Waxy potato amylopectin has longer internal and external linear chains than rice or corn amylopectin that are capable of retrograding to a higher degree, but its molecular recrystallization is impeded by unprotonated phosphate groups. Here, we studied whether retrogradation and gel properties of waxy potato starch can be enhanced by lowering pH. The gel strength of waxy potato starch was strongly inversely correlated with pH, going from 10 to 4, and its magnitude was higher at pH values in which the ζ potential of the system was low. Waxy potato starch formed a strong aggregate gel driven by the formation of intermolecular double helices (G′ drop25–95 °C ≈ 1358 Pa, melting ΔH = 9.5 J/g) when conditions that reduce electrostatic repulsion (pH 4, ζ = −1.7) are used, a phenomenon that was not observed in low-phosphorylated waxy cereal starches (i.e., waxy rice and corn).

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Recent scientific evidence indicates that protein hydrolysates contain bioactive peptides that have potential benefits for human health. However, the bittertasting hydrophobic peptides in protein hydrolysates negatively affect the sensory quality of resulting products and limit their utilization in food and pharmaceutical industries. The approaches to reduce, mask, and remove bitter taste from protein hydrolysates have been extensively reported. This review paper focuses on the advances in the knowledge regarding the structure-bitterness relationship of peptides, the release mechanism of bitter peptides, and the debittering methods for protein hydrolysates. Bitter tastes generating with enzymatic hydrolysis of protein is influenced by the type, concentration, and bitter taste threshold of bitterness peptides. A "bell-shaped curve" is used to describe the relationship between the bitterness intensity of the hydrolysates and the degree of hydrolysis. The bitter receptor perceives bitter potencies of bitter peptides by the hydrophobicity recognition zone. The intensity of bitterness is influenced by hydrophobic and electronic properties of amino acids and the critical spatial structure of peptides. Compared to physicochemical debittering (i.e., selective separation, masking of bitter taste, encapsulation, Maillard reaction, and encapsulation) and other biological debittering (i.e., enzymatic hydrolysis, enzymatic deamidation, plastein reaction), enzymatic hydrolysis is a promising debittering approach as it combines protein hydrolyzation and debittering into a one-step process, but more work should be done to advance the knowledge on debittering mechanism of enzymatic hydrolysis and screening of suitable proteases. Further

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The effects of reduced glutathione (GSH) on dough rheology, water state and distribution, gluten conformation, and protein molecular weight distribution were investigated. Addition of GSH (0.02−0.04%) resulted in a more viscous and less elastic dough with decreased G 0 and increased tanδ values, which suggested decreased cross-links in gluten network and a weakened dough structure. The molecular weight of proteins was reduced by the GSH-induced cleavage of intermolecular disulphide bonds. Fourier transform infrared spectroscopy showed a high fraction of β-sheet formation at the expense of α-helix and β-turns, indicating a destabilised secondary structure and protein depolymerisation. GSH increased water release from the gluten network in dough resulting in an increase in freezable water content and caused water redistributed from bound water to weakly bound water. This study provided insights into correlation between wheat dough rheological properties and gluten structure influenced by GSH.