Rheological characterization and applications of zein and whey protein gels

Zein;Rheology;Gelation

Nonthanum, Panadda

关键词: Zein;    Rheology;    Gelation;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/46719/Panadda_Nonthanum.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Protein gelation is an interesting scientific phenomenon of wide commercial impact. Gels are used to control rheological properties in a number of industrial processes from petroleum to pharmaceutical and food industries. Gels are helpful in encapsulation of bioactive compounds, but may be objectionable in membrane processing. In this work two examples of gels will be considered, zein and whey protein gels.Zein, a major corn protein, is a mixture of the polypeptides α-, γ-, ß-, and δ-zein. α-Zein is a major fraction comprising 70-85% of total zein mass and γ-zein is the second most abundant at 10-20%. Commercial zein extracted from corn gluten meal, a byproduct of corn wet-milling, contains mostly α-zein while a new potential zein product obtained from ground corn in dry-grind ethanol operations contains also α-zein with a substantial amount of γ-zein. γ-Zein has a high cysteine content relative to α-zein and is believed to affect zein rheological properties. Rheological properties of zein were investigated by ARES-G2 rheometer. Modulus data showed that zein samples containing γ-zein had measureable gelation times under experimental conditions, contrary to samples with no γ-zein, where gelation was not detected. Results were attributed to the formation of disulfide bonds by the cysteine in γ-zein. The presence of γ-zein also contributed to the porous structure of cast zein films leading to high water vapor permeability while films cast from α-zein showed packed layers of relatively lower permeability. Whey protein gels were used to entrap nanosized droplets of lutein and stabilize them against re-aggregation. Gels were produced in and ethanol-water media and later freeze-dried to stabilize them for storage. Results of this work are expected to be useful in the design of zein extraction processes, the development of zein films, and protein gel applications.