Use of γ-irradiation to produce films from whey, casein and soya proteins: structure and functionals characteristics

Abstract

g-irradiation and thermal treatments have been used to produce sterilized cross-linked films. Formulations containing variable concentrations of calcium caseinate and whey proteins (whey protein isolate (WPI) and commercial whey protein concentrate) or mixture of soya protein isolate (SPI) with WPI was investigated on the physico-chemical properties of these films. Results showed that the mechanical properties of cross-linked films improved significantly the puncture strength for all types of films. Size-exclusion chromatography showed for no cross-linked proteins, a molecular mass of around 40 kDa. The soluble fractions of the cross-linked proteins molecular distributions were between 600 and 3800 kDa. g-irradiation seems to modify to a certain extent the conformation of proteins which will adopt structures more ordered and more stable, as suggested by X-ray diffraction analysis. Microstructure observations showed that the mechanical characteristics of these films are closely related to their microscopic structure. Water vapor permeability of films based on SPI was also significantly decreased when irradiated. Microbial resistance was also evaluated for cross-linked films. Results showed that the level of biodegradation of cross-linked films was 36% after 60 d of fermentation in the presence of Pseudomonas aeruginosa. r

Effects of Gamma Irradiation on Nutrient Composition, Anti-nutritional Factors, In vitro Digestibility and Ruminal Degradation of Whole Cotton Seed

“…However, decrease in the solubility of protein observed in current study is in agreement with the results of Abu et al (2006) and Lacroixa et al (2002) who demonstrated gamma irradiation decreased protein solubility due to denaturation occurring through cross-linking of chains and protein aggregation. Moreover, treatment of canola meal with gamma irradiation was successful in reducing degradation of protein by rumen microorganisms and increasing intestinal digestibility of feed protein (Shawrang et al, 2008).…”

Characterization of chitosan/caseinate films

“…5,7 Some authors have studied the effects of processing variables, such as type and content of plasticizers, and storage conditions (relative humidity and temperature) on rheological, mechanical, thermal and functional properties of sodium caseinate films. 1,5,7,8 Other publications have been focused on the addition of different polymers such as starch, 9,10 whey protein isolate (WPI), soy protein isolate (SPI), 6,11 or gelatin 12,13 to caseinate films in order to improve physical, barrier, and solubility properties. flexibility and processability) or to add functionality to films.…”

Modification of the properties of milk protein films by gamma radiation and polysaccharide addition

“…This arises from the fact that both these processes result in the creation of crosslinks between the protein chains, although irradiation appears more effective in the case of caseinates or soya proteins, while heating is more effective in the case of globular milk proteins containing high amounts of lactoglobulins (whey protein isolate (WPI) and whey protein concentrate). 14,16 Previous studies have also shown that using a mixed composition containing calcium caseinate (CC) with WPI, accompanied by the appropriate combination of irradiation and heating, enables the production of films with higher tensile strength and lower permeability to water vapor than using each protein alone. 17 It was, moreover, discovered that the addition of a small amount of polysaccharide (carboxymethylcellulose, pectin, agar) to the film composition (at a level of 50 g kg −1 of protein) may facilitate production of films characterized by good barrier properties and high mechanical resistance.…”

“…13,20 A denser protein network with a larger content of β-strands and β-sheets was detected in irradiated and/or heated proteins than in reference proteins. 13,16,22 The changed protein conformation is expected to alter other physicochemical properties apart from the functional properties of the films. On the other hand, the changes in physicochemical properties of solutions, gels and films deliver important information concerning modification of the polymer structure.…”