Formation and characterization of okra polysacchradies/whey protein isolate polyelectrolyte complexes and their film making properties

In this thesis, determination of optimal conditions for okra polysaccharide extraction, formation and characterization of gum polysaccharide and whey protein isolate polyelectrolyte complexes and determination of film making properties. In the study, yield, viscosity, zeta potential value and polysaccharide content were selected as responses in the experimental plan determined by response-surface method in order to investigate the effects of different temperature, solid-solvent ratio and time on extraction process. Then, whey isolates were added to the okra polysaccharides in different ratios and film making properties of these complexes were investigated. In the first part of the study, after pretreatment for fresh okra and dry okra polysaccharide extraction was performed according to the experimental plans determined by response-surface method. Polysaccharide extraction from fresh okra was carried out at 20, 30, 40°C; 30, 60, 90 minutes; 1/5, 1/8, 1/10 solid-solvent ratio and polysaccharide extraction from dry okra was carried out at 20, 30, 40°C; 30, 60, 90 minutes; 1/30, 1/40, 1/50 solid-solvent ratio. The collected supernatant was precipitated with ethanol in a 1: 3 ratio followed by filtration and freeze-drying in a lyophiliser at -56 ° C for 24 hours and sieved using a 425 µm pore size screen. Viscosity , electrical conductivity measurement, zeta potential (ζ) measurement were determined for the characterization of okra polysaccharides, fourier transform infrared (FTIR) analyzes were performed. Optimal extraction conditions optimization study showed that the optimum parameters are 89.93 min time,1/10 solid-solvent ratio, 20°C temperature for polysaccharides obtained from fresh okra, and 87.97 min time, 1/50 solid-solvent ratio and 21.67°C for polysaccharides obtained from dry okra. In the second part of the study, gum polysaccharides and whey protein isolates were complexed and films were produced from these complexes and film thickness measurement, thermal analysis, SEM analysis were performed. It was determined that the thickness of the film samples varied between 0.0495-0.0924 mm and the peak temperature values varied between 166.97-250.88°C by DSC measurements in the films.