Polymerization and product characteristics of polyphenols of Pinus sylvestris var. mongolica barks and protein.

Polymerization of polyphenols and protein is affected by multiple factors. This study was designed to clarify the optimal polymerization conditions of gelatin and polyphenols from Pinus sylvestris var. mongolica, with soy protein isolate (SPI) as protein substrate. The characteristics of product were analyzed with infrared spectrophotometry and differential scanning calorimetry (DSC), and our goal was to improve the polymerization rate. The results showed that: for polyphenols-gelatin polymerization, the optimal conditions were the mass ratio of polyphenols to gelatin 2∶1, reaction temperature 40 ℃, 30-min duration and pH 7.0. Under these conditions, 70.35% of polyphenols were polymerized. For polyphenols-SPI polymerization, the optimal conditions were the mass ratio of SPI to polyphenols 4∶1, reaction temperature 30 ℃, reaction time 20 min and pH 5.0; in this case, 47.21% of polyphenols were polymerized. The polymerization rate of polyphenols-gelatin was significantly higher than that of polyphenols-SPI (P0.05). IR spectroscopic results showed that polyphenols and proteins were cross-linked, resulting in the OH stretching vibration and intensive absorptions were detected at the 3 600-3 200 cm-1. OH, CH, NH, SH and other groups had obvious changes after polymerization. The results of DSC showed that heat denaturation temperatures were raised after polymerization.