Modified Of Wheat Gluten And Its Application In Ice Cream

Wheat gluten is a protein extracted from wheat or wheat flour. The application of glutenin the food industry is limited because it contains a variety of hydrophobic amino acids henceits solubility is low. In order to expand the application of gluten and increase economicbenefits, the use of limiting enzyme hydrolysis, organic acid heating deamidation treatmentand a combination of limiting enzyme hydrolysis with organic acid heating deamidationtreatment was applied on wheat gluten, which was then used in ice cream. These threemethods were applied to increase the functional properties of wheat gluten. The quality of theice cream samples was then analyzed to determine the best treatment.According to the effect of the hydrolysis process and degree of hydrolysis (DH) valuesof different enzymes (alcalase, neutral proteases, flavor protease and protease complex) ongluten, alcalase was selected as the best way of restricting enzyme hydrolysis. With respectto the free amino acid content of acetic acid, tartaric acid and citric acid, heat modifiedreactions determined the optimal conditions for the organic acid deamidation reaction.Combined organic acid heating deamidation with enzymatic hydrolysis was applied as acompound modification method. Finally, these three gluten modification methods were usedto modify gluten.Infrared spectra, molecular weight distribution, SEM micrographs, surface potential andlaser confocal microscopic results showed that alcalase enzyme significantly cut the proteinpeptide bonds such that the molecular weight of modified gluten was less than10kDa. Thehydrophobic groups of gluten were exposed and protein structural changes were observed.The surface properties of the protein were severely damaged. The molecular weight of glutenmodified with organic acid was larger, with distribution bands between31~43kDa and66.2~94.7kDa.Organic acid modified gluten proteins maintained their macromolecularfeatures and emulsifying properties improved. The molecular weight of samples fromcombined organic acid heat deamidation and alcalase enzyme hydrolysis was less than10kDa. The structure of the proteins changed substantially. In addition, oil droplets gatheredsignificantly, hence the emulsion properties were poor.It was concluded that organic acid modification can better improve the functionalproperties of gluten proteins, such as solubility, emulsification, foaming, compared to theother two methods. Physical properties namely hardness, swelling, melting rate, particle sizeand sensory evaluation of ice cream samples made of organic heat-modified gluten were alsostudied. The results showed that increase in the replacement rate results in ice slurry viscosityand the hardness also increasing. Furthermore, the particle size distribution was uneven andthe melting rate decreased. Sensory indicators of the ice cream showed that those sampleswith20%skim milk replaced with citric acid modified gluten were the best.