Irradiation technology has been shown to be a possible preservation technology used to prolong the shelf life and provide microbial decontamination of spices. In this study, the molecular mechanisms of the irradiation-induced accumulation of polyphenols in star anise were explored using metabolomics combined with ultra-high-performance liquid chromatography quadrupole-Orbitrap (UHPLC-Q-Orbitrap) high-resolution mass spectrometry. Fifty-six star anise samples from different areas processed with 2–10 kGy doses of irradiation were compared. The effect of post irradiation storage times ranging from 0 to 70 days was also evaluated. A total of 161 metabolites with variable importance on projection greater than 1 were characterized, and significant differences in flavonoid content in star anise were observed after irradiation. Absolute quantification was used for the quantification of distinctive compounds, and the limit of quantitation of the components was 1.90–6.53 μg/kg. The flavonoid content was stable on the 28th day of storage. The average content of flavonoids increased by 2–9 times due to the breaking of glycoside bonds in star anise by irradiation. C 15 H 11 O 7 + m/z 303.13045 and C 3 H 3 O 2 + m/z 71.01276 were defined as the characteristic fragments of flavonoids according to the mechanism of fragmentation. Checking the extraction ion chromatogram (EIC) characteristic fragments allows straightforward screening of untargeted flavonoids.
The main purpose of this work present a novel method for preparation of the polypropylene/polybutadiene/polyacrylamide (PP/PB/PAM) blends induced by pre-irradiation, the grafting reaction was conducted and completed before melting of the PP, and the formed grafted polymers served as the compatibilizer to enhance uniform dispersion in the melting stage subsequently. The EPR analysis manifests that there was peroxide on the PP powders after irradiation, which decomposed and induced grafting reaction when elevating temperature over 80 °C. The DSC and POM also demonstrated that the crystallization enhancement resulted from the heterogeneous nucleation attributed to both the grafted chains and their interactions. The hydrogen bonding interactions also assisted to construct the heterogeneous network structure in the melts appearing the nonlinear rheological behavior, and exhibited improved melt properties such as strain hardening and shear thinning like that of LCBPP's. Moreover, FTIR analysis confirms that H-bond interactions existed in the melts, their intensity and strength depend on both the PAM content and temperature. Having enhanced the melt strength and elasticity for the network structure in the melt, the PP/PB/PAM blends present well foaming performance especially in the sc-CO 2 with water process. The foams are obviously improved in the morphology and uniformity, and with much thinner cell walls, which originates from strengthening cell nucleation and plasticization after incorporation of the PAM. It is possible to tailor the linear polypropylene in a simple and practical way, which might broaden the field of possible applications and make light-weight PP a more competitive comparing to conventional used LCBPPs.
危险品化学品经营许可证（带存储）