Protein Concentrates Produced from Shorts Bran as a By-product of Semolina Manufacturing: Functional Properties and Utilization as Egg-replacer in Muffin Cake

The objective of this study was to investigate functional properties of the proteins from shorts bran and evaluate their potential as egg-replacers in muffin cakes. Two different shorts bran (SB-1 and SB-2), provided from semolina manufacturing industry as a by-product, were used in the extraction of protein concentrates (PC). A pH-shift extraction was performed by using distilled water (PC-1W and PC-2W) or 0.15 M NaCl (PC-1S and PC-2S). Extraction yields of the PC were between 4.6-6.7%. The protein contents ranged from 79.1 to 86.7% on dry weight basis. Molecular weight distributions of the proteins were investigated by SDS-PAGE. Water holding and oil absorption capacity of PC were determined. Solubility, emulsifying and foaming properties were investigated at 1.0% protein concentration as a function pH (2-10). Solubility properties of salt extracted PC were generally higher than that of the water extracted PC. The best results for protein solubility, emulsifying and foaming properties were obtained at strong acidic and basic media. Protein concentrates were used as egg-replacers in the formulation of commercial muffin cakes (MC) at different concentrations (1.7-3.3%). The height, volume, specific volume and cooking loss of MC decreased after addition of PC. The MC prepared with 3.1% PC-2W without whole egg had the highest moisture content (24.6%). Water activities of the control and PC-incorporated MC changed in the range of 0.80-0.85. The hardness of MC including PC was generally lower than control one, besides the difference among springiness values were not significant (p>0.05). Because of promising foaming properties, PC originated from shorts bran could be applied in foam type products as surface active agents and has potential roles as egg-replacer in muffin cake formulations.