Effect of pullulan concentration and pH on the interactions between whey protein concentrate and pullulan during gelation

Abstract

BACKGROUND: Whey protein concentrate (WPC)/pullulan (PUL) hydrogel is applied as a microencapsulation wall material to protect probiotics. However, the interactions between WPC and PUL during gelation have not been clarified. In the present study, the effects of PUL concentration and pH on the interactions between WPC and PUL during gelation were evaluated with respect to appearance, zeta-potential, sulfhydryl group amount, surface hydrophobicity and infrared spectroscopy measurements. The rheological properties of WPC/PUL gels were also determined. RESULTS: The results obtained showed that a proper concentration (0.40 g mL-1) of PUL could improve the gel by enhancing the strength of hydrogen bonding, electrostatic interactions and exposure of hydrophobic groups, whereas too much PUL inhibited the formation of disulfide bonds. Furthermore, hydrophobic interactions, disulfide bonds and hydrogen bonds were destroyed in varying degrees under an alkaline environment. The rheological results also demonstrated a similar effect of PUL concentration and pH on the storage modulus (G') of WPC/PUL gels. CONCLUSION: When the WPC/PUL gel was formed at PUL concentration of 0.40 g mL-1 and pH 7.0, the interaction between WPC and PUL could be enhanced, which is beneficial for the future application of WPC/PUL gels in the food industry.

Nanofibers added with citral: Characterization and their application to postharvest control of Fusarium pseudocircinatum in bananas

“…Hence, the nanofibers protected citral from the formation of off‐odor compounds due to UV light exposition retaining 15.25% of the volatile fraction of the EO after the test. The protection of citral against oxidation produced by UV light can be mainly related to the high branched degree of pullulan and H‐bonding and electrostatic interactions between the polymers (Cheng et al, 2011; Zhang et al, 2020).…”

“…Consequently, its conductivity decreases, reducing the stretching of the liquid jet and increasing the fiber diameter (Poudel et al, 2020). Besides, the formation of H-bonding, ionic, and hydrophobic interactions between the polysaccharide and the protein can contribute to reducing the nanofiber diameter (Zhang et al, 2020). To prevent the formation of beaded fibers, high concentrations of pullulan have been used (20%, w/v) (Drosou et al, 2018).…”

Materials Used for the Microencapsulation of Probiotic Bacteria in the Food Industry

“…Pullulan is also tasteless, odorless, colorless, and has thermostable properties. Recently, it has been proposed that whey proteins can be combined with polysaccharides to produce edible films that can extend the shelf life of products and reduce moisture loss [ 80 ].…”

Influence of environmental pH on the interaction properties of WP‐EGCG non‐covalent nanocomplexes

“…Non‐covalent interactions are usually relatively weak and reversible; they include hydrogen bonding, hydrophobic forces, electrostatic, and van der Waals forces 7 . The most important factors driving non‐covalent interactions are assumed to be hydrophobic interactions between hydrophobic amino acid residues of proteins and non‐polar aromatic rings of polyphenols 8 . Hydrogen bonds are also a kind of interaction between proteins and polyphenols that play a crucial role in maintaining the stability of their complexes 9 .…”

“…7 The most important factors driving non-covalent interactions are assumed to be hydrophobic interactions between hydrophobic amino acid residues of proteins and non-polar aromatic rings of polyphenols. 8 Hydrogen bonds are also a kind of interaction between proteins and polyphenols that play a crucial role in maintaining the stability of their complexes. 9 The preparation environment might play an important role in protein-polyphenol interactionsspecifically, changing the environmental pH might complicate the binding process and binding affinity.…”