壳聚糖-肉桂精油复合涂膜的制备及其对核桃贮藏品质的影响

目的研究壳聚糖(Chitosan,CS)浓度和肉桂精油(Cinnamon Essential Oil,CEO)添加量对复合膜性能(力学性能、透氧率、吸湿率、抗氧化性)的影响及最佳复合涂膜对核桃贮藏品质的作用效果。方法采用不同质量分数(1%、1.5%、2%)的CS与不同质量分数(0.1%、0.2%、0.3%、0.4%)的CEO制备复合涂膜,对涂膜的各项性能进行表征,采用最佳比例的复合涂膜处理核桃,测定核桃在贮藏期间的营养及氧化相关指标的变化。结果质量分数为1.5%的CS和质量分数为0.3%的CEO制备的复合膜具备良好的机械与抗氧化性能,经过涂膜处理后的核桃相较于对照组和纯CS处理组能够有效保持核桃在贮藏期间含水量、可溶性蛋白、脂肪的含量及较高的过氧化物酶(Peroxidase,POD)活性;同时抑制了核桃在贮藏期间酸价、丙二醛含量、多酚氧化酶(Polyphenol Oxidase,PPO)活性的增加。结论添加CEO能够有效提升壳聚糖涂膜的性能,最佳比例制备的CS-CEO复合涂膜可以较好地保持核桃在贮藏期间的营养与抗氧化品质。

Morphology-controllable synthesis and characterization of CeO_2 nanocrystals

CeO2 nanocrystals with different morphologies were synthesized by adjusting the pH value of the starting solution in water-in-oil microemulsion. The obtained samples were characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）. thermogravimetric analysis and different thermal analysis （TGA/DTA）, Brunauer-Emmet-Teller （BET） surface area measurement, ultraviolet-visible absorption （UV-vis） spectroscopy and photoluminescence （PL） spectroscopy. Results show that the mor- phologies of CeO2 were transformed from granular to spherical and to rod-like while the pH of the starting solution varied from 5 to 8 and to 11. All samples were indexed to the phase of Ce02 and Ce（OH）4, and the molar ratio of Ce02 to Ce（OH）4 was deduced to be about 0.25, The morphologies of CeO2 nanocrystals had but slight influence on their specific surface areas, UV-vis spectra and PL spectra, The band gap energies of different morphological samples were estimated by UV-vis spectroscopic method,