Effects of tea polyphenol palmitate on the crystallization of rice bran oil

The development and application of compound formulation of natural antioxidants in Idesia polycarpa maxim. Oil

Idesia polycarpa Maxim. is valued for its high oil yield, which fruit has high oil content and good health effects. However, the large amount of unsaturated fatty acids in the oil is easily oxidized, and its storage intolerance has seriously restricted its marketing. In order to slow down the oxidation rate of Idesia polycarpa Maxim. oil, this study found that the most effective single antioxidant was rosemary extract through the screening of seven different natural antioxidants. The experiments were designed using the response surface method to compound three individual natural antioxidants with good anti-oxidative effects, namely rosemary extract, tea polyphenol palmitate, and ascorbic acid palmitate. A comprehensive model was established to determine the optimal anti-oxidative compound formulation, which was found to be 0.45 g/kg of rosemary extract +0.21 g/kg of tea polyphenol palmitate. The effectiveness of the best compounded natural antioxidants under simulated frying temperature (160 °C) was then examined. The results showed that the antioxidant capacity of the compound formulation was significantly increased, and the generation of secondary oxidation products was inhibited and the loss of unsaturated fatty acids was reduced. Therefore, the compound antioxidant-added Idesia polycarpa Maxim. oil not only showed good storage resistance, but also improved the safety of use under high temperature environment. The results of this study significantly improved the oxidative stability of Idesia polycarpa Maxim. oil, provided a theoretical basis for replacing synthetic antioxidants, promoted the industrial development of Idesia polycarpa Maxim. oil and expanded other applications.

Preparation and structural characterization of epoxidized soybean oils-based pressure sensitive adhesive grafted with tea polyphenol palmitate

Vegetable oils-based pressure sensitive adhesives (PSAs) are green and sustainable but face unsatisfactory adhesion strengths and are prone to aging during storage and application due to the existence of residual double bonds and massive ester bonds. Nine common antioxidants (tea polyphenol palmitate (TPP), caffeic acid, ferulic acid, gallic acid, butylated hydroxytoluene, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, and tea polyphenols) were grafted into epoxidized soybean oils-PSA (ESO-PSA) system to enhance antiaging properties and adhesion strengths. Results showed ESO-PSAs grafted with caffeic acid, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, tea polyphenols, or TPP didn't occur failure with TPP having best performance. The optimal conditions were ESO reacted with 0.9 % TPP, 70 % rosin ester, and 7.0 % phosphoric acid at 50 °C for 5 min, under which peel strength and loop tack increased to 2.460 N/cm and 1.66 N, respectively, but peel strength residue reduced to 138.09 %, compared with control (0.407 N/cm, 0.43 N, and 1669.99 %). Differential scanning calorimetry and thermogravimetric results showed TPP grafting increased the glass transition temperature of ESO-PSA slightly but improved its thermal stability significantly. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance results showed TPP, phosphoric acid, and rosin ester all partially participated in the covalently crosslinking polymerization of ESO-PSAs and the rest existed in the network structures in the free form.