Characterization of tertiary conjugate of gelatin-flaxseed (Linum usitatissimum) mucilage- oxidized tannic acid

In this study, a tertiary conjugate of flaxseed mucilage (FM)-gelatin–oxidized tannic acid (OTA) at two acidic and alkali pHs was fabricated. The total amount of biopolymers and added OTA was 2% (w/w solution) and 5 % (of total biopolymers), respectively. Fourier transforms infrared spectroscopy and solid state UV-visible spectroscopy were applied to confirm the complex formation and volume, solubility and phenolic content of the complexes were determined. Then, the effect of OTA concentration (0.5, 2.5, 5 and 10%) and reaction temperature (30, 40 and 50 °C) of gelatin with OTA were also evaluated through scanning electron microscopy analysis, yield complex and colorimetry. It was found that the addition of OTA to gelatin solution at alkali pH created strong bonds and a stable complex. The water solubility of acid complex (6.1%) was higher than that of alkali sample (3.6%). The optimal condition, regarding to high phenolic content and low solubility, was 5% OTA and the reaction temperature of 30 °C. This complex, may be suitable to apply for various applications such as protection of sensitive food ingredients from oxidative stresses and controlled release of bioactive components in delivery systems in food industry.