine content of APIs decreased due to heating effect. Heat treatment resulted in an improvement in the thermal stability of APIs such as lower weight loss which is evident from the results of denaturation temperature, enthalpy and improvement in gelling characteristics (highest values of loss modulus and storage modulus at higher thermal temperatures). In vitro digestibility increased up to 87.55% when API was heated at 100 °C for 30 min. L*, b*, and chroma values of heat-treated APIs were found higher than native APIs. The results suggest that the heat treatment induced conformational and structural changes showing positive impacts on the physicochemical, nutritional, and gelling characteristics of the APIs which are important for the processing and application of proteins.