In situthermal modification of kafirin using infrared radiations and microwaves

Abstract

BACKGROUND Kafirin is a prolamin protein located in the corneous endosperm of sorghum. The conventional thermal processing of kafirin reduces its solubility, which limits its utilization in the food industry. Therefore, the study was aimed to investigate the effect of in situ thermal modification of kafirin using two different electromagnetic thermal treatments, namely infrared (IR) and microwave (MW) radiation, on the physicochemical, structural, thermal, and antioxidant properties. RESULTS The results demonstrated that both the thermal modifications improved yield, purity, and solubility of the kafirin with a decrease in hydrophobicity. However, IR‐treated samples showed higher solubility (910.67 g kg−1) and lower hydrophobicity (387.67). The IR modifications also improved the ratio of α helix/β sheets to a great extent. The alterations in the disulfide content were concomitant with the improvement in the thermal stability of kafirin. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed variations in the band intensities of β‑ and γ‐kafirin, indicating alterations in the kafirin subunits. Morphological examination of kafirin revealed surface withering and agglomeration. Notably, IR treatment improved the antioxidant activity more efficiently (from 32.11% to 74.05%). CONCLUSION Although both the IR and MW treatments modified kafirin, the effect seemed to be more pronounced in IR modification. The IR‐modified kafirin had better solubility and lesser hydrophobicity than MW‐modified kafirin. The physicochemical and structural changes induced by IR treatment improved the biological activity of kafirin, in terms of antioxidant activity. Therefore, it was concluded that the in situ IR modification of kafirin can alter its characteristic properties, improving its potential as a food ingredient. © 2021 Society of Chemical Industry.

Evaluating the influence of cold plasma bubbling on protein structure and allergenicity in sesame milk

“…61 Semwal and Meera reported that increase in α-helix in sorghum protein during microwave treatment was due to aggregation of proteins (formation of disulfide bonds while unfolding proteins). 62 They also stated that water present in the sample could have promoted hydrogen bonding in amino acids cross-linkage. In a study on ultrasonicated whey protein, aggregation of proteins caused by cavitation revealed that β-sheets cross-linked to form aggregates at prolonged ultrasonication time.…”

Advances in Extraction, Structure, and Physiochemical Properties of Sorghum Kafirin for Biomaterial Applications: A Review

“…Self-assembly is a process by which a disordered system is converted into an organised structure without any external stimulus, but it relies on weak interactions such as van der Waals and capillary and hydrogen bonds. Both kafirin and zein exhibit an evaporation-induced self-assembling mechanism [36,65]. The evaporation-induced self-assembling mechanism is a process that involves two or more solvents, and one of these solvents evaporates faster.…”

“…The evaporation-induced self-assembling mechanism is a process that involves two or more solvents, and one of these solvents evaporates faster. As a result, the polarity of the solution system increases, and this change drives the self-assembly of the protein [65]. This means that in evaporation-induced self-assembly the formulations of kafirin in aqueous alcohol systems undergo an increase in the polarity of the solvent, as alcohol tends to evaporate faster than water.…”

“…The ring was seen to enlarge with the addition of new β-sheet strands. Various other studies have been proposed for self-assembling mechanisms of prolamin protein at the micro/nano scale, predominately based on evaporation-induced self-assembly formation [41,65,67].…”

“…The ring was seen to enlarge with the addition of new β-sheet strands. Various other studies have been proposed for selfassembling mechanisms of prolamin protein at the micro/nano scale, predominately based on evaporation-induced self-assembly formation [41,65,67]. The formation of zein particles has been proposed as "zein being amphiphilic in nature and have a higher tendency to self-assembly in aqueous phases based on a balance between inner hydrophobic to outer hydrophilic segment" [68].…”