17E-16
Chemically modified maize gluten: Evaluation of its functional properties
A. Gálvez, P. SUAREZ, I. Flores, M. Quirasco, and A. Farrés. Food Chemistry and Biotechnology, National Autonomous University of Mexico, Fac. Química. Conjunto E, Lab. 312. Ciudad Universitaria., Mexico City, 04510, Mexico
Maize gluten, a proteinic (~60% protein) byproduct from wet milling, has little application due to its low functionality. In preliminary experiments, 0.1N–0.25N HCl treatments for deamidating gluten, resulted in better emulsifying properties.
The objective of this study was to evaluate the effect of different conditions of acidic deamidation on the emulsifying properties of maize gluten, as well as to examine their relationship with the degree of deamidation (°D) and degree of hydrolysis (DH).
Gluten suspensions (5% protein) in 0.12N HCl were deaminated at 60, 70 and 80°C, during 0.5, 1, 3, 6, 9 and 11 h. Enzymatic detection of the ammonium released was used to assess °D. DH was determined quantifying soluble protein after TCA precipitation. Deamidated gluten emulsions were prepared at 1% protein. Emulsion Activity Index (EAI) was determined spectrophotometrically. Emulsion Stability (ES) measured the amount of oil released after centrifuging emulsions.
Native gluten initially showed an emulsion stability (ES)=0±0 % and emulsifying activity index (EAI)=3.04±0.73 m2/g. An increase in temperature and time of treatments enhanced emulsifying properties, as well as both, °D and DH, as expected. However the relationship between °D and emulsifying properties (ES and EAI) is not linear, since at the same °D a wide range of emulsifying indices and emulsion stabilities were found as shown in Table 1.
Results imply that enhancement of functionality by deamidated gluten is not only due to DH or °D, but also to denaturation due to thermal treatments. Therefore in shorter periods of time, with a careful temperature increase, a product with a good potential for industrial applications could be obtained.
Session 17E, Food Chemistry: Proteins
8:30 AM - 12:00 PM, Tuesday AM Room Hall N-1