Improving Laccase Catalyzed Cross-Linking of Whey Protein Isolate and Their Application as Emulsifiers

Abstract

Whey protein isolate (WPI) was chemically modified by vanillic acid in order to enhance its cross-linkability by laccase enzyme. Incorporation of methoxyphenol groups created reactive sites for laccase on the surface of the protein and improved the efficiency of cross-linking. The vanillic acid modified WPI (Van-WPI) was characterized using MALDI-TOF mass spectrometry, and the laccase-catalyzed cross-linking of Van-WPI was studied. Furthermore, the vanillic acid modification was compared with the conventional approach to improve laccase-catalyzed cross-linking by adding free phenolic compounds. A small extent of the vanillic acid modification significantly improved the cross-linkability of the protein and made it possible to avoid color formation in a system that is free of small phenolic compounds. Moreover, the potential application of Van-WPI as emulsifier and the effect of cross-linking on the stability of Van-WPI emulsion were investigated. The post-emulsification cross-linking by laccase was proven to enhance the storage stability of Van-WPI emulsion.

Cross-linking proteins by laccase: Effects on the droplet size and rheology of emulsions stabilized by sodium caseinate

“…As observed in this work, emulsion composed of protein (vanillic acid modified WPI) and laccase also showed polydisperse droplet size distribution with some secondary peaks and a slight increase in mean droplet size when compared to emulsions stabilized only by protein (Ma et al, 2011). The increase in mean droplet size could be associated to the formation of a thicker interfacial layer due to modifications in caseinate structure caused by cross-linking of protein onto interface (Chen et al, 2010).…”

“…Ferulic acid is a small molecule that can easily interact with the laccase or protein substract, improving cross-linking. Ferulic acid can transfer electrons to protein, which can be bounded by radical or directly bounded between two residues of tyrosine of protein (Ma et al, 2011). According to Steffensen et al (2008), α s -casein was not fragmented or covalently bonded when treated only with laccase, while the addition of ferulic acid leads to aggregates formation with molecular weight higher than 206 kDa.…”

“…Many enzymes, such as tyrosinase, laccase and transglutaminase, have been used to improve the functional properties of proteins Lantto, Puolanne, Kalkkinen, Buchert, & Autio, 2005;Littoz & McClements, 2008;Ma, Forssell, Partanen, Buchert, & Boer, 2011). Laccase is a copper-containing oxidase enzyme that oxidize their substrates by a one-electron removal mechanism leading to the formation of free-radicals.…”

Formation and microstructural characterization of whey protein isolate/beet pectin coacervations by laccase catalyzed cross-linking

“…Meanwhile, studies have also shown that laccase can cross-link whey protein isolate (WPI) in the presence of phenolic acids (Ma, Forssell, Partanen, Buchert, & Boer, 2011). It is therefore possible that the laccase used in our experiments may initiate WPIeWPI cross-linkings, beet pectinebeet pectin cross-linkings, and/or WPIebeet pectin cross-linkings between pre-formed complex coacervations.…”

Enzymatic modification of dairy product texture

“…Whey proteins have been polymerized with different origin laccases in the presence of chlorogenic acid (Faergemand et al, 1998), ferulic acid (Steffensen et al, 2008), vanilic acid (Ma et al, 2011), and apple or cherry phenolics (Tantoush et al, 2011). Similarly, caseins have also been cross-linked either in the presence or absence of phenolic mediators (Ercili Cura et al, 2009;Hiller and Lorenzen, 2009;Paananen et al, 2013;Selinheimo et al, 2008;Stanic et al, 2010;Steffensen et al, 2008).…”