Tensile, Solubility, and Electrophoretic Properties of Egg White Films as Affected by Surface Sulfhydryl Groups

Abstract

Films plasticized with polyethylene glycol were cast from alkaline (pH 10.5, 11.0, or 11.5), aqueous egg white (EW) solutions with or without heating (40°C for 30 min). Prior to casting, concentration of surface sulfhydryl (SH) groups was determined and they increased (P < 0.05) (3.81-19.45 mM/g protein) with both pH and heating, presumably due to protein denaturation and cleavage of disulfide (S-S) bonds. Concentration of surface SH groups correlated (P < 0.05) with film tensile strength (r = 0.70), elongation at break (r = 0.86), and film total soluble matter (r = -0.94). Most likely, surface SH groups formed S-S bonds through air oxidation and/or sulfhydryl/disulfide interchange, thus contributing to EW film formation. SDS-PAGE patterns in presence or absence of 2-mercaptoethanol confirmed occurrence of S-S bonding in dried EW films.

Physical properties of egg albumen and cassava starch composite network formed by a salt-induced gelation method

“…Briefly, the forces within the protein aggregates present prior to salt addition are generated by intra-and inter-molecular disulfide bond formation during pre-heating step. The later process of Na + -induced gelation (i.e., of the heat-denatured proteins) involves the simultaneous aggregation of soluble proteins, of which the aggregation rate can be controlled by NaCl concentration (Handa, Gennadios, Froning, Kuroda, & Hanna, 1999;Woodward & Cotterill, 1986). Therefore, increasing of EA suspension's pH from 8 to 11 in our study would give rise to the formation of a three-dimensional network with varying mechanical properties.…”

Effects of plasticizers, pH and heating of film-forming solution on the properties of pea protein isolate films

“…In their study TSM of the films increased when pH of FFS was increased from 7.0 to 9.0, but no differences were found when pH was further increased to 11.0. On the other hand, Handa et al (1999) have displayed that TSM of egg white films decreased linearly with increasing pH of film forming solution. These results indicate that the changes in protein film TSM after pH adjustment are related to psychochemical characteristics of film-formers (e.g.…”

Effect of different concentrations of olive oil and oleic acid on the mechanical properties of albumen (egg white) edible films

“…Film was formed using casting process following previous work (Handa et al, 1999). Dried albumin [egg white powder (9 g/100 ml water)], polyethylene glycol (average M.W.400; 60% w/w of dried EW; plasticizer) was prepared.…”